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Other ADA Gear => ADA Cabinet Simulaters => Topic started by: GuitarBuilder on November 09, 2014, 12:37:15 PM

Title: Favorite vintage ADA cabinet simulator
Post by: GuitarBuilder on November 09, 2014, 12:37:15 PM
Tell us why!
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on November 10, 2014, 02:04:29 AM
The only ones I've used are the MP2 cab sims, always been very happy with them, even used them for MP1 by running the MP1 outs into the MP2 loop returns, also sounded good.  More recently MikeB put a GCS-3 in his MP1 loop, that also sounds great through my studio monitors.
Mmm why? For the MP2 cab sims (which I've use allot for recording and rehearsing at home), they just sound like playing through the cabs but heaps more convenient and I don't upset the neighbors LOL. So in a way I find them transparent (if that makes sense).
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on November 10, 2014, 03:15:07 PM
The ampulator,why,well because it's special,you have alot of tonal options.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: RobbHell on November 24, 2014, 01:58:51 PM
The Ampulator is a Gem.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on November 25, 2014, 01:03:42 PM
A Gem?
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 27, 2014, 07:35:47 AM
I don't know how old this thread is because the board is not showing me the date, so forgive me if this is severely necro...

I like the MicroCabs because they can be modded to be more cab-like.  On their own, none of the ADA cab emulators that I know of (I don't know about the new GCS's) are really that accurate to any actual cab responses I've seen.  You could make the argument that the Ampulator has the closest and most sophisticated response (though it's very similar to the MicroCabs), but its notch filters are still a bit too extreme (as are the MicroCabs).

In practice, it doesn't matter too much though... because all of them still sound good and your ears really aren't that sensitive to the areas where they're 'weak' anyway.

But some simple mods can make the MicroCabs more cab-like.  Another simple low-pass filter on the output increases its high-end rolloff to much more like an actual cab.  And a simple resistor in series with the wire that goes to the cab selection buttons (one resistor for each channel) can adjust the frequency notches to more like a real cab.

There are lots more other things you can do to make the MicroCabs almost identical to a real cab frequency response (at least close enough that your ears couldn't detect the difference) but some of them get more involved and provide additional control 'options' rather than improve the ones that are already there.  Just the simple additions mentioned above put the MicroCab responses closer than practically any of the analog cab sims available.

Here's a modded MicroCab with a slew of 'additions'...

(http://i207.photobucket.com/albums/bb16/Brynner737/ModdedMicroCabfront.jpg~original)

That one has a switch for guitar or open-back (or bass) cab, a knob to adjust the cab resonance point from 125Hz to 240Hz (like a 4x12 to open 2x12), switches to tweak the mic types (bright, flat, mild to mimic the presence boosts some mics have), a mid-shift button to mimic Marshall style vs. American or German cabs, depth knobs that mimic the distance the mic is from the cab or the effect of multiple mics, and speaker baffle switches to mimic the effect of floating vs fixed baffles.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: El Chiguete on November 27, 2014, 09:59:13 AM
Rob get working on this!!!
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on November 27, 2014, 01:07:57 PM
That sounds interesting.Can you give some more details?
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 27, 2014, 02:56:42 PM
Sure.  I took the frequency responses of the MicroCabs and compared them to dozens of actual cab frequency responses that I either took myself or collected from a host of sources (other people's cabs, the FFTs of cab impulses, Axe FX models, etc).  Then I went about mimicking the responses of the cabs I wanted to emulate by tweaking the filters in the MicroCab and also adjusting some of its behaviours to be more accurate to the real things.  The "extra" features, like the resonance adjust, baffle type, depth, etc, were put in to mimic cabs that the existing circuit couldn't do without affecting some of it's other cab settings... so adjustment ranges were needed and pots and switches added for that.

I also added another circuit board in the MicroCab that adds more frequency notches to the existing response.  In stock form, the MicroCab has four major notches in the 4x12 settings.  A real cab has many notches - four major notches are sufficient, but there are also other, smaller, notches that characterise the response.  So I added 3 extra notch filters on an extra circuit board to match the cabs I was emulating.

But, the first thing that jumps out about the MicroCab is that its frequency notches (at points determined by the circuit) are too extreme.  The Ampulator is the same; the MP-2 cab emulation is different.  In practice, that doesn't matter a huge amount because the notches are very narrow at their peaks and only affect a narrow range of frequencies.  But it's an easy "fix" (add a resistor), so why not do it?  The next thing is that the MicroCab only has a 2nd order low-pass filter on the high-end roll-off.  Cabs roll-off more aggressively than that.  Some emulators have 5th order roll-offs but, from the real cab responses I have, that's too aggressive.  Most cabs roll-off more like a 3rd or 4th-order LPF, and that's easy to achieve in the MicroCab by simply adding one cap in the right place (and forming a 1st-order LPF in series with the existing filter = 3rd-order).

I wanted to better emulate open-backed cabs (or large and ported cabs) so I could use it with bass and get a more authentic Fender response.  So I added the cab type switch, which lets more bass through and attenuates the big resonance point that closed 4x12's have.  2x12's also resonate at higher frequencies than 4x12's (or, more accurately, they don't have a strong resonance point below ~240Hz), so I put in the pot to dial the resonance from 125 Hz (like a Marshall 1960B or big slant cab) to 240 Hz (like a typical 2x12).

The Mic switches are to account for the presence peak that some mics have (like the Shure SM-57), but others don't (like many condensers), and some are in the middle (like the original Sennheiser MD421).

Most closed-back cabs will have a major frequency notch at 500-625 Hz.  The mid-shift button accounts for that by shifting the major notch in that region around by ~125 Hz.  For instance, some Engl and Peavey cabs seem to notch lower, but Marshall and Mesa cabs usually mid-notch in the 600-620Hz range.

A single mic, up close to a 4x12 cab, will produce many deep frequency notches as the proximity of the speakers to the mic cause phase cancellations.  But as the mic is moved away from the cab the response will smooth out.  The summed response of multiple mics will also smooth out the response.  So the "Depth" controls dial the depth of the frequency notches up and down to mimic mic distance and/or multiple mics.

Floating baffle cabs don't have a pronounced notch in the mid-frequency range.  This is a large part of the reason why vintage cabs tend to be middier and honkier than modern cabs.  Plywood baffle boards don't have as strong a notch there as MDF boards, either.  So the "SPKR BAFFLE" switches control the depth of that notch to either be characteristic of a modern 4x12, a vintage style floating baffle board, or a plywood board 2x12/4x10.

I know that might all sound vague and arbitrary when laid out like that, so I'll try to post some example frequency responses.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 27, 2014, 03:52:39 PM
This is the response of a Peavey JSX 4x12 cab with four UK Celestion G12M-25 Greenbacks with an SM57 on-axis in the centre of the cap...

(http://i207.photobucket.com/albums/bb16/Brynner737/CelestionG12M6402inPeavey4x12-SM57on-axiscentrecap_resize.jpg)

This is the response of a stock MicroCab...

(http://i207.photobucket.com/albums/bb16/Brynner737/ADAMicroCabVint4x12-stock.png)

This is the response of a modded MicroCab with the extra board added to produce the "mini notches".  (All the "extra features" controls are set to neutral so they aren't affecting the response)...

(http://i207.photobucket.com/albums/bb16/Brynner737/ChA4x12Vintage_resize.jpg)
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Systematic Chaos on November 27, 2014, 10:33:28 PM
...some totally awesome stuff...

WOW, that´s an interesting read and def something worth following! Could all that be integrated in one of MJMPs Monstercabs as well??
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on November 28, 2014, 03:16:33 AM
Hey Casey, great read  :thumb-up: There's a temp fix for the time of post time/date issue (link in the news feed which cycles on top of home page), you need to set a time zone/display preference in your profile, I put some instructions in a post which the news thingy has a link to (hey Dante, we need to fix this LOL).
@SC, I daresay MJMP could indeed incorporate/integrate into his Monstercabs (seems very plausible (do I here some PMs going on LOL)).
So with the SM57 proximity, do you add some bass for the close mic proximity effect ?
Another mic worth emulating is a Bayer M88 (in my day often used for kick drum as is designed as a male vocal mic with 80hz enhancement).
From memory, Seni 421's were reasonably flat, also a popular tom mic, but hi SPL capable so good cab mic
57/58 obviously 5khz boost (presence/cut)
EV RE20 flattest of them all
It's great your doing it for real in analogue not using DSP.
And thanks for sharing  :wave:
Cheers R
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 28, 2014, 07:08:21 AM
WOW, that´s an interesting read and def something worth following! Could all that be integrated in one of MJMPs Monstercabs as well??

I think you'd have trouble fitting the additional board to make the mini-notches because it sits in the spot where the load resistors would be placed.  But if you could find the room to squeeze it all in there, there's no reason it wouldn't work.

Here's a gut shot of the modded MicroCab as I was doing the mods.  You can see the extra board on the right (it isn't mounted as of that photo, just laid there as I tested it)...

(http://i207.photobucket.com/albums/bb16/Brynner737/ModdedMicroCabguts.jpg)

I didn't want to put in load resistors because I modded a Marshall Power Brake to more accurately mimic an actual speaker load.  So I didn't need the MicroCab to act as a load box.  I took frequency traces of some amps' outputs at their transformers and compared that to their behaviour when connected to various loads (actual speaker cabinet and a few load boxes and attenuators).  Then I tweaked the Power Brake to get the amps' signal at the amp's output transformer reacting the same.  Speakers don't provide a flat impedance, their impedance changes with frequency and that varying impedance is reflected back to the power amp and effects how amp reacts and distorts.  Some people actually prefer a flat resistive load rather than a real speaker (as evidenced by all the Palmer and 'big resistor' users like Satriani and Eddie Van Halen ;)), but I was going for maximum speaker load 'authenticity'.

Here's what a typical guitar speaker impedance curve actually looks like...

(http://www.gregcutshaw.com/Electronics/Speaker%20Impedance.jpg)

Here's the output of my Marshall JVM (at the transformer) through a 4x12 cab (two Celestion G12T-75s and two G12-65s in the cabinet)...

(http://jvmforum.com/phpBB3/download/file.php?id=2279)

Here's the output of my Marshall JVM (at the transformer) through a resistive attenuator...

(http://jvmforum.com/phpBB3/download/file.php?id=2241)

As you can see, the amp is reacting very differently through a resistive load... though, like I said, some people prefer that.  (And there are reasons for that, like no resonance at ~130 Hz and the high frequencies tend to sound 'smoother'.)

And here is the output of my Marshall JVM (at the transformer) through a Power Brake modded to mimic the load of my cabinet...

(http://jvmforum.com/phpBB3/download/file.php?id=2280)

As you can see, that's just about dead-on.

So with the SM57 proximity, do you add some bass for the close mic proximity effect ?

The stock MicroCab already does that as much as you'd ever need it to with the "Thump" control. :)  I didn't need to touch that.

Quote
Another mic worth emulating is a Bayer M88 (in my day often used for kick drum as is designed as a male vocal mic with 80hz enhancement).
From memory, Seni 421's were reasonably flat, also a popular tom mic, but hi SPL capable so good cab mic
57/58 obviously 5khz boost (presence/cut)
EV RE20 flattest of them all
It's great your doing it for real in analogue not using DSP.

As someone with an engineering background, and having done my share of DSP courses, I understand that I shouldn't feel this way... but I don't feel entirely 'comfortable' with the idea of using DSP on guitar.  I have some very nice DSP-based effects (like reverbs, delays, modulation effects, and even overdrives/distortions) but given the choice, I still 'like' the idea of analogue more... except for maybe reverb, delay and chorus.  I think the less DSP you can use before the signal hits the board, the better.

I realize the SM57 is pretty much the industry standard for miking electric guitar cabs, but I wanted to give the uCab the option of mimicking different mics purely for the convenience of it.  Of course, you could accomplish the same thing with an EQ, but there was still a little space on the front so I thought, "Why not build it in?"  I just looked at the frequency responses of some popular guitar mics and tweaked the high-end to match.

I should also mention that I voiced the two channels of the uCab differently.  One is based around a particular set of cabs (a Marshall 4x12 with G12M Greenbacks on the Vintage 4x12 setting) and the other mimics different cabs (a Marshall 4x12 with G12-65s on the Vintage 4x12 setting).  Because there are enough settings to cover lots of bases there's also a Mesa-Boogie 4x12 with V30s in there, some Fenders, some bass cabs, etc.  I used probably 50 real cab responses to match them up as best I could.  Even the settings that had to be partially compromised for the sake of other settings with a few dB here and there on an EQ and you can nail them.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 28, 2014, 07:30:57 AM
I promised to post some samples in another thread, so here they are.

The first one is the raw signal through the uCab bypassed...
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 28, 2014, 07:33:09 AM
This is through the modded uCap, but before the extra board to produce the mini-notches was added.  The reverb is from a Lexicon MX300 set for a mild 'room' reverb.

Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 28, 2014, 07:35:14 AM
This clip is through the completed uCab with the rest of the instruments added.  Again, reverb from a Lexicon MX300.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 28, 2014, 07:37:37 AM
Same song as above but a different section... no lead guitar yet.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on November 28, 2014, 12:38:42 PM
Sounds really good  :thumb-up: i really like the sound although i'm not a big believer in cab sims,your µcabs are sounding more "real".

I also saw you added a few jacks on the rear,what are these for?
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 28, 2014, 02:13:19 PM
I also saw you added a few jacks on the rear,what are these for?

Those are separate speaker level inputs.  I converted the input to the µCab II circuit, but that makes a lot of the range of the "Level" knob unusable.  So those jacks just knock the speaker level down to preamp level before it's fed to the circuit.

Obviously, a device like this is not going to be able to mimic speaker breakup (though much of the high frequency response of guitar speakers is due to 'distortion' anyway and is captured in the frequency response).  But I do find that putting a soft-knee compressor between the amp output and µCab input does a nice job of mimicking speaker compression before it hits the cab emulation... not needed for modern high-power ceramic magnet speakers, but it does lend some extra authenticity to the Greenback setting... or Alnico, especially.  I think that's a piece of the puzzle that people often overlook... or just don't think there's a way to address.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on November 29, 2014, 01:44:21 AM
Cool, nice playing BTW and definitely sound like well miked cabs.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Systematic Chaos on November 29, 2014, 04:10:19 AM
Sounds boss!!   :metal:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 29, 2014, 05:45:38 AM
Thanks, I'm not completely pleased with that recording yet but, other than some preliminary mixing, nothing has been done to it... it's still in progress.

I didn't use my favorite cab setting on the µCab for that recording.  There was a wire loose in Channel A (my Greenback channel) that would cut in and out intermittently, so I went with Channel B (Celestion G12-65).  There's not a huge difference between the two, but the G12-65 emulation is, as would be expected, a little more mid-scooped around 1kHz than the Greenback emulation.  I think it makes the heavy guitars sound more 'metal' and aggressive than I was going for, but it might work out in the end.   I also pushed them a little too far forward in the mix, but I'll adjust that before it's finished.

I'm thinking about running the µCab into a mic pre before it's sent to the board.  The µCab shapes the frequency response like an actual cab but a colourful mic pre can be an important part of the sound of an actual miked cab on its own.  That's one part that's missing when you just plug the µCab straight in.  So I'm thinking of a chain, more like this...

power amp --> load/direct box --> soft-knee compressor --> µCab --> mic pre --> reverb --> board/interface

I think that should put the icing on the cake.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on November 29, 2014, 09:48:56 PM
Good idea, I've got a TLA Ivory 4 chan valve preamp which I was going to try between the MP2 sim outs and the desk. I've use it on direct bass, sounded lovely.
One change I'd make to your chain though is I'd mix the reverb in via the desk (2 aux/fx sends and return down 2 channels), that way (apart from easier control), you can use a digital reverb without distroying the analogue signal. Also I'd use 4 tracks, L/R guitar, L/R reverb then you can run the reverb full wet and have control of it later in the mix.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 30, 2014, 03:11:44 AM
Very good points.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Systematic Chaos on November 30, 2014, 04:14:26 AM
.....
I think that should put the icing on the cake.
(http://fc04.deviantart.net/fs71/i/2013/188/2/a/the_guitar_must_sound_like_this_______by_s1impikenz-d6cenny.png)
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on November 30, 2014, 05:33:39 AM
Absolutely SC + 1  :thumb-up:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Dante on November 30, 2014, 09:05:58 AM
Casey - Thanks so much for all your insight!! This is groundbreaking stuff right here & it makes the Depot a valuable resource - so thanks again :bow:

Quote
There's a temp fix for the time of post time/date issue (link in the news feed which cycles on top of home page), you need to set a time zone/display preference in your profile, I put some instructions in a post which the news thingy has a link to (hey Dante, we need to fix this LOL).
Yes Richard, I know... :facepalm:

I have this fear of breaking the entire forum trying to fix that stupid date problem  :nono:  I'm sure there's somebody smarter than me about such things & the answer will present itself to us in time   :thumb-up:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on November 30, 2014, 12:26:19 PM
I'll post more "tech" details if anyone wants them... but I didn't write them down on any schematic (electronics record keeping is a recurring fault of mine).

That chocolate cake picture is making me crazy.  I just ended a diet today and I'm trying to control myself. :)


Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on December 01, 2014, 03:37:18 AM
Hey Casey, go the feast/ famine for 2 day diet (I just do it naturally, it's all a balance), my ex says she's lost weight and a couple of cms so working for her and some say backed by the science. I'm not a sweet tooth but that cake looks good  :thumb-up:

@Dante, I know what you mean, hey at least we have a work around until you and I work it out, we'll get to it, not quite like the mail, it comes and goes (mostly goes for me LOL, but MJMP gets the emails religiously, I thinks he's gods fav LOL, and deservingly so  :bow: ).
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on December 01, 2014, 01:27:54 PM
I'll post more "tech" details if anyone wants them... but I didn't write them down on any schematic (electronics record keeping is a recurring fault of mine).

That chocolate cake picture is making me crazy.  I just ended a diet today and I'm trying to control myself. :)

Well i'm interested in more tech details,maybe i could mod one of my µcabs that way.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 01, 2014, 06:27:55 PM
I'm up against a few deadlines at work before the Christmas break, but I'll try to label the Spice models of the modded µCabs so they'll make sense to anyone who has the original schematic and knows the circuit.  You have to cut a few traces and add the extra board for some of the mods, but you can also mix-and-match what parts you want and what you don't.

I don't know what it is with the chocolate cake... maybe I have a chocolate deficiency or something.  I'm not usually a cake person, but that thing is messing with me. ;D



Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on December 02, 2014, 10:57:38 AM
Ok no hurry,take your time.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rabidgerry on December 03, 2014, 02:23:51 PM
Casey I 've found a microcab going for cheap, it is however untested and has no power supply.  I'm trying to convince the guy to sell it to me.  Would you take the risk?

Also what is the difference between the microcab 1 and 2?
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 03, 2014, 03:17:35 PM
I think it depends on your comfort level with electronics.  Personally, I'd go for it because I know enough about the µCab to fix just about anything that could be wrong with it, but you have to make a judgement call based on your own situation.

Having said that, I got my first µCab for $30 because one of the channels didn't work.  It turned out to be a loose wire that I found and fixed in a matter of minutes.  That µCab was in very good shape as well... maybe because it didn't get much use because one of the channels didn't work. ;)




Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on December 04, 2014, 02:53:37 PM
Gusy I 've found a microcab going for cheap, it is however untested and has no power supply.  I'm trying to convince the guy to sell it to me.  Would you take the risk?

Also what is the difference between the microcab 1 and 2?

The PSU is a 16Vac adapter,which is a bit harder to find

The diff between the I and the II is the II can handle higher input levels and has a build in PSU.Soundwise they are the same.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 09, 2014, 03:16:36 PM
I didn't use my favorite cab setting on the µCab for that recording.  There was a wire loose in Channel A (my Greenback channel) that would cut in and out intermittently, so I went with Channel B (Celestion G12-65).

I finally fixed that wire.  It was the A Channel signal wire connecting the main board to the input/output board.  The solder joint was loose.  I re-soldered all the board-to-board wires while I was at it.  Solid as a church now. :whoohoo!:

Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on December 10, 2014, 04:14:12 AM
Hey go Casey, happy days  :thumb-up:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 10, 2014, 08:04:39 AM
Yeah, it's nice to have it in tip-top shape again.  It wasn't too hard to track down, but I hate troubleshooting circuits with a passion.  I must have broke the solder joint when I squeezed the board in when putting it together after the last mods, because it was fine when I tested it on the bench... one little solder joint and you have to take the whole thing apart again.

Actually, the µCabs aren't that easy to work on because you have to take the whole thing apart to work on the boards.  The components are packed fairly tightly, and they have delicate traces that are easy to lift too, if your soldering iron is too high wattage.  Not saying that I haven't seen worse but, in comparison, the MP-1 is much more convenient to mod.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on December 10, 2014, 01:26:27 PM
+1  :thumb-up:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rabidgerry on December 17, 2014, 07:56:29 AM
I think it depends on your comfort level with electronics.  Personally, I'd go for it because I know enough about the µCab to fix just about anything that could be wrong with it, but you have to make a judgement call based on your own situation.

Having said that, I got my first µCab for $30 because one of the channels didn't work.  It turned out to be a loose wire that I found and fixed in a matter of minutes.  That µCab was in very good shape as well... maybe because it didn't get much use because one of the channels didn't work. ;)

I'm not bad with electronics, but I have no idea what half the stuff does.  I just know how to solder and take stuff apart.  I can follow guides with pictures pretty well  ;)

I never got that microcab by the way.  I'm looking at another one now, lets hope I win the auction!!!  Micro cab II
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Kim on December 19, 2015, 12:47:29 PM
Sorry for hitting an old thead; I haven't fully navigated around this forum yet, so I still have much to discover...

Is this mod for the Microcab still a thing?  I think I'd be very interested in modding mine. 

Moderators:  maybe this thread needs to be Split? 
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on December 19, 2015, 01:45:40 PM
Well it's actually dead,i haven't heard anything from these mods in quite some time.Too bad actually,looked promising
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 21, 2016, 04:14:26 PM
Sorry it's dead... I'm still around in the background.  In fact, I'm going to be opening up the uCab and making a slight adjustment to the 'thump' control in the next day or two... nothing serious, but some of the mods I did a long time ago decreased the effect of 'thump' so I'm going to get it back to stock levels.  It isn't really necessary, because I think too much 'thump' doesn't sound good anyway, but in the the interest of 'authenticity' I'm going to put the full range back in.

Anyway, if any members here are still interested and want to ask me anything about what I've done, go right ahead.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on December 22, 2016, 02:58:46 AM
Haven't been through the whole thread yet, so maybe already covered..

The sound clips I heard back in the days with Thump active to me sounded overcooked.
IMHO, having this extra whoumps in the abdominal region was somewhat hype'ish back in the days, but really doesn't do too much good.

However, it of course may have some use for some for some types of music with some gear that finalizes it in a useful way, so I'd suggest maybe doing the mod to make it easily adjustable, or maybe better, using a two-step switch, intended for 'just some effect' and 'full punch' ;)
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 22, 2016, 08:44:15 AM
It is too much.  The idea was to emulate the proximity effect of an SM57, which it does it spades, but also to the point that it isn't usable unless it's turned down.  I haven't been able to mic a cab with an SM57 and get near the amount of 'thump' that the uCab can get.

When I modded it I reduced the range of the "thump" control to about half of what it originally was.  So now it won't get too 'thumpy' but I can't help but think the range of the thump control should be more dramatic.

I'll play with it this afternoon and decide what I'm going to do.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on December 22, 2016, 11:02:39 AM
Ah yeah, I see you points..  just to clarify, I do not own a microcab.
I follow this discussion because I miss a touch of the SM57 proximity in my MP-2 emulations, without which they tend to be a Bit on the lifeless side of things, so just might go about adding some limited version of the Thumpf into those filters..
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 22, 2016, 01:27:51 PM
I ended up bringing back the 'thump' but not so much that it gets ridiculous... about 1 dB down from stock at the highest setting.  After a few hours tweaking it, I'd say it's right at the upper end of what an SM57 could possibly get in terms of thump when right up against the grille cloth.  I don't see the point in any more 'thump' than that because it simply isn't realistic.

Yet, at the same time, it is a very useful feature.  It gives a realism to the cab emulation that many emulators don't have.  With the 'thump' down too far it does seem 'lifeless' but, more importantly, also a little 'fake'.  The proximity effect emulated by the 'thump' control does go a long way to making your ear think it's hearing a mic'ed cab.

But it's a delicate balance... too much and it muddies the sound (yet muddy at least in a realistic way :))).

It's a relatively simple thing... just a few extra dB fairly narrowly focused around 125 Hz and it starts to sound 'cab-y'.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on December 23, 2016, 02:25:50 AM
Isn't 125 Hz a Bit on the low side?
It was my impression that the thumpf should be related to the resonance of the an adult chest cavity, which to my understanding is round about 180 Hz..

As an example, up'ing the 170 Hz EQ point in the MP-2 does buy me a bit more realism, whereas 100 Hz makes it sound swampy, and 280 Hz adds more of a body-fullness.

Also, can we really detect the difference of the filter set at standard vs the subtle change of just ~1 dB?
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 23, 2016, 06:13:22 AM
Good point about chest cavity resonance.  The SM57 tends to peak higher - at around 200Hz - as well.  But the 'thump' on the uCab is centred at 125Hz because that's approximately the resonant point of a Marshall 4x12 with almost any 12" Celestions.  You can see it on the frequency response of just about any such cab.  Older 4x12's with earlier Celestions tended to resonate a bit higher, as do 2x12's and 1x12's.

You can see it quite dramatically on the graph below.  These are frequency sweeps I took myself of two 4x12's.  The black line is a Marshall 1960A with Celestion G12-65 and G12T-75 speakers in an X pattern - SM57 on-axis up to the grille cloth at the centre of the dust cap of a G12T-75; the red line is a Peavey JSX 4x12 with four UK Celestion G12M-25's, under the same mic'ing conditions.

(https://s28.postimg.org/6wonkgdjh/Celestion_G12_T_75_vs_G12_M_25.jpg)

As you can see, the resonant peak at roughly 125Hz is quite pronounced on the G12-65/G12T-75 cab and is also present on the G12M-25 cab, but not quite as 'thumpy' and shifted to a little higher frequency (though not by much and really more like an absence of the stronger peak at ~125Hz).  I think that's exactly what would be expected of G12M's compared to the higher powered and 'punchier' G12T-75.

But that peak also tends to reduce and smooth out as you move the mic back and when you mix multiple mics.  So if you want an accurate cab emulation you need to be able to adjust that resonant peak accordingly.

The 'Room EQ' on the MP-2 is something similar to a cab resonance control.  It sweeps from about 95Hz to 160Hz, but it is more broadly focused and less peaky than a single close-mic'ed 4x12 would be... it's more what you would see with more distant mic'ing and mutliple mics.  Lots of analog cab emulators do it that way, with no distinct cab resonant peak to speak of or a very broad one, including most direct boxes and all the Tech 21's SansAmps.  It's also a simpler circuit to emulate the broader, smoother peak.

You'd be surprised the difference a dB can make at that 125Hz peak.  For instance, the stock uCab's 'thump' control has a range of about 3.88 dB.  At '0' it sounds thin and weak and at '10' it sounds overbearing and muddy.  I cut it down to about a 1.5 dB range when I did some mods, but that didn't seem noticeable enough.  So now I have it at about 2.65 dB and it seems perfect - enough to get a good close-mic'ed type 'thump' but not so much that it's unrealistic.  I also have a resonance control, so I can shift the resonant point around from ~125 to 240Hz... and an 'open/bass' switch, so it can emulate an open or ported cab.  That covers pretty much all the basses.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on December 23, 2016, 06:55:31 AM
Lovely info!
Interestingly, when setting up my MP-2 EQ'ing for a more traditional rock/metal sound (but not for modern djenty stuff), I tend to end up with the EQ points/levels somewhat akin to the graphics above.

Examining such graphics somewhat vindicates me in my idea that what I feel is mostly missing in a filter approach, is indeed how the upper frequency part, jagging up'n'down quite finely, merely needs some sort of comb filtering.
Oh, and the fact that the more simple filters do not have the slope steepness on either side flank to accurately mimic the roll-off of actual speakers, thus still producing too much higher frequency fizz. The low side flank can be simulated by combining the Low and 100 Hz EQ's.

We're getting there. Small moves, Ellie, small moves..
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 24, 2016, 05:09:13 AM
What the uCabs and Ampulator have in common is that they include those comb filter notches to a much greater extent than most other analog cab sims.  That gives them a more realistic single, close-mic'ed cab flavour. 

Roughly 80 Hz to 1.2 kHz seems to be the most crucial range in terms of those frequency notches and peaks.  The higher ranges don't seem to matter nearly as much... as long as the high roll-off is right (which rolls off like a 2nd or 3rd order filter... the stock uCab is only 1st order).

If you think about it, that would be sort of obvious though, because the frequency range of a standard-tuned electric guitar spans 82 Hz (low E) to 1.175 kHz (high D - 22nd fret on the high-E string).  The lower ranges, say 82 Hz to 500 Hz, is where the bulk of the content is going to be.  That's where the rhythm work and chording is, and the significant harmonics of those notes are all in range of the speakers/cab.  Any frequency content the guitar can produce above 1.175 kHz are harmonics of decreasing strength... and if you're playing that high on the neck it is inevitably 'simple' single notes, not complex chords at the 22nd fret. :D  Not saying that the notches up there completely don't matter, but they are harder to notice and most analog cab emulators don't seem to bother with them at all.

Also, the further you move the mic away from the cab, the more those high-frequency notches smooth out.  Add in multiple mics and the response can get smoother again.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on December 24, 2016, 11:37:38 AM
Well.. I can see your points, but it seems to me you're analysing the electric guitar fully clean.
Once distortions are applied, the rate of fall-off of the harmonics changes quite dramatically, as distortion will add quite a lot of additional higher harmonics.
Hence my suggestions on using comb filtering in the upper mids to [guitar] treble region.
BTW, I'm well aware of the comb filter in the ucab, just never calculated it's frequency range.

Now, it is entirely possible that I'm in error on this, and if so, very simply because I might confuse my above statements with the fact that neither the ucab nor the MP-2 rolls off at the high end are any more than a 1st order function - like you stated.
As such, it's absolutely possible that I mostly just need a steeper slope on the high roll-off, check the results, and only then look into what else might be needed.

Another mechanism lending to your observations is that, when playing high up on the board, distorted trebles does sound less fizzy, which, even when the roll-off is a mere 1st order function, nevertheless does make the harmonics hit the slope much earlier than when playing further down.
As such, those higher notes automatically gets filtered off decently more smoothly, again supporting your comments.

Hmnn.. I'll go do the Om thing, poke the akashic in the 10th dimension, and ask my spiritual masters for guidance.. :bow:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 24, 2016, 04:43:44 PM
The point I was trying to make, and I think you said also, is that with high frequency notes the harmonics are simply too far apart and too high in frequency for the 1.2 ~ 5 kHz notches to impart much of an effect.

For instance, with a 1 kHz fundamental and even a severely distorted signal (say a pure square wave) the first significant harmonic will be at 3 kHz and the next at 5 kHz, which is past the roll-off of the low-pass filter.  So only the response of the cab (or emulation) at 1 kHz and 3 kHz will have an effect on the sound you hear.  Which is what you were saying.  At slightly lower frequencies the harmonics from ~ 1 kHz to 5 kHz will be in range, but they will also be spaced fairly widely apart and decrease in magnitude (of 1/n) with increasing order.

Lower frequencies, on the other hand, will have many more harmonics that will fall in range of the filters.  With a fundamental of 120 Hz, you could get harmonics at 240, 360, 480, 600, 720, 840, 960, 1.08k, 1.2k, etc.  So there is much more range for the notches to 'hit' the harmonics and impart their effect on the overall tone.  Plus, the lower frequencies are where you're going to be chording, and so playing several notes at a time which are themselves natural harmonics of each other (at least if you're in tune and playing the right notes :D).

It's just more unlikely that you'll 'hit' the high frequency notches with strong magnitude notes or harmonics, so they don't seem to have nearly as much an effect as the mid notches that can come into play much more significantly.

I modded my uCabs to have 2nd order high roll-offs.  I looked at dozens of cab responses and I just don't think 3rd order is really necessary... some cabs roll-off steeper, some more gradually, but most Marshall 4x12s are in the 2nd-3rd order range.  And it's much easier to filter a little more with EQ than it is to try to add sparkle back in when it's gone.

If you've got the fizzies I think the higher order filter is definitely in order... and it's an easy mod.

Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on December 25, 2016, 03:21:39 AM
We have reached consensus. I bow to thy observation skills.
But of course.. I missed observing the harmonics being spaced out further and further as we go up the range.

Good discussion ;)
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 27, 2016, 12:22:57 PM
Actually, I find the stock ADA cab emulations (uCabs and Ampulator at least... and the MP-2 as well from looking at the circuit) tend to be both too dark and also a bit fizzy.  I find extending the roll-off frequency a bit higher and increasing the filter to 2nd (maybe 3rd) order does the trick... gives you more brightness and clarity but also rolls of the higher fizzy frequencies more aggressively.

But I also think most people don't realise that an on-axis close-mic'ed cab with a distorted amp is really quite fizzy.  Most of the cab emulations I've looked at roll off the high-end sooner and more aggressively than any real cab I've mic'ed.  It seems they're trying to emulate the 'finished product' you get after EQ'ing, mixing and mastering - not really the raw, fizzy beast a close-mic'ed cab actually is.  An exception is the Tech 21 PSA.  That one seems to leave more of the high-end fizz in there.  Presumably with the understanding that the user will be studio savvy enough to realise that EQ is there to take care of that, if need be.

Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on December 30, 2016, 10:39:26 AM
Actually, I have to correct something I said earlier about the range of the uCab 'Thump' control.  I had my numbers mixed up because I'm taking sweeps right now and I'm getting a range of 6.93 dB for the stock uCab.  I've modded mine to have a range of 5.73 dB.  The range was 2.83 dB when I felt it didn't have enough.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: MarshallJMP on December 30, 2016, 12:28:41 PM
I must say this is a very interesting topic.  :thumb-up:
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Harley Hexxe on December 30, 2016, 12:40:22 PM
I've been following it, but it's getting in the realm of over-thinking it for my taste.

I'm getting good results from my MicroCabs, so I can't complain.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on December 31, 2016, 03:05:18 AM
I've always been happy with the MP2 cab sims, they work great into my studio setup.  They also do a great job on a MP1 (plug into the MP2 loop returns and use a zero'd patch).
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on January 02, 2017, 03:23:00 PM
In that case, this is what the MP-2 cab emulation is doing (green line is 4x12, blue is 2x12, Room EQ set at 12:00)...

(https://s30.postimg.org/aehhzhash/ADA_MP_2_cab_sim.jpg)

That's based on a spice model, but it's accurate.

It's a smoother curve than the uCabs and Ampulator, which are more comb filter-ish.
Title: Re: Favorite vintage ADA cabinet simulator
Post by: rnolan on January 02, 2017, 07:30:41 PM
Cool, thanks CB  :thumb-up: . I've found I prefer the 2 x 12 setting, the 4 x 12 sounds a bit boxy
Title: Re: Favorite vintage ADA cabinet simulator
Post by: Casey_Butt on January 03, 2017, 04:55:29 PM
Cool, thanks CB  :thumb-up: . I've found I prefer the 2 x 12 setting, the 4 x 12 sounds a bit boxy

It's probably that dip the 2x12 setting takes at 500 Hz (vs. 600 Hz for the 4x12 setting).  The dip there seems to 'open up' the mids and adds clarity... think of Fender clean vs Marshall.  Fenders typically notch the mids lower than most higher gain amps/cabs... it's part of the 'clear' sound.  Having said that, I have a solid-state Fender from the '80s that dips at around 1 kHz and it's probably the best clean sound I've ever heard (Blackfaces and other tube amps included)... just 'big' and detailed sounding.  Which brings to mind something else...

The MP-2 2x12 emulation keeps the response down at just past 1 kHz and peaks at just over 2 kHz.  That's a classic recipe for clarity.  In fact, Boss has been using that recipe (down at 1+ kHz and peaking at 2+ kHz) for the 'enhance' feature on their bass limiter/enhancers and various multi-effects pedals since the late 1980s.  The old Boss LM-2B Bass Limiter/Enhancer dipped at 1kHz and peaked at 2kHz for the 'enhance' control, as did the Boss BE-5B and the modern ME series digital guitar and bass multi-effects units.

Title: Re: Favorite vintage ADA cabinet simulator
Post by: van Sinn on January 04, 2017, 03:36:34 AM
Cool, thanks CB  :thumb-up: . I've found I prefer the 2 x 12 setting, the 4 x 12 sounds a bit boxy

It's probably that dip the 2x12 setting takes at 500 Hz (vs. 600 Hz for the 4x12 setting).  The dip there seems to 'open up' the mids and adds clarity... think of Fender clean vs Marshall.  Fenders typically notch the mids lower than most higher gain amps/cabs... it's part of the 'clear' sound...
The MP-2 2x12 emulation keeps the response down at just past 1 kHz and peaks at just over 2 kHz.  That's a classic recipe for clarity.

It's not only that 500 Hz dip, but also that the 4x12 is ~2 dB more up at 200 Hz and ~3 dB up at 300 Hz, which does bring about a decently more voluminous lower body.
While this 2-3 dB difference may not seem that much, still, when combined with the differences in the mid-scoop, it's no wonder that the 4x12 sounds decently darker - despite both emulation rolling of at the same 12 dB/octave and from the same frequency.

I must confess I had expected the high roll-off differences being more pronounced.
Good pspicing!  I must get back into such analysis at some point.

Oh BTW, it would be very interesting seeing a phase analysis; you know, how the phase changes over frequency can have significant impact on tone, even if amplitude levels don't change too much.
With this I'm thinking about how the filter circuit changes from 2x12 to 4x12 could produce different phasing  characteristics..