Anybody have any experience with HandWoundTransformers?
How do they perform?
How do they compare to other transformers, like electra-print, magnequest or One Electron?
Alex
How do they perform?
How do they compare to other transformers, like electra-print, magnequest or One Electron?
Alex
Do a search on them in AudioAsylum.
A synopsis would be something like "if you wait a really long time, you'll get something that's worth what you paid for it:.
A synopsis would be something like "if you wait a really long time, you'll get something that's worth what you paid for it:.
I ordered a pair of outputs for a pp/ul EL-84 power amp I'm designing. Delivery was slow (I waited a long time).
They are actually quite nice. The finish was well done. Completely better looking than Hammonds with those fugly industrial knockouts.
These are the 7.6k primary, 25 watt models. I haven't put them on the bench to give you a high f3 figure and my signal generator only goes down to 15 hz but I believe they're pretty good. The prototype is running on Dyna Z-565s and when I temporaried the Handmades in, I only had to pull the high end in a little to re-stabilize the amp. Very few transformers can stay with a Z-565 at high f3. They sounded wonderful.
They are actually quite nice. The finish was well done. Completely better looking than Hammonds with those fugly industrial knockouts.
These are the 7.6k primary, 25 watt models. I haven't put them on the bench to give you a high f3 figure and my signal generator only goes down to 15 hz but I believe they're pretty good. The prototype is running on Dyna Z-565s and when I temporaried the Handmades in, I only had to pull the high end in a little to re-stabilize the amp. Very few transformers can stay with a Z-565 at high f3. They sounded wonderful.
I've been busy because everything I do must, apparently, be done twice.... be done twice.
Damned compters won't do what you want them to do, anyway. what you want them to do
anyway
How you been? ?....😉
Damned compters won't do what you want them to do, anyway. what you want them to do
anyway
How you been? ?....😉
Well... As Reddy said... again and again (😉), it took a loooooooooooooooooong time to get them. I got their single ended ones. Haven't had the chance to try them yet. By the time I got them the time to play came and went.
But they do look beautiful. I will let all know how they sound when I get the chance FWIW.
Gabe
But they do look beautiful. I will let all know how they sound when I get the chance FWIW.
Gabe
HANDROLLED.
Hello Gabe,
Pls. do let us know and if you could measure them as well that would be great.
Cheers,😉
Hello Gabe,
Pls. do let us know and if you could measure them as well that would be great.
Cheers,😉
Hi Gabe,
How long is long time? weeks, months, years, forever?
Just want to have an idea.
Thanks everyone,
Alex Deveza
How long is long time? weeks, months, years, forever?
Just want to have an idea.
Thanks everyone,
Alex Deveza
I am having a bad experience with handwoundtransformers.
I orderd a replacement power transformer for a klh-model eight
from him (David Lucas). He initially did not ask for sufficient
specification to build the unit, promised delivery in 4 weeks,
and took my money gladly. Two months later I asked about
my transformer and he said he lost the order and that I would
have it in two weeks. A month later he stopped responding
to my inquiries. I have since, uselessly asked for a refund.
It has been 4 months since I ordered the transformer and I
have not seen it or my money. I would caution anyone who
plans to order something from him. At least dont expect to
get it in a timely manner.
I orderd a replacement power transformer for a klh-model eight
from him (David Lucas). He initially did not ask for sufficient
specification to build the unit, promised delivery in 4 weeks,
and took my money gladly. Two months later I asked about
my transformer and he said he lost the order and that I would
have it in two weeks. A month later he stopped responding
to my inquiries. I have since, uselessly asked for a refund.
It has been 4 months since I ordered the transformer and I
have not seen it or my money. I would caution anyone who
plans to order something from him. At least dont expect to
get it in a timely manner.
OPT frequency response, and testing for that, is actually a complex can of worms. It's not discussed enough and it's poorly understood by a lot of otherwise knowledgeable people, including me.
When I say I've put an OPT on the bench and tested it, that means in circuit. The amp (push-pull) is running open loop with stability networks disconnected. The output tube and operating conditions (triode, UL, etc.) are stated, indicating AC plate resistance. Meaning that signal source impedance is the wild card in how that OPT behaves at HF. I monitor signal voltage across the primary with a scope and I record frequency (HF) response across a stated resistive load on the secondary. The load affects things, too. (A real world reactive load throws another one-eyed jack in there.) I do this because it's the only test results that mean anything to me. And I'm saying this from memory because I don't even do that anymore. I just design and build the amp with OPTs that are generally considered to be good.
If a manufacturer states that this transformer is -3db at 8 hz and 52 khz, all I really know is that they've discovered some unknown miracle situation that allows the tx to behave that way. Hammond's -1 db spec at rated power is considerably more useful, especially for single-ended, at LF.
Perhaps it would be more useful to be given a leakage inductance and winding capacitance figure specific to that OPT. Then you could calculate that with series resistance and see at which frequency the whole affair is going to turn into a resonant tank.
Are there any transformer engineers here? And we don't want any of this, "well, first you need a basic understanding of the principles of FM." (****ing magic!) 😉
When I say I've put an OPT on the bench and tested it, that means in circuit. The amp (push-pull) is running open loop with stability networks disconnected. The output tube and operating conditions (triode, UL, etc.) are stated, indicating AC plate resistance. Meaning that signal source impedance is the wild card in how that OPT behaves at HF. I monitor signal voltage across the primary with a scope and I record frequency (HF) response across a stated resistive load on the secondary. The load affects things, too. (A real world reactive load throws another one-eyed jack in there.) I do this because it's the only test results that mean anything to me. And I'm saying this from memory because I don't even do that anymore. I just design and build the amp with OPTs that are generally considered to be good.
If a manufacturer states that this transformer is -3db at 8 hz and 52 khz, all I really know is that they've discovered some unknown miracle situation that allows the tx to behave that way. Hammond's -1 db spec at rated power is considerably more useful, especially for single-ended, at LF.
Perhaps it would be more useful to be given a leakage inductance and winding capacitance figure specific to that OPT. Then you could calculate that with series resistance and see at which frequency the whole affair is going to turn into a resonant tank.
Are there any transformer engineers here? And we don't want any of this, "well, first you need a basic understanding of the principles of FM." (****ing magic!) 😉
HEY! This is a DIY forum, not a..... uh..... oh.....
Actually, there may not be any transformer engineers here per se (versus those who may likely have more knowledge about it than I). I guess it is a specialized art. How many DIYers actually roll their own transformers???
At any rate, I did write a page on transformers and included some in depth tekkie stuff from a guy who is a transformer engineer.
http://members.tripod.com/~gabevee/transform.html
Hope this helps. And no... no FM.
As for the RCL resonance thingy... I think that the capacitance/indutance is such that the natural oscillation is very low frequency. Careful design, NFB, and good filter caps tend to stabilize that. Hence why I get on my
about using a large enough filter cap after the choke to filter out the lowest audio frequencies, not just 120 Hz. It is there to also help isolate the audio to each stage, and not allow bleeding from one stage to the other, let alone to another channel in the case of stereo.
So, the internal LC properties need also to be coupled with the capacitance of overall windings to the case, resistance of the plate, capacitance of the power supply, etc. etc. etc.
Otherwise... the internal workings of the transformer without anything else would be purely theoretical. In other words... you wouldn't see the transformer ringing at its resonant frequency because it isn't in a circuit.
As for its effects on frequency response... as someone else pointed out, some circuits can actually improve on the theoretical limits. Case in point: I used the Hammond 125ESE in a 300B amp. The specs are supposedly 100-10,000 Hz (or thereabout) I got 50-17,000 Hz. The 300B had whatever it took to overcome the internal LC properties to extend the response. Go figure!
Another side point: The plate resistance of the tube in the case of single ended will damp any resonance or ringing, since it is low enough. Hence another reason why triodes are desirable.
Gabe
Actually, there may not be any transformer engineers here per se (versus those who may likely have more knowledge about it than I). I guess it is a specialized art. How many DIYers actually roll their own transformers???
At any rate, I did write a page on transformers and included some in depth tekkie stuff from a guy who is a transformer engineer.
http://members.tripod.com/~gabevee/transform.html
Hope this helps. And no... no FM.
As for the RCL resonance thingy... I think that the capacitance/indutance is such that the natural oscillation is very low frequency. Careful design, NFB, and good filter caps tend to stabilize that. Hence why I get on my
about using a large enough filter cap after the choke to filter out the lowest audio frequencies, not just 120 Hz. It is there to also help isolate the audio to each stage, and not allow bleeding from one stage to the other, let alone to another channel in the case of stereo.So, the internal LC properties need also to be coupled with the capacitance of overall windings to the case, resistance of the plate, capacitance of the power supply, etc. etc. etc.
Otherwise... the internal workings of the transformer without anything else would be purely theoretical. In other words... you wouldn't see the transformer ringing at its resonant frequency because it isn't in a circuit.
As for its effects on frequency response... as someone else pointed out, some circuits can actually improve on the theoretical limits. Case in point: I used the Hammond 125ESE in a 300B amp. The specs are supposedly 100-10,000 Hz (or thereabout) I got 50-17,000 Hz. The 300B had whatever it took to overcome the internal LC properties to extend the response. Go figure!
Another side point: The plate resistance of the tube in the case of single ended will damp any resonance or ringing, since it is low enough. Hence another reason why triodes are desirable.
Gabe
Thank you, Gabe. I don't like confusion and ignorance - especially my own.
As I said, so far I've always used the best iron I could for the budget and stretched bandwidth and stability as far as it would go. But I really don't know what I think I should about OPTs.
On the other hand, why let ignorance stand in the way of progress?
As I said, so far I've always used the best iron I could for the budget and stretched bandwidth and stability as far as it would go. But I really don't know what I think I should about OPTs.
On the other hand, why let ignorance stand in the way of progress?
lemme try again
I lack clarity as I grumble about a lack of clarity. I got a burr under the saddle when I realized that after all this time, everything I've learned and everything I've done, I still don't have a stand-alone tx test that I'd consider useful for myself or anybody else.
I've collected a pretty big technical library over the years. We call it McGraw-Hell. Do you want to discuss "ideal transformer" behaviour forever? Examine endless equivalent circuit diagrams? Sort your way through miles of mathematical embroidery? Well, there you go.
I actually regret the time I've wasted over the years taking a "rigorous and comprehensive approach". Eat your engineering, it's good for you. Useless clutter.
Radiotron and on and on... 4th ed., does eventually cough up what's described as a standard test of merit for OPTs. If you know the turns ratio and have a signal generator that swings several hundred volts, at maybe 5 hz to 100khz, again, there you go.
We lost David Hafler a few weeks ago. Now, there was your transformer authority, but, look! Every Dyna power tx I ever saw was a marginal, hot-running maypop! And why was the PAS tx doing double duty as a fuse? How important is anything?
And they wonder why we existentialists tend to sit in the back corner of the coffee shop and rarely speak.
I lack clarity as I grumble about a lack of clarity. I got a burr under the saddle when I realized that after all this time, everything I've learned and everything I've done, I still don't have a stand-alone tx test that I'd consider useful for myself or anybody else.
I've collected a pretty big technical library over the years. We call it McGraw-Hell. Do you want to discuss "ideal transformer" behaviour forever? Examine endless equivalent circuit diagrams? Sort your way through miles of mathematical embroidery? Well, there you go.
I actually regret the time I've wasted over the years taking a "rigorous and comprehensive approach". Eat your engineering, it's good for you. Useless clutter.
Radiotron and on and on... 4th ed., does eventually cough up what's described as a standard test of merit for OPTs. If you know the turns ratio and have a signal generator that swings several hundred volts, at maybe 5 hz to 100khz, again, there you go.
We lost David Hafler a few weeks ago. Now, there was your transformer authority, but, look! Every Dyna power tx I ever saw was a marginal, hot-running maypop! And why was the PAS tx doing double duty as a fuse? How important is anything?
And they wonder why we existentialists tend to sit in the back corner of the coffee shop and rarely speak.
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