As requested I've started this thread here about my first build of an integrated tube amp.
It has:
An Aikido phono stage using 6N1P and 6N2P.
An Aikido headphone amp using 6N5P and 6N6P that will drive 32 ohm headphones (but I use 470 ohm ATH-R70x)
An Aikido Cathode Follower using 6N1P
A CCDA driver stage using a 6N1P
A 6N2P inverter configured in floating paraphase (it's simple and works well)
And a push pull tetrode connected 6P1P using LM317 as CCS cathode loads.
The output tube are cathode coupled with 1000uf caps and the CCS is bypassed with a 10000uf cap in series with two back to back diodes with a 10k resistor across them (the diodes)
I left out the zeners because apparently when they bias then effectively short the 10000uf cap and become a wire
http://www.tubecad.com/2011/08/13/Push-Pull Cathode Bias CCS Amplifier Class-AB 3.png
Many of these ideas I read about on tubecad.com but I've tweaked the values and adapted the designs to use modern, cheap available parts.
The output transformers are actually toroidal power transformers. By using CCS I eliminated the DC unbalance in the transformer which makes a toroid actually work very damned well.
The transformers are Triad VPT12-1080 and they're cheap enough. The 25VA rating makes is good because the inductance is higher due to the smaller wire in the winding. I measured it around 180H across the coil.
The power supply is basically a voltage doubler off an isolation transformer with choke filtering and GIANT caps lol.
There is no noise from the speaker on this rig unless there is a signal. It's the quietest amp I've ever build or heard (Mainly because of the lack of 120Hz mechanical hum from the over-taxed power transformer).
Lemme know what you think?
Koda
It has:
An Aikido phono stage using 6N1P and 6N2P.
An Aikido headphone amp using 6N5P and 6N6P that will drive 32 ohm headphones (but I use 470 ohm ATH-R70x)
An Aikido Cathode Follower using 6N1P
A CCDA driver stage using a 6N1P
A 6N2P inverter configured in floating paraphase (it's simple and works well)
And a push pull tetrode connected 6P1P using LM317 as CCS cathode loads.
The output tube are cathode coupled with 1000uf caps and the CCS is bypassed with a 10000uf cap in series with two back to back diodes with a 10k resistor across them (the diodes)
I left out the zeners because apparently when they bias then effectively short the 10000uf cap and become a wire
http://www.tubecad.com/2011/08/13/Push-Pull Cathode Bias CCS Amplifier Class-AB 3.png
Many of these ideas I read about on tubecad.com but I've tweaked the values and adapted the designs to use modern, cheap available parts.
The output transformers are actually toroidal power transformers. By using CCS I eliminated the DC unbalance in the transformer which makes a toroid actually work very damned well.
The transformers are Triad VPT12-1080 and they're cheap enough. The 25VA rating makes is good because the inductance is higher due to the smaller wire in the winding. I measured it around 180H across the coil.
The power supply is basically a voltage doubler off an isolation transformer with choke filtering and GIANT caps lol.
There is no noise from the speaker on this rig unless there is a signal. It's the quietest amp I've ever build or heard (Mainly because of the lack of 120Hz mechanical hum from the over-taxed power transformer).
Lemme know what you think?
Koda
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The volume controls are both cheap 100k pots. The headphone doubles as a line amp and has it's own volume/output. The selector switch is a chinese NOS "silver" 11x4 rotary switch. The grounds are switched with the left and right and the fourth pole is for the LEDs.
I have so many RCA's for the following:
Minidisc loop
Cassette loop
Computer loop
Phono loop (I DJ and use the tube preamp for the Traktor interface)
Laptop loop (for recording the mixes)
CD in
TV in
Bluetooth in
Tuner in
Preamp out.
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So many Russian tubes... Need to paint it a nice scarlet and call it The Red Scare Integrated Amplifier! 
Killer idea. What operating point have you got the 6P1P running at?
I'm using output toroids in my latest project but with a cross-coupled garter bias arrangement, a 6SN7 flea-power push-pull that is currently using $10 5volt power toroids as outputs, and using the 6N8s, 6N9S russian 6SL7, 6SN7 equivalents. I'm thinking of using similar transformers for my other design, which is nearly the same front-end, just CCS loaded on the first triodes' plates, and using the 6P6S (russian 6V6GT) for outputs. Might build that one up with the 6N2P in one version...
I've also got a design going using TubeCad's Hafler Matrix surround decoder circuit in the works, using 6N23P (russian 6DJ8) that will end up as an integrated analog matrix/surround sound receiver for music and gaming... Not sure if I want five/six channels all on one chassis as a true integrated design though, most likely end up with RCA outs so it can run external stereoblocks so I can swap in power amps as I see fit, or build up more.
Killer idea. What operating point have you got the 6P1P running at?
I'm using output toroids in my latest project but with a cross-coupled garter bias arrangement, a 6SN7 flea-power push-pull that is currently using $10 5volt power toroids as outputs, and using the 6N8s, 6N9S russian 6SL7, 6SN7 equivalents. I'm thinking of using similar transformers for my other design, which is nearly the same front-end, just CCS loaded on the first triodes' plates, and using the 6P6S (russian 6V6GT) for outputs. Might build that one up with the 6N2P in one version...
I've also got a design going using TubeCad's Hafler Matrix surround decoder circuit in the works, using 6N23P (russian 6DJ8) that will end up as an integrated analog matrix/surround sound receiver for music and gaming... Not sure if I want five/six channels all on one chassis as a true integrated design though, most likely end up with RCA outs so it can run external stereoblocks so I can swap in power amps as I see fit, or build up more.
So many Russian tubes... Need to paint it a nice scarlet and call it The Red Scare Integrated Amplifier!
LOL Well it's mainly because they sound perfectly fine to me (it's the circuit more than the tubes for me) and NOS western tubes are expensive. Plus USSR tubes sound better than chinese one to me... 22 tubes in this amp and the whole kit is about 50 bucks.
300V 56ma
I'll beat the **** out of them because they're cheap and they're basically a 9 pin 6V6.Nice! I have one circuit in a DAC that uses a 6DJ8 but otherwise I've never needed to use it. I could parallel 2 6N3P tubes and get something similar.
As for flea power you might like 6N6P. Think what you were thinking about building but double the current, half the voltage. 120V 28ma 11.5ma/V and they're about 5 bucks each. Dual triode.
Super flea power goes to the 6N3P.
1W push pull. 27000r-a-a.
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The russian tubes are in my opinion some of the most overlooked tubes in audio when used properly, some may not be exact equivalents, but that's why we build. Also, any competently done circuit will not notice the difference of what's screen printed on the glass
I refuse to use Chinese tubes.
Only thing keeping me from the 6P1P is that I already have plenty of the 6P6S on hand, and prefer octal socketed power tubes.
The 6N2P is for all reasonable purposes an actually good 12AX7 with a 6volt heater, and the 6N1P is not a 6DJ8/6922 (the 6N23P is, however...) but has similar gain enough to be used in designs that use one just for voltage amplification at moderate drive current. Both great tubes.
The 6N8S and 6N9S in particular are a great deal, around $2.25 each and they can take a beating for sure. The 6P6S and 6P14P also do great when you don't flog them too hard, but the floggings are why there are -EV versions If you want to have some real fun, grab the 6N13S (6AS7G equivalents) and run them at 100volts across each tube, with 100mA current, like shog suggests in his toroid threads. I have, and I can honestly ay they are my #1 favorite tube because of it. Use a pair in push-pull with a 120-0-120:10 25-50VA power toroid as an output for 8ohm speakers, and be amazed at how these suckers sound. Anywhere from 8-10 watts out depending on how you do it.
I design conservatively, anyway. Need more power? Get more sensitive speakers, go AB2, or choose a bigger tube. I like my tubes to last, even if I have a whole pile of them.
I do need to grab some 6N6P and 6N3P next time I buy a mess of tubes, I hear many accounts of low THD, good sound, and high quality with them.
I refuse to use Chinese tubes.
Only thing keeping me from the 6P1P is that I already have plenty of the 6P6S on hand, and prefer octal socketed power tubes.
The 6N2P is for all reasonable purposes an actually good 12AX7 with a 6volt heater, and the 6N1P is not a 6DJ8/6922 (the 6N23P is, however...) but has similar gain enough to be used in designs that use one just for voltage amplification at moderate drive current. Both great tubes.
The 6N8S and 6N9S in particular are a great deal, around $2.25 each and they can take a beating for sure. The 6P6S and 6P14P also do great when you don't flog them too hard, but the floggings are why there are -EV versions
If you want to have some real fun, grab the 6N13S (6AS7G equivalents) and run them at 100volts across each tube, with 100mA current, like shog suggests in his toroid threads. I have, and I can honestly ay they are my #1 favorite tube because of it. Use a pair in push-pull with a 120-0-120:10 25-50VA power toroid as an output for 8ohm speakers, and be amazed at how these suckers sound. Anywhere from 8-10 watts out depending on how you do it.I design conservatively, anyway. Need more power? Get more sensitive speakers, go AB2, or choose a bigger tube. I like my tubes to last, even if I have a whole pile of them.
I do need to grab some 6N6P and 6N3P next time I buy a mess of tubes, I hear many accounts of low THD, good sound, and high quality with them.
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The russian tubes are in my opinion some of the most overlooked tubes in audio when used properly, some may not be exact equivalents, but that's why we build. Also, any competently done circuit will not notice the difference of what's screen printed on the glass
Indeed!!
Actually I find it more like a 6SL7 TBH
No it's not. They might work and sound fine but they aren't the same.
The 6N8S and 6N9S in particular are a great deal, around $2.25 each and they can take a beating for sure. The 6P6S and 6P14P also do great when you don't flog them too hard, but the floggings are why there are -EV versions
I design conservatively, anyway. Need more power? Get more sensitive speakers, go AB2, or choose a bigger tube. I like my tubes to last, even if I have a whole pile of them.
I do need to grab some 6N6P and 6N3P next time I buy a mess of tubes, I hear many accounts of low THD, good sound, and high quality with them.
I got 45 6N8S for $100 Canadian a few years back. I run them with 400V without problems...
I've plugged a 6P6S into a circuit I designed for 6P3S and they worked fine even at 23W on the plate. No glow. They ran at about 250c though.
I've used 6N13S and 6N13T (Chinese) and both worked just as well as my NOS Mullards.
6N6P is an amazing tube. And the 6N3P is the most overlooked tube to me.
150V Plate (or double it and run Aikido)
240R cathode
12000R plate resistor
8ma current
And linear!
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6N3 does look pretty good...
I wonder what I could get out of one with 185v supply, ~90v on the plate, and driving a split load phase splitter (also 6n3) with around 45v across each load resistor... might be a cheaper candidate for the 6DJ8 in such a design... I'm trying to figure out a good way to swing ~75v peak-peak into a push-pull pair of 6AS7G that need about 32v each for full output, off of a single ~160 volt supply. I know it's cutting it close, but I want to avoid using an additional supply for the driver stage. The 6DJ8 would work but isn't exactly cheap anymore...
I wonder what I could get out of one with 185v supply, ~90v on the plate, and driving a split load phase splitter (also 6n3) with around 45v across each load resistor... might be a cheaper candidate for the 6DJ8 in such a design... I'm trying to figure out a good way to swing ~75v peak-peak into a push-pull pair of 6AS7G that need about 32v each for full output, off of a single ~160 volt supply. I know it's cutting it close, but I want to avoid using an additional supply for the driver stage. The 6DJ8 would work but isn't exactly cheap anymore...
I think it would swing the voltages. You might have to run it hot though. Say 15ma? (Yes it exceeds the spec, who cares, they're like a dollar.) say 3k Ra and Rk on the splitter.
That or a Hammond 124B. instead. They sound good and they're pretty cheap.
Really though you could just get the 360V rail from a voltage doubler. This whole amp runs on one, they work if it's done well. Then you could probably use a 6N2 in floating paraphase.
That or a Hammond 124B. instead. They sound good and they're pretty cheap.
Really though you could just get the 360V rail from a voltage doubler. This whole amp runs on one, they work if it's done well. Then you could probably use a 6N2 in floating paraphase.
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The previous version of the 6N13S amp had dual stacked 165v supplies, and worked well, just a little bulky since it was using a ~200VA toroid from ebay that was way bigger than it needed to be for the amp. I may end up just running a small 6 volt transformer backwards off of a heater winding and stack that on top, lets me go a little simpler, and use the 6N2P or 6N9S so that I have enough gain to use a good bit of global NFB. The toroid will get reused as the supply for a five channel version in the future, 1 amp at 165 volts, and 78.75 watts of heater power just in the output stages alone... And of course they are all in that handsome ST/cokebottle glass
We likely wont have to run the furnace in the winter while it's running
We likely wont have to run the furnace in the winter while it's running
I used banana plugs on 15 gauge speaker wire for the 12V (all heaters are series connected) and a female to female 5.5/2.1mm DC jack cable. The wire is rated to 300V and the amplifier end of the cable has it's power recessed to avoid shocks.
The power supply is a 12V30A switching supply with an 8200uf filter cap and a 300VA isolation toroid into a voltage doubler into two 6H chokes in parallel and a 3500uf cap. The 12V supply floats.
The power supply is a 12V30A switching supply with an 8200uf filter cap and a 300VA isolation toroid into a voltage doubler into two 6H chokes in parallel and a 3500uf cap. The 12V supply floats.
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