Well, I built the amp and after checking the wiring and voltages, it works wonderfully and sounds really nice. The only thing of note is the 6n1 cathode voltage in the schematic is 1.7v and 100v plate but mine is measuring 2.2v and 120v, is this too high?
I also notice a slight blue glow at the base of the Chinese 6p3p's anode plate where they meet the mica insulation which gets brighter with higher volumes. Any concerns?
I also notice a slight blue glow at the base of the Chinese 6p3p's anode plate where they meet the mica insulation which gets brighter with higher volumes. Any concerns?
What happened to siliconray, are they still in business?
When I go to siliconray.com they seems to be in the construction business not audio.
When I go to siliconray.com they seems to be in the construction business not audio.
I decided to give this kit a try after not having built a tube amplifier this year.
DIY Tube Amplifier Kit 6P3P + 6N8P Single Ended Tube Power Amplifier Kit | eBay
It went together pretty straight forward but with 2 feedback networks I did have oscillation. I eliminated the one from the OPT to driver tube and decreased the value of the resistor going from output tube to driver tube to have adequate feedback for this pentode amplifier and this cured the problem. I do not understand why there are two feedback circuits and may someone can fill me in on why. Upon receiving the kit I was pleasantly surprised to find a NOS Russian 5U4U rectifier tube and NOS Russian 6H8C for the driver tubes. The output tubes were Chinese 6P3P and they did sound OK but I swapped them for some NOS Russian 6P3S's with an improvement in sound. I am very impressed with the quality of the OPT's for such a very inexpensive kit. Stainless steel chassis with holes already drilled, decent iron,tubes and Chinese parts for $192. shipped. As far as sound, very good with nice bass. I measured 4.5 watts at clipping with a nice looking square wave at 1Kz. A touch of ringing I am not too concerned about at the moment. The square wave falls apart above 10K hz which can be expected with inexpensive OPT but the sine waves look good from 20hz to 20K hz. The 4.5 watts is far stronger than the figure. I do own very efficient horns but even with my 85db test speakers the amplifier had authority and I could not detect clipping at a very high volume in my kitchen. Very satisfied with the value.
DIY Tube Amplifier Kit 6P3P + 6N8P Single Ended Tube Power Amplifier Kit | eBay
It went together pretty straight forward but with 2 feedback networks I did have oscillation. I eliminated the one from the OPT to driver tube and decreased the value of the resistor going from output tube to driver tube to have adequate feedback for this pentode amplifier and this cured the problem. I do not understand why there are two feedback circuits and may someone can fill me in on why. Upon receiving the kit I was pleasantly surprised to find a NOS Russian 5U4U rectifier tube and NOS Russian 6H8C for the driver tubes. The output tubes were Chinese 6P3P and they did sound OK but I swapped them for some NOS Russian 6P3S's with an improvement in sound. I am very impressed with the quality of the OPT's for such a very inexpensive kit. Stainless steel chassis with holes already drilled, decent iron,tubes and Chinese parts for $192. shipped. As far as sound, very good with nice bass. I measured 4.5 watts at clipping with a nice looking square wave at 1Kz. A touch of ringing I am not too concerned about at the moment. The square wave falls apart above 10K hz which can be expected with inexpensive OPT but the sine waves look good from 20hz to 20K hz. The 4.5 watts is far stronger than the figure. I do own very efficient horns but even with my 85db test speakers the amplifier had authority and I could not detect clipping at a very high volume in my kitchen. Very satisfied with the value.
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Hi guys, I'm about to take the plunge on Raindance's schematic.
Can anyone confirm if there are 4 - 22uf 450v caps on this, one each for plate 1-6 on input driver, and one each on b+ g2, or maybe this is one shared like the original schematic.
Raindance, hopefully you can confirm if your out there.
Can anyone confirm if there are 4 - 22uf 450v caps on this, one each for plate 1-6 on input driver, and one each on b+ g2, or maybe this is one shared like the original schematic.
Raindance, hopefully you can confirm if your out there.
There's two 22uF 450v caps in that circuit, one shared on the driver plates and one on the grid supply. I've built a variation of that circuit using a 6BZ7 and two 6BW6 into a pair of Tomiko OPT's with great results.
I got one of these a few years ago, but was non very happy with the sound, a bit rough and waffly. it seems that my version is the same circuit as raindance circuit. I tested it was running about 6 db of feedback. I changed the feedback resistor to 1k (was 2k), and it is now running at 10dB and is quite listenable now, nice and clean and tight. interestingly this feedback ratio should be back to the 10k - 1k that is mentioned earlier.
hello all ...
i build the kit 5Z3P / 6P3P / 6N1 ... and replace the tube ... GZ 32 / EL 300 / 6N2P-EV , change the résistor 330 Ohms to +/- 500 Ohms for EL 300 ( mode penthode ) , change résistor 47 Kohms to 100 Kohms for 6N2P .
not feed back for use and not test power max ...
i build the kit 5Z3P / 6P3P / 6N1 ... and replace the tube ... GZ 32 / EL 300 / 6N2P-EV , change the résistor 330 Ohms to +/- 500 Ohms for EL 300 ( mode penthode ) , change résistor 47 Kohms to 100 Kohms for 6N2P .
not feed back for use and not test power max ...
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hello if my speakers are 4ohms, shouldn't the feedback be taken from the 4ohm trafo tap instead of 8ohms?
Hi,
Ive just built the 6p3p amp and all working well except one side has bad distortion, both 4 and 8 ohm, ive switched the tubes around, checked the wiring, switched over blue and red coming from that OPT and still there, Other side is working fine, any thoughts on what it could be? Thanks for any help
Seth
Ive just built the 6p3p amp and all working well except one side has bad distortion, both 4 and 8 ohm, ive switched the tubes around, checked the wiring, switched over blue and red coming from that OPT and still there, Other side is working fine, any thoughts on what it could be? Thanks for any help
Seth
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