ADA Depot - A Forum To Support Users of ADA Amplification Gear

ADA Preamps => MP-2 => Topic started by: Dante on July 27, 2014, 02:51:07 PM

Title: Gain delay with Warm Hi Gain voicing
Post by: Dante on July 27, 2014, 02:51:07 PM
I know this was discussed on the old Depot, but I don't know if it was specifically about this voicing. When I switch to a specific patch (that is using the Warm Hi Gain voicing), there is about a 2 second delay before the patch is fully voiced. That is, the gain is lower for that initial 2 seconds, and it takes that long for the patch to 'warm up' to the actual sound, a very high gain.

It seems to be much worse now than before, and I've just been avoiding that voicing altogether. Any thoughts?
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on July 28, 2014, 04:52:27 AM
Hey Dente, it's a long shot but may ???? be related to another thread where he's coming from clean patch to higher gain but experiences significant vol drop, although unlike yours his (IIRC) dosn't come good and requires powers cycle to fix (and not sure if it then repeats..still working through it with him).  At MJMPs suggestion got him to try loop outs > amp to rule out the tail end of circuit, he still get the issue (would indicate that it's before the loop).  I'm thinking you "may???" have early stages of similar.  As I say long shot, but he's going to similar patches.
Is it always ? or after a while ? e.g. when you turn it on does it happen right away ? I don't recall this on the previous forum so can't add, MJMP may remember ?
Cheers R

Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on November 06, 2016, 12:08:46 PM
Thread resurection!

Dante, have you found a solution?

I have similar issues when I switch from "dynamic" high or vintage channels to any other hi gain or vintage channels. It seems ok to go from Ultra to Warm, but it feels like using the dynamic channel is "cooling down the tubes' or something.

I don't know about the clean channels... I don't play clean that often :).
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: vansinn on November 07, 2016, 12:23:46 AM
I used to have the same experience when changing to Voicing 10; however, the only preset currently using V10 no longer seems to have this setup delay. Inexplicable. Magic!

I do not have the answer, but, per intuition, believe it is either the Vactrols [that controls the tube's operating conditions] starting to take a looong time to go from one setting to another, or some capacitor(s) related to those setup circuitries, that are down in value.

And the debunker: To my knowledge, Vactrols aren't typically reported as going half-dead with age, so.. we're back to the guessing game - or better, elementary electronics measurements.. ;)
And I can't use my mini lab, as all is defunct due to selling my apartment.


EDIT: While Vactrols may not go SOA (slow of age), they're often referred to have slow reaction times, and some reports indicate this is often a matter of the surrounding circuitry not properly driving the Vactrol, so, could be I'm not off on thin ice after all..
Potentially interesting read: https://groupdiy.com/index.php?topic=43011.0

Methinks it's the surrounding electronics causing problems for [some of] the Vactrols.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Dante on November 07, 2016, 07:34:25 AM
Sorry, Rawk777, I don't have any breakthroughs to share. I have been using my MP-1 Classic primarily, the MP-2 is in a 2u rack with an FX unit for running straight into the board or a combo.

I think van Sinn may be onto sumting though....
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 07, 2016, 09:10:35 PM
Possibly unrelated  :dunno: but I thought I'd throw it in, have you set the patch change speed to "Fast" (default is set to "Normal") in the System Edit > Midi Function Menu?
This option came with later EPROM update and isn't mentioned in the manual I have.  MP2 program changes were quite slow (particularly compared to MP1) before this update.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: vansinn on November 08, 2016, 06:35:00 AM
Just to notice: I use fast preset change, and observe no audible artifacts during switching, compared to standard switching.
Will do a quick comparison and report on whether this affects the very slow preset change in voicing 10 that I used to have.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on November 11, 2016, 08:12:13 PM
I did not notice any difference between fast and normal for the "gain delay" issue, but since I was set to normal, my mp2 is now faster to change patches :) !!!

p.s. To be honest, the speed difference is not too explicit, hehe.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 11, 2016, 10:22:52 PM
I noticed the speed difference allot when I first got my MP2 as I'd been gigging with MP1 up to that point.  The fast change upgrade came out pretty quickly IIRC and was important for me back then as I was changing patches allot in that band.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Harley Hexxe on November 12, 2016, 05:06:11 AM
I've never experienced any kind of issues like that with either of my MP-2's.

   Dante, has this issue always been there with yours. or it is something that developed, and got worse over time?

    I'll explain why I ask; I'm wondering if mis-matched tubes might cause an issue like this, or possibly one of the tubes may be getting weak,( such as the low gain tube ), and causing a lag when switching to a higher gain setting?
    Does it also do this when you are switching to a lower gain tube voicing?

       Harley 8)
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Dante on November 12, 2016, 08:29:42 AM
Harley,

If I had to guess, I'd have to say it has been slowly getting worse...because I didn't notice it before. Honestly, I haven't used my MP-2 much, but I'll play around with it a bit to see what's going on. I would like to get to the bottom of this, as those tones are fantastic once they warm up, I'd hate to not be able to use them because of a simple glitch.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Harley Hexxe on November 12, 2016, 10:26:02 AM
Dante,

    I don't really know if the tube mis-match is to blame, but I suspect it may have something to do with it. At this point, I wonder if a set of matched tubes, or even a set of replacement tubes might fix the problem. If the 12AT7 is getting weak, and trying to come up to a higher gain level, that might explain the sag. Too bad you don't have a tube tester, that would take a lot of the guess work out of it.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on November 17, 2016, 07:56:41 PM
Well, I am using a set of new tung-sol tubes (I dont' know if they are matched, but they are both new).
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Harley Hexxe on November 18, 2016, 05:08:08 AM
Well, I am using a set of new tung-sol tubes (I dont' know if they are matched, but they are both new).

   Dante is using a 12AT7, and a 12AX7 in his MP-2. There is less gain in the 12AT7, and the MP-2 is expecting to see more.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on November 18, 2016, 05:34:09 AM
The gain difference isn't that much if you replace a 12ax7 by a 12AT7, in the same circuit it will be 59 vs 53 (or 35.3 vs 34.5 dB)
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 18, 2016, 05:54:41 AM
Hey Harley, you may be onto something here  :dunno: , the 12AT7 needs/wants much higher current than 12AX7, the MP2 circuit is designed for 12AX7s and the 10 tube "voices" are created by manipulating a bunch of variables and (some eq) so current draw will be a factor.  The lower gain is probably not as big a deal (hey not that I'm an eggspurt here, MJMP and others may be able to edify us more). A 12AU7 may be a better choice if you want to turn the gain down a bit ?, IIRC they are lower current than 12AT7 and lower gain than 12AX7.  While I haven't tried using 2 different 12A?7 tubes in my MP2, I think the MP1 circuit (particularly with MDRT as it delivers significantly more herbivours) may be more tolerant. Of course the other way is to use 12AX7s (and not necessarily the same brand/type) and wind back the OD/drive setting(s) if you want to clean it up a bit.

But I think you and I are on the same page liking/recommending long plate 12AX7s for the MP2 as they seem to suit the MP2 circuit.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Harley Hexxe on November 18, 2016, 07:19:12 AM
@ MJMP,
    I know it isn't a big difference, but it might be enough after a long enough period of time.

@ Richard,
   Yes, we are on the same page with the MP-2. I'd rather not try to downplay the gain it comes with, and just let it work the way it was meant to, and use it primarily for the modern amp sounds. The MP-1 and the Classic can give me all the vintage tones I'm looking for, so why try to make the MP-2 do the same thing?  :crazy:
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 18, 2016, 08:06:00 AM
I'm starting to envisage a guit rack that has all 3 preamps (need to get a classic now LoL) for just that reason. And I'm really happy I've picked up 2 MP1s (one for live rack one for studio (I can use the MP2 cab sims for the studio MP1 by going into the MP2s FX returns, I tried this before with Mikes MP1, works a treat)).  But obviously not everyone can afford one of each.  I was really happy with my MP1 tones back in the day (and miss them a bit), and also happy with the MP2 when I moved onto it, a classic I will get someday  :dunno: and maybe use an MB1 for cleans ??  Hey MJMP, there's an option to try for clean tones  :thumb-up: . While I didn't linger long I tried a guitar through MB1 and it sounded great for cleans, food for thought...
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on November 18, 2016, 08:12:54 AM
Yeah didn't think of that, using the MB-1 for cleans, well I could try it out.

I would not use a 12AU7 in the mp-2, that's going to be worse.You won't be able to bias it correctly, and the same goes to some extend also for the 12AT7.
The MP-2 has some sort of bias circuit between each half tube, maybe it's got something to do with that.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 18, 2016, 08:28:05 AM
Thanks MJMP, that's good to know and I suspect you may be right about the bias between the triodes.  Then best is stay with 12AX7s, not necessarily the same model/brand (although that's my preference), and just adjust your OD/drive settings.  Also try the in between voicings, and hey there are 10 voices!.

As I said I didn't linger long using MB1 for cleans but it had lots of promise, definitely worth a try, it sounded good on humbuckers, tamed them quite nicely, I was politely impressed from a quick trial and swore to come back to it...
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on November 18, 2016, 08:44:44 AM
Only the MP-2 has this bias circuit, they were planning on also using it on the MP-1 plus but in the end didn't use it. Now the whole MP-1 plus idea didn't came so...
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on November 18, 2016, 02:03:59 PM
Could you do some kind of tutorial to show how to bias the mp2 correctly? I'd be glad if this could fix my drive delay issue :).
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on November 18, 2016, 03:07:42 PM
I had a few problems with one of the bias circuits but it always resulted in distortion on the clean channels, so I don't think it has got something to do with the bias circuit.
Are all your clean sounds clean?
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: vansinn on November 19, 2016, 01:47:28 PM
Those bias circuits have another function  besides providing (programmable IIRC) bias, but about this, I'll have to dig out old discussions about this with Rand (analog designer at ADA and former member in here).
At least, I don't see them having anything to do with the problems discussed here, maybe unless some components are DOA.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on November 19, 2016, 08:24:44 PM
I have a bit of dirt on the clean channels if the drive is at 100%, but that seems normal to me.

EDIT:
The 3 clean voicings (1-Crystal Clean, 2-Spanky Clean, 3-Fat Clean) are a lot louder than the other ones (4-10).
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on November 19, 2016, 08:57:01 PM
I think the problem is with Voicing 4 (vintage brown), 6 (dynamic vintage) and 8 (dynamic high gain).

I just did a couple more tests to see what is going on, and this is what I get:

No problems

Problems

Dante, do you get the same results?
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 20, 2016, 02:11:02 AM
Wow, that's a curly one  :dunno: . When I get back home this week I'll play around a see if I get similar results.  I've never used voice 4, 6 or 8, just voice 1, 5, 9 & 10.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: vansinn on November 20, 2016, 09:57:55 AM
Well, over the years, I've used all voicings, and don't remember these issues (though, one or two voicings have had delays, just in an isolated way).

This is over my head - though, as a start, I shall with vigor suggest replacing all electrolytic capacitors..
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on November 20, 2016, 04:04:31 PM
This seems to be more either a switching problem or there are also 2 vactrols in there for some tone shifting.

I wrote all 10 voicings vs fet switching down years ago,I'll look it up and see if there's something in common with those 3 voicings.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Dante on November 22, 2016, 07:49:08 AM
I think the problem is with Voicing 4 (vintage brown), 6 (dynamic vintage) and 8 (dynamic high gain).

I just did a couple more tests to see what is going on, and this is what I get:

No problems
  • If I exclude voicings 4,6,8, I can go from any voicing to any voicing without any problems.
  • I can go from any voicing to voicing 4,6,8 without any problems.
  • I can go from voicing 4,6,8 to voicing 4,6,8 without any problems.

Problems
  • If I go from voicing 4,6,8 to any voicing other than 4,6,8, I experience gain delay, (even on clean channels).

Dante, do you get the same results?

Not sure, but I can't wait to try  :thumb-up:
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on November 22, 2016, 10:19:06 AM
Ok I just had a look and it seems F4 (see tube schematic MP-2) is only on ,on voicings 4,6 and 8.It controls 2 Fets (Q322,Q317) and the 2 vactrols on the tubeboard.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on November 22, 2016, 10:39:55 AM
Mmmm, you may have found the culprit, go MJMP  :whoohoo!: .  Interesting I've never used those voices.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: Rawk777 on March 21, 2018, 08:37:49 PM
I'm not really good with schematics... Does it mean there is something I can do to fix the problem?


___
**Wow... the delay of my question is more important than the delay on these MP2 voices!
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on March 22, 2018, 03:16:50 PM
Well have a look on the schematic 852, you will see on the bottom left side level shifters, there you will find F4.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on March 23, 2018, 01:10:03 AM
Hey MJMP, I saw those, I'm not sure how to interpret them though (and what is F4 when it's at home ?).  Would replacing the 2 Fets (Q322,Q317) and the 2 vactrols on the tubeboard fix it ?
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on March 23, 2018, 10:17:00 AM
Well those Fx switches various fet's on and off to get different sounds. If you look around the same schematic you will find those Fx all around usually going to the gate of a FET and the base of that 2N3904 transistor that switches those vactrols.
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: rnolan on March 24, 2018, 04:11:42 AM
Hey MJMP, The bit I'm struggling with is - so there are 3 vertical rectangles side by side (which represent ??).  MP2 voice settings on the left and F assignments on the right.  I couldn't fathom/read how the voice settings match up/are assigned to the F settings, so I'm looking for voice 4, 6 & 8 on the left but struggle to see how they relate/connect to F4 (just following the horizontal connection lines).  Obviously I don't know how to read/interpret this kind of schematic  :facepalm: .

But the question Rawk777 (or Rawk 111, 111, 111, or Rawk rwx, rwx, rwx.. sorry couldn't help it, bit of a unix thing..) needs answering is can it be fixed ? Would replacing the 2 Fets (Q322,Q317) and the 2 vactrols on the tubeboard fix it ?
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: MarshallJMP on March 24, 2018, 08:37:17 AM
Ah ok, well depending on the voice you select, some F's will go on and some go off. I have a list  (maybe I even put it on the depot somewhere) which are on on each voicing.

For Rawk777, those vactrols are very slow devices so it could be that these are the problem.Maybe other mp-2 users could try to mimic the settings you use and see what happends?
Title: Re: Gain delay with Warm Hi Gain voicing
Post by: vansinn on March 25, 2018, 10:03:16 AM
Well.. I can tell that my two MP-2's react at different speed on Voicing 9+10 and one of the 4/5/6 ones; can't remember which one.
I definitely believe the Vactrol's are getting slower at going from one to another setting on one of the MP-2.