Hi,
I have pondered a more powerful single ended design than the SE El509 in triode or SE300B'
Both the 6C33C and GM70 are capable of at least 15 - 20 watts
The GM70 run at lower B+ say 750- 850v DC appeals to me
I have some 6C33C tubes but read they are problematic to balance and stabilize .
Welcome idea's on this issue and driver tubes used .
I have pondered a more powerful single ended design than the SE El509 in triode or SE300B'
Both the 6C33C and GM70 are capable of at least 15 - 20 watts
The GM70 run at lower B+ say 750- 850v DC appeals to me
I have some 6C33C tubes but read they are problematic to balance and stabilize .
Welcome idea's on this issue and driver tubes used .
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There is a GM70 amp in Glass Audio:
https://www.google.com/url?sa=t&rct...dition-1.pdf&usg=AOvVaw1Q2raJXR7irvpfCe6F5O4W
The sch shows it runs off B+1100V but could be lowered, detail maybe revealed when we do a simulation to compare. It's driven by a choke loaded 300B, need 6W or more to drive GM70 to 30W. OT is 8K or more which is very different to 600 ohms for 6c33c. I have a CF output (200:8) 6c33c amp, the bass is good. One day I'll rewinding the OT to get better high freq response.
https://www.google.com/url?sa=t&rct...dition-1.pdf&usg=AOvVaw1Q2raJXR7irvpfCe6F5O4W
The sch shows it runs off B+1100V but could be lowered, detail maybe revealed when we do a simulation to compare. It's driven by a choke loaded 300B, need 6W or more to drive GM70 to 30W. OT is 8K or more which is very different to 600 ohms for 6c33c. I have a CF output (200:8) 6c33c amp, the bass is good. One day I'll rewinding the OT to get better high freq response.
Attachments
Here are a few snapshots hope will help you in your project and GM70 spice model.
Attachments
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Great 800v DC,
Cardas seems the only decent wire with a Dielectric strength to work at this voltage, and over 1000v DC is very problematic.
Cardas seems the only decent wire with a Dielectric strength to work at this voltage, and over 1000v DC is very problematic.
One thing I don’t understand about the 600 ohm load for the 6c33. It has an Rp of <100 ohms correct? Most wisdom says your transformer should be 2-3x Rp. Why is 600 the golden number?
Higher load Z is higher efficiency, more watts out per bottle.
IF the tube can stand the high voltage implied by high dissipation at high impedance.
The way most tubes were designed, "2X to 5X" was a good rule of thumb.
Also remember that Rp is a function of plate current. The 80-120 number is for 550mA, far more than we would run in a power amp. At 60W 250V we would be 240mA or so, and Rp will be higher than what they wrote on the datasheet. Rp may be nearer 200 Ohms, and "300" now seems low, "600" is spot-on the middle of "2X-5X".
As you certainly know GM70 means a lot of money in transformers but it linear and bias run stable a full year, also good if you live in a cold area as it generate 180W of heat in your room (just one GM70 tube).
Its not fair people complain on 6C33 bias, the tube have Russian military standard not commercial grade, can resist a nuke blast, have the thickest glass in audio, have two cathodes, a big metal solid anode, hi trans-condutance and delivery lots of Triode power at low 200VDC, not need 1200VDC to sound good, heat dissipation are ''only'' 80W per tube, all this at under $30 per tube.
This maybe help:
Alert on 6C33 Bias x Hi-Fi Amps Use
You're correct.Typically 8W at 6% THD:
Single Ended ECC99 - 6C33C Amplifier with regulated tube PS
A little non-linear tube for SE,maybe for PP.
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You can use RS1003/SRS551 in A2 class for 15+ Watts.
As I said, GM-70 isn't cheap to build, but with a good driver, it can deliver 30+W with low THD.
As I said, GM-70 isn't cheap to build, but with a good driver, it can deliver 30+W with low THD.
Usually the third grid of the pentode (triode connection) is connected to the GND or the cathode. Why is the third grid connected to the anode?
813 SE triode amps
813 SE triode amps
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1000v plus , insulation to the B+ rail, wiring , tube sockets and airflow are certainly issues that could potentially effect possible Corona discharge , arcing under the chassis .
Corona discharge - Wikipedia
Corona discharge - Wikipedia
