EL84 - Decware inspired build
I really just wanted to post some images in the gallery but couldn't find it. This is an EL84 power amp with attenuator. It is based on the Decware Zen. Tubes are Russian 6N1P and NOS Japanese National EL84s. I recently replaced the rec tube with a Sophia Princess 274B mesh plate. Looks better. Amp plays well through my 98db efficient Beyma 12" concentrics.
I really just wanted to post some images in the gallery but couldn't find it. This is an EL84 power amp with attenuator. It is based on the Decware Zen. Tubes are Russian 6N1P and NOS Japanese National EL84s. I recently replaced the rec tube with a Sophia Princess 274B mesh plate. Looks better. Amp plays well through my 98db efficient Beyma 12" concentrics.
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Some pictures of my Morrison Micro 2A3 build
The version I built is slightly different from the schematic as I had parafeed transformers and chokes available.
J.C Morrison's choice of operating point is a bit unusual as there is nearly 80mA plate current on each 2a3. I tried altering resistor values to achieve the 'classic' 250v 60ma point - the amp worked but the magic was gone so I'm sticking with the original design and hoping my tubes have a reasonably long life.
The power supply is in a separate box - photos to follow once I have tidied it up a bit.
No hum problems? What is the grid voltage
Not sure what the voltages are now - will measure and post when I get a chance.
I had big hum problems to start with - was using the power supply from another project that had a lot more filtering than the Morrison schematic. Reducing the size of the capacitors to 5 uf input and 50 uf after the choke made a big difference, but to get things really quiet I had to fit 50 ohm pots across the 2a3 heaters with the wiper connected to the cathode bypass cap.
I had big hum problems to start with - was using the power supply from another project that had a lot more filtering than the Morrison schematic. Reducing the size of the capacitors to 5 uf input and 50 uf after the choke made a big difference, but to get things really quiet I had to fit 50 ohm pots across the 2a3 heaters with the wiper connected to the cathode bypass cap.
Nice!6C33 pp amp, the Brute55....
How hot does the chassis get?
Intentionally No Triode SE....
...finished last summer - C3M Pentode and KT150 UL with global gnfb. Around 18W@10% THD. Works really well, have my other amps collecting dust on the shelves since
Marcus
...finished last summer - C3M Pentode and KT150 UL with global gnfb. Around 18W@10% THD. Works really well, have my other amps collecting dust on the shelves since
Marcus
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...finished last summer - C3M Pentode and KT150 UL with global gnfb. Around 18W@10% THD. Works really well, have my other amps collecting dust on the shelves since
Marcus
Outstanding and beautiful! C3m + kt150 is a sure win.
805 and 8000 amplifiers
Photo of the 805amp and 8000amp; i recently made.
The 8000 amp uses a huge Hammond transformer, the 805 amps have C core's made by by Bob Sugden. both amps sound very good, the 805 best as the internal impedance, best suits the Altec horn boxes loaded with well damped RCF15N401's.
Phil
Photo of the 805amp and 8000amp; i recently made.
The 8000 amp uses a huge Hammond transformer, the 805 amps have C core's made by by Bob Sugden. both amps sound very good, the 805 best as the internal impedance, best suits the Altec horn boxes loaded with well damped RCF15N401's.
Phil
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Here are pictures of my JE LABS 300B amps, Angela power transformers, Hammond output transformers and chokes. GZ37/CV378 (military grade Mullard rectifier tubes), 5692 RED BASE RCA pre-amp tubes, EH 300B tubes (until I can afford a ''real'' 300B tubes).
Very nice!
If you use that speaker please do yourself a favour and remove the amp from the top... The tubes will thank you!
Greetings
Very nice!
If you use that speaker please do yourself a favour and remove the amp from the top... The tubes will thank you!
Greetings
Thought you'll write " If you use that speaker please do yourself a favour and remove the mouse from the bassreflex hole"
Wow! Care to post schematics?my new tube pre-amplifier uses 8x GE6072 black plate triple mica,2x5687,Mullard GZ37 rectifier.
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