I just ordered one of these...

[VelvetGeorge]

Well, similar in many ways:

triode gain stages

bias adjust for output device

output transformer

the parts are all much smaller. But if you can build the 100 watt kit, you should be able to build this. I had to turn my iron down to avoid cooking anything. And there are some really small solder contacts so a magnifying glass will help.

But I can't recommend the kit highly enough. A great way to get a ballsy sounding pre.

george

[Myopic Void..]

George,

I have the SCA 1272 modules from Tim. I like them and they are an improvement over my 1402 board pre's. My Ampex 350's tube pre's are pretty rich sounding but the 1272's are more robust. I had some AMD broadcast console modules that used the same API 312 discret Op Amp but they pretty much blew IMO compared to the 1272's or Ampex 350's. I sold them.

As you now the 1272's are a bit tedious to build, it is easy to make a mistake and damage the pads or put a Tantalum in backwords etc. Putting together a Metro 67 is much much easier IMHO. Wire length prep for the Output Tranny was very important...those holes are so bloody small. SCA 1272's are not cheap when you get into the proprietary chasis and power supply but the chasis construction is superb and new PS3 power supply can supply more juice than the originals. From what I have been told the circuit is more spot on than the Vintech stuff. I think it is about 500.00 with shipping total per channel made to order. I am about to order another 1272 from Tim. I am not sure about the API stuff plus you need to get the better OP AMP for a $80.00 upcharge.

Using the 1272's tracking to my Ampex 1" 8trk or 1/2" 4trk at 15ips sounds very robust, and they color the sound alot more than my Ampex tube pre's. I have not used them to track on digital so what the gains are there I have no idea.

I did a back to back live recording with the Mackie XDR pre's and then the 1272's, the difference was really obvious. More 1272's on the way...

Cheers,

Eric

Caveat...watch out for the bottom trim pot as it is so loose feeling it can easily be bumped and a little minor turn makes a big change in the gain. I wish the had used a pot with more resistance.

[VelvetGeorge]

I agree on the trim pot. I might change that resistor on the board to make it a 6db fine adjustment. That would allow setting it full up or down when the 5db per click gain knob gets you in the right range.


VG

[Myopic Void..]

Let me know what the PCB number resitor you change and what you think about it after you do. I had a bad problem when I was using my live mobile tape unit, I think the 1272 pot moved on it's own due to the high SPL from a Acoustic 301 cab about 10-15 teen feet away (as you know the sound wave on a 18" folded horn about 15-20 feet out can slap you around a bit if you are in the line of fire. LOL. It caused the guitar track #4 to drop out a DB or more. Unless it was tape drop-outs?...but I suspect the culprit was the 1272. I thought about taping the pot down but it would look unsightly and perhaps damage the chasis paint. You sound like you have a good solution.


Eric

If you think of any cool tweaks let me know. I was temted to put CC resistors in some places but real estate on the 1272 PCB is limited...

[Bainzy]

You could always try getting 1/8w CC's, they have some NOS ones at http://www.surplussales.com

[Lou]

http://www.seventhcirclestudios.com/SCA/SCA.htm

the 1272 kit. Looks cool. And cheaper than a real 1272 module at around $600. I'll post my progress and findings on the kit.

I just can't stand the Muckie pres any longer. I really need to capture the sound of my amps, if I'm going to sell them online.
It's a leap of faith to buy an amp without playing it first as it is. Let alone, to not at least here it represented properly.


Sounds like a great excuse for me to invest in some recording gear....


George

Hey George...I have been lurking around and found this preamp you built...How does it sound?