Mate, miss-read the flag. Good to meet. I see you guys are copping lockdown again too. Not as bad as Vic. Good time to be doing sometime into DIY audio. Time to Haka down!
Yeah absolutely! Only Auckland is locked down, I'm down near Wellington so were level two. It's only a matter of time though. If I could afford some OPTs I'd have a go at building a tube amp, but they're hard to get and expensive to get here in NZ
Edcor in America makes excellent and cheap OPTs. Go for the 15W open frame as the cheapest. They do take months to ship though.
EDCOR - Single Ended Tube Output Transformers
EDCOR - Single Ended Tube Output Transformers
Thanks Mark , I'll look into it. Until then, I really do enjoy the tube/chip amp combo, so much dynamics and clarity.
Here's my four-channel LM3886 amp with balanced inputs and soft start. All circuits and board layouts are my own design. I'll probably publish the schematics and board layouts before sometime soon (if there's interest). I also have some extra PCBs I could sell.
The amp is very quiet (despite the proximity of channel 4 to the power transformer) with no perceptible hum or buzz. Output noise should theoretically be somewhere in the 20-30µV range (A-weighted), but I don't have the means to measure this at the moment. DC offset is less than 1mV.
The amp is very quiet (despite the proximity of channel 4 to the power transformer) with no perceptible hum or buzz. Output noise should theoretically be somewhere in the 20-30µV range (A-weighted), but I don't have the means to measure this at the moment. DC offset is less than 1mV.
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Superbly done, I really like the way you've done the layout. I wish we could get plywood like that in the UK.
Cheers
Hi ! very nice amp ... i like the layout a lot.
sorry ... i have a question ... why not move the PSU board with diodes and caps closer to the amps boards, placing it between the two ?
is there a reason to keep it instead closer to the mains transformer ? just asking ...
Thanks a lot
My 10p worth would be length of leads. I ended up with two main components in a big box and put the pots on one side.
Cheers
Cheers
Hi ! yes that was exactly my doubt. I understand now that it is better to place the psu board (i.e. diodes bridge + supply caps) closer to the mains transformer. Issue closed.
Thanks a lot.
Your amp looks nice , are you planning to use those 4 channels for active speakers?
I would like to see the schematic if you dont mind,
Thanks
Gabe
Yes, I'm using it for the big two-ways I built earlier this year. The amps I was using previously were too noisy (audible hiss at the listening position).
Here's the schematic (excluding power supply stuff):
It's basically just an instrumentation amp. The input buffers run off a ±15V regulated supply.
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I just clicked on "the big two-ways " link ,
WOW! You are an artist. How is one lm3886 amp handling that big woofer?
Thanks for sharing.
WOW! You are an artist. How is one lm3886 amp handling that big woofer?
Thanks for sharing.
Nothing. I have an 8-channel DAC connected to a Raspberry Pi which does the signal processing required for the crossovers. I don't generally use any analog sources, just digital music files.