Obsessed with the Quad Eight 312/310/MM403 sound - any ideas?

[PhilipMarlowe]

As the title says I'm obsessed with the sound. Electrodyne has got the 511 EQs and the 501 preamps but the EQs lack one whole band and have other frequencies as well. Short of buying extremely expensive vintage versions, what are other options for people in Europe specifically looking to get that sound?
Any schematics of the 310 or MM403 would be appreciated. I posted schematics of the 312 in another thread for people to find.

 

[knave101]

I'm glad to hear that you like these. I have a bunch of 310, and 312 eqs i'm finally about to mount after 35 years of procrastination. I looked for the 312 schematic and didn't find it. I do have some QE documentation if it might help.

Here are some photos of the 312 vs 310, and some of the CA27 documentation. input pins for 312.

 

[thomasdf]

I am also totally in love with these modules / sound / topology but they are super rare in Europe and crazy expensive...
My dream console would be a 12ch of this ... obv full DIY heh

 

[Viitalahde]

Quad Eight is awesome. Almost 20 years ago I built a passive EQ based on the Pultec circuit with a Quad Eight line amp+Jensen output transformer after it. I don't have the EQ anymore but I still remember how good it sounded.

 

[Gold]

Big QE fan here. I used MM312S in my mastering rig for over 20 years.

 

[Viitalahde]

Big QE fan here. I used MM312S in my mastering rig for over 20 years.

Did you sell them?

 

[Gold]

Did you sell them?

I still have them with PSU and UTC LS30's on the Input. I have more of them too. Some of them I came close to destroying in my youthful exuberance and when no one knew what they were. If I knew they would become so valuable I wouldn't have been so cavalier.

 

[Viitalahde]

I might ask you to sell me a pair at some point..

 

[Gold]

I might ask you to sell me a pair at some point..

Cool. If you want a pair that needs to be stitched back together I'll sell them cheap. All parts included.

 

[mjrippe]

Let's move those datasheets to the Technical Docs thread, where I have posted the 312 and 310 schematics.
I had a client with line input only 310s and I added the mic pre circuit and racked them with original QE meters. It was a helluva lot of work but turned out great.

 

[samplebias2]

I'd also love to own one, a single racked unit... for the final bass cut/sculpting of the Cylon voice, just how they did it in 1978. It takes a few trips through 511, 712, and the 312 EQ's to get it just right. It's the final missing piece in my studio!

 

[knave101]

I finally had my 312's mounted. They look awesome and sound great. 28VDC power supply.
I also had my Langevin 252 EQ's mounted as well. Original QE amp cards...and 3/4 original output transformers...I'll put an original in there someday...or not. 4 more to mount someday. Waiting on my 312 mic/EQ channels. I have nothing this nice to compare them to, but they do sound nice, as I recall when I last used them in 93.

 

[ach]

Does anyone have, or know where to find, replacements for the "pointer knob" under the Quad Eight style dual concentric knobs?

 

[sneak]

I finally had my 312's mounted. They look awesome and sound great. 28VDC power supply.
I also had my Langevin 252 EQ's mounted as well. Original QE amp cards...and 3/4 original output transformers...I'll put an original in there someday...or not. 4 more to mount someday. Waiting on my 312 mic/EQ channels. I have nothing this nice to compare them to, but they do sound nice, as I recall when I last used them in 93.


View attachment 105038View attachment 105039

Woah, awesome setup!! I've only heard good things about the Langevin EQ's. I only recently found out about them after seeing Eric Valentine use em in a video.

 

[knave101]

Thank you!
Heritage audio now makes a faithful recreation it would seem of the Langevin EQ in the Motown knob, rather than slider format. I have a Heritage 2 channel Neve type preamp with EQ and I sold my Warm 273EQ as the Heritage was in my opinion, better sounding (that is only my opinion, and in no way a critique). I think their gear is really good.

The 252 EQ is very subtle and very noiseless, with not too much cut boost at each frequency, only what you would need for a track or mix that is fairly good to begin with. You have to toggle it in and out to hear what the differences are pre-post. So in this way it is very musical indeed. The EQ points are on the money for where the action is, so to speak. Nothing like any other graphic EQ I've ever used.

 

[sneak]

@knave101 Great info, that must be why people are able to make such aggressive moves with it. Glad the EQ points are working for you.

About the Quad Eight 312s; Are there any posts here that helped you in getting those racked up with line cards and all? Did you separate the PSU?

 

[knave101]

@knave101 Great info, that must be why people are able to make such aggressive moves with it. Glad the EQ points are working for you.

About the Quad Eight 312s; Are there any posts here that helped you in getting those racked up with line cards and all? Did you separate the PSU?

I didn't rack them. Rob Harvey at WorldProAudio did. He's a great guy, tons of experience, and reasonable price too.

 

[sneak]

I didn't rack them. Rob Harvey at WorldProAudio did. He's a great guy, tons of experience, and reasonable price too.

Nice! Just checked out their site, loving the write-ups on mods they offer, they have awesome ideas. Thanks for sharing.
I've been looking to rack some modules myself so if you decide to sell the 4 extra 312's you mentioned, I'm all ears

 

[knave101]

The QE Rack is finally finished! Thanks Rob at WorldProAudio!
For the Preamps, I had to get the proper input transformers from David Gerren at Cinemag, use my original QE output QE-3041 transformers and one CA-37 amp card from the original QE Board. Then get two Op-Amp cards AM4 from Ken Hirsch....and you have two preamps with EQ! The circuit boards on the 310's have places for the AM4 and input transformer....so it was fairly straightforward to add the parts to complete the preamp.

I will have to compare against my A-Designs Pacifica....which is my all around favorite pre, and is designed after the QE from what I understand.

Note the Antelope Studio Synergy Core....which is a real nice interface.

 

[MidnightArrakis]

I'm glad to hear that you like these. I have a bunch of 310, and 312 eqs i'm finally about to mount after 35 years of procrastination. I looked for the 312 schematic and didn't find it. I do have some QE documentation if it might help.

Here are some photos of the 312 vs 310, and some of the CA27 documentation. input pins for 312.

[I have a bunch of 310, and 312 eqs] -- Should you ever wish to have additional 310 and 312 EQ's, I can "Reverse-Engineer" the PCB's as shown in your photos and then provide you with the GERBER and N/C Drill data files to have new/old PCB's fabricated!!! I have "Reversed-Engineered" several API mixing console PCB's for a guy who was restoring an original 1974 API mixing console and he wanted all "New/Old" circuit boards because the actual original circuit boards were just "worn out". In addition, an aerospace company had once contacted me and had hired me to "Reverse-Engineer" a circuit board that had been originally designed back in 1979 for some model of a U.S. fighter jet back then. The aerospace company wanted me to not only "Reverse-Engineer" the original PCB (with -- NO SCHEMATIC -- no less!!!), but they also wanted me to "modernize" the layout by converting all of the "Thru-Hole" components to new "Surface-Mount" components. SHEESH!!! In the end.....instead of the aerospace having to use the original manually "hand-taped" artwork from 1979 to have new PCB's fabricated, they now could use modern GERBER and N/C Drill data files for their new circuit boards. And.....as a significant side benefit.....unlike the original 1979 circuit boards that had lots of vias, I was able to design their new PCB -- WITHOUT -- any vias because my CAD PCB-design software allows me to "see" things while routing the board that the original PCB Designer could never imagine!!! I know this because I also used to "hand-tape" PCB's!!!

In any case.....I'm here if you need any "new/old" PCB's and/or sheet-metal designs for chassis and front-panels. TAA-DAA!!!

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