Please re-read post #10, do you really need 300W?! And where can you get the OPT that can work with the 2.2kV B+? These are the key questions that you need to work out.
Wimpy OPT's and lowish voltages will not work well with the 813's. The filament/cathode will not support the peak emission needed to crank Pink Floyd on less than about 1250 volts, which requires a high impedance OPT.
I tested the 813's at the upper limit of my bench power supply which is 650 volts. I tried triode and pentode configuration with a 5000 ohm, 6600 ohm, 10,000 ohm , and 13200 ohm load. The most power I could get was around 35 watts with a 6600 ohm load. I can do that with 6L6GC's. Game over, tubes sold.
Pete Millett built a single ended (one tube per channel) 813 amp that ran on 800 to 900 volts. He gets about 20 watts at clipping and around 10 watts at 1% distortion. Details here:
813 SE triode amps
A decent amp with 813's to get over 100 watts per channel will require over 1000 volts of B+ and still need a rather high impedance OPT.
A couple pictures from my 813 tests are included.
Want to crank Floyd on a budget, read through the DCPP thread, including my modifications for a 125 WPC amp. At least 12 of them have been built including the 3 that I made. With good parts this thing can put a Metallica concert (without the pyro) in my living room through 96dB speakers with 15 inch woofers. It uses $20 worth of tubes and off the shelf transformers.
http://www.diyaudio.com/forums/tube...p-p-power-amp-design.html?highlight=6l6GC+AB2
I tested the 813's at the upper limit of my bench power supply which is 650 volts. I tried triode and pentode configuration with a 5000 ohm, 6600 ohm, 10,000 ohm , and 13200 ohm load. The most power I could get was around 35 watts with a 6600 ohm load. I can do that with 6L6GC's. Game over, tubes sold.
Pete Millett built a single ended (one tube per channel) 813 amp that ran on 800 to 900 volts. He gets about 20 watts at clipping and around 10 watts at 1% distortion. Details here:
813 SE triode amps
A decent amp with 813's to get over 100 watts per channel will require over 1000 volts of B+ and still need a rather high impedance OPT.
A couple pictures from my 813 tests are included.
Want to crank Floyd on a budget, read through the DCPP thread, including my modifications for a 125 WPC amp. At least 12 of them have been built including the 3 that I made. With good parts this thing can put a Metallica concert (without the pyro) in my living room through 96dB speakers with 15 inch woofers. It uses $20 worth of tubes and off the shelf transformers.
http://www.diyaudio.com/forums/tube...p-p-power-amp-design.html?highlight=6l6GC+AB2
Attachments
Last edited:
I don't have much experience with the 6C33. The high heater current melted the contacts in the (wrong) sockets that I tried them in. I never got around to trying them in proper sockets, and they were sold when I had to seriously reduce my stash of tubes before moving it all 1200 miles.
I think there is merit to using the heaters in series not parallel. Its kinder to the sockets..and contacts.
I found it easier to float the heater supply with a polypropylene cap..let it charge up via leakage..
Regards
M. Gregg
Last edited:
Assuming the OP has to use the PT with B+ around 2kV, where would he even find a OPT that has the high primary impedance and the high power capacity required? I assume this one has to be a custom job and likely cost $$$ to get one done...
813s are RF finals, and should be reserved for RF experiments. If he doesn't want to do that, then sell 'em and use the proceeds for types better suited to audio power amplification. Hams will definitely want them. Getting 100+W doesn't require extreme voltages and load resistances. (attached).
6CB5: This one gets past the century mark for less than half the voltage, and with a pretty good h3 estimate. Tone it down a bit, and you improve that estimate, though you drop below 100W.
6LW6: Easily gets past the century mark with very moderate voltages. h3 estimate looks very good, and that's without doing anything weird like screen drive. Evenn though the 6.3V version is rare and expensive, there are lots of variations with odd heater voltages that are neither rare nor expensive.
814: Does better than 200W, though requires a higher plate voltage (but still under 1.0KV). another RF final that will need to go into Class AB2, but has some good lookin' h3 estimates. Will need a good grid driver as this one will pull grid current. Possible problem as the operation will be deeply into Class AB, and that could mean x-over.
Attachments
Last edited:
How about configure output as SEPP? Can drive electrostatic speaker directly and if transformer is used, the restriction is much relax. 100W @1.3% THD, when HT is +-2KV, output go up to ~200W
Attachments
Last edited:
The supply is limited to +2KV AFAIK, for 100W, why even bother using the 813's as the others have already mentioned... Gotta go big or go home.😀
If you build with conventional PP (ie non ultra-linear or zero feedback) you have incurable transient distortion. Your circuit you post is of date, in the day when neither ultra-linear nor Williamson was invented, so get real.
Take it easy, man. No disrepect was intend for your sim, please read the spec's on the Altec before you poo-poo it, "incurable transient distortion", really? Neither UL (now that's a can of worms) nor Williamson topology was needed to make a decent amplifier despite what some may think.
Whooo easy on you two.
I am open to ideas. After looking at all the responses, I'm thinking I might step down from the 813pp idea.
How about we change this to "What would you recommended"
What I'm looking for is something with plenty of power and good sound quality with a reasonable build cost. A OPT for a 813pp would require a remortgage!.
Im interested in all your views and opinions, but please keep it civil. If you do make a post please throw in some pro's and con's of the schematics. Im interested in hearing what you have to say.
Cheeers
I am open to ideas. After looking at all the responses, I'm thinking I might step down from the 813pp idea.
How about we change this to "What would you recommended"
What I'm looking for is something with plenty of power and good sound quality with a reasonable build cost. A OPT for a 813pp would require a remortgage!.
Im interested in all your views and opinions, but please keep it civil. If you do make a post please throw in some pro's and con's of the schematics. Im interested in hearing what you have to say.
Cheeers
I think you need to specify your requirements in more detail, e.g., what're the spec's for the speakers that you plan to use with the amplifier, and what you consider to be "loud", since everyone has his/her own idea on just how loud Pink Floyd should be listened to...🙂 If you have efficient speakers, you might be surprised what you can get away with...
Just to throw the cat amongst the pigeons ..😀
RH Amplifiers: RH813 – The Flagship Project
Regards
M. Gregg
RH Amplifiers: RH813 – The Flagship Project
Regards
M. Gregg
This isn't very specific. What is "plenty of power"? The criteria are mutually exclusive. If you want power and sonic quality, that means big and expensive OPTs. That's going to drive up the cost right there. Cheap OPTs aren't good and good OPTs aren't cheap.
- Status
- Not open for further replies.