Recently i finished my first projects, so i decided to take some pictures.
Leach: Dual mono, 2 x 300VA toroids, measured 2x125W @ 8ohms, 2x240W @ 4 ohms (the amp was singing), damping factor >600 @ full power into 8ohms at 1kHz sine wave, assuming much greater at 50 Hz. I was a bit disappointed when supply voltage dropped by 10V at full power, i don't think bigger caps would help?!?
BOSOZ: Nothing special, just added op amp (BB OPA 227) based phono stage. For now i'm using it only unbalanced.
Questions and suggestions are welcome.
Leach: Dual mono, 2 x 300VA toroids, measured 2x125W @ 8ohms, 2x240W @ 4 ohms (the amp was singing), damping factor >600 @ full power into 8ohms at 1kHz sine wave, assuming much greater at 50 Hz. I was a bit disappointed when supply voltage dropped by 10V at full power, i don't think bigger caps would help?!?
BOSOZ: Nothing special, just added op amp (BB OPA 227) based phono stage. For now i'm using it only unbalanced.
Questions and suggestions are welcome.
Attachments
Very nice work. I like the matching design. Very nice pictures. Hope it sounds as good as it looks. Bigger caps will help for peaks.
Thermal things
Why don't You put Bosoz Mosfets on one heatsink. It's a very important thing. Each channel transistors must be thermal coupled.
Why don't You put Bosoz Mosfets on one heatsink. It's a very important thing. Each channel transistors must be thermal coupled.
There's one funny thing about Leach. More i load it more it's getting cold. It's hottest when idling.
Thermal Things 2
You could put an aluminium "C"- form to connect heatsinks. I think, you should try.
You could put an aluminium "C"- form to connect heatsinks. I think, you should try.
Mad K: you can get it here: http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=OPA227
It's a great OP amp sonically comparable to OPA 134 or OPA 604. Originally this phono stage was based on NE5534 but BB's are much much better.
Hugonot: thanks, i will.
It's a great OP amp sonically comparable to OPA 134 or OPA 604. Originally this phono stage was based on NE5534 but BB's are much much better.
Hugonot: thanks, i will.
zverina said:
Which circuit are you using? There's no RIAA application for that chip.
In fact the OPA28 might even work a little better. If it sounds close to the OP37 (as BB/TI claims) then if maybe a good option to try.
Carlos
sorry, i don't have schematics on my comp, just on paper. It's a bit older design of line preamp + phono stage (ELEKTOR - Top Amp) originally based on tantal caps, but i don't like them so i've put ELNA's instead.
if, you're interseted i can scan schematics and parts list, but for now i have only this:
if, you're interseted i can scan schematics and parts list, but for now i have only this:
Attachments
mains ground
Hello Zverina,
Very nice work.
I see you connect mains ground to the audio ground. Are you sure the mains ground in your flat is clean enough and not derived from bridging the neutral? I had troubles with it. Such a connection caused degradation of sound.
Hello Zverina,
Very nice work.
I see you connect mains ground to the audio ground. Are you sure the mains ground in your flat is clean enough and not derived from bridging the neutral? I had troubles with it. Such a connection caused degradation of sound.
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