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Author Topic: Screaming from ADA  (Read 10514 times)

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Dna^Yay

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Screaming from ADA
« on: Time Format »

So i have been having some issues with my ADA, just as an experiment i crank my distortion flat out on everything OD 1/2 MG and EQ except chorus, insane squealing can be heard (not feedback) as even if it is at a low volume and i am standing outside the room it happens.

This also happens on the clean solid state channel, high pitched squealing even at a low volume. So i heard that tubes can become worn out and microphonic which could cause the squealing. So decided to put some new tubes in ECC82, a lot less gain to try it again. Ok distortion channel is fine as there is hardly any gain and is crunchy, but there is still a squeal on the solid state channel.

What i want to know is, is this standard behaviour for an ADA or might there be some issues with something on the board?

Am contemplating doing a few mod`s for it but not sure if it needs a repair.
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rnolan

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Re: Screaming from ADA
« Reply #1 on: Time Format »

Which ADA do you have (eg MP1, MP2 etc) ? I'm guessing it's a MP1. Turning all the gains up full and also the eqs up full (eq adds/subtracts lots of gain depending on the settings) will make pretty much any preamp squeal regardless of overall volume (eg power amp turned down) as there is just SO much gain in the preamp.  Does the SS squeal with more normal eq settings ?  The rule of thumb with eq is to keep unity gain (ie what you put in volts wise is what you get out albeit with a modified frequency response) so the gain is made and controlled in the valve/SS circuits the eq shouldn't add or subtract from that.  So if you boost with the eq you should also cut about the same amount to make sure you are not adding or subtracting gain. So far your issue seems to be related to your gain structure.  However, if all your gain structure is ok (it wont be with all eqs up full), then there may be other issues.
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MarshallJMP

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Re: Screaming from ADA
« Reply #2 on: Time Format »

Can you post the settings you use on the SS channel?
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Dna^Yay

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Re: Screaming from ADA
« Reply #3 on: Time Format »

Literally Everything maxed out, except the chorus which is at 0
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darralld

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Re: Screaming from ADA
« Reply #4 on: Time Format »

Next question is why would you want to max out everything.
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Dna^Yay

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Re: Screaming from ADA
« Reply #5 on: Time Format »

Just trying to see if that the squealing was normal or if there was an issue with it, got it 5 years ago and it's never been serviced and started seeing some issues with it so wanted to double check to see of that was normal or of my unit needed something replaced on the board.
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rnolan

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Re: Screaming from ADA
« Reply #6 on: Time Format »

I'd say the squealing is because the eq is maxed out, try dropping the eq settings to more normal levels, by maxing out the eq you add 57 dB of gain (low 16dB + treb 16dB + mid 12 dB + pres 12 dB = 57 dB) on top off the full gain of both tubes. Eq should unity gain (boost a bit, cut about the same).
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Dna^Yay

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Re: Screaming from ADA
« Reply #7 on: Time Format »

Ok got you, glad there isn't anything wrong with it. What frequency bands are the bass miss and treble at? Have heard a Voodoo mod would fix the bandwidth but they are out of business now, is it possible to replace some caps/resistors/opamps to get the unit running better?
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rnolan

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Re: Screaming from ADA
« Reply #8 on: Time Format »

Hey Dna^Yay, there are quite a few mods for the MP1 (http://www.marshalljmpmodshop.net/index.htm) and we are very lucky to have MJMP here on the depot to help out, the MDRT replacement transformer is a "must have" in my view, some of the other mods depends how you play and how much GAIN you want.  I'm not across what the centre freq are in the MP1 eq, but they are good for guitar (what they were designed for).  The stock MP1 units are IMHO awesome, but yes there are some improvements, I migrated to the MP2 when it came out, and I like it even better although I do miss aspects of the MP1.
I'd offer these suggestions when you create new patches: ADA pre-amps are designed for loud live use, yes you can turn them down for home/recording etc but they like to be cranked up (and sound so much better in stereo).  When you create a new patch from scratch, you need to do it at stage volume (not always easy I appreciate), then you can turn the volume down when/if required, the other way, then the sounds don't work so well live (massive difference in dynamic range/you ears frequency response). Typically drive OD1 harder than OD2 (or the same as OD2, better gain structure less noise at high gain), I always dip the Mids by -4 or sometimes more, and generally presence +6 (or more, the presence will be ~6k) and adjust Low and Treb to suit.  The MP1 chorus is to die for (just ask RandallRG (hey Steve)), so worth playing with, generally I adjust the depth to 100 and turn the rate off 0.0 which gives a nice short doubling delay in stereo (when I don't want a chorus effect). The other approach (obviously) is to pick a factory preset (eg 001 Marshall) move it to a new spot (eg 112) and modify to your hearts content.  For live use, I work with one bank of 10 sounds (then you don't have to change banks (much)), I've settled on bank 11 so 110 and 111 are clean patches (111 a little louder), 112 main rhythm (and lead with vol pedal), 113 old rhythm sound (now over the top lead, I'm getting older  ??? ) etc with various effects.  Effects wise I pretty much run with some mild delay and always some reverb (in stereo), send this through a decent transparent power amp (tube or ss) and a couple of cabs..... heaven on a stick.
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MarshallJMP

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Re: Screaming from ADA
« Reply #9 on: Time Format »

Well i have to disagree with that 57dB.You need to see this as 4 seperate blocks,each has it's own freq. So you can't just add them all up.

Now about the squaling,if you max out everything,yes you could get into this kind of problems.Like Rnolan says,don't go beserk on this.Like for instance the SS cleans.What i do i set the master volume at 10.0 and i use the OD1 setting to get the desired volume.Since OD2 acts like a compressor in the SS channel i wouldn't go past 3.0,else you will get too much compression and too much noise.Again this is only on the SS channel.
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Dna^Yay

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Re: Screaming from ADA
« Reply #10 on: Time Format »

Thanks for the input guys, I had been toying with the idea of mods for about 2 years now and had previously been in touch with MJMP about getting an ultra + mod minus the 3TM and the tubes.

As I said before I was just boosting to see if my unit had an issue or not, microphonic tubes were something i had read about and also i had read about the mp1s can be quite noisy so kind of put the squealing into either one of those brackets. Only issue so far is that the front input jack is dodgy.The next assignment is doing the right mods.

I tend to have my distortion at about 5-6 on OD 1 and 2 and master gain at 7... if that, with the eq I normally boost the mids to about 8 bass either 2 or 4 and treble 4 or 6 and then the presence around 8.I do understand about cranking the volume more for a richer sound hence why I pretty much crank my Engl power amp and have the Ada volume only on 9 0 clock so the poweramp tubes are breaking up more.

The issue for me for the past year or so has been deciding whether to get a mod or not. Am quite capable of doing most of the mods myself, also was deciding whether to get the mdrt or mercury magnetics transformer which voodoo amps used to use with their platinum mods.

Then whether I change the stock board for setting else or keep it, personally I think it already has enough gain and I was worried about losing the clean channel if I got the 3TM, but recently I have been weighing out the tube clean and SS and deciding whether to make the tube clean more of a crunch channel.

So as of yet all I know I will do is the standard battery mod, change some of the jacks, my EPROM is already 2.1 and do the transformer but stumped about a new board or replace some parts on the stock. Then you throw changing some caps resistors and opamps into the equation, literally no idea where to start there and if there are schematics for these changes or if it is something only MJMP knows to do.

Did fall in love with the chorus.... Then I got an ada 2fx and MY GOD!!! Have not heard something that sexual since a Roland jazz chorus amp, only issue is the bloody delay section is kaput

Sorry for the long rant ;)
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rnolan

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Re: Screaming from ADA
« Reply #11 on: Time Format »

Some of the mods are posted here (http://adadepot.com/index.php?topic=148.0) (thanks MJMP).  The mods you are thinking off all make sense to me obviously jacks are a no brainer, and the MDRT a good idea (wish there was one for the MP2).
Well i have to disagree with that 57dB.You need to see this as 4 separate blocks,each has it's own freq. So you can't just add them all up.
On reflection I spose you could argue that the are -3dB reductions at the crossover points and the shape of the eq band will also make a difference, the main point being though that eq can add/subtract quite a lot of gain and needs to be carefully considered in your overall gain structure.
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MarshallJMP

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Re: Screaming from ADA
« Reply #12 on: Time Format »

I also like the 2FX,the flanger RULES IMO.

About the Mercury transformer,i bought one just to try it out and it's just a copy of the original one,same voltages and it doesn't enhance the sound in any way.Wasted money IMHO.

About the 57dB,don't forget this is an amplification factor of almost 1000 times,that's alot you know.Also important about the tonesection is the order of the filters,in the mp-1 they used 1st and second order filters.

http://en.wikipedia.org/wiki/Audio_crossover

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rnolan

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Re: Screaming from ADA
« Reply #13 on: Time Format »

Thanks MJMP, I'll check the wiki article, have you seen this one:
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MarshallJMP

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Re: Screaming from ADA
« Reply #14 on: Time Format »

yes i did,some heavy things in that article.
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