Quad Pre Modded for Stereo

Triaxis, Quad Preamp, Stereo Power series, Recto Preamp

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JD
Donating Member
Posts: 202
Joined: Sat Jun 16, 2007 3:27 pm
Location: Australia

Quad Pre Modded for Stereo

Post by JD » Tue Jan 21, 2020 4:10 am

I have loved the sound of my quad pre but the mono output of Ch1 & 2 has bugged me so I decided to seperate the preamps so I could run them in stereo.
I installed another input for ch2, removed the reverb and eq/reverb mixer circuit, used the recording outs for new outputs after the eq circuit of each channel.
I used 2 short cables from the new outlets to the effects returns which makes them separate channels bypassing the mixer circuit
I removed LDRs 2, 3, 4, 5, 6, 7,14 and 15, as these were used to allow switching between Ch1 and 2.
I always had a problem with volume and high end loss when using Ch1 and 2 together before now they sound great together.
I installed pull switches for lead mode, with LDRs bypassed the clean channel is always engaged so it works the same as the preamps in the Mark amps, I run the TC Electronic mimiq pedal in front of the quad into 2 x cabs sounds great its a keeper for sure.
Last edited by JD on Sun Jul 05, 2020 1:10 am, edited 1 time in total.

JD
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Posts: 202
Joined: Sat Jun 16, 2007 3:27 pm
Location: Australia

Re: Quad Pre Modded for Stereo

Post by JD » Thu Jan 30, 2020 6:03 am

Post Deleted
Last edited by JD on Sun Jul 05, 2020 1:10 am, edited 2 times in total.

timothymartin220
Bottle Rocket
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Re: Quad Pre Modded for Stereo

Post by timothymartin220 » Thu Jan 30, 2020 12:54 pm

JD wrote:
Tue Jan 21, 2020 4:10 am
I have loved the sound of my quad pre but the mono output of Ch1 & 2 has bugged me so I decided to seperate the preamps so I could run them in stereo.
I installed another input for ch2, removed the reverb and eq/reverb mixer circuit, used the recording outs for new outputs after the eq circuit of each channel.
I used 2 short cables from the new outlets to the effects returns which makes them separate channels bypassing the mixer circuit
I removed LDRs 2, 3, 4, 5, 6, 7,14 and 15, as these were used to allow switching between Ch1 and 2.
I always had a problem with volume and high end loss when using Ch1 and 2 together before now they sound great together.
I installed pull switches for lead mode, with LDRs bypassed the clean channel is always engaged so it works the same as the preamps in the Mark amps, I run the TC Electronic mimiq pedal in front of the quad into 2 x cabs sounds great its a keeper for sure.

https://ibb.co/7tLDy80
https://ibb.co/RvrqPrB
I am confused, i just read the manual for this unit and it is the same as the studio preamp....meaning stereo out operation....how is it you had to mod it to do something it already does? (yes the individual channels come out mono, but they sum to a stereo output after the effects loop...meaning all effects and signals already come out stereo(frankly any division of the signal before the effects loop is pointless, because the signal is fed mono into any effect and then the effect adds its stereo mojo.....unless what you did was to make a stereo effect unnecessary and make the unit feed into the stereo outs without an effect to split the signal.....which to my way of thinking is also unnecessary......or did you go with both units feeding out at the same time so you get a different signal from each side....ie, mark ii right and mark iii left).....please clarify)

JD
Donating Member
Posts: 202
Joined: Sat Jun 16, 2007 3:27 pm
Location: Australia

Re: Quad Pre Modded for Stereo

Post by JD » Thu Jan 30, 2020 1:27 pm

Stereo input Stereo output, Mark 2 on the left Mark 3 on the right. When I was using it before I modded it I was only using 1 channel and thought it was a bit of a waste So I thought why not use both.
If you read my first post it says I was getting tone loss with both leads activated like one was sort of cancelling the other out.
Now no tone loss, sound is so much better, I was going to sell it because of this and I got 2 x Studio Pre's for stereo now I use the Quad.
Using it with the mimiq pedal gives a great stereo spread which I use on the input because it sounded like crap using the stereo returns before I modded it.
Mimiq pedal works a lot better before the Lead channel.

Marshall_SLX
Mark I
Posts: 31
Joined: Sun Mar 29, 2020 12:15 am

Re: Quad Pre Modded for Stereo

Post by Marshall_SLX » Sun Mar 29, 2020 1:47 am

My Quad also suffered from that tone suck when both channels were engaged... it also suffered the same issue when both GEQ's were engaged via the footswitch even if i was only playing 1 channel... yet if both GEQ's were engaged via the toggle switches there was no tone suck... had a tech go over it he said its a design flaw of the unit... i cant believe theres not more info on it or more people havnt noticed it... its a huge issue along with the fact than channel 2 is half the volume of channel 1 on the same settings... ive had my tech fix all this up but yea these Quads while a great way to get high quality cheap mk tones they are still limited to 1 or 2 great sounds at a time like the mkiii is... if i had my time again ide get a mkiv, triaxis or mkv even... my entire quad setup incl tech fees cost the same as a used mkv.

JD
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Posts: 202
Joined: Sat Jun 16, 2007 3:27 pm
Location: Australia

Re: Quad Pre Modded for Stereo

Post by JD » Sun Nov 22, 2020 12:48 am

I have finished modding the Quad pre, as well as each channel being independent of each other I have done the ++ mod to both channels which are switchable by either pull switch on master control or by footswitch.
I have installed a power supply board and 4 relays to handle switching of ++ mods, lead mode .
The lead mode is also switchable via pull switch on lead drive or footswitchable via jack.
FU-2 Footswitch no longer required just tip to ground footswitch.
Reverb has been disconnected as it is mono.
Removed all Ldrs except lead mode and eq.
Getting rid of Ldrs fixed my volume drop problems.
Small demo video.
https://www.youtube.com/watch?v=7fFsnZk ... e=youtu.be

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