ADA Depot - A Forum To Support Users of ADA Amplification Gear
ADA Preamps => Original MP-1 => Topic started by: FoneBone on June 21, 2014, 09:41:48 AM
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Is there a way to setup the trimpots correctly only with the guitar? MY T1 is nearly at 12 o'clock, T2 is at 7 o'clock, and T3 is between 1 and 2 o'clock.
Thx in advance.
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I've found an answer (in german) in another forum and attached an PDF.
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Any chance of a translated version ? Euero dudes ?
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I will try to translate it in the next week... :thumb-up:
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(http://www.abload.de/img/trimpots_2011_correct3ko3y.png)
Source: http://www.musiker-board.de/userthreads-e-git/381016-ada-user-thread-3.html#post5586825 (http://www.musiker-board.de/userthreads-e-git/381016-ada-user-thread-3.html#post5586825)
Short translation:
1) Never touch trimpot 3 and 4!!! Only set these trimpots when they are far away from 12 o’clock!
2) To setup trimpot 2 (OD1) just set OD1 to 10.0, voicing should be clean or dist. tube, and play palm mutes on the lower E string. Turn trimpot 2 until the clipping LED of OD1 just blinks in your played rhythm. (Btw. I’ve never seen my OD1 clipping LED light up?!)
3) In the german translation trimpot 1 (OD2) should be completly open.
I’m sorry for my bad english and I don’t take any garantee that this is the only and correct way to setup your trimpots of the MP-1!
Maybe MarshallJMP can tell us more about it! ;)
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Go FoneBone, thanks for sharing/caring, your English seems fine to me (need to teach you Australian LOL) IIRC MJMP had a .pdf about setting MP1 trim pots, involved a scope though..
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You mean this here:
http://adadepot.com/index.php?topic=187.msg972#msg972 (http://adadepot.com/index.php?topic=187.msg972#msg972) :thumb-up:
But I don't have a scope :-\
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Oh well, just have to use you ears, mmm seems you have already :thumb-up:
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Now I've tried to understand the MP1-alignment from the other posting. Can someone please tell me what "TP F" in point 2 and 3 and "KB" in point 6 is?
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Dude...."FoneBone" why would you say & I quote..."Never touch trimpot 3 and 4!!! Only set these trimpots when they are far away from 12 o’clock!" ????
I have ALWAYS set mine to Taste or Ear & (to me anyway) they all sound Killer! ???
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Dude...."FoneBone" why would you say & I quote..."Never touch trimpot 3 and 4!!! Only set these trimpots when they are far away from 12 o’clock!" ????
I have ALWAYS set mine to Taste or Ear & (to me anyway) they all sound Killer! ???
Hi RandallRG, please don't missundestand me... but I have just translated the german posting... It's not my opinion!!!
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(LOL)!!....No problem Buddy! It's all good... :metal:
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Well it's best to stay away from trimpot 3 and 4.Why?Trimpot 3 is the SS alignment,if SS channel is clean stay off it.Same for pot 4,if the chorus is clean and present stay off it.Normally pot 4 is around 11 o'clock.To fine tune these you need a scope.
You can set pot 1 and 2,here you raise or lower the OD1 and OD2 range.
TP-F is a test pin but these where only present in the older V1 mp-1's.It's actually the output of the tubeboard.
KB is the small red 3 pin connector near the front vol pot.
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T2 is the only Trimpot you can Adjust... doean't mean you need to either. Do not mess with the other trimpots.
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Marshall/Robb....W-O-R-D Dudes! Marshall I understand about the T4 Chorus Trimpot. Mine didn't sound right so I adjusted it & got it to sound 100% Killer. :metal: :thumb-up: ;)
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Thanks MArschallJMP and RobbHell! :bow:
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Marshall/Robb....W-O-R-D Dudes! Marshall I understand about the T4 Chorus Trimpot. Mine didn't sound right so I adjusted it & got it to sound 100% Killer. :metal: :thumb-up: ;)
Hey Steve, you like to fiddle LOL, good to hear you got it optimal (killer) and you didn't have a scope. Have you run your stuff in stereo yet ???? :metal:
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Now I bought an old russian scope to setup my trimpots. And I use this instructions (http://adadepot.com/index.php?action=dlattach;topic=187.0;attach=127). Here are some pictures:
1. Setting up T2 (OD1)
(http://i.imgur.com/XICGOiql.jpg)
(http://i.imgur.com/6sSu1SSl.jpg)
I've used an iPhone app as signal generator and set it for 600mVp-p (-13.5dB) sine wave at 2kHz.
The orange results/settings are the expected ones, the pink results/settings are what I got.
2. Setting up T1 (OD2)
(http://i.imgur.com/hPYwSNXl.jpg)
(http://i.imgur.com/JYYU4nYl.jpg)
3. Should I change V2???
(http://i.imgur.com/zqK8h1Ul.jpg)
4. Setting up T3
(http://i.imgur.com/bnxSkJFl.jpg)
(http://i.imgur.com/RALvn3ol.jpg)
5. Setting up T4 (part1): I wasn't unable to find R223, maybe MarshallJMP could help ;)
6. Setting up T4 (part2)
(http://i.imgur.com/7StYywEl.jpg)
(http://i.imgur.com/E1eHOojl.jpg)
Maybe some one can tell me what's the problem with T1 & T2, T3 & T4 seem to be okay?!
And a little addition: I'm a noop in electronics, but I like to learn :D
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New happy ADA user here...
So last night I tried adjusting the trim pots for OD1 and OD2 with no major effect on amount of gain, then came across this thread...
Questions
-How much is this supposed to change the gain amount
-By messing with these did I potentially mess anything up where I need to readjust/fine tune with an oscillator and all that as shown above?!
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These are just the factory settings,these are not intended to give more gain,just the correct gain.But you can safely play around with these.
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Usually I don't necro a thread, but FoneBone did such a great job of documenting this procedure with pictures, that I felt this would be the best place to continue.
I have a version 2 MP-1 and I have done a complete recap of the unit. knowing that value tolerances of the old caps to the new could change alignment, I wanted to verify the settings.
Step one was to set the MP-1 to Clean Tube mode and OD1 at 10.0. Then inject a 600mVp-p sine wave at 2kHz. Measure U4 at pin 1 and set T2 (trimpot) to achieve 15Vp-p.
Well my initial setting was 9.4Vp-p but was unable to set 15Vp-p due to limits of the T2 trimpot being min 5.2Vp-p to max 10.4Vp-p.
Any insights anyone? :dunno: I was wondering if those alignment instructions are for version 1 only but I don't think much has changed in version 2.
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The instructions should work for the V1 and V2 MP-1's.
When you cranck the trimpot, does the signal distort?
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The sine wave is not clipping even at the max I could achieve of 10.4Vp-p. I have played the preamp and the distortion presets seem to have decent amount of distortion when playing. I’m not truly familiar with this preamp so I couldn’t say what is a normal amount of gain. That’s why I wanted to align it per a service manual.
I wrote ADA for the actual service manual for this, but they just ignored me and didn’t answer. I wonder how accurate these hand written notes are? Maybe they were under pressure to copy it fast as it wasn’t supposed to be released and maybe some values or settings are off.
At this point the preamp is over 30 years old, I can’t see why they wouldn’t release the actual service manual.
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I never had any problems getting to 15Vpp unless there was a problem. If it's not clipping you can rule out the diode/zener circuit.
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I rechecked some of the upper trace caps connections and reflowed some others and now have about 13Vp-p. Still not the 15Vp-p that it calls for but I was able to get a hold of another MP-1 v2 and it had the exact same output at U4 pin 1 of 12.8-13Vp-p. I'm going to call this case closed as I am getting 23Vp-p on output F with the sine wave clipping. I imagine there are going to be some tolerances from unit to unit and the fact two separate units had identical measurements lower than spec kind of confirms my suspicion that it's OK to be a little low.
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That's strange, I serviced dozens of MP-1's and never had this problem. Are you 100% sure that your input signal is 600mVpp? Verified with the scope?
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Well I'm never 100% sure as I'm not a trained EE, I did take 1.5 year of EE classes back in the day, but I went into aviation. Now that I'm about to retire I combining hobbies of Electronics and guitars. I've built many electronic kits, successfully recapped older vintage rack gear Furman PQ3, and Lexicon PCM41 and a Marshall 2204 that I reconverted back to EL34's from the American 6L6's.
Having said all that I'm still learning, and the MP-1 is the most complicated piece I've taken on yet. Here of some pictures of my setup. I have a dual signal generator set up both channels outputting the same signal. My oscilloscope is a dual channel and the MP-1 signal is the yellow trace and the blue trace is the signal generator straight in. The yellow trace is on 5V divisions and the blue on 100mV divisions.
(https://sn3302files.storage.live.com/y4mAnE0-9koEMITRGWtFnYDXhhG1C8CdTZJlMWm0JRzv7GDOPkGRPIS9_6QlRhUbXzjiU1S_sGVBFOuXx4NlrZ2i2ln1eCWrVHmOmzLmgN6Vx5i6qlAlt73ulLQRnQllaDiIms4Fn0pLHRRAAlf1edz4_-SC0U4e2FGzKnB7q-NkRxhCooG5n15YXaq5nVm2JG0?width=1024&height=768&cropmode=none)
(https://sn3302files.storage.live.com/y4m5WEOpFom0TvJC1Sz8y3hug6q6Gz_9_qpL8F68gkVNrSICtZ8gN_fgQep9UxSC5v0vsIS9qUGZuso3PvhP9khA07GIVu-38fhMtlUGBZij-awY4jgcybiQhkLKF4R0FElpl00Yf_Hb9eexawj2WSRlWMmUeJmOMLxoGZm_y2mNpKnO0dww4xncUYRv4ehnNf4?width=1024&height=768&cropmode=none)
(https://sn3302files.storage.live.com/y4mUbMaVEoKREYBZzGUcPTLWO55zRmYj608IOVYbzZFI1--L6SevtLX0YDXHbVheATdRIPSx08-AXQOHVPoBIPXjaTqtFBzcVd2-l2vp1C2PZLWWsqzPEoQ03f_mwWOVCmuhxb29HMH7xekQzYkfM7LbkIhGY-7rmonng9j8iOLVDJgModWO04F32s2rp-akOPT?width=1024&height=768&cropmode=none)
(https://sn3302files.storage.live.com/y4mkFUs3HV_hfUBFFvB4RXrTs4D0vbHHEra14f3fKcc5b6hsp7_c_U5RJ8ZsmJfN8NC4tu2hMPIMZPRi7CSi6ilZaQ0AwvEkXT1uEUk8Atv6xc9aE9EEcFuje63E6g0LbaSG6COpyd3BFo2gvEcAwBm4F19TI2RV9x499OatKiwys38LXWOirIJiq1HUlVPCI0J?width=768&height=1024&cropmode=none)
(https://sn3302files.storage.live.com/y4mb-NopyHmGHQaPpa3RS25N-GNzF9Zp1HNrzh-qPrpuQv65pf0q5potYojoLdw6rALyfFCoAbmoazHtUqepgs46HAEAnlf7w65-bO9-0xgfG0rHvFjpW8JxsrQX-pBlJG9JhoTa2zsW5FJKwWGtq2MbXYSWXNXly9XoSFFm7cefA3yjBkG_e9zVmQz6JOz1VpX?width=1440&height=768&cropmode=none)
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Are your probes set to 1X or 10X en is the setting in the scope the same?
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Be back in a couple of days to verify, but I'm 99% sure both scope and probes are 1X.
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Did you measure the input signal at the input jack?
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No I didn’t measure the input signal at the Jack. I feed the second signal channel directly to the oscilloscope just for reference. But I’ll do that when I get back.
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Ok let me know. I use a BNC T connector, one side to my scope the other side goes to UUT (unit under test), this way you can make sure it's correct.
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I have set up only one signal which comes from my signal generator (BNC-1/4") to the input of the MP-1. I have 2 channels on the oscilloscope, channel 2 measures the signal at the back of the input jack from the solder terminals, channel 1 is connected to U4 pin 1. This time I have all the connections made BEFORE I turn on the MP-1. Previously I turned on the MP-1 and then made connections which took about 1 min.
When I initially turned it on I had about 16Vp-p, I adjusted T2 to 15Vp-p. After about 45 secs the voltage starts a slow but continuous drop to about 11.2Vp-p without touching it. That takes about 2-3 minutes. So I'm thinking that this is heat related as the tubes warm up the area something is heat sensitive and it drops the voltage. Before by the time I connected everything up the voltage had already dropped to below the 15Vp-p that it initially can make, so I never saw that. It seems it should be able to hold a steady voltage at 15Vp-p though.
(https://sn3302files.storage.live.com/y4mJAbZNC52tT_h_DvrYbzYLRpNStOaww38Ljv0Wjc3EtZbDvhZapD24Wyn77f9mCkEuFlcTnm9VqXfeK-CDy-MZ8Ho5_GUafnAqsSNUCRVzVjEz9iCLpGGcQ428PGgdcht9AsedSRk3u28-eoVbTDpwkF-LSrMB9dMrOvBRyXbye0nnwb5WIqZTcxMTINnpAJf?width=1024&height=768&cropmode=none)
(https://sn3302files.storage.live.com/y4mG0yKfHvkpmaUBPb4_VrgQsh5X44OyXRl8PxnGWfSJf3WlXLOCHpDtrWIdWppK_ShKGyPIKWGOTlS5-C3QPNZYSelkTrDPXIyQstJOrc5SaquqlVzY9fMrHJkKz7wEU7vlOGDR9smijYY50RcmUMqqVMBXAwh1S7U6McaAWqo7yX04s9LTQDm-5CF3W6ZDMr-?width=1024&height=768&cropmode=none)
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Try replacing D16 with a 1N400X (X= 1-7), these are not so heat sensitive as the 1N914 or 1N4148 diodes in there.
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How about D44, D45, D46, and D8? These are closer to the tubes.
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I don't think these are the problem, these form a clamp circuit and your sine wave does not get clamped.
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I replace D16 with a 1N4007 and kept it up a little for cooling as in your picture. That has indeed solved the heat drifting problem and I can now set the 15Vp-p.
Of course fixing one problem leads to another. :facepalm:
Now at step 2 in the alignment instructions, I can only get OD-2 at 0 down to 15.4Vp-p with the Trimpot 1 turned all the way down. The sine wave is also in almost full clipping. :???:
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First measure the voltage at R4 or R1, one side should be 190V, then check R6,5,3,2 with an ohm meter, they should be 100k (mp-1 powered off)
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First measure the voltage at R4 or R1, one side should be 190V, then check R6,5,3,2 with an ohm meter, they should be 100k (mp-1 powered off)
I'm getting 194.8V after the rectifier section, all the resisters on the tube board are within 5% tolerance.
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Voltage is a bit high, could be that R9 is going up in value, should be 240k. Check if R48 and R18 is connected to the vactrol.
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Voltage is a bit high, could be that R9 is going up in value, should be 240k. Check if R48 and R18 is connected to the vactrol.
Actually I didn't find a resister that was over 2.5% tolerance values, I was just using the resister stated tolerance values for comparison. R48 and R18 are connected to the Vactrol. As for R9 I don't remember the value (it was within 2.5%) and I can't test that one on the board. I removed all resisters that couldn't be tested directly on the tube board and verified values. I could pull that one off again and give you the actual value if you think that's the culprit.
The other major player here I thought was op-amp U2 (TL072CP). Ok I put in a new op-amp with little to no change, put in a socket and replaced with the original op-amp.
I just got in some new matched EH 7025 tubes and threw them in, I am now able to get the OD2 voltage at 10Vp-p, BUT trimpot 1 is still at its min CCW position to achieve this. In Step 3 of the alignment I get 21.4Vp-p with OD2 set at 10.
So even though I still think something is wrong having to set trimpot 1 at it's minimum level to get the proper setting, I moved on to Step 4 with the amp in Solid State mode and checking the voltage at U8 pin 1, I get only 7.5Vp-p, should be around 11Vp-p. Disturbingly Trimpot 3 has NO effect of the voltage reading at U8 pin 1. Uugh! This amp is driving me crazy :crazy: As a side note as it's not part of the alignment process but checking test point F on S.S. I get 21Vp-p with a fairly square wave distortion.
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OD2 is common for the SS compressor and the OD2 setting in the tube voicings that's why you have 21V at point F.
Now what is trange is that all 3 settings you had/have problems with are done by U14, not sure but did you tried to swap U13 and U14?
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Now what is strange is that all 3 settings you had/have problems with are done by U14, not sure but did you tried to swap U13 and U14?
Yes that was the very first thing I did when we started this long and winding road, and because the Vactrol was bad and a heat sensitive diode it masked any problems there. So, I was very fortunate to be able to find replacements for U13 & U14 and have removed and replaced the old ones. The good news is that the tube section is now working properly, both OD1 & OD2 are adjusted properly and the Trimpots are close to centered now as they should be. Yeah! :banana-jazz-smiley-emoticon: I feel like I can see the light at the end of the tunnel now.
The bad news is that the S.S. section is still reading low at about 7.5Vp-p and T3 has no effect when adjusted. So looks like this is using one side of the of U14 which is now new and working properly on the tube side so I would say this chip is eliminated as a problem. That would leave U6, U7, U8, the clipping diodes and a bunch of resisters and T3 to check.
I noticed on the schematic that R46 in circled and on my unit R46 is not installed from the factory.
Another schematic difference is that the preamp schematic shows T3 to be 5KΩ but on the V2 layout map, it shows 2KΩ. Without removing from the board my T3 shows 1.7KΩ
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Great news about the tube side :thumb-up:
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Follow up to my Solid State channel alignment issues. Well not sure I have an issue now or not. The alignment procedure doesn't really mention what the OD2 setting should be when this measurement was taken. I have since measured U8 with OD2 at zero (6.4Vp-p) and with OD2 at 10 and I get the 11.4Vp-p as per the alignment procedure. However T3 still has no effect that I can see on the p-p voltage of the S.S. channel.
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The OD2 has to be set to 10.0.
Now I checked 5 MP-1's I have lying around for the moment and 4 of them have the 2k pot and one has the 5k pot. None of them had R46 installed.
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Ok then the S.S. section is set right with OD2 set to 10. But I am wondering why T3 has really no effect on the voltage. Should I ignore that or search for something else that could be wrong?
Another thing I noticed from the v2 PCB layout sheet, it lists R46 value as OMIT, so thats another change they made from the original schematic.
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I've tested another MP-1 v2 which has a 2KΩ T3 Trimpot. It was initially adjusted about 1 o'clock and was 0.87KΩ. The reading from U8 pin 1 was 11.2Vp-p and adjusting T3 "SEEMED" to have no effect, just like mine. Upon further examination, if you are not looking directly at the oscilloscope while changing T3 you won't notice a change. This is a very subtle adjustment and it barely moves the wave. Until I was looking at the scope and sweeping T3 from stop to stop, I didn't notice any change.
So I went back to mine swept it back and forth and then setting it to maximize the wave and bringing it back a "hair". Took a measurement of T3 and it was 0.88KΩ and around 1 o'clock as the other MP-1.
I'm calling the S.S. setting solved.
MarshallJMP, I know you've been through a lot of these and can you confirm that the adjustment of T3 is very subtle, and hard to see unless you sweep the trim pot?
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Yes I can confirm this.
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(I'm calling the S.S. setting solved.) :whoohoo!: :thumb-up: