Hi rnolan
Thank you for your replay.
I use my MP 1 as a preamp into a return fx loop of a dsl 50 (power amp only)
The TC eq in front is to adjust eq for different guitars i use (LP, stratocaster, telecaster).
The two notes torpedo live is a professional load box and cab sim and stands just after the power amp - i do not use real cabs; from there the signal goes to some effects (not used all togheter obviuosly) to mimic a studio setup where effect are added post cabs and mics.
I choose fx using a voodoo lab gcx midi rack looper (forgot to mention, sorry)
ADA digitizer used for chorus (sort of an analog vibe chorus)
Intellifex is for 3 or 8 voices chorus
SPX 90 for Symphonic preset only.
These fx are before the stereo line mixer which is used to put my delay and rev in parallel with the signal.
All fx are set to unity gain.
I'll try to do what you suggest.
Thank you
Peter

Hey Duce, so has it stopped working?

Here's my thinking...
Ok battery dies, so no changes kept, you replaced battery, that will keep RAM powered up.

From my experience, not that I've had data errors, is various things trigger full power up diagnosis e.g. remove and re-insert chips (RAM, EPROM, CPU).  The other culprit I've been dealing with with my friend is the ribbon cable from the front panel to the PCB.  In his case it wouldn't boot up at all.  He's now replaced the ribbon cable socket on the PCB (same as MP-1 socket, and thanks MJMP ). But he also had to (very carefully) expose the conductive material on the ribbon cable end that plugs into the socket.  Any one of those contacts that fails can cause issues from no boot, to partial etc.

So worth checking .

Hey Peter, I suspect your problem is with the other units (and gain structure) in the signal chain, and you have allot of them.  And -9 bass is extreme  .

Start simple, LP > MP-1 > mixer > Monitors.  Make that sound good and bring in other units to do what you want when you want.  You may have too much tops like this as the MP-1 is designed to go into 12" speakers and, full range has much more top end (tweeters etc.).  Is the torpedo a cab sim, if so you could use it in the MP-1 loop, or last before the monitors.  BTW the MP-1 headphone out is a cab sim (sort of) so you can use it to get a stereo out to the mixer if you have too much tops.

To trouble shoot your current setup, try putting all the units in bypass and bring them in one at a time.

So my main question is, you have 8 (ish) fx units in you signal path.  Why?  what does each one do that you want/like? and what are the settings on them?  (e.g. they all have input and output gain (boost?) and can change the frequency response).  You have a TC eq up front, why? you shouldn't need it, though I get some like a unit to boost the gain at the front end. So what is is set to?

I'm wondering if you are using the MP-1 like a distortion pedal? Not that that isn't doable but it's not optimal, it's an amazing pre amp controllable via midi, not a pedal.  IMHO the MP-1 should be the main player in a rig and bring in other things to enhance that (e.g. various Fxs).  But hey there are many ways to get a sound. 

My signal chain is:
guitar LP R7 with Slash pickups - TC 1128 Eq - ADA MP1 - DSL 50 fx loop return - torpedo live - ADA digitizer - Intellifex blackface - SPX 90 - Rane sm 28 line mixer - 2 Roland SDE 2500 - SDR 1000+ - analog mixer - monitors.
Always too much bass...
 
Peter

While this seems a bit sacrilegious (since I'm an analogue tube die hard), but the cheapest and easiest (probably) way to get close to an authentic MP-1 (without having one) would be a small cheap(ish) laptop with a VST wrapper program (e.g. cantabiles VST wrapper, free) and the Nembrini Audio MP-1 VST ($30 USD).

Hey Harley, yes all the B200s schematics we have are posted in the vault

Hey Duce, if you haven't done this already (and you have replaced the filter caps), try re-flowing all the solder joins.  The bottom comes off and makes this reasonably easy.  It fixed my B200s.  Also make sure the jacks don't ground to the chassis, although that tends to make a horrible hum not so much a buzz.

That's not to say there isn't a different problem (that MJMP can help with more than me) but it's a good starting point.

When I did the re-flow, some of the joins needed some additional solder, some didn't.  Obviously be careful not to over heat the join and lift a pad .

Quote from: Kazinator on October 28, 2024, 10:07:58 PMThere is just a bit of "tubbiness" to it, likely because it extends into the upper mids. Next, I will try changing R167 to 3.1 kΩ. That will move the center up to 4.6 kHz.

I did this yesterday and was quite pleased with the result! I jammed on this for a bunch of hours.

I can hardly believe what is coming out of the rig, with the equalizer flat to 4 kHz.

Overall, my impression is that the repurposed Presence isn't focused enough on its core frequencies, so there is an issue between the tone being a bit dark, or else a bit brittle, without the point in between being a great sweet spot. The fizz doesn't grate on the ears or anything. But speaking of which, with the two midrange cuts, there is a lot of remaining high end past 5 kHz that I'm rolling off externally.

So, overall good success for a Round 1, but I'm now thinking about Round 2:

I would like to change the Mid control (which I have not touched) so that it spans the entire range currently occupied by Mid (560 Hz) and Treble (1.0 kHz). It might be centered on, say, 800 Hz, and wider than stock.

Then Treble could be higher than stock (2.5 kHz) rather than lower. Say, boost a bit past 4 kHz. (That one is easy: pair of 5.6n capacitors).

Then Presence could be set higher than stock also, so it can be set negative, and start cutting somewhere past 5 kHz. Well out of the way so that it doesn't take the bite out of the tone.

IDEA: If we change the C-R-R-C band-pass network in Presence to C-R-C-R, we can get a two-pole high pass, so when used for cutting, it will cut -12 dB per octave after the second knee frequency.

Are the schematics for the B200S in the vault?

We should have it in there. My guess at this time would be to check the values of the resistors connected to the filter caps to see if they've drifted out of tolerance. After 35+ years, it's very likely.

  When I get to my B200S, I'll be checking those out too as well as recapping elsewhere on the board. (I would use carbon film resistors in the power filtering section).

@ Dante,

   Look at what TC Electronic did with the 2290 delay. I have that pedal, and it's freakin' amazing!

   Same with Roland, look at the SDE3000, or SDE3000EVH, just to name a few.

   All are fully programmable. I don't think it would be too much of a stretch to get the MP-1 in a Synergy sized module these days, but I agree with you, the cost would be a lot more than the average Synergy module.