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Unread 10-23-2011, 08:08 AM   #1 (permalink)
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1987x LAR/MAR PPIMV mod

20 minutes ago I finished modding my 1987x.
Tried it and it sounds pretty good to me. Haven't cranked it up higher than 8:30 o' clock for longer than a second, but I can say that at low volume levels it sounds better than any attenuator I have tried so far.

Pics:

Before starting:





5K6 swamp resistors installed:



Gnd5 and QR wires and 220k resistors removed! Bias wire installed:


Installed the other wire:


Under the PCB:



Wires that go to pin 5 of the power tubes installed:



Wired up the pot:



Hole drilled in chasis:


Ready to install the pot:



Ready to put it back in it's cabinet:



Done!





Cheers!
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Unread 10-23-2011, 08:39 AM   #2 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Congratulations! Was this your first mod?
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Unread 10-23-2011, 08:49 AM   #3 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Originally Posted by hbach View Post
Congratulations! Was this your first mod?
Thanks!
No, I've moddded my 800 before. I have done some mods on pedals and guitars too.
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Unread 10-23-2011, 11:45 AM   #4 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Nice job!

Has anyone tried this on a 1959?
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Unread 10-23-2011, 04:18 PM   #5 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Nice job!

Has anyone tried this on a 1959?
Thanks, midnight!
Many people have. Should work just as well as on my 1987. The mod is exactly the same, except that the wires that go to the power tubes go to V4 and V6 (there are jumpers between pin 5 of V4 and V5 and pin 5 of V6 and V7 on a 1959) instead of V4 and V5.
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Unread 10-23-2011, 06:13 PM   #6 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

I have it on my 2061 clone and it works great too. It just uses a different pot value.
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Unread 10-23-2011, 07:18 PM   #7 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Nice job!

Has anyone tried this on a 1959?
I have one on my 1959 clone and it kicks ass
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Unread 01-01-2012, 10:27 AM   #8 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Hi, I'm looking at buying at 1987x with the effects loop in the near future and would like to maybe have this mod done by a proffesional since I suck at this sort of stuff. Is there a schematic available for this?

Thanks, Josh
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Unread 01-01-2012, 11:18 AM   #9 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Oops Nevermind. I did some more research and using this mod in conjuction with an amp having an effects loop is not the best. I guess it's OD pedals for room volume and cranked for the stage
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Unread 01-01-2012, 01:37 PM   #10 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Oops Nevermind. I did some more research and using this mod in conjuction with an amp having an effects loop is not the best...
There shouldn't be any issue using a PPIMV in an amp with an effects loop. What concerns did you have?
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Unread 01-01-2012, 01:55 PM   #11 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

I read a post here in the forum mentioning something about since the PPIMV mod uses the PI that when using the effects loop it would be distorted because the PI works with the Effects Loop? Unless I completely read it wrong.
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Unread 01-01-2012, 02:27 PM   #12 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Originally Posted by Neaves The Wicked View Post
I read a post here in the forum mentioning something about since the PPIMV mod uses the PI that when using the effects loop it would be distorted because the PI works with the Effects Loop? Unless I completely read it wrong.
I can send you the schematic and manual I found if I can find it somewhere haha. PM me your email.
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Unread 01-01-2012, 02:39 PM   #13 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Awesome, Thanks!
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Unread 01-01-2012, 03:34 PM   #14 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Quote:
Originally Posted by Neaves The Wicked View Post
I read a post here in the forum mentioning something about since the PPIMV mod uses the PI that when using the effects loop it would be distorted because the PI works with the Effects Loop? Unless I completely read it wrong.
The effects loop is right before the PI and the master is after it so any effects should sound the same as they do without the PPIMV. You can make the PI overdrive a little more when turning down the PPIMV, mainly because negative feedback is reduced, but the overall sound from effects should be okay.

I've never heard anyone mention any problems when using the MV with a loop. However, my amps don't have loops so I can't say for sure based on experience.
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Unread 01-01-2012, 03:44 PM   #15 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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The effects loop is right before the PI and the master is after it so any effects should sound the same as they do without the PPIMV. You can make the PI overdrive a little more when turning down the PPIMV, mainly because negative feedback is reduced, but the overall sound from effects should be okay.

I've never heard anyone mention any problems when using the MV with a loop. However, my amps don't have loops so I can't say for sure based on experience.
Just wondering... do you use any modulation effects?
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Unread 01-01-2012, 03:45 PM   #16 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Oh Ok what you said sounds familiar to what I read. Yup I messed that up,

Thanks Guys!
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Unread 01-01-2012, 04:08 PM   #17 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Quote:
Originally Posted by Lespaulnmarshall View Post
20 minutes ago I finished modding my 1987x.
Tried it and it sounds pretty good to me. Haven't cranked it up higher than 8:30 o' clock for longer than a second, but I can say that at low volume levels it sounds better than any attenuator I have tried so far.





Cheers!
Good work!

What was the cable and the gauge of it that you used?

Did you use a dual 250K pot with the two 2.2MEG resistors?

Did you use metal flame or carbon comp or carbon film?

I want to try this mod on my '88 2205 as well.


Regarding the FX loop together with a PPIMV? I have the LarMar PPIMV on my Ceriatone 2555 which has an FX loop. There's no issues there. But the Jubilee loop is a very different topology than most loops, as the Jubilee loop is before/upstream of the tone stack and before the last gain stage as well.

The thing I've noticed with the PPIMV on the 2555, is that it is actually not all that useful. The Jubilee seems to actually get a bit harsher using the PPIMV and running the normal Master Volume up past 8. And the PPIMV negates the Presence circuit as well somewhat. I am actually thinking of removing the PPIMV on the 2555 and use the vacant hole to try something else. Maybe a Resonance control.

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Unread 01-01-2012, 04:40 PM   #18 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Originally Posted by jonzguitar View Post
Just wondering... do you use any modulation effects?
I use chorus occasionally but mainly just a couple of clean boosts. I have run a phaser and flanger in front of the amp and they sound fine. Just my opinion, but the only time you really need a loop is for reverb or delay when using a lot of preamp gain. I use an analog delay in front when clean or lightly overdriven and it works fine.
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Unread 01-01-2012, 05:06 PM   #19 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Good work!

1) What was the cable and the gauge of it that you used?

2) Did you use a dual 250K pot with the two 2.2MEG resistors?

3) Did you use metal flame or carbon comp or carbon film?
1) I don't know I just got some decent size coax wire

2) I used a 220K pot, and the 2.2 meg resistors

3) carbon film
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Unread 01-01-2012, 07:11 PM   #20 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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1) I don't know I just got some decent size coax wire

2) I used a 220K pot, and the 2.2 meg resistors

3) carbon film
Coax cable like what is used on a cable box to TV?
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Unread 01-03-2012, 01:33 PM   #21 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Many use RG-174 coaxial cable----- this has PVC inner insulation that is sensitive to heat so it can be tricky to solder in place---- there are other types with PTFE (aka Teflon) inner insulation available.
This place has several types listed---scroll down to Coaxial Cable: Wire

PS-- FWIW i use RG-174 and i'm careful when soldering it---- but Lar/Mar PPIMV's can be installed without using shielded cable----- it depends on the routing needed in the particular amp--- Here's a Lar/Mar PPIMV i put in an SIR #34 Mod Marshall 4010 --- twisted pairs work just fine in many cases----i just built a (mostly) Metro 50 watt 1987 clone (w/leftover Metro chassis, faceplates, turretboard, and PT) and i used twisted pairs for the Lar/Mar PPIMV on this one--no pics yet.
4010 with Lar/Mar:
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Unread 01-03-2012, 01:47 PM   #22 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

I want to do this too, was it difficult? And we need sound clips...
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Unread 01-03-2012, 01:57 PM   #23 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Coax cable like what is used on a cable box to TV?
Yes, but stereo coaxial cable and just regular coax cable.

Regular for the bias wire (the thickest one)
And the stereo coaxial cable for the other wire.
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Unread 01-03-2012, 02:02 PM   #24 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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I want to do this too, was it difficult? And we need sound clips...
I'll try to record some soundclips when I have time. It wasn't very hard IMO, but I don't think it's a beginner mod. Wiring up the pot was tricky actually, especially the one I had, that is actually meant to solder onto a PCB. (no holes in the lugs) you can see the pot was tricky on the pic, my soldering on that pot is really nowhere near as clean as it usually is.
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Unread 01-03-2012, 02:14 PM   #25 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

The modded 4010 was one of the amps used in this demo of several SIR/AFD-type modded amps i built or modded--- the 4010 was used in the right rhythm track------ the lead tracks are the white 14/7 watt shown in the pic (#34 Mod preamp-- into EL84 x 2, cathode biased--- pentode/triode switch to drop from 14 to 7 watts).
No Lar/Mar PPIMV on the 14/7 but a similar 25 watter (6v6 x 2) i built does have a Lar/Mar.
Demo: SoundClick artist: gldtp99 - page with MP3 music downloads

Lar/Mar in the 25 watt #34 Mod:


i used twisted pairs from the board to the PPIMV pot and shielded cable (RG-174) from the pot to the output tubes on this one---i was concerned about interference from high voltage wires---- this one wasn't built initially with a Lar/Mar (added with the #34 Mod) so it isn't the best looking example i've ever seen ---it does work 100%---- the amp was built first as a near stock 25 watt JCM 800 with a "Power Dampering" type of MV----everybody likes it better like this--- this one wasn't used in the demo above--i had five total SIR/AFD-type amps to pick from for the musicians who played on the tracks--- three 50 watters (incl the 4010 above), the 14/7 used on the leads, and this 25--- this is the only one that didn't get used but it sounds pretty much the same as the others--- one player liked it the best out of all of them but it got lost in the shuffle in the studio that day......................gldtp99
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Unread 01-03-2012, 02:50 PM   #26 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Cool, sometime this year I will be doing the same. My amp is handwired and is a little Frankenstein anyway.

Nice clip gldtp99...
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Unread 01-03-2012, 03:52 PM   #27 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

Now just need to add this very easy mod... and we're all done



ja nie te danke maatje
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Unread 01-03-2012, 04:03 PM   #28 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

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Now just need to add this very easy mod... and we're all done



ja nie te danke maatje
Ha! Google translate!

I was actually considering a 1 wire mod, is there a way to make it switchable?
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Unread 01-03-2012, 04:26 PM   #29 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

een draad mit skakelaar, ik is 'n Afrikaner flaams

Last edited by Strateuphoria; 01-04-2012 at 06:21 PM.
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Unread 01-04-2012, 04:19 AM   #30 (permalink)
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Re: 1987x LAR/MAR PPIMV mod

are you going to do the onewire mod?

post soundclips!!
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