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 Post subject: Re: MPC Compressor
PostPosted: Tue Jan 18, 2011 9:14 am 
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Joined: Wed Feb 10, 2010 5:02 am
Posts: 658
Location: River Bend, North Carolina
I'm ASTOUNDED !!!! I wish I had bought all those MPC modules that I ran across over the years now.

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JD's Electras


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 Post subject: Re: MPC Compressor
PostPosted: Thu Jan 20, 2011 1:27 pm 
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Joined: Thu Jun 17, 2010 1:50 pm
Posts: 1569
Location: New Jersey
Jead wrote:
I'll miss it. Hopefully the stompbox version is just as good.

Stompbox arrived - I think I like it better than the MPC. It seems more adjustable but that could just be rationalization. :huh:


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 Post subject: Re: MPC Compressor
PostPosted: Thu Jan 20, 2011 1:32 pm 
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Joined: Thu Jun 17, 2010 1:50 pm
Posts: 1569
Location: New Jersey
heato wrote:
Rats! I was hoping that you might (or someone out there) would pop theirs open and draw/ photograph the guts for a little soldering fun. But Hey, congrats on the high sales price. I guess you just struck while the ebay iron was hot!

heato - I don't know if this helps, but I could easily get some pics of the innards of the 602C pedal. The board is really packed with stuff and I think it's significantly larger than the MPC boards.


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 Post subject: Re: MPC Compressor
PostPosted: Thu Jan 20, 2011 5:12 pm 
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Joined: Wed Dec 20, 2006 8:47 pm
Posts: 18
Sure, if it is the same circuit, it might be made to fit in a module. I have a dead phase shifter i have been putzing with, I have tested most everything, and replaced the rest, but still a compressor module would be cool.

Thanks!


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 Post subject: Re: MPC Compressor
PostPosted: Fri Jan 21, 2011 8:21 am 
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Joined: Thu Jun 17, 2010 1:50 pm
Posts: 1569
Location: New Jersey
heato - I posted some pics in a different thread. Let me know if I can do anything else to help clarify.
viewtopic.php?f=26&t=5317


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 Post subject: Re: MPC Compressor
PostPosted: Sat Jan 22, 2011 9:33 pm 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 433
Location: Saint Louis
heato wrote:
Sure, if it is the same circuit, it might be made to fit in a module. I have a dead phase shifter i have been putzing with, I have tested most everything, and replaced the rest, but still a compressor module would be cool.

Thanks!


Any of the Electra pedals, starting with the 5xx series and the 6xx series are not going to be the same circuits as the MPC modules.

All the MPC circuits were developed here in Saint Louis by John Karpowicz. They were generally patterned after other products, with adaptations and minor changes. I've posted before on the similarity between the MPC phasor and the E-H Small Stone. Karpowicz created original circuit boards made to fit the MPC module format.

On the other hand, the 500 pedals (and the later 600's) were made for SLM by a Japanese manufacturer. The company developed their own pedal designs, and you could order them with your own brand name, cosmetic design, and packaging. They had an entire line of contemporary pedals, so if you wanted to market pedals with your brand name on them, all you had to do was meet a minimum order. That's why you can find the exact same circuit, in the exact same enclosure, but sold under different brand names. The 500 series was also sold as Boston, Loco Box, Nadine, Redson, Rolling, and Volz. The 600 has been seen with Omnifex (SLM) and Solec labels. There are probably more examples than those I've listed.

The OEM manufacturing arrangement is not unusual. At one point, SLM marketed the E-H Small Stone. Looks EXACTLY like an early Small Stone, but says Electra on it:

http://www.effectsdatabase.com/model/electra/870/875

That's the deal behind Danelectro making guitars for Sears to sell under their house brand Silvertone. And Valco making amps for, well, almost everyone. Including SLM. Find a 1960's amp with the brand name Custom Kraft... it's Valco made, sold through Saint Louis Music Supply. I've had one for years, no photos, but I found an example of the same model I own:

http://www.mylespaul.com/forums/squawk- ... t-amp.html

Ok, sorry... way off on a tangent. Anyway--

Heato: check the large electrolytic capacitor in your dead Phaser. It's probably 500uf at around 16v, and it connects the V+ rail to ground. I had one that failed short. Remove the cap and test the module-- if that's the problem the module will work OK without it. You can then replace it with anything 300 to 600uf, any voltage above 12 or so. Whatever will physically fit.


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 Post subject: Re: MPC Compressor
PostPosted: Sun Jan 23, 2011 6:12 am 
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Joined: Thu Jun 17, 2010 1:50 pm
Posts: 1569
Location: New Jersey
Great info ultra sonic - thanks. Love the amp too 12 - 15 watts?


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 Post subject: Re: MPC Compressor
PostPosted: Sun Jan 23, 2011 8:39 am 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 433
Location: Saint Louis
Jead wrote:
Great info ultra sonic - thanks. Love the amp too 12 - 15 watts?


Less-- maybe 5 watts. Similar to a Fender Vibro Champ, plus reverb, and a 12" speaker. And a much bigger cabinet!

5Y3 rectifier, 6V6 single ended output, and a few 12AX7s. I think the schematic is the same as another Valco made amp, the Gretsch 6152.


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 Post subject: Re: MPC Compressor
PostPosted: Sun Jan 23, 2011 11:40 am 
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Joined: Thu Jun 17, 2010 1:50 pm
Posts: 1569
Location: New Jersey
I figured with the 4 12ax7's it may have pushed more. I bet it gets real nice breakup when dimed and records well. Those older Jensen special designs were pretty nice speakers too. Nice amp!


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 Post subject: Re: MPC Compressor
PostPosted: Sun Jan 23, 2011 12:08 pm 
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Joined: Wed Dec 20, 2006 8:47 pm
Posts: 18
Thanks for the info, and the pictures of the compressor pedal. I have tested (and found bad) the 470uf cap, and replaced it. Now I am waiting for the replacement 6800pf caps to arrive. I damaged them when I used a bit too much heat to remove that pesky potting wax. :blush:


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 Post subject: Re: MPC Compressor
PostPosted: Sun Jan 23, 2011 12:51 pm 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 433
Location: Saint Louis
Jead wrote:
I figured with the 4 12ax7's it may have pushed more. I bet it gets real nice breakup when dimed and records well. Those older Jensen special designs were pretty nice speakers too. Nice amp!


The output tube, 6V6 in this case, determines the overall power of the amp. Spec on the 6V6 makes it capable of up to 12-ish watts, but it's probably not pushing that much in this design.

The Jensen's are cool speakers. I may have even had this one reconed years ago-- can't exactly remember!

Unfortunately, this amp has never sounded as good as I wished. I have all the electrolytic caps on my next parts order, so it will get an overhaul soon. If that doesn't bring it around, it will get modified into something I like. But it IS cool to have a "real" size speaker in a low watt amp. That one thing that I was always disappointed about with Champs, and the like. 8" speaker just sounds too narrow.


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 Post subject: Re: MPC Compressor
PostPosted: Sun Jan 23, 2011 12:52 pm 
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Joined: Wed Feb 11, 2009 1:50 pm
Posts: 433
Location: Saint Louis
heato wrote:
Thanks for the info, and the pictures of the compressor pedal. I have tested (and found bad) the 470uf cap, and replaced it. Now I am waiting for the replacement 6800pf caps to arrive. I damaged them when I used a bit too much heat to remove that pesky potting wax. :blush:


Good luck, let us know how it works out.


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