ADA Depot - A Forum To Support Users of ADA Amplification Gear
ADA Preamps => MP-2 => Topic started by: W.Laturno on January 12, 2014, 07:08:11 PM
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I played a show this past Friday night and when I turned on the amp channel one was making god aweful noises . . I switched channels only to find my clean channel stopped this noise.
After playing around I've come to realize this: any tube voicing above 6 and this noise was imediate, sometimes after having the unit on the noise would go away.
When I go home and swapped out tubes, this seemed to be better, but if I put the voicing on 10 and cranked the gain and OD - I could make the noise again. so I lowered the voicing and such and play a steady note for a while. The amp seemed to go through a cycle....stange things are happening and I think I may need some new components.
I've heard about a noise mod, but have not been able to find out much . .. . I'm hoping someone out there can help me.....
I[ve got another show in 14 days and no amp.....
I hate to say it, but maybe I need to ditch this old gear and step into the modern. . . . :dunno:
I've written to MarshallJMP already on this topic as well....
Will.
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You've got mail :D
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Hey Will, I'm sure you can get it sorted, My MP2 set up (and previous MP1 rig, still in use) have been great for many years and showing no signs of dying and in no way dated. I'd hate to go back (modern) as it's all tone cloning these days (yuck). I'm sure MJMP will get you sorted.
Cheers Richard
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A million thanks to MarshallJMP ! Cheers !!
I now have the necessary mod informaiton and parts ordered.....
I appologise too for starting this thread before I checked under the LETS GET TECHNICAL area....I was just thinking MP-2 area.....but heads up to others if you have motorboating ( not what you think, I thought that too :facepalm:) . .
http://en.wikipedia.org/wiki/Motorboating_(electronics)
the noise mod info should be added to Schematics area for sure.....
regards,
Will.
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So since you are done I thought I might semi-hack your thread and ask a few related questions.
On MP1, there is one out of 30 outlets on stage where I don't get an annoying ground loop buzz. This is the kind of buzz that is loud enough that you cannot have at all. The one outlet is conditioned by a furman power conditioner.
First question: does the noise mod reduce ground loop noise or should I get a power conditioner?
Second question: how much tube preamp noise does the noise mod reduce? 50%? 25% 90%?
My caps are really old but it just sounds like an old tube amp to me; not silent.
Are you getting solid state quietness from the noise mod? Seems that this would make the noise mod effort worth while for me.
David
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Hey David, hack away ;) , ground loops are/can be a thing unto themselves (well sometimes :-) e.g. don't be on the same circuit as the venue's refrigerators), my limited understanding of the noise mod(s) is they reduce noise while increasing (allot, in some cases in conjunction with an additional tube(3TM Mod)) gain (i.e better s/n ratio), but not associated with ground loop noises.
Q 1, noise mods will reduce noise in the various circuits they apply to (i.e better signal to noise ratio (ADA preamps have allot of gain!)), nothing to do with ground loop; hey but a power conditioner is a good idea with MP1/2, they're ok on decent mains but not to fond of fluctuating power (e.g. generators, & refrigerators!!!).
Q 2, I've never really chased the "totally silent"; high gain tube oriented guitar is always on the edge, that's it's nature, well to me anyway (or get an AxeFX tone cloner etc), I will say though, having used a number of high gain tube setups (over 40 years now) ADA preamps are the best I've ever used (MP1/MP2 :thumb-up: )
Cheers Richard
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The noise mod won't fix groundloops.Groundloops can be very tricky to resolve.
A power conditioner is always a good idea.
How good the noise mod works depends mostly on the condition of the caps in the PSU.The more worn out the better it will work.Now the noise mod is not just about reducing noise but also about enhancing the sound.I didn't just pick out a random set of caps and parts but i did experiment allot with different manufacturers to get the best.A good amp starts with a good power supply.
Yes all 3 voicings are affected by the noise mod.But what the noise mod doesn't do is getting rid of so called outside influences like transformers and other poluting magnetic stuff that gets picked up by your pickups or cables.
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Thank you for the replies.
Please allow me to ask some pointed questions.
So when do you know you need a noise mod?
My caps are probably original and I get some hiss in my unit that the other guitarist who uses solid state distortion does not have.
I am ok with the hiss and so far the sound guys have been ok with it-but I am under the influence of ADA so consider my judgment impaired.
The noise mod is a big project and it seems to me, the uninformed, that unless I get a 75% or more reduction in a normal level of tube noise (normal tube noise, not problem tune noise levels), I wonder if it has enough benefit to justify the work.
Additional question: I understand that ground loop noise is the result having an AC power source and not a wall wart. If this is the case is there a mod to add a DC adapter to power the ada MP-1? (Note I am not talking about the MC1 adapter, but an actual ADA preamp power source coming from a wall wart). I know everyone loves wall warts, but if it saves me the hassle of finding a successful power conditioner I am all for it.
David
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Hey David, MJMP can no doubt help with the MP1 noise mod details, but as he said previously, the amount of improvement is dependent on the starting point (current state of components) so hard to put a % measure. If, as you say the unit is stock, there will be benefit from doing it and it will also enhance the sound.
Age of and choice of tubes will also play a part. If the tubes are also original, then it's very likely time to change them, basically, you need 2 high gain, low noise, low microphonic 12AX7 tubes. ADA recommended a tube change every 2 years for the MP1 but this obviously is dependent on use. This post (http://adadepot.com/index.php?topic=300.0) is one of the many here relating to tubes and tube choice (this BTW is a very subjective area). Actually a change of tubes may go a ways to solving your problem(s)
As the MP1 is a tube preamp, I don't think a DC power supply (like Alesis use with Quadverb etc) would not be sufficient as the tubes need (AC?)heater current etc which comes from the power transformer. However, a very worthwhile mod is the MP1 MDRT transformer replacement (http://www.marshalljmpmodshop.net/miscellaneous_parts_and_replacement_tubes.htm). A decent power conditioner (e.g http://www.furmansound.com/product.php?div=03&id=PL-PRODMCE) will help (as you found on the 1 in 30 outlets :thumb-up: ). The link is to the 220-240v version that I'm interested in, the same is also available in 120v. From what I've found out recently, the Furmans have a good reputation.
Cheers Richard
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Thanks Richard - I missed that point he made and I understand now.