I would probably go for these at $89 Bucks.
Z565-48 17.5 (35W) Watt Triode USA Output Transformer for Dynaco MADE IN USA
although the Edcors will be close and are $30 bucks cheaper.
Cheers,
Ian
Z565-48 17.5 (35W) Watt Triode USA Output Transformer for Dynaco MADE IN USA
although the Edcors will be close and are $30 bucks cheaper.
Cheers,
Ian
HELP 
I built the 6v6 version about a year ago and it's been going great.
I just upgraded the power supply to deliver the revised output stage CCS voltages of +33v and -80v. These were previously +56v and -48v.
I've also changed the output CCS current to 3ma using the specified 47k and 220r resistors in post 1358 page 136.
My problem is that the CCS now pulls the +33v supply to 0v and the pus smokes! If I disconnect the CCS, the pus is ok.
I've checked the CCS parts configuration and nothing appears wrong (I only changed two resistors p CCS). I'm stumped, and would appreciate your help or thoughts.
Kind regards
Andrew
I built the 6v6 version about a year ago and it's been going great.
I just upgraded the power supply to deliver the revised output stage CCS voltages of +33v and -80v. These were previously +56v and -48v.
I've also changed the output CCS current to 3ma using the specified 47k and 220r resistors in post 1358 page 136.
My problem is that the CCS now pulls the +33v supply to 0v and the pus smokes! If I disconnect the CCS, the pus is ok.
I've checked the CCS parts configuration and nothing appears wrong (I only changed two resistors p CCS). I'm stumped, and would appreciate your help or thoughts.
Kind regards
Andrew
Ok, I might have made some progress....
The +33v is from a Zener that is connected to the b+ via a 45k resistor. It seems that four lots of 3ma current draw from the CCS was too much.
I've dropped the CCS to 1.5ma each and everything almost seems to work. Three tubes will bias up but one draws zero current. I've swapped the tubes and it's not the tube and the opt in not open circuit.
The +33v is from a Zener that is connected to the b+ via a 45k resistor. It seems that four lots of 3ma current draw from the CCS was too much.
I've dropped the CCS to 1.5ma each and everything almost seems to work. Three tubes will bias up but one draws zero current. I've swapped the tubes and it's not the tube and the opt in not open circuit.
Thank you for your suggestion. I've put my multimeter in series with the +33v supply and the total measured current draw is 12ma and the measured voltage is zero.
My series resistor with the zener is made up of three 15k resistors and if I short out one to drop the series resistance to 30k, nothing changes (ie still 12ma and the measured voltage is zero).
My series resistor with the zener is made up of three 15k resistors and if I short out one to drop the series resistance to 30k, nothing changes (ie still 12ma and the measured voltage is zero).
The current draw is too much for a zener supply off the main B+.
The power rating of the required zener and dropping resistor become too large.
That is why I rebuilt these supplies when I increased the source follower currents.
Use the power supply circuit from post 1358 to generate the + and - low voltage supplies.
Cheers,
Ian
The power rating of the required zener and dropping resistor become too large.
That is why I rebuilt these supplies when I increased the source follower currents.
Use the power supply circuit from post 1358 to generate the + and - low voltage supplies.
Cheers,
Ian
Dear Ian,
I'm definitely building Baby Huey, still not sure which version, EL84/ECC803 or 6V6/6SL7. Can you please tell me your impressions on difference between these two versions, and which one would you recommend?
Do you have any OPT winding plans for Baby Huey, transformer-making professional will make them for me but he needs a detailed winding plan.
Greetings from Croatia,
Zoran
I'm definitely building Baby Huey, still not sure which version, EL84/ECC803 or 6V6/6SL7. Can you please tell me your impressions on difference between these two versions, and which one would you recommend?
Do you have any OPT winding plans for Baby Huey, transformer-making professional will make them for me but he needs a detailed winding plan.
Greetings from Croatia,
Zoran
Zoran,
I think the EL84/ECC803 version is probably a little better. The Baby Huey feedback scheme relies on trading some output tube gm for reduced rp and therefore a higher gm tube like the EL84 should be better.
Having said that - I personally love the 6V6/6SL7 version and that is what I'm running on my HiFi system at the moment.
Cheers,
Ian
I think the EL84/ECC803 version is probably a little better. The Baby Huey feedback scheme relies on trading some output tube gm for reduced rp and therefore a higher gm tube like the EL84 should be better.
Having said that - I personally love the 6V6/6SL7 version and that is what I'm running on my HiFi system at the moment.
Cheers,
Ian
Two things...
1) Would the increased Miller capacitance of paralleled UL EL84's cause a problem for a single 12AX7 LTP? I suspect it would, and Ian will probably say the MOSFET-follower version of Baby Huey would be the best candidate for wiring up with paralleled EL84s.
2) The Poinz Musical Machine uses triode-wired EL34s, not the plate-to-grid feedback Baby Huey uses. I've wondered how a 6GK5 LTP would do driving EL34-triodes. I figure they yield just barely enough gain to swing the 30V peak needed to drive the EL34 grids to full power.
--
1) Would the increased Miller capacitance of paralleled UL EL84's cause a problem for a single 12AX7 LTP? I suspect it would, and Ian will probably say the MOSFET-follower version of Baby Huey would be the best candidate for wiring up with paralleled EL84s.
2) The Poinz Musical Machine uses triode-wired EL34s, not the plate-to-grid feedback Baby Huey uses. I've wondered how a 6GK5 LTP would do driving EL34-triodes. I figure they yield just barely enough gain to swing the 30V peak needed to drive the EL34 grids to full power.
--
I converted a Chinese Music Angel Push Pull EL34 to this scheme for one of the nieces, Kate. It worked very well.
I have not tried them but I expect it would work well with KT77 or KT88 too although 6L6's suggestion above of using parallel push Pull EL84 would provide even higher gm on each push pull side and maybe better.
I have Output Transformers on the shelf for both a pair of KT88 (Hammond 1650P Raa=6K6 60 watts)and a parallel pair of EL84 (Hammond 1650N Raa=4K3 60 Watts), these are projects I have not got around to yet.
They are sitting there with a transformer set for a pair of 300B SET monoblocks, a pair of Hammond 1650T (Raa = 1K0 120 Watts) and a pair of Plitron CVDV2100-CFB/H 100W toroidals for a quad off KT88 each and a pair of Plitron PAT4006 Torroids which I was thinking of using for parallel push pull 300Bs .
Should stop buying bits and do more building with the parts I already have.!!! Been mostly building Git. Amps of late.
Unless using the simple Curent Source biased EL84 + 12AX7 schematic from the Wiki then Rogons suggestion that you should use the MOSFET source follower version is right. This is "required" to meet the Max Rg1 specifications for the output tubes and limit loading on the phase splitter.
Cheers,
Ian
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Hi, a newbie here. I've been reading this thread diligently for quite a while and finally got to the end of it. What a resource! And I have to compliment everyone involved who has contributed, especially Gingertube. If everyone could keep their equanimity as well as he does, all while doing it in such a humorous self deprecating manor, it would be a better world.
I definitely would like to apply the ideas on this thread to something new. Maybe this is worthy of its own thread but I want to run it up the flagpole here first just to see if anyone salutes. Hopefully not everyone just gives it a rasberry. There are many ideas from guitar amps that are applicable to high fidelity. I owned a hi-fi amp that sounded fantastic that was made by a guitar amp company. It was fantastic for playing all kinds of music. It was only produced for a couple of years and the one I owned eventually self destructed from overheating the power transformers several times. It was a PP design utilizing 2each EL84 and 1 6v6 per side. 6 tubes total for each channel and 12 output tubes total. You can probably get an idea why the power xfmrs died repetitively. You could choose pentode or triode mode for each tube pair by a switch that move the G2 wire from output transformer to B+. In essence you had a sound palette to paint with and it worked just as well for hifi as it does for guitar. The alterations weren't for "effects" any more than choosing pentode, ultralinear, or triode topology in a hifi amp is ever considered an "effect". To go with that there was also modifiable global feedback.
I would like to try this idea with the Baby Huey topology. I would use one el84 and one 6v6 per side PP (4 total per channel) and have both el84 and 6v6 pairs changeable independently between pentode and triode modes. I really don't expect to ever use both pairs in triode mode but that particular switching comes with the territory. Since there is more driving capacitance in the output tubes than is preferable it would have to be buffered, like the 6v6 schematic has. Basically I would use the 6v6 schematic and would add a second buffer for the el84 pairs along with the added el84s themselves.
A situation like this really does require different levels of plate to plate feedback because the same level of feedback can't be expected to be optimum for all different configurations. I really think that this can be made to work, except maybe for all output tube in triode mode. But from experience with that previous amp that configuration tended to have an overly polite sound.
What thinks you? Is this crazy? Or is it just crazy enough to be a good idea.
I definitely would like to apply the ideas on this thread to something new. Maybe this is worthy of its own thread but I want to run it up the flagpole here first just to see if anyone salutes. Hopefully not everyone just gives it a rasberry. There are many ideas from guitar amps that are applicable to high fidelity. I owned a hi-fi amp that sounded fantastic that was made by a guitar amp company. It was fantastic for playing all kinds of music. It was only produced for a couple of years and the one I owned eventually self destructed from overheating the power transformers several times. It was a PP design utilizing 2each EL84 and 1 6v6 per side. 6 tubes total for each channel and 12 output tubes total. You can probably get an idea why the power xfmrs died repetitively. You could choose pentode or triode mode for each tube pair by a switch that move the G2 wire from output transformer to B+. In essence you had a sound palette to paint with and it worked just as well for hifi as it does for guitar. The alterations weren't for "effects" any more than choosing pentode, ultralinear, or triode topology in a hifi amp is ever considered an "effect". To go with that there was also modifiable global feedback.
I would like to try this idea with the Baby Huey topology. I would use one el84 and one 6v6 per side PP (4 total per channel) and have both el84 and 6v6 pairs changeable independently between pentode and triode modes. I really don't expect to ever use both pairs in triode mode but that particular switching comes with the territory. Since there is more driving capacitance in the output tubes than is preferable it would have to be buffered, like the 6v6 schematic has. Basically I would use the 6v6 schematic and would add a second buffer for the el84 pairs along with the added el84s themselves.
A situation like this really does require different levels of plate to plate feedback because the same level of feedback can't be expected to be optimum for all different configurations. I really think that this can be made to work, except maybe for all output tube in triode mode. But from experience with that previous amp that configuration tended to have an overly polite sound.
What thinks you? Is this crazy? Or is it just crazy enough to be a good idea.
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I guess I should add that both el84 and 6v6 would use just one plate to plate feedback resistor and one cross connected resistor. But I imagine they will have to be switchable for the different configurations. There's a lot of things to think about in these little details. Any switch, including the pentode/triode mode switch, would involve a lot of wiring coming together and it might be tough to implement so hum or noise does not get induced in the wiring or the switches themselves.