So after some inspiration from Lingwendil, I have created an affordable flea power amplifier.
Total cost to build was under $100 USD including the power brick and boost converter. It took me 8 hours from start to finish to build.
Total power is 5.5W, THD = 0.2% without gNFB.
I used a cake pan as the chassis ($6 CAD), and surplus power transformers for the OPTs ($12CAD@a1parts.ca) I didn't have the mounting hardware, so I propped them up on wire spools and used tie wraps to affix them.
Resistors are "MF" from China except the power resistors for the gain/PI which I had left over from Digi-key, coupling caps are X2 MKP safety caps, imitation Nichicon RC filter caps for the gain/driver, Jamicon cap for the main reservoir.
Sounds great for a <$100 USD amp, for sure.
Thoughts?
Total cost to build was under $100 USD including the power brick and boost converter. It took me 8 hours from start to finish to build.
Total power is 5.5W, THD = 0.2% without gNFB.
I used a cake pan as the chassis ($6 CAD), and surplus power transformers for the OPTs ($12CAD@a1parts.ca) I didn't have the mounting hardware, so I propped them up on wire spools and used tie wraps to affix them.
Resistors are "MF" from China except the power resistors for the gain/PI which I had left over from Digi-key, coupling caps are X2 MKP safety caps, imitation Nichicon RC filter caps for the gain/driver, Jamicon cap for the main reservoir.
Sounds great for a <$100 USD amp, for sure.
Thoughts?
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Well, in reality I'm using TL783 I pulled from 6N13S amp I built. They are TI.
If I was actually using LM317 I'd use these: 10pcs LM317 LM317T TO-220 1.5A Voltage Regulator IC | eBay
If I was actually using LM317 I'd use these: 10pcs LM317 LM317T TO-220 1.5A Voltage Regulator IC | eBay
They don't offer the program to Canada the last I tried. Besides I just use 10 cent Chinese ones because they work fine. Even when I ran them at over 100c for months before I noticed I'd undersized the heatsink! I get TI TL783 from Digi-key or mouser though. Usually when I need more than 37V it's more than 50V, too.Why not get them straight from TI? Free shipping with their sample program.
My favorite version of the LM337 is the HV version, btw.
Unless they are exceeding the max specs of the tube, it won't give you 10 watts RMS. I generally take whatever wattage rating a Chinese amp has, and divide by 3.One amp using 6N6 as OPT in the ebay config as SEPP output 10W+10W.
Glad you like it
Ok so I've settled on a 2k gNFB resistor connected from SPKR+ to first cathode. More Linearity.
I would use a VPT18-1390 transformer as the OPT if I wasn't trying to use junkbox parts.
I should mention that I'm still using a line stage topology. After the gNFC it needs about 3V...
Ok so I've settled on a 2k gNFB resistor connected from SPKR+ to first cathode. More Linearity.
I would use a VPT18-1390 transformer as the OPT if I wasn't trying to use junkbox parts.
I should mention that I'm still using a line stage topology. After the gNFC it needs about 3V...
I love the super-cheap wafer sockets for the 9-pin tubes. Won't they get all dried out and start to warp? That's the only problem I've had with those. Theoretically they will have worse leakage capacitance than ceramic or phenolic sockets, but I dunno about in real life...
I've always wondered about a PPPP (four 6N6P envelopes per channel, or 8 6N6P envelopes for a stereo amp, into a 3k p-p load).
I've always wondered about a PPPP (four 6N6P envelopes per channel, or 8 6N6P envelopes for a stereo amp, into a 3k p-p load).
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I would use a VPT18-1390 transformer as the OPT if I wasn't trying to use junkbox parts.
Any reason the AnTek version 115+115:9+9 25VA toroid wouldn't work as well?
http://www.antekinc.com/content/AN-0209.pdf
Any reason the AnTek version 115+115:9+9 25VA toroid wouldn't work as well?
http://www.antekinc.com/content/AN-0209.pdf
That should work well with the secondaries connected in parallel for an 8R load.
Series connect the secondaries for ~1300 or so load, and use it for the 6AS7 experiments too
Well, it's actually designed to be a 1.1W class a amp with peaks into 5.5W so in normal operation they won't exceed by much. The average Pd is 4.6W, idle is only about 3W. Considering this amp was made from junk, I'm happy with it. I agree though, OPT should be closer to 8k, I just don't have any right now. These aren't even dual primaries, just a 0-115-220 tapped primary, 15VA coil. It was more like "hey I wonder if these would work?"
My next projects are 36LW6 and GU29 amps... Just waiting on parts and a tool.
The wafer sockets are actually made by Cinch and were NOS from the 60's. I usually use bakelite or ceramic sockets, though.
The Antek should work fine, too. I just don't know about their shipping costs to Canada as I usually buy through Digi-key or Mouser.
I was thinking of an 8 tubes/channel amp but right now that chassis has 16 6P1P triode connected for 6W (class A limit 24W) into 3k Raa.
My next projects are 36LW6 and GU29 amps... Just waiting on parts and a tool.
The wafer sockets are actually made by Cinch and were NOS from the 60's. I usually use bakelite or ceramic sockets, though.
The Antek should work fine, too. I just don't know about their shipping costs to Canada as I usually buy through Digi-key or Mouser.
I was thinking of an 8 tubes/channel amp but right now that chassis has 16 6P1P triode connected for 6W (class A limit 24W) into 3k Raa.
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