A question for Planet10 and others:
One of my adult sons has shared some remorse about not building an amp with me. Well he's 32 this year and I told him it's not too late.... at least while I can still see and solder! I'm looking for a push-pull schematic that can drive more conventional speakers and does not break the bank on iron needed. I've built many 2 stage single ended amps, mostly using DHTs but I use/prefer high efficiency horns.
Please send any ideas my way!
Thanks,
Jim
One of my adult sons has shared some remorse about not building an amp with me. Well he's 32 this year and I told him it's not too late.... at least while I can still see and solder! I'm looking for a push-pull schematic that can drive more conventional speakers and does not break the bank on iron needed. I've built many 2 stage single ended amps, mostly using DHTs but I use/prefer high efficiency horns.
Please send any ideas my way!
Thanks,
Jim
I also prefer something with a lower parts count so it's easier for him to understand. I have plenty of iron for the power supply and boxes of boutique parts to use. I will need to purchase a pair of outputs.
It's only ~20W/channel, but a Pete Millett DCPP amp might be fun for him, vs a p-p build. It's a big red PCB, so easy peazy to build. http://www.pmillett.com/DCPP.htm
Edcor has a trans. bundle, but you can buy the OPT's separately if you wish.
There's also a 50W monoblock version is you need more lower.
jeff
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This is the best example of a simple, low power push pull tube amplifier.
Notice that it is intended for modern 120VAC power.
You can call to see when it is in stock. Supply your own tubes.
https://www.dynakitparts.com/shop/st-35-kit-120-vac/
Notice that it is intended for modern 120VAC power.
You can call to see when it is in stock. Supply your own tubes.
https://www.dynakitparts.com/shop/st-35-kit-120-vac/
A Magnavox 9302 fits that if you want EL84 power. Use Edcor 8 ohm OPT's. Ditch the hum and balance pots with fixed resistors. If you want to swing for a modern PT with 125v input get the Hammond. Then the heaters will be happy. It's a great amp in stock form.
Yes but if you read my original post you will see that this son would never use high efficiency speakers that would mate with a 300B. Building a nice DHT amp would be best but does not fit the application. Actually, if I were going this route, I'd use the JJ 2A3 - but again, not enough power.
Thanks,
Jim
Do you have an output power target in mind? There have been many good EL84 and EL34 designs posted in DIYaudio in recent years.
I've been running my DCPP amp for 13 years. Haven't changed the tubes yet. I bought lots of spares, which I may never need.
jeff
My matched quad of Mullard EL-34 tubes is now 47 years old, and in perfect health.
So is the Mullard GZ-34 rectifier running them.
So is the Mullard GZ-34 rectifier running them.
6JN6s have gotten expensive since Pete published his amp... $7.50 to $8 each! (vacuumtubesinc.com and findatube.com) I think a spare set would be affordable.
If you're looking for 30-40W, EL34 would be the way to go. The higher power tubes for Pete's PCB are a lot harder to find.
If you're looking for 30-40W, EL34 would be the way to go. The higher power tubes for Pete's PCB are a lot harder to find.
You don't need to sacrifice your love of SET DHT amps in order to get the performance you are looking for. GM70s are cheap, a couple of switch mode PSUs will heat them quite nicely and you can get 20 watts out of a single tube. Paralleling them is also very possible for 40 watts per channel.
That's still dirt cheap compared to any ordinary audio tube with similar ratings.
Pete created a Version 2 of the 50W PCB, so that you can use whatever output tube you want. It just has a big hole where the socket pads would normally be.
jeff
Plenty of the smaller TV Sweeps around yet. ( 17 or 18 Watt tubes ) (multiply TV Sweep Watts by 1.33 for Audio tube Watt equivalents)
12GE5 are $3 (same tube as 12/6JN6 except for pinout) at Vacuumtubes.net.
6HD5 are $3 (same as 6HJ5) 24 Watt tube
13GB5 are $3 cap
21JV6 are $3
12GT5 are $3
21EX6 are $3 22 Watt tube Octal, cap
21LG6 are $4 28 Watt tube, cap
26DQ5 $5 24 Watt tube Octal, cap
6CB5A $5 26 Watt tube Octal, cap
22KV6 are $6 22 Watt Novar base
21HB5A are $6
6HJ5 are $12 24 Watt tube
The 22 Watt to 28 Watt tubes can give you a 50 Watt P-P Amplifier readily.
12GE5 are $3 (same tube as 12/6JN6 except for pinout) at Vacuumtubes.net.
6HD5 are $3 (same as 6HJ5) 24 Watt tube
13GB5 are $3 cap
21JV6 are $3
12GT5 are $3
21EX6 are $3 22 Watt tube Octal, cap
21LG6 are $4 28 Watt tube, cap
26DQ5 $5 24 Watt tube Octal, cap
6CB5A $5 26 Watt tube Octal, cap
22KV6 are $6 22 Watt Novar base
21HB5A are $6
6HJ5 are $12 24 Watt tube
The 22 Watt to 28 Watt tubes can give you a 50 Watt P-P Amplifier readily.
Just plug some $3 6HD5 tubes in for a super 50 Watt Amp. No plate caps.
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I'd like to achieve 30-40 watts. I assume this pushes me into the EL34/6CA7 family.
My main amp is a GM70 amp but no way I'd tackle an amp like that for a first amp build with a novice! Very high plate voltage, good output iron is pricey. Amp gets much larger and heavier. The GM70 is my favorite amp however.
mmm kinda. EL34 maybe 30 - 40 very hot watts.
Can use actual real power tubes with efficiency
We like our Beam Tetrodes and go 60 - 70 watts no problem 6550
Something easy is the old Dynaco Mark III ( IV)
restore vintage unit or build with new chassis
Save money Yank the sleazy 34 and run normal diodes for even more power
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