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Author Topic: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod  (Read 48851 times)

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herbyguitar

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #150 on: Time Format »

So the pedal (filter) has to go in front of the MP1... That explains a lot since all my effects go through the effects loop and that's why the 'fix' didn't originally work for me.
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #151 on: Time Format »

So the pedal (filter) has to go in front of the MP1... That explains a lot since all my effects go through the effects loop and that's why the 'fix' didn't originally work for me.

Correct: straight in front of MP-1 input (front or rear input should make no difference for a V2, I assume).
In the loop you would connect chorus, delay and similar effects that must be after preamp and before power amp.

A buffer (or a buffered pedal) must be connected to main input, just after the guitar.

Note: a true bypass pedal will have no effect, of course. As an alternative, a pure buffer like TC Electronic Bonafide would be perfect. I just repeat that Boss DS-1 buffer seems to have a good effect on MP-1's overall tone.

About the filter (different from a buffer), that's made by a couple of resistors that could be soldered to MP-1's main input jack's tip and ground lugs directly.
But this should be tested yet.
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herbyguitar

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #152 on: Time Format »

I run wireless and all my pedals (effects) are in a rack. I would have to put a pedal in line and stuff it inside my rack. Not too big a problem but not really convenient.
« Last Edit: Time Format by herbyguitar »
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #153 on: Time Format »

I run wireless and all my pedals (effects) are in a rack. I would have to put a pedal in line and stuff it inside my rack. Not too big a problem but not really convenient.

Well, you can just run a test and see what happens.
I would disconnect wireless devices and use cables.

Just put a buffer or a buffered pedal between guitar and MP-1's input.
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MarshallJMP

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #154 on: Time Format »

Well this is quite a strange solution for this. The MP-1 also has a FET input buffer. Now a low pass filter won't help because you can hear the frequency, so you can't filter that out else you get a gap in the audible frequency range. I think it's more of a phase issue and acoustic feedback together with some capacitive or inductive stuff that is going on in the cable. Using a buffer makes everything low impedance between the guitar and the MP-1, this way you get another phase/frequency plot.
Now I'm thinking out loud you know, not sure if this is the case.
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #155 on: Time Format »

Well this is quite a strange solution for this. The MP-1 also has a FET input buffer. Now a low pass filter won't help because you can hear the frequency, so you can't filter that out else you get a gap in the audible frequency range. I think it's more of a phase issue and acoustic feedback together with some capacitive or inductive stuff that is going on in the cable. Using a buffer makes everything low impedance between the guitar and the MP-1, this way you get another phase/frequency plot.


This describes an incredibly bad luck!  :lol:

So, do you still think that putting a 560K resistor in R17 would be an attempt that worth a try?
Or can it be something that went wrong with the FET input buffer in the MP-1, after mods?

I did the test with 2 different buffered pedals and it works the same way.
Now I'm about to buy a TC Electronic pure buffer and see what happens.
« Last Edit: Time Format by Iperfungus »
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MarshallJMP

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #156 on: Time Format »

Don't think the R17 will work. Was this unit a V1 or V2?
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #157 on: Time Format »

Don't think the R17 will work. Was this unit a V1 or V2?

It's a V2.
Rev. G board.

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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #158 on: Time Format »

Quick update guys.

I bought the small TC Electronic Bonafide buffer...a pure buffer with a very, very good S/N ratio.
Placed it in front of MP-1 and the result is the same...or also better, because the overall signal's quality is awesome.
The squeal is kept away by any buffer here and I can fully enjoy the killer tone of this MP-1.  :headbanger:

One of these days I'm gonna open the ADA and mess around with internal gain trimpots for OD1 and OD2.  :lol:
« Last Edit: Time Format by Iperfungus »
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rnolan

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #159 on: Time Format »

Hey Max, seems you have found a workable solution  :thumb-up: , now we need to work out why and, if applicable, come up with a way of building it into the unit (possibly as part of the MDRT mod).
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #160 on: Time Format »

Hey Max, seems you have found a workable solution  :thumb-up: , now we need to work out why and, if applicable, come up with a way of building it into the unit (possibly as part of the MDRT mod).

Ciao Rich!

Well, yes...this is a very good workaround and can 100% get rid of the issue.
Now the best would be to understand it and fix it.  :thumb-up:

I assume that if this problem would be 100% related to mods, it should arise in the same way with any unit that has those mods.
More or less the same happens to my MP-1 and to the ones owned by MikeB and herby.
As soon as they will have time to run a simple test with a buffer or a buffered pedal (the Boss DS-1 or any other Boss pedal will do the job...they are all buffered) in front of their MP-1s, we'll know if this WA would work for everyone...but I assume that it will.

Then, as I discussed with Phil, I think that the only way to understand where in the signal path (input stage?output stage?) the issue has its origin would be that he, as soon as he will have time of course, would take a MP-1 with the same mods (SS+ Ultra with MDRT), connect it to a power amp and speakers with no other devices in between, connect a guitar and set a patch with my "extreme" settings:

OD1 : 7.5
OD2 : 7.5
Master : 5.5
Bass : 6
Mid : 6
Treble : 9
Presence : 12

With such patch and no buffer the MP-1 should squeal like a hot girl having an orgasm.  :lol:

I assume it will be not so easy to come to a full understanding and find the fix...also because, as Phil explained, the MP-1 already has its FET buffer...maybe that buffer needs to be modified to lower impedance more?
It's still not so clear if the issue could come from an internal oscillation (but in that case the buffer should have no effect, I assume...) or from an external radio frequency captured by cable/guitar and sent into the MP-1 to be amplified by tubes.
We also do not know if environmental conditions could modify it (frequency peak due to different source of radio frequency/noise/disturb? different locations?).
It's a little messy, yes.  :lol:

But we've a starting point, at least.  :banana-upsidedown:

 
« Last Edit: Time Format by Iperfungus »
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herbyguitar

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #161 on: Time Format »

I haven't unpacked my MP1 yet but I do remember the issue was lessened or worsened by the type of tubes.

I ran:
Electro-Harmonix
JJ
Mullard
Sovetek
Tung-Sol
and a couple that I didn't know what they were.

JJ was the quietest and Mullard was noisiest. Don't know if it has any bearing at all. Just an observation.
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bunkyloo

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #162 on: Time Format »

Holy crap I just got the noise mod and the ss tube board but no MDRT I have started doing it but got busy I hope I don't have any trouble. :o
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #163 on: Time Format »

I haven't unpacked my MP1 yet but I do remember the issue was lessened or worsened by the type of tubes.

Don't know if it has any bearing at all. Just an observation.

On my side, I didn't find any difference with different tubes: more or less, the issue was the same with all tubes I tested.
Of course, this doesn't mean anything...
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Iperfungus

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Re: Herby's attemt @ SS Mod, Noise Mod, MDRT Mod
« Reply #164 on: Time Format »

Holy crap I just got the noise mod and the ss tube board but no MDRT I have started doing it but got busy I hope I don't have any trouble. :o

No panic.
It seems that in some way the issue has something to do with MDRT, in some cases at least.
Do your mods and come back with results: the tone is killer.  :thumb-up:
And if, as I suspect, without MDRT you'll find no issues...well, this could confirm the aboves.
« Last Edit: Time Format by Iperfungus »
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