I had some 5867A's, some 4PR400 (a pulse rated 4-400), and a pair of 4-1000's. I sold them all for this very reason. The required plate voltage and load impedance make this a very difficulty OPT to wind unless you can live with less than HiFi specs. Thw size and heat load of such an amp is out of the question in south Florida. I can't play my 40 WPC SE tube amp for more than an hour even with both AC units cranked to 60 degrees.
I did keep a few 833A's and the power transformer from a big Harris transmitter just in case I decide to build something stupidly big, but I doubt it will ever happen.
My current project is a more mild mannered 125 WPC stereo power amp that fits inside a 3RU box.
Wolfpunk and Champ Electronics have set the example. Now I guess I need to get off my butt and build the "big one" that I have been talking about for maybe 10 years but haven't built. I think I will need 8 output tubes, 4 per 500 watt channel! Anyone who knows me knows what kind of tubes they will be. And yes I already have the OPT's.......rated for 400W each at 20 HZ!
Champ has built two very different design 1 KW guitar amps:
The Champ CBA-20807 1000 Watt Amplifier - Part 1
Champ 1000 Watt Tube Amp
You should do it! Join the 1kW club haha.
I've seen those other kW amps and I wanted to go the transmitting tube direction at first until I started trying to find someone to build the transformers. Trafomatic said they could do it but the price would have been substantially more than I was willing to pay given the uncertainties of a project like that. Not only that but those voltages are scary. I've tasted 650VDC before through my hand and that was no laughing matter. Touch 2.5kV and you're dead instantly.
I've seen those other kW amps and I wanted to go the transmitting tube direction at first until I started trying to find someone to build the transformers. Trafomatic said they could do it but the price would have been substantially more than I was willing to pay given the uncertainties of a project like that. Not only that but those voltages are scary. I've tasted 650VDC before through my hand and that was no laughing matter. Touch 2.5kV and you're dead instantly.
I started down the road to a 100+ WPC SE tube amp 5 or 6 years ago using 833A's. I paid a transformer winder who makes OPT's that are well respected on this forum to make me a prototype OPT. I put together a quick and highly unsafe prototype amp to test the OPT. The results were not good enough for HiFi use but it would make a wicked 200 watt SE guitar amp. I may build it some day, but I really have no use for it. The picture shows the prototype. The large chassis on the left is a power supply out of an old Motorola base station transmitter. It is rated for 1500 volts at 500 mA. The yellow Radio Shack clip lead carries the 1500 volt output! The amp chassis in the middle is my 845SE amp with the output tubes removed. The 833A is connected with clip leads. Note the high tech vice grips and hose clamps socket for the 833A. The custom OPT is to the right of the 833A and the 500 watt load resistor is in front of it.
6 years ago there was a thread about making a big amp using paralleled 807's. Someone mentioned some surplus Plitron OPT's that were rated for 400 watts at 20 Hz for $137 each. I grabbed a pair and so did a few other forum members. They were all sold in 3 or 4 days. I have been using them for experiments ever since, but they really want to find a happy home in a nice BIG amp. At low power (150 watts) the 3db points are below 6 Hz (my measurement limit) and 70 KHz. I have run them up to 525 watts at 1KHz.
I took one of Pete Millett's big red boards (engineers amp), paralleled both channels, stuffed it with 35LR6's, and connected both channels to one of these OPT's. I used a bench supply that goes to 650 volts and limits at 1.7 amps. At full tilt the amp made 525 watts at 5% distortion (just into clipping) and drew about 1.3 amps. The pictures show operation at 504 watts, the 3% distortion point.
When the time comes I think that I will do a pair of mono block amps in rack mount chassis. Probably 4 RU each. I have tubes that are bigger than the 35LR6, so 4 will be enough for anything short of continuous sine wave operation. I just finished a driver board design for the little 125 WPC amp that will also work here. I will need to find a suitable power supply probably using a big toroid, or a combination of smaller ones.
Attachments
I have a new replacement output transformer for the Trace Elliot V-8, which had 8 KT-88 for one channel. The transformer only has the same amount of iron as the V6 output transformer, but the windings are different. Just mentioning it because it's on sale for 1/3 off from the parts supplier in the US. But it's a guitar amp transformer, not hi-fi, and probably doesn't go very high or low at those power levels. But it's a LOT cheaper than the plitron.
Impressive. Wish I could have got some of those plitrons. That was a total steal at that price! And they don't make them anymore. So I went and took some shots of my scope and voltmeter showing 500 watt output of one side at 1kHz, clipped 625 watts, and for those that don't believe me, an unclipped 492 watt 20Hz output into 4 ohms. Only problem is I can't post pics from my phone so it'll have to wait til I get to work Monday since I don't pay for internet at home. I know, sounds like a cop out but its true!
Plitron still has the PAT-4141-00 in their catalog. Same specs at the ones I have but it is encapsulated. There is just one minor drawback.....they are $469 each.
I checked their surplus page and there is an absolute monster toroid that would make an awesome bench supply for tube amps. It is rated for 2.4 KVA and has five 120 VCT windings. Wire them all in series and you have a 600 volt 4.1 amp secondary with a tap every 60 volts.
It weighs 50 pounds and costs $280 though.
I checked their surplus page and there is an absolute monster toroid that would make an awesome bench supply for tube amps. It is rated for 2.4 KVA and has five 120 VCT windings. Wire them all in series and you have a 600 volt 4.1 amp secondary with a tap every 60 volts.
It weighs 50 pounds and costs $280 though.
You talk about insanity !
Well a big tube amp has been on my agenda for some years now. The slight problem I have is - funding ( lack of ) - and somewhere to plug the beast in.
Maybe I should invest in a 50 KVA diesel generator as well while I'm at it. There are a number of water cooled triodes you could use in push-pull that will deliver 100 KW or more. Tubes such as the following list made by Thales in France, are readily available through Richardson Electronics.
Triode RS CJ - Thales
And you will need a few transformers for these monsters - So buy yourself a copy of the >
"High Power, High Voltage, Audio Frequency Transformer Design Manual" which shows how to design Audio Transformers up to 250 KW continuous, with a working 10 KW design in the text.
Here is the link I placed with the basic info available through NTIS in the USA >
http://www.diyaudio.com/forums/tube...ltage-audio-frequency-transformer-manual.html
Here is a sample of the volumes in the series >
http://www.dtic.mil/dtic/tr/fulltext/u2/403400.pdf
HIGH POWER, HIGH VOLTAGE, AUDIO FREQUENCY TRANSFORMER DESIGN MANUAL: GENERAL ELECTRIC CO HOLYOKE MA: Amazon.com: Books
Best of luck finding quality hifi speakers - but at least try using maybe 8 of these jackhammers at 4KW RMS each for the sub woofers >
MTX Audio JackHammer Subwoofers
A 10kw all tube stereo ping pong bass rig?
Frankly... that sounds insane.
But to be fair the warning of such is right there on the face plate.
Well a big tube amp has been on my agenda for some years now. The slight problem I have is - funding ( lack of ) - and somewhere to plug the beast in.
Maybe I should invest in a 50 KVA diesel generator as well while I'm at it. There are a number of water cooled triodes you could use in push-pull that will deliver 100 KW or more. Tubes such as the following list made by Thales in France, are readily available through Richardson Electronics.
Triode RS CJ - Thales
And you will need a few transformers for these monsters - So buy yourself a copy of the >
"High Power, High Voltage, Audio Frequency Transformer Design Manual" which shows how to design Audio Transformers up to 250 KW continuous, with a working 10 KW design in the text.
Here is the link I placed with the basic info available through NTIS in the USA >
http://www.diyaudio.com/forums/tube...ltage-audio-frequency-transformer-manual.html
Here is a sample of the volumes in the series >
http://www.dtic.mil/dtic/tr/fulltext/u2/403400.pdf
HIGH POWER, HIGH VOLTAGE, AUDIO FREQUENCY TRANSFORMER DESIGN MANUAL: GENERAL ELECTRIC CO HOLYOKE MA: Amazon.com: Books
Best of luck finding quality hifi speakers - but at least try using maybe 8 of these jackhammers at 4KW RMS each for the sub woofers >
MTX Audio JackHammer Subwoofers
I never saw them or I would have been tempted to get a second set. It seems that Plitron had them on their surplus page for nearly 2 years until they were mentioned in the 807 thread. I grabbed the first set with intentions of getting more after testing the frequency response (no specs were given). They were all gone 3 days after I placed my order.
As promised, here are some output results. Sorry for the flash on my scope screen! First one shows 45VAC RMS into 4 ohms, the second clipped at over 50, and the last is the output at 20 Hz. The frequency is displayed in the top corner of my handheld meter. There is some distortion thereat 20Hz. Some of that is from my subpar signal generator though. It doesn't do the best at low frequencies, I really need to get a better one. But you can see there is no crossover distortion or clipping going on with full output at that frequency.
Attachments
You appear to be under a misconception?, crossover distortion occurs at very LOW power levels, not at high power levels (and isn't something that valve amps do anyway).
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.