Thank you! It sure is nice if every now and then form is on a par with function...
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Hello, I pass some pictures of my amplifiers (version 1 and 2):
What is this beauty??
Well, great looking amplifier(s).
But I am quite puzzled why you want to have two independent headphone stereo amplifiers on one chassis.
You shouldn't due to CMRR, but obviously 2.5Vpp ripple is a lot for a single ended voltage stage with 6db PSRR like a common cathode amp
I made it for a headphone store. It would be possible to test two different headphones when working from the same source.
The store owner then said that customers quickly made their choice of headphones. He provided two models of headphones to choose from and set the buyer the desired musical composition. Or buyers brought their CD
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This is a normal SE amplifier. The trasformer is recalculated to work with headphones. The outputs are designed for 25 and 100 ohms. Circuit and PCB for a single channel. 6N8S and 6P6S tubes. his amplifier Board has been available for 10 or 12 years.
Audio-O-Moron 40W amplifier
I have finally boxed my Raspberry Pi controlled P-P amplifier. It ended up rather monstrous! All metal sheet was hand beaten into submission. No a single laser cut to be found in this construction!
Summary:
P-P output stage using toroidal OPT
Bias monitored & controlled by the RPi
Takes a range of power tubes (6550, KT88, 6L6, EL34 etc), the Rpi makes the bias adjustments as set from front panel (25-90mA)
B+ approx 400V
Driver is Pete Millet's P-P driver boards
Tone control is Braxandall. Can be switched off & out of the circuit via the front panel.
Pout = 40W RMS into 8 Ohm (visible distortion on scope)
Distortion at 2W is approx 0.1% (2nd & 3rd harmonic)
I have finally boxed my Raspberry Pi controlled P-P amplifier. It ended up rather monstrous! All metal sheet was hand beaten into submission. No a single laser cut to be found in this construction!
Summary:
P-P output stage using toroidal OPT
Bias monitored & controlled by the RPi
Takes a range of power tubes (6550, KT88, 6L6, EL34 etc), the Rpi makes the bias adjustments as set from front panel (25-90mA)
B+ approx 400V
Driver is Pete Millet's P-P driver boards
Tone control is Braxandall. Can be switched off & out of the circuit via the front panel.
Pout = 40W RMS into 8 Ohm (visible distortion on scope)
Distortion at 2W is approx 0.1% (2nd & 3rd harmonic)
Attachments
That's the dedication. I had one of those 10 years ago. They weight approximately metric ton. Had to sell as it was incompatible with any living space.
It has its own charm for an engineer without WAF-issues
Anyway congrats for finishing such a build. Hopefuly the RPi is online and can be controlled by an app
The only way it should be done. I once saw a video of some Indian(?) guy making a VW floor pan out of a piece of sheet metal using nothing but a hammer and a couple blocks of wood. The result was pretty impressive. So is this amp.
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wow! that looks like a lot of work and great result. Any photos of the inside?
Here are 2 inside photos, the first is the lower chassis with the auxiliary PSUs and RPi:
5V for RPi with LiPo 3.7V charger & backup 15V for the LT3751 capacitor charger demo board (that I had salvaged from a previous project) which generates the -110V for the control grid supply +-15V for the grid voltage amplifiers 18V ac for the driver board, to generate the -Vneg needed Filament rectifier & relay control
The 2nd photo shows the driver & power tube arrangement with the bias control. The 3 toroids are B+ PSUs and the centre for filament. The OPT are below the power tubes.
Attachments
