Hello,
Do you guys know any proven 2A3 / 5687 ... design in class A with output transformer in normal (not parafeed) configuration?
I can say over the last several years I have successfully built a normal amplifier what will serve me for several years. On the other hand, I'm struggling with headphone amps. Main targets are an old and excellent HD565 ovation, a new HD800.
I've made really good solid state amps and lately I made an excellent OTL class A tube headphone amp which has the sound I'm looking for. The main problem is not that it is 25kg and eats 200W standby. The main problem is that mains swings 10+ Volts at my street and when there is a sudden change, I see hear that it sounds distorted for a second and when I removed padding and looked at membrane I saw it puches several mm that time. It can be several Volts DC at the headphone jack when the mains changing 10+ Volts. I know I should have smaller output cap, but than the bass gets weaker.
Anyway, I think I'm tired of anything else, I want to make a class A SE or PSE transformer output (with DC bias, so not magnetic zero cross) headphone amp. Do you have a suggestion?
Thanks,
JG
Do you guys know any proven 2A3 / 5687 ... design in class A with output transformer in normal (not parafeed) configuration?
I can say over the last several years I have successfully built a normal amplifier what will serve me for several years. On the other hand, I'm struggling with headphone amps. Main targets are an old and excellent HD565 ovation, a new HD800.
I've made really good solid state amps and lately I made an excellent OTL class A tube headphone amp which has the sound I'm looking for. The main problem is not that it is 25kg and eats 200W standby. The main problem is that mains swings 10+ Volts at my street and when there is a sudden change, I see hear that it sounds distorted for a second and when I removed padding and looked at membrane I saw it puches several mm that time. It can be several Volts DC at the headphone jack when the mains changing 10+ Volts. I know I should have smaller output cap, but than the bass gets weaker.
Anyway, I think I'm tired of anything else, I want to make a class A SE or PSE transformer output (with DC bias, so not magnetic zero cross) headphone amp. Do you have a suggestion?
Thanks,
JG
If you like the harmonic profile of tube amps, try SS MOSFET source follower in SE Class A operation. Many headphones on this forum are like this and sound great. Just look at the title and you will see many with the words “SE Class A”. If you want, a tube first stage followed by a MOSFET output stage hybrid will give you all that same tube sound without all the iron of an output transformer.
This Estudiante HPA sounds great;
El Estudiante Headphone Amp – wauwatosa tube factory
You might also look at the MOFO speaker amp - driven by a tube preamp will do exactly what you want. It can also drive 8 ohm speakers to 11w. It’s very quiet - essential property of headphone amps.
Build This MoFo!
If something more compact or portable is what you are looking for, there are even pocket Class A headphone amps.
This Estudiante HPA sounds great;
El Estudiante Headphone Amp – wauwatosa tube factory
You might also look at the MOFO speaker amp - driven by a tube preamp will do exactly what you want. It can also drive 8 ohm speakers to 11w. It’s very quiet - essential property of headphone amps.
Build This MoFo!
If something more compact or portable is what you are looking for, there are even pocket Class A headphone amps.
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It could be, but the point is, I do not wan to experiment more. I have spent a lot over the last years on Ck2III, TPA6017, b22, OTL tube SE A. All are great in it's class and the OTL tube amp does what I want. The problem is, I also want the safety, the freedom provided by the output transfomer's isolation.
Unfortunately with the OTL tube amp, I made a mistake taht after it proved itself on a test model, I've designed a box for it, got it lasercut, bent, sintered, I built it into and realized after hours that I have this problem. Can't fit a regulator tube now. I need to make a new assembly plate a new box, it is almost starting from scratch and if I do that, I start on a known way now.
Thanks,
JG
I did tried in an air wired model where the transformer was a small Hammond 119DA. It was good, but the OTL amp was a step further for me in sound.
Thanks,
JG
I can not say I like the tube sound in general. Not. I also do not like tubes, the limited lifitime, all the heat, the size etc. But, at power amp, I think it just outperfoms solid state. Unfortunately. An example, I found that people loving tube sound, prefer 300B over 2A3. I prefer 2A3, that is more natural to me. At least in the AN amps I listened so far. So, it is not that I'm after the "tube sound", but this Estudiante HPA made me thinking I may try it. I even have an old 5687 based preamp what I used before the preamp I have now. The mosfet buffer would not fit at all, but I may use it to make a benchtop model.
Thanks,
JG
You won't get the desired results trying to parafeed an airgapped transformer. I can't say I have ever heard an OTL. Always been curious.
The 119DA is airgapped?
I know it is not a top line at all, but I do not think it is airgapped.
JG
It isn't, my mistake. Quality really makes the difference here. If you are looking for cheap, then toroids can sometimes perform well keeping in mind they do have a number of limitations. Stay within their parameters and they can be quite rewarding. I also have a few Electraprint's that are very good.
Hello,
It was some time ago when I was here, but now I'm back to to the original question. I did built a mini amp with IC which is surprisingly OK, but I'm just back to make an SE triode output headphone amp. I did read this again: Headphone Amp | Tubelab . What output transformer you use?
Otherwise, now I gave up that I will use small noval socketed tubes, I'm looking now to use 2A3 for power tube.
Do you have recommendations?
Thanks,
JG
So what you're looking for is a small noval socket pre/driver tube(s) into a 2a3 via a transformer in a SE configuration? I assume it will be driving ~600ohm headphones?
You may find something like a loftin-white frontend driving a 2a3 with a lundahl transformer would work. However the designs I've been exploring are balanced circlotrons with transformers.
Typically the primary is 2.5-2K for a SE 2a3 configuration.
180 Ohm and 300 Ohm now, but it would be nice to have secondary config for lower impedance headphones also like Grado's. The most important is 300 Ohm.
On thransformes, I know only one, unfortunately the primary impedance seems too high, about 3.5k.
https://www.lundahltransformers.com/wp-content/uploads/datasheets/2774.pdf
On thransformes, I know only one, unfortunately the primary impedance seems too high, about 3.5k.
https://www.lundahltransformers.com/wp-content/uploads/datasheets/2774.pdf
Sowter is the other of the shelf option in Europe (UK actually, so beware taxes).
OT for headphones are quite expensive. A much cheaper decent parafeed option is made by edcor and sold by Don-Audio: Edcor PCW10K-7K/300-32, 24,37 € . I used it in this design: https://www.diyaudio.com/forums/tub...ns-parafeed-headphones-amp-2.html#post4037465
It should be a lot better than that Hammond, unless used with a cathode follower. The Mapletree Ear uses the 119DA in that configuration and is really not a bad amp. They even provide the schematic if you want to have a look at it: https://www.mapletreeaudio.com/manuals/Eplus HD II users manual.pdf
OT for headphones are quite expensive. A much cheaper decent parafeed option is made by edcor and sold by Don-Audio: Edcor PCW10K-7K/300-32, 24,37 € . I used it in this design: https://www.diyaudio.com/forums/tub...ns-parafeed-headphones-amp-2.html#post4037465
It should be a lot better than that Hammond, unless used with a cathode follower. The Mapletree Ear uses the 119DA in that configuration and is really not a bad amp. They even provide the schematic if you want to have a look at it: https://www.mapletreeaudio.com/manuals/Eplus HD II users manual.pdf