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 Post subject: IIC+ mod to Quad?
PostPosted: Mon Feb 12, 2007 9:10 pm 
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Mark II

Joined: Mon Nov 06, 2006 10:24 pm
Posts: 61
I've heard the first channel of the Quad is based upon the IIC. Does anybody know the differences between the IIC and IIC+ to enough of an extent that it would be possible to mod my Quad to IIC+?


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 Post subject:
PostPosted: Tue Feb 13, 2007 12:31 am 
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Mark III

Joined: Fri Sep 02, 2005 5:26 pm
Posts: 460
Location: juneau, ak/phoenix, az
Funny that you ask :) This idea has popped in and out of my mind for quite some time now since I own a Studio (based on the IIC preamp) and a Quad. Theoretically speaking, it is possible because the quad ch1 is pretty much a IIC preamp section that would require a few tweaks overall including the lead circuit. Even ch2 could be modded since it's also pretty close.

I actually printed out the schematics for my quad and some C+ schematics to compare and there's only a few differences which "should" be easy to change. Now I'm only talking on a very basic level, swapping out components so they match on paper. How would it sound? I dunno :D

I DO know that snowman had his studio modded to C+ specs so it can be done. Bendinelli supposedly really digs the Quads too :)


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 Post subject:
PostPosted: Tue Feb 13, 2007 12:40 am 
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Mark II

Joined: Mon Nov 06, 2006 10:24 pm
Posts: 61
I'm thinking about doing it. I was considering doing what you said you did with the schematics, and maybe I will do that if it's as simple as you say. I'll check it out. I'm also thinking about adding just a tad more available gain to the ch1 lead.


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 Post subject:
PostPosted: Tue Feb 13, 2007 12:58 am 
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Mark III

Joined: Fri Sep 02, 2005 5:26 pm
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Location: juneau, ak/phoenix, az
Yeah I have started to go down that route, then I open up the quad and slowly turn away :D


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 Post subject:
PostPosted: Tue Feb 13, 2007 1:03 am 
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Mark II

Joined: Mon Nov 06, 2006 10:24 pm
Posts: 61
Yeah, just took a look and tried to trace out what I'd need to do. Basically adding a few capacitors and resistors to the lead stage, and possibly changing a few thought the values are pretty close so it'd probably be unnecessary. Also the lead master/master volume circuit after V12B needs to be changed significantly.


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 Post subject:
PostPosted: Tue Feb 13, 2007 5:07 am 
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Single Recto
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Joined: Tue Apr 18, 2006 3:18 am
Posts: 1126
Location: Italy
Do you all think the differences between IIC and IIC+ are more relevant in the preamp or in the poweramp section?

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 Post subject:
PostPosted: Tue Feb 13, 2007 12:19 pm 
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Mark III

Joined: Fri Sep 02, 2005 5:26 pm
Posts: 460
Location: juneau, ak/phoenix, az
I think they're equally important but having the preamp section would probably be better than just having the power section you know? I mean look at JP's current rig where he's using a C+ preamp, external graphic EQ, and a recto poweramp and he's still getting great tones :)


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 Post subject:
PostPosted: Tue Feb 13, 2007 4:43 pm 
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Single Recto
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Location: Italy
you're right, I forgot JP's rig! That ugly green rack unit... :?

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 Post subject:
PostPosted: Tue Feb 13, 2007 5:18 pm 
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Bottle Rocket

Joined: Wed Feb 07, 2007 5:45 pm
Posts: 18
Where can i find pics of the JP rig your referring to?


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 Post subject:
PostPosted: Tue Feb 13, 2007 6:18 pm 
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Mark II

Joined: Mon Nov 06, 2006 10:24 pm
Posts: 61
I just drew the schematic for the Quad channel 1 lead circuit with IIC+ modifications. There are still other modifications around the lead drive/master volume section which I'll draw up sometime soon. Added components are in red, components whose values are changed are in blue, and components whose values do differ but not significantly are in green (I don't think it's really worth changing out the green ones).

Edit: I screwed up the schematic. Here's how it should look:
Image


Last edited by schnarf on Tue Feb 13, 2007 10:26 pm, edited 1 time in total.

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 Post subject:
PostPosted: Tue Feb 13, 2007 6:59 pm 
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Mark III

Joined: Fri Sep 02, 2005 5:26 pm
Posts: 460
Location: juneau, ak/phoenix, az
rickgk wrote:
Where can i find pics of the JP rig your referring to?

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Image
Image


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 Post subject:
PostPosted: Tue Feb 13, 2007 7:16 pm 
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Mark III

Joined: Fri Sep 02, 2005 5:26 pm
Posts: 460
Location: juneau, ak/phoenix, az
schnarf wrote:
I just drew the schematic for the Quad channel 1 lead circuit with IIC+ modifications. There are still other modifications around the lead drive/master volume section which I'll draw up sometime soon. Added components are in red, components whose values are changed are in blue, and components whose values do differ but not significantly are in green (I don't think it's really worth changing out the green ones).

Image


Which C+ schematic did you use? I don't recall the two additional resistors on the input :)


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 Post subject:
PostPosted: Tue Feb 13, 2007 10:18 pm 
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Mark II

Joined: Mon Nov 06, 2006 10:24 pm
Posts: 61
It was posted somewhere on here. Here it is:

Image

Also I realized I screwed up the schematic a little bit. Here's how it should look:

Image


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 Post subject:
PostPosted: Sat Feb 17, 2007 6:05 pm 
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Mark III

Joined: Fri Sep 02, 2005 5:26 pm
Posts: 460
Location: juneau, ak/phoenix, az
Have ya tried anything yet? I got all the way to the point of pulling the quad out of my setup and removing the cover again...then stopped dead in my tracks. Mesa and their crazy super nice tight wiring :P


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 Post subject:
PostPosted: Thu Apr 26, 2007 7:09 pm 
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Mark III

Joined: Fri Jun 09, 2006 11:31 am
Posts: 227
Location: Jacksonville, FL
bump

Did anyone try this yet? Is it worth the effort?

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