tomb
Member of the Trade: Beezar.com
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The last time I talked to Cinemag, or had someone follow my recommendation to purchase them, Cinemag had no issue winding just two for a customer. Transformer mfrs (including Edcor) tend to be OK with that, as long as the part # is something they've already produced. Getting them to wind custom transformers that they've never done before is usually much more expensive and requires a volume purchase, most likely.Thanks for the info, very interesting.
I'd love to try some Lundhahls.. I have been looking at their website and they only seem to list 3 headphone specific models, none with an input impedance of 10k and suitable secondaries. I think I could try and work it out with respect to turns ratio but I'm not sure how close they would be, I also have limited knowledge in this field so aren't that confident. The Papa Rusa design specifies "The various (secondary tap) configurations allow for about an 8k load with 32 ohms, a 20k load with 300 ohms, and everywhere in between with other headphones.". I also noticed that the way they have secondaries set up I'm not sure how easy it would be to have switchable secondary taps, do you have to just wire it for one specific impedance?
That leaves the Cinemags, I see that the CM-15615PC is a custom order, maybe I could just order these? Are there any published specs with info on secondary taps etc?
Please forgive all my novice questions, this is really the first tube amp I've built from a schematic by myself.
They should be able to make those CM-1561PC pair for you without much issue. You just call them up, discuss what you want, and give them a credit card #. You can ask them any questions while you're at it. You might ask for David, if he's still there and mention that they were for ECP/Beezar Audio's T3 (Torpedo III) amplifier. The CM-1561PC has two output windings (optimized for low and high impedance) that can be controlled with a simple DPDT switch on the output. Unfortunately, I don't seem to have an actual schematic in my files, but Doug Savitsky made them as an exact replacement for the Edcor PCW10K-7K/300-32 (used on the Torpedo I). They can be found here: https://edcorusa.com/products/pcw-1...1&_sid=2581b6de7&_ss=r&variant=41236729200827. So, if you order the Cinemags, they'll be the same (electrically) as the Edcors. The difference is the Cinemags were a bit taller - can't remember how much, maybe 1/2" - 3/4" taller.
Lundahl is a different animal altogether. They have exclusive distributors that they work through and typically do large batch manufacturing for catalog stock items only once a year. They'll still pretty much custom wind whatever you want, as long as you order 50 of them. They're definitely better than either the Cinemags or Edcors, but probably not as much difference as between the Cinemags and Edcors. Trying to put numbers to subjective listening, it's sort of like the Cinemags are 50% better than the Edcors, while the Lundahls are 20% better than the Cinemags, if that even makes sense.
Doug had a number of them leftover from our T4 builds and sales. The thing to do - if you want to try the Lundahls - is send Doug a PM here on Head-Fi (user account: dsavitsk). Ask him if he still has a pair of the T4 Lundahls and if he'd sell them to you. The Lundahl is electrically identical to the Edcor and Cinemags, but output impedance for the low Z winding is a bit higher (50 ohms optimization, if I remember correctly). Besides quality, the Lundahls also have a very low DC resistance compared to either the Cinemags or Edcors, which is important for low impedance headphones. DC resistance tends to govern with low impedance loads. At least that's what I understand from conversations with Doug.
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