ADA Preamps > MB-1

ADA MB1 Version 1.15 Troubleshooting

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Andrea86:
Hi, i'm Andrea from Italy and i'm a new member.
I'm writing because i have some problems with my ADA MB1 version 1.15.
Problem N°1: Compression doesn't works. I have to set it OFF always because when i use it (also at the minimum)
the sound gets distorted and it's a complete disaster, total mayhem...
Problem N°2: Master control at both Tube and Solid State part doesn't sound good when i put it from 4.6 and over. i have to stay within 4.4 and obviously doesn't sound so punchy as it should works.
I'm completely without any idea of what kind of problems my preamp has.
Pls help me if you can!!!
Thanks a lot in advance.
Andrea

rnolan:
Hi Andrea, welcome to the depot BTW.  There's a couple of MB1 users here with lots of experience and they are sure to help out here as/where they can (go Bass dudes :thumb-up: ). But I can help a little I think.

A couple of questions to help trouble shoot:
* How old are the tubes (they should be changed every year or 2 years, but depends on how often/long you turn it on), also they go off/degrade very slowly so you don't notice (until you put some new tubes in  ;) ), I suspect new tubes are a good idea regardless (there's quite a bit of discussion here re tubes, you'll need 2 x high gain low noise 12AX7 tubes (easy to change yourself BTW) I'd recommend JJ's (e.g. http://www.dougstubes.com/preamp-tubes/12ax7-ecc83-7025/jj-ecc83.html) or my fav, Mullard Short plates(http://www.dougstubes.com/preamp-tubes/12ax7-ecc83-7025/mullard-cv4004-12ax7.html)), Peter/BDS what do you recommend ?
* what settings are you using when the compressor overloads (total mayhem (all settings in the distorting patch pls)) (this maybe gain issues or maybe a component problem ?) or a known problem ?
* what bass are you using ? is it active? if so when was the last battery change (dieing batteries....?) ?
* what power amp and speaker box, how's it patched ? or are you going direct into a desk/pa ?
* do you plug through anything else before the MB1 (e.g. tuner, effect thingy) ?, do you use other effect devices in the chain ?
* Are all your leads good ? (guitar/patch/speaker)Also MJMP (who's our all things ADA tech guru  :bow: ) will be able to help, and not doubt have some more targeted questions...
Regardless of the current problem (which we can hopefully help sort you out soon), there are a couple of mods really worth doing (when/if you can afford $'s wise):

* Tubes (2 x new 12AX7s)
* The MDRT replacement transformer (http://www.marshalljmpmodshop.net/miscellaneous_parts_and_replacement_tubes.htm), to me this is a no brain-er.
* EPROM upgrade (easy to do yourself)  to v2.05 same page (on MJMP s site) as above.
* There are also some noise mods worth considering (reduce noise in the MB1), Peter and MJMP are more across thoseRegards Richard

rnolan:
You may want to check this out BTW (http://adadepot.com/index.php?topic=446.0;topicseen)

MarshallJMP:
Maybe somthing is wrong with the +-15V?

Andrea86:
Hello to you all  :)
First of all thank you for your answers and your time! i really appreciate!!!
About the question you made:
- i changed the tubes but nothing happened...
- i used the same settings when the compressor worked, it broke up in a second while i was playing so in my opinion there's nothing wrong with the settings. Obviously i changed my settings after the compressor stopped working.
- i use a Fender Precision Bass directly plugged into the ADA MB1 and other stuff, here it is:
  bass > ada mb1 > trace elliot XV valve (1 tube) > DBX compressor (send return to the Trace elliot XV) > Trace Elliot RA 300 > Trace Elliott Speaker
Without ADA MB1 all works perfectly so it's only a problem about ADA...
So at this point probably it's a EPROM or Transformer problem don't you think?

Best regards Andrea

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