Hi,
I'm considering to make a smallish class AB tube amp, with power of about 15 watts or so. I'd prefer to use 6V6 tubes as I have some NOS tubes lying around. Also, I'd prefer to use Edcor's transformers as they are relatively inexpensive.
So, what schematic would you recommend?
I'm considering to make a smallish class AB tube amp, with power of about 15 watts or so. I'd prefer to use 6V6 tubes as I have some NOS tubes lying around. Also, I'd prefer to use Edcor's transformers as they are relatively inexpensive.
So, what schematic would you recommend?
simple 6V6 stereo tube schematic
This is as simple as it gets, just use the best caps and resistors you can afford! Pianolydia
P.s. If you want class AB then go with (2) 6V6;s per channel in the output stage and use PP output transformers, that will make it a class AB1 amplifier! then you would connect the ultra linear tap to the screens! the output would be about 15watts per channel.
This is as simple as it gets, just use the best caps and resistors you can afford! Pianolydia
P.s. If you want class AB then go with (2) 6V6;s per channel in the output stage and use PP output transformers, that will make it a class AB1 amplifier! then you would connect the ultra linear tap to the screens! the output would be about 15watts per channel.
Attachments
Last edited:
power transformer
EDCOR
XPWR007
Power transformer for a 120V, 60Hz. or 240V, 50/60Hz. line to 550V (275-0-275) at 200mA center tapped, 6.3V at 6A and 5V at 3A.
$57.33 USD
Availability: Product is built to order.
Be the first to review this product
Add to compare list
Primary (Input) Voltage *
120Vrms, 60Hz.
240Vrms, 50/60Hz.
EDCOR
CXPP25-8-2.5K
25W, push-pull tube output transformer for 2.5K Ohms to 8 Ohms.
$49.74ea. USD
Availability: Product is built to order.
Be the first to review this product
Add to compare list
7130 National Parks Highway · Carlsbad, NM 88220 · U.S.A. · (800) 854-0259 · (575) 887-6790 · FAX: (575) 887-6880 · sales@edcorusa.com
DCOR
Electronics Corporation
edcorusa.com
CXPP Series
PuSh-Pull OutPut tranSfOrmerS
CXPP25-8-2.5K
25W, push-pull tube output transformer for 2.5K Ohms
to 8 Ohms.
Design
Mathematically designed to produce exact plate and screen
voltages.
Primary (Input)
The input is designed for a 2.5K Ohms impedance source.
Secondary (Output)
The output is designed for a 8 Ohms speaker impedance.
Magnet Wire
All units are wound with the finest virgin copper magnet wire.
All windings use heavy insulated wire to provide excellent
manufacturing yield, lower customer cost and superior life.
The Core
EDCOR uses the finest M6 line grain oriented steel cores. Each
unit is hand stacked to assure at least 92% stack.
The Bobbins
EDCOR’s royal blue bobbin with black finishing tape.
Termination
The terminations are UL1015, 20 ga. lead wire.
Mounting
This unit comes with steel end bells for mounting with the use
of four screws. The end bells are powder coated Gentian Blue
(RAL 5010) to add to your tube display and overall appearance.
Specifications
Wattage
25W
Primary (input) Impedance
2.5K Ohms
Screen/Grid Tap
40%
Secondary (output) Impedance
8 Ohms
Frequency Response
20~20K Hz., <1dBu
THD+Noise
<0.1% @ 1K Hz.
Bobbin Material
Glass Filled Nylon 6/6
Flamability Rating
Class B 130°C
Core Material
M6 29 ga. line grain oriented steel
Termination
UL1015, 20 ga. lead wire
Mounting
Powder coated steel end bells
Weight
4.5 lbs.
Dimensional Drawing
15000-EI125-125-0X
Compliance
RoHS, REACH
EDCOR
XPWR007
Power transformer for a 120V, 60Hz. or 240V, 50/60Hz. line to 550V (275-0-275) at 200mA center tapped, 6.3V at 6A and 5V at 3A.
$57.33 USD
Availability: Product is built to order.
Be the first to review this product
Add to compare list
Primary (Input) Voltage *
120Vrms, 60Hz.
240Vrms, 50/60Hz.
EDCOR
CXPP25-8-2.5K
25W, push-pull tube output transformer for 2.5K Ohms to 8 Ohms.
$49.74ea. USD
Availability: Product is built to order.
Be the first to review this product
Add to compare list
7130 National Parks Highway · Carlsbad, NM 88220 · U.S.A. · (800) 854-0259 · (575) 887-6790 · FAX: (575) 887-6880 · sales@edcorusa.com
DCOR
Electronics Corporation
edcorusa.com
CXPP Series
PuSh-Pull OutPut tranSfOrmerS
CXPP25-8-2.5K
25W, push-pull tube output transformer for 2.5K Ohms
to 8 Ohms.
Design
Mathematically designed to produce exact plate and screen
voltages.
Primary (Input)
The input is designed for a 2.5K Ohms impedance source.
Secondary (Output)
The output is designed for a 8 Ohms speaker impedance.
Magnet Wire
All units are wound with the finest virgin copper magnet wire.
All windings use heavy insulated wire to provide excellent
manufacturing yield, lower customer cost and superior life.
The Core
EDCOR uses the finest M6 line grain oriented steel cores. Each
unit is hand stacked to assure at least 92% stack.
The Bobbins
EDCOR’s royal blue bobbin with black finishing tape.
Termination
The terminations are UL1015, 20 ga. lead wire.
Mounting
This unit comes with steel end bells for mounting with the use
of four screws. The end bells are powder coated Gentian Blue
(RAL 5010) to add to your tube display and overall appearance.
Specifications
Wattage
25W
Primary (input) Impedance
2.5K Ohms
Screen/Grid Tap
40%
Secondary (output) Impedance
8 Ohms
Frequency Response
20~20K Hz., <1dBu
THD+Noise
<0.1% @ 1K Hz.
Bobbin Material
Glass Filled Nylon 6/6
Flamability Rating
Class B 130°C
Core Material
M6 29 ga. line grain oriented steel
Termination
UL1015, 20 ga. lead wire
Mounting
Powder coated steel end bells
Weight
4.5 lbs.
Dimensional Drawing
15000-EI125-125-0X
Compliance
RoHS, REACH
Last edited:
As soon as UL mode enters the picture, NFB of some kind is needed to ensure an adequate damping factor.
Dig into the archives for "El Cheapo". It will yield approx. 12 WPC, in UL mode. The 'AQ5 shown in the schematic is, for all practical purposes, a 6V6 in a 7 pin mini bottle. Therefore, parts value changes are not required.
Dig into the archives for "El Cheapo". It will yield approx. 12 WPC, in UL mode. The 'AQ5 shown in the schematic is, for all practical purposes, a 6V6 in a 7 pin mini bottle. Therefore, parts value changes are not required.
Member
Joined 2009
Paid Member
He said he has NOS 6V6's
Yes, NFB will need to be applied for proper Damping factor, If that issue can be solved, then he could use the Schematic I just sent him.......or He could use the El Cheapo and wire in the 6V6's then it will be all good!
Yes, NFB will need to be applied for proper Damping factor, If that issue can be solved, then he could use the Schematic I just sent him.......or He could use the El Cheapo and wire in the 6V6's then it will be all good!
Last edited:
No, that's a no NFB triode mode design. To get the kind of power the OP indicated, either UL or full pentode mode "finals" are needed. Especially with full pentode, NFB of some kind is essential for adequate voice coil control.
Ian's Amp,
6V6 AB1 Ultralinear with balanced shunt feedback. 6SL7 front end.
I would recommend using a bigger chassis than I did - it was a PITA shoehorning everything into that little box.
The design of this amp is covered in its own Baby Huey Thread which is way too long to wade all the way through.
NO NFB required.
Cheers,
Ian
6V6 AB1 Ultralinear with balanced shunt feedback. 6SL7 front end.
I would recommend using a bigger chassis than I did - it was a PITA shoehorning everything into that little box.
The design of this amp is covered in its own Baby Huey Thread which is way too long to wade all the way through.
NO NFB required.
Cheers,
Ian
Attachments
Last edited:
Why don't you use a 6AQ5 instead? far less microphonics. I think that triode or pentode sound better than UL.
I have tested this circuit with different output tubes including EL34, 5881, 6L6 and 6V6 with reduced supply voltage (310 V).
I used 10k to 8 OPT with 6V6, but I noticed that some 8k would be more suitable.
I used 10k to 8 OPT with 6V6, but I noticed that some 8k would be more suitable.
An externally hosted image should be here but it was not working when we last tested it.
http://www.diyaudio.com/forums/tubes-valves/220677-new-6v6-build-suggestions-needed.html
Some modifications were made to the schematic during the thread, but they are built with Edcor power trans, choke and output as mono-blocks. Made about 10 watts, I have had these on every day for about a year. Early on lost a Tungsol 6v6 and swapped them all for JJ 6V6S and they are solid.
Working on basically a variant of the schematic above (artosalo) with 5881's but a stereo version and cathode bias. Work in progress.
http://www.diyaudio.com/forums/tubes-valves/252595-ez215-stereo-5881-amp-project.html
FYI - If you need transformers from Edcor they are swamped worse then usual. I just got mine last week March 13th on an order from Jan 15th.
I like the 6V6 and with not much more cost you could go with 5881's. I do like the sound of the 6V6 amps 🙂
Sandy
Some modifications were made to the schematic during the thread, but they are built with Edcor power trans, choke and output as mono-blocks. Made about 10 watts, I have had these on every day for about a year. Early on lost a Tungsol 6v6 and swapped them all for JJ 6V6S and they are solid.
Working on basically a variant of the schematic above (artosalo) with 5881's but a stereo version and cathode bias. Work in progress.
http://www.diyaudio.com/forums/tubes-valves/252595-ez215-stereo-5881-amp-project.html
FYI - If you need transformers from Edcor they are swamped worse then usual. I just got mine last week March 13th on an order from Jan 15th.
I like the 6V6 and with not much more cost you could go with 5881's. I do like the sound of the 6V6 amps 🙂
Sandy
I guess I'll go either with SandyG's schematic (btw, where's the final schematic of your amp?) or 'El Cheapo'. Anyways, would this be OK as output transformer? EDCOR - GXPP15-8-8K
Would this be an OK power transformer? I intend to use a solid state rectifier, and possibly a capacitance multiplier to filter the supply voltage. EDCOR - XPWR050
Also, why the El Cheapo has so large negative supply? I mean, the constant current source is made with semiconductors, so is that really necessary?
Would this be an OK power transformer? I intend to use a solid state rectifier, and possibly a capacitance multiplier to filter the supply voltage. EDCOR - XPWR050
Also, why the El Cheapo has so large negative supply? I mean, the constant current source is made with semiconductors, so is that really necessary?
Last edited:
8K primary output transformer will work better with EL84 tubes and according to Poinz who made the 6V6 Musical Machine amp 10K or higher was much sonically better with that tube. He liked the Silk 10K OPT's the best.
The well regarded Dynaco clone Z-565 could be used as PPP in triode mode with any of the mentioned circuits with close to the power you want.
The well regarded Dynaco clone Z-565 could be used as PPP in triode mode with any of the mentioned circuits with close to the power you want.
Last edited:
Joku -
I don't think I updated it up this site, but check my personal tube amplifier website I think it's good on that. I also have the original schematic from the Silvertone amp, which used a tube that is similar to a 12AX7 vs the 6SL7 that I used.
EZ10 10 Watt 6V6 Amplifier | EZ260
If you do build the 6V6 make sure you read the other thread as a few good ideas came up.
For the power supply get this software, it's free and I think can help get you into the ball park with selecting a power transformer. Note that what I used in the EZ10 was to support tube rectifier, and even with the GZ34 it may be just a bit high on plate voltage.
Duncan Amps PSUD - PSUD2
Sandy
I don't think I updated it up this site, but check my personal tube amplifier website I think it's good on that. I also have the original schematic from the Silvertone amp, which used a tube that is similar to a 12AX7 vs the 6SL7 that I used.
EZ10 10 Watt 6V6 Amplifier | EZ260
If you do build the 6V6 make sure you read the other thread as a few good ideas came up.
For the power supply get this software, it's free and I think can help get you into the ball park with selecting a power transformer. Note that what I used in the EZ10 was to support tube rectifier, and even with the GZ34 it may be just a bit high on plate voltage.
Duncan Amps PSUD - PSUD2
Sandy
"El Cheapo" is a price/performance project. The negative supply shown is very economical. However, a different supply whose rail voltage is "shorter" should be fine.
"El Cheapo" employs global NFB. Magnetic headroom is needed to avoid O/P trafo core saturation induced by the deep bass error correction signal. For UL mode "finals", use the Edcor CXPP25-8-7.6K.
It's just that having a negative supply increases cost and complexity as you have to have a second power transformer.. It would be easier to find a small transformer with lower voltage than to find a small 125V secondary trafo.
Also, what kind of supply voltage "El Cheapo" uses? I didn't find that from this thread: http://www.diyaudio.com/forums/tubes-valves/169914-el-cheapo-builders-thread.html
Btw, does your amp have a global negative feedback, too? Is the smaller Edcor transformer sufficient with it?
Last edited:
Hmm, looks like that costs only like ten bucks more, so I guess that's an option, but it seems to be twice as heavy as the smaller trafo. However, would it be possible to limit the bandwidth at lower frequencies to allow using a smaller trafo? My speakers go only to 60Hz or so, so I don't really need frequencies under 50Hz. On the other hand, the better trafo indeed is just $10 more..
Yes, the EZ10 does have global feedback. I really enjoy the sound of the EZ10's they are my everyday amplifiers on my computer and about the only downside is they don't have as much gain as other amps, but it works out just perfect with the DAC I'm using with my computer and they have no hum or noise.
To save some $$ you can eliminate the choke. I have the 15watt output transformers as I recall (check the EZ10 site, I think the schematic has what I used).
Again check out thread I posted here on DIYAUDIO that will have some tips if you are going to build one.
I hope to begin working on the 5881 amp soon, hopefully will sound as nice as the 6V6's with a touch more power.
Sandy
Sandy
To save some $$ you can eliminate the choke. I have the 15watt output transformers as I recall (check the EZ10 site, I think the schematic has what I used).
Again check out thread I posted here on DIYAUDIO that will have some tips if you are going to build one.
I hope to begin working on the 5881 amp soon, hopefully will sound as nice as the 6V6's with a touch more power.
Sandy
Sandy
Tofu; Why not buy PPCad, TubeCad and design your own!
Design your own amplifier using these programs, along with Duncan's PSU II
Power supply designer, and build your own circuit....It would be easier, and less parts! These programs are only $9.95 ea. on Glassware site, because John Broskie needs the money, and we need his software. Only Caveat is, that it runs on 32 bit XP Windows not windows 7 or 8....... Just a thought to consider! Pianolydia P.s. that's Joku not Tofu, Sorry....
Design your own amplifier using these programs, along with Duncan's PSU II
Power supply designer, and build your own circuit....It would be easier, and less parts! These programs are only $9.95 ea. on Glassware site, because John Broskie needs the money, and we need his software. Only Caveat is, that it runs on 32 bit XP Windows not windows 7 or 8....... Just a thought to consider! Pianolydia P.s. that's Joku not Tofu, Sorry....
- Status
- Not open for further replies.