[Goosepond]

It's obviously strictly for looks, especially if you llike tubes!!!

Gene

[srb]

I wouldn't have or want 24 tubes in a power amplifier let alone in a preamp / headphone amplifier!  Doesn't make a lot of sense.

[FullRangeMan]

These 24 tubes will make alot of heat let alone when need new tubes will not be a minor expense.

[Archguy]

It's obviously strictly for looks, especially if you llike tubes!!!

I daresay.  Knowing relatively little about circuitry I still have to think that some number of those tubes aren't doing anything functional.

  I'll bet the Chinese could make a reasonable copy for $2,000.

Douk are clearly down with historical re-creations:
http://www.ebay.com/itm/Douk-Audio-Classic-Power-Amplifier-Hi-Fi-Stereo-2-0-Channel-Amp-2-150W-Gold-2016/272265554611

[Archguy]

Archguy

The APC box will improve safety and longevity - transformers will not run so hot, tubes will run at or close to correct voltages.

Tube amps don't use regulated power supplies, so an amp made for 110 volt use on a typical mains circuit here in NC, for example, will get as much as 126 volts. This translates to roughly 15% overvoltage on every single voltage in the amp. So 6.3 volt heaters will now be 7.2 volts, and so on. If the high voltage supply was supposed to be 350 volts, it will be just over 400 volts. I have confirmed this by measurement, but it isn't something for subjectivists to be alarmed about

Sometimes the effects of the increased voltage are mysteriously magnified by the transformer being ever so slightly more efficient at 60Hz (when it is designed for Chinese 50Hz).

A lot of people think the USA mains is 115 volts. It is actually nominally 120 volts which is already about 10% high for Chinese 110 volt gear. 10% is a lot at high voltages.

Hope this makes sense.

Thanks again for your helpful information.  I was one of those who thought that voltage fluctuations between 110 and 120 were considered just fine or 'in the range' by the power company, as well as appliance mfrs.  I'll pick up one of those APC boxes for the winter.  Because until them I'm using SS components I think.  However, my goal is to have the first house in America heated entirely by tube amplifiers!

[mick wolfe]

Heated with tube amplifiers My small listening room combined with an 845 based SET satisfies that parameter.  Another note regarding your recent purchase. How are these amps biased? I don't see mention of bias pots, bias settings or a self biasing circuit. ( the latter probably not possible at the "nearly free" price point) Thx and good listening.

[Archguy]

Yeah I mentioned that on my vid comments.  My nearest guess is that when they need biasing, you give them away in the Karma forum.

Since mine are gonna be winter-only, maybe they'll last a couple years

[mick wolfe]

Actually nothing to lose considering the price. When it starts to lose its magic, drop in a fresh set of matched tubes and cross your fingers.

[srb]

Strange—there is no mention of power output in the specs. In fact, there is almost no meaningful information about this device!

Not even MTBF ..... Mean Time Between Fires ? 

[mick wolfe]

Not even MTBF ..... Mean Time Between Fires ? 

Must be monitored at all times. Short bathroom breaks are permitted.

[raindance]

Thanks again for your helpful information.  I was one of those who thought that voltage fluctuations between 110 and 120 were considered just fine or 'in the range' by the power company, as well as appliance mfrs.  I'll pick up one of those APC boxes for the winter.  Because until them I'm using SS components I think.  However, my goal is to have the first house in America heated entirely by tube amplifiers!

A bit of background on the problem with Chinese gear not targeted specifically at the US market - their mains voltage is 220V 50Hz. They use a dual primary on their transformer, with the primaries wired in series for 220V and parallel for 110V. Without the APC voltage regulator, all bets are off regarding the gear potentially catching fire if a capacitor voltage rating is exceeded or a resistor exceeds its wattage rating.

Equipment made for the US market is designed from the start for 120 volts 60Hz. So the "normal" fluctuations we experience won't cause a fire.

[Archguy]

Actually nothing to lose considering the price. When it starts to lose its magic, drop in a fresh set of matched tubes and cross your fingers.

Seriously, when your tubes need biasing you can just replace them?  That'd be cool.  But how to I know which ones need it?  I suppose I need some kind of tester.  This is one of several reasons I'm glad this thread isn't in the tube circle.  They'd be plotzing about now.  Or awhile ago.

A bit of background on the problem with Chinese gear not targeted specifically at the US market - their mains voltage is 220V 50Hz. They use a dual primary on their transformer, with the primaries wired in series for 220V and parallel for 110V. Without the APC voltage regulator, all bets are off regarding the gear potentially catching fire if a capacitor voltage rating is exceeded or a resistor exceeds its wattage rating.

Equipment made for the US market is designed from the start for 120 volts 60Hz. So the "normal" fluctuations we experience won't cause a fire.

Thanks again for your explanations.  Good info!  BTW I just bought an amp imported from Japan.  Step-down transformer included which I hope is enough.  Can't help it, the thing is beautiful.  The amp, not the transformer. 

I'd better check and make sure my homeowner's insurance is in force.  They raised my deductible from 1,000 to 1% of home value. Sucks.
It was either that or pay a much higher premium, and I've never even made a claim.  But I digress.

[mick wolfe]

All the tubes listed on page 1 of this thread ( from the  eBay spec sheet) are readily available. 6P1's are no longer in production, but there's probably a boatload of them in a warehouse somewhere. The 6H8C is the Russian equivilent of a 6SN7.  The rectifier tube( 5z4p) is also available.