That's awesome news! Enjoy your new preamp!
All this activity in this thread made my solder gun itchy, hence my glow tubes are back in as of yesterday. Chose a sample VR150 and VR75 each, in series, such that I get about 220V DC on the top of the gyrator, which is adjusted then for 150V DC on the plate of the 26. I chose the two on purpose because I like both the purple and the orange glow. Shallow, I know. 😀
And all this thanks to Andy! -- who stirred the waters about DHTs on this planet. He'll go down in history as 26-Andy!
All this activity in this thread made my solder gun itchy, hence my glow tubes are back in as of yesterday. Chose a sample VR150 and VR75 each, in series, such that I get about 220V DC on the top of the gyrator, which is adjusted then for 150V DC on the plate of the 26. I chose the two on purpose because I like both the purple and the orange glow. Shallow, I know. 😀
And all this thanks to Andy! -- who stirred the waters about DHTs on this planet. He'll go down in history as 26-Andy!
Attachments
For the 26 you could use the octal 0D3 or the 7 pin 0A2 to get 150v. I've used both. Any views on relative merits of either?
I almost got mine fully assembled, just need to mount the volume control and RCA connectors. Initial testing has been positive - no hum, no microphonics. Sounds great.
The thread has been very helpful - Tx.
The thread has been very helpful - Tx.
I almost got mine fully assembled, just need to mount the volume control and RCA connectors. Initial testing has been positive - no hum, no microphonics. Sounds great.
The thread has been very helpful - Tx.
Nice build! Any reason why you are using two K&K Shunt regulator(1 per tube) instead of only one?
I use the same sockets. For resistors(filament bias), I have mine inside as well but i use aluminum plates to shield the heat flow to the chassis. The aluminum plates are lifted about 5mm.
An externally hosted image should be here but it was not working when we last tested it.
Amandarae - ditto on your nice build too.
I thought having a dedicated regulated B+ for each channel will further reduce B+ noise.
I thought having a dedicated regulated B+ for each channel will further reduce B+ noise.
I almost got mine fully assembled, just need to mount the volume control and RCA connectors. Initial testing has been positive - no hum, no microphonics. Sounds great.
The thread has been very helpful - Tx.
Nice build congrats, only one box?
I see you are using aluminium clad cathode resistors. You may want to consider something better. I tested out a whole lot of resistors for filament bias a while ago, and to my ears the best were types such as this:
Ohmite Wirewound Resistors 20 Watts 10 Ohms | eBay
Very tasty if you're in the USA. I'd go for them!
Too bad they don't ship to Canada.
Hey guys, has anyone tried a mosfet buffer in the 26 preamp? I get lower thd in simulation. I might just try it one of these days.
The second image is the thd values for the one with the buffer, the third image for the circuits without a buffer. I guess this could be the poor man's alternative to an output transformer when the next stage has a lowish input impedance.
Hey guys, has anyone tried a mosfet buffer in the 26 preamp? I get lower thd in simulation. I might just try it one of these days.
The second image is the thd values for the one with the buffer, the third image for the circuits without a buffer. I guess this could be the poor man's alternative to an output transformer when the next stage has a lowish input impedance.
Attachments
An externally hosted image should be here but it was not working when we last tested it.
My 26 Preamp. Thanks for this thread and the helpful guys keeping this thread as educational as can be.🙂
Abe
Still lots of "available" room, Felipe!😀
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Abe
