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Low voltage Tubelab sse


I am a first time tube amp builder and I am gathering information on building a single ended amp. The Tubelab SSE looks interesting to me but the rather high B+ voltage is a bit disconcerting. I haven't found any modified schematic employing a lower voltage

If I use a 325-0-325 xfmr, would it work properly except at a lowered power output? If not, what other changes need to be done?



2004-07-05 10:23 am
Praki, I have a TSE with 300B and I'm very happy with it, as I hope you will be with your SSE.

These tubes need their correct voltage, I'd not think on lowering it.
Rather I'd think in making a neat custom build and being VERY careful with your own security.

Anyway surely George will answer your request.

Best luck
what other changes need to be done?

A 325-0-325 volt transformer will supply 350 to 400 volts depending on the line voltage, the rectifier tube and output tubes being used. The only modification that should be needed for this voltage range is a slightly lower cathode resistor for the output tubes to keep the current in the desired range.

At B+ voltages much below this range the 10 K resistor connected to the 10M45 chips should be replaced with a wire jumper or a low value resistor to give the 10M45 more headroom. I needed the jumper on my 6V6 amp (325 volts B+ from a 275-0-275 volt transformer) to cure some distortion.
I used an Allied Electronics 6K56VG for my 6V6 SSE and for my 45 based TSE. It is a good budget transformer made by Hammond but it has a 120 volt primary only......not sure where you are located.

The SSE uses old RCA 6V6GT's in triode mode with Edcor XSE15-8-5K OPT's, makes about 2 watts per channel and is about the closest thing to a 45 DHT amp you can get for about one third the cost of a DHT amp.
I also built a low voltage SSE using Edcor XPWR009-120 power xfrmr with specs --> 550V (275-0-275) at 175mA center tapped, 6.3V at 4A and 5V at
3A. OPT's are Edcor GXSE15-8-5K.
It plays very nicely with 6V6 output tubes, also 6F6 and 6K6 tubes using suitable cathode bias resistors.

As George mentioned, for B+ voltages below 350V the resistors R14 and R24 that connect to the 10M45 chips should be replaced with wire jumpers.

With different tube rectifiers such as 5AR4, 5V4, 5Z4, 5W4, 5Y3, 6087 you will be able to dial in a range of B+ voltages. A higher B+ voltage can be had
with the SS rectifier and you can install both SS and tube rectifier using a switch to select between the two.
I concur with Tubelab that the 6V6 SSE in triode is about as good as it gets. I prefer the common GE 6V6GT, personally.

If I had a do over, I think I would go with the Edcor GXSE transformer over the Edcor XSE, or one of the smaller Transcendars. One or the other is on my upgrade list, likely the Transcendar.

A fair amount of information is starting to compile on low power low voltage SSE's down in the Tubelab forum. As Spendorite notes, there are a lot of low power tubes that work very well.