SET pre-amplification?

I recently took an old 6b4g SET amp and converted it into a preamp. WOW!...I never have been so close! I get 90% of that SET sound but with the benefit of a higher power tube or SS amp at the end of the chain. I am still playing with this and I have found the only draw back is hum. It is 60 Htz which is normal heater hum so possibly the filaments should be DC heated not AC. Just sharing so you to can experiment. Good luck!
Thanks for sharing.

Did you provide some sort of low impedance load at the output (e.g., 8 or 16 ohms), to prevent the possibility of damage to the output transformer and/or output tube from inductive kickback in the transformer?

Best regards,
-- Al
Can you share with us how you converted a SET amp into a preamp? I have a 300B SET amp and want to do the same thing.

To Almarg...Yes I used an old Carver wide band coupler which has prebuilt transformer and resistor step down from high gain to low gain for interconnects. I dont beleive you can find one as nice as this one prebuilt. I bought this one in the early 80,s. If you are like me you are a DIY,er and using Ohm,s Law.
However to be clear I am sure there is a simple way to use a SET for a preamp. The whole original reason for this was I realized that most RCA interconnects used about as much power as my 5 watt 6b4g tube put out. So I am going to try straight wiring my RCA interconnects directly to the neg and pos terminals using the RCA shielding as the neg and the center as the pos. The low power SET amp may not like this due to impedence but there are ways around that as per my last message. I will add a resistor(8 ohm)or(4 ohm) in parrallel and in series to lower voltage and amperage or just one way. This is the easy way to attempt this feat. I am using the volume control on my SET amp as the volume for my stereo now but I could put it after my preamp and still use the SS preamp as volume control.
I can help you with this if you want to try this. A 300B would sound great! The 6b4g is an octal 2A3 so lots of great midrange. I would try using resistors from Mills. You can buy these on line at parts express.BUT I would try to find a device like my Carver coupler. I know car audio stores have high to low adapters for car radios to turn the power out channels in to low level RCA signal levels for amps and being most SET amps are less than 25 watts this shouldnt be a problem. The Carver coupler I am using is the same thing just made specifically for home audio. That should work. If you still have issues I will get exact specs for your amp and help you build one just for it. Let me know if I can help further. Jay
I will part with my Carver coupler for trade or money if anyone is interested. I will post pix of the coupler in my system in tweaks. I think I could build my own in fact I know I can so I am willing to acceppt any reasonable offer.
What tube preamplifiers are not single ended triode (SET) designs?
Not all preamps are single ended and even the ones that are dont use 2a3 or 300B,s for the signal. Well I am sure that this already exist however I couldnt afford it so thus this Idea.
OK, I was under the impression that most were (based upon a certain manufacturer using this as a major selling point, when is was NOT per many... posting to the contrary).

Seen posts of people using (SET) headphone amps as preamps, but I only remember an early Musical Fidelity model off the top of my head, used in this nature.

Old production 6b4g's are no longer inexpensive, but I'm certain you are already aware of this.

Yes! That was my reasoning behind my 6b4g amp. All the glory of a 2a3 but a 3rd of the price. Or less. But I dont have to give up quality. I am quite surprised by the performance of my old SET amp and the tubes have a good long life.
And yea manufacturers love to baffle with BS instead of Wow with wisdom. its just marketing given its bad marketing. I try to learn as much as I can before a purchase. Ive learned you need to KNOW not think you know in this hobby or you will be taken advantage of quickly and you will be broke with a bad sounding rig and that my friend is a travesty.
Jayb77 have you tried using a 45 or a type 10? They make less power, so you can get greater bandwidth out of the OPT (and you don't really need the power). Plus the 45 is supposed to have it all over the 2A3 (although I suspect that most of that has to do with the additional bandwidth you get the the lower power).
Supratek DHT preamps (Cabernet and Grange) use 45, 300B, PX4, 101D, 26 or 33 type tubes and have that beguiling SET magic.
Atmasphere I am considering the purchase of a Jame Burgess 45 right now. My brother let me hear his and wow. Just when you think it couldnt get is. As soon as I get it I will give my thoughts butIm sure Ill like it.