ADA Depot - A Forum To Support Users of ADA Amplification Gear
Let's Get Technical => All PREAMP Tech Tips & Support => Topic started by: Chamai on October 12, 2014, 03:31:57 AM
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Hi all, new member here
I really need some help with my stock ADA.
Every time i strike the note C on any octave when chorus is mixed with distortion, i get this weird swelling, tremolo sound. It sounds like the chorus is set to a super slow rate. distortion and chorus by itself works flawlessly. Could bad tubes cause this issue?
UPDATE: its not only the note C that this happens, its all random. I found the issue is caused by output B. When I plug my power amp to output A, everything works flawlessly. Anyone know what could be wrong with output B?
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Hey Chamai, it seems to be stetting up a resonance around C (BTW are you A440 or A445 Europe ?). It could be tubes ?, (though not an issue I've come across before ?, though new tubes can't ever hurt >:D :thumb-up: )
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Hey Chamai, it seems to be stetting up a resonance around C (BTW are you A440 or A445 Europe ?). It could be tubes ?, (though not an issue I've come across before ?, though new tubes can't ever hurt >:D :thumb-up: )
a440 is the american version right? im not really sure, i bought it from some guy here in canada. hes the original owner i believe. here is what i found out. when i have distortion + chorus on the same time, the c notes swells when Chorus depth is set from 14-18. anything from 1-13 is good, and 19 + is fine too.
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Could be a strange artifact from the chorus,since it only happends on one particular setting.
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I figured it out. This only happens on output B. If i connect the ada mp1 to my power using output A, its all good. anyone know the reason?
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Mmm, I have some ideas but wouldn't say I know, I'm a with MJMP as it may be a strange artifact (as in it's not meant to happen, and normally wouldn't), (hey MJMP, is the signal stereo before the chorus i.e. are there 2 signal paths through it ?). Stereo (and mono) chorus is a combination of slight (very short <=40ms) delay and modulation of one of the 2 signal paths. This is designed (originally) to simulate a 12 string (each string pair is picked very slightly differently in time (delay) and each string modulates (spins) slightly in and out of tune with the other, modulation (of pitch)). In a mono unit the 2 paths are mixed back together, in a stereo unit (like MP1 chorus) the separate paths are fed to left and right outs (typically BTW as there's other ways to do it). So it seems your getting a resonance artifact (but I'm theorising here) in the B path. Maybe replace the chorus chip ? (MJMP ?).
Big question ? are you running stereo ? if not then A out will not necessarily have the delayed/modulated sound (which does vary in volume and pitch (modulation)), that's on the B out, combine the 2 A/B in stereo and you have stereo chorus and may answer the riddle ?
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After the loop the signal is split in 2 mono signals and the chorus is mixed with the A output and the chorus signal is also phase shifted 180° and then mixed with the B output.This way you get the stereo effect.But since one side has a phase shift (only the chorus signal) some frequencies will be amplified and some will be notched,depending on what time delay you use.
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hey all, thanks for the reply
i am just running mono. here is my setup:
ada pre amp (output A) to mosvalve 962 (input A) = this works 100%
i think you guys are on the spot about output B being responsible for the phase shift. i never knew the ada's chorus is stereo
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The ADA is a whole new animal when you run it in stereo, I'll never go back...to mono... If you can, run ADA MP1/2 into stereo power amp/cabs, it will melt you, seriously :thumb-up:
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again, i really appreciate the help. my ada is running great. i am just waiting until december when i am all by myself since the wife is taking the kids back to her hometown, which means more money for myself to spend without feeling guilty. hopefully i get pick up another ada pre amp locally.
looking for both mp2 and the classic and picking up another mp1 for backup.
just bought a noise gate today and wow it made a difference.
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Hey Chamai, happy to help :thumb-up: MP2 (which is what I moved on to years ago from MP1) is a very different animal >:D lots more gain and lots more features. You can also plug the MP1 A/B outs into the MP2s loop returns and use the MP2 cab sims for recording the MP1 direct.
There's a bunch of noise mods available for the MP1 and also the MDRT transformer upgrade (http://www.marshalljmpmodshop.net/index.htm), so where are you in the world ? I'm in Canberra Australia, MJMP's in Belgium.
Cheers R
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i live in vancouver BC canada. hopefully i can find something in canada at least so i won't get killed by shipping.
i like to keep all my stuff stock with no mods. you can say i am kinda like an old school rack gear collector that likes to keep all stuff original. recently a good friend gave me a fostex 3180 analog reverb unit. i hooked it up with my ada and i think its pretty cool. i just like the feeling of running vintage gear.
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Couldn't agree more, I'm an analogue die hard also. The MP1 noise mods, EPROM upgrade and MDRT are really worth doing though IMHO.
Noise mods don't change the sound just make the unit quieter
EPROM is midi switching improvement IIRC
MDRT will open up the sound a little as it provides better power for the tubes, IIRC MJMP said the original MP1 transformer wasn't particularly well designed.
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just picked up a 2nd mp1 today and picked up a digitech gsp pro for total of $210 CAD. the only thing with this mp-1 is the rubber protecting the power cable cracked. so it exposes a bit of wire. but all cables are intact and not damage. is it possible to replace the power cable on the mp-1 in the future just incase?
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:whoohoo!: good score :thumb-up:
When you say exposes some wire what do you mean, as in do you see the separate cable(s) but the wires are covered in their insulation or you see the metal inside ? Cable = wire inside insulation, wire = metal wire inside the insulation (live, dangerous etc).
And yes you can just get a power lead (e.g any old jug/IEC cable and cut off the IEC plug) and solder the appropriate 3 or 2 in US etc to the correct spots in the MP1.
MJMP may have advice on cable protector, I suspect it's not a big deal and you can find similar easily (though you'll have to free up the lead from one end or other to feed it through the new rubber protector)
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. is it possible to replace the power cable on the mp-1 in the future just incase?
Yes just buy a replacement and replace it,done it alot of times.
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no metal exposed. there is just a gash on the out black cable. I can see the blue and white cables inside. but no metal though
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Well just recomend you change it,just for safety.
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yea i think i should do it too
there is a shop that does custom attenuator and amps in town, i prob bring it to that guy.