Input transformer for Altec tube pres

[atavacron]

Thought I'd try to break the noob status by sharing what I've been working on...

I've been trying to figure out a cost effective alternative to buying two more Peerless 4722 octal-base transformers for my Altec 1567A. Evilbay is incredibly frustrating (seems that the moving cartridge phono guys have latched onto the 4722 as a matching transformer for their Denon players), and these little green cans are going for upwards of $150 a pop.

So I looked at the Jensen, Sowter, Lundahl and Cinemag sites. Lo and behold, there it is: the Cinemag CMQEE-3440A. As close to a drop in replacement as you're gonna get. I wish I had an original 4722 spec sheet to compare, but all of the basics are the same...there's even an extra 600 ohm tap on the 3440A...bonus!

So I called Tom at Cinemag, who was incredibly informative and a super-nice guy. He even offered to put his transformer in an octal can for me,* though I don't want to trouble him with that process for a one-off order.** Tom said that a user had done a comparison of the 4722 and 3440A in an Altec preamp circuit, and the difference is that the 3440A has a 2-3db rolloff up above 16k. Works for me, and you can't beat the $50 pricetag.


* If you're going to go that far you might want to just pony up for Vintage Loop's $140 4722 replacement that uses a Jensen - I'm assuming it's the JT-115K-E, but forgot to ask when I was on the phone with the knowledgeable Mr. Robert Payne.

** Anybody know where I can buy an empty octal can?

[adadan]

If I were you, I'd probably just order the transformers from Cinemag already in the octal cans, but if you just want to grab one for testing purposes, you can easily buy a plastic octal tube base for a couple of dollars from Antique Electronic Supply (among other places), wire up the transformer leads to the appropriate pins, and glue it with some temporary glue (silicone or something like that would probably work).

The transformer is already in a shielding can, with is shown on Cinemag's drawing to be 1.13" diameter; the octal tube bases are about 1.25" outside diameter, so the transformer might even just fit inside the octal base. Even if not, they are close enough in size to stick together one way or another.

Not the sturdiest option, but probably good as a quick kludge to test the transformer. . .

[markjazzbassist]

looking to find other alternatives as well for a 1566, any ideas? i might have to try the cinemag option.

[emrr]

Note the QE in that part # is Quad Eight, those are the early '70's Quad Eight preamp input transformer. They may need a secondary load resistor, or Zobel network, to work close/same as the original Altec. I found them strangely sensitive to loading effects compared to similar ratio vintage transformers.