As I said you can always make a cover that screws in like an OPT with EI core and end bells. Can you? Not a difficult task really.
Otherwise buy an EDCOR 25W or something similar. At affordable price there is not much to rave about.
Otherwise buy an EDCOR 25W or something similar. At affordable price there is not much to rave about.
That LL1682 can be placed in this housing:
The specific housing type is the “1638” type. Both the transformer and housing is available from the US distributor, Erhard Audio.
Best,
Anand.
The specific housing type is the “1638” type. Both the transformer and housing is available from the US distributor, Erhard Audio.
Best,
Anand.
Too bad end bells are a requirement or else you could go with Monolithic magnetics. http://www.monolithmagnetics.com/products#Push-Pull-output-transformers
I haver the 8k PP transformers and the sound is amazing.
I haver the 8k PP transformers and the sound is amazing.
Never Get Old, you might like to look up old Radio Design Handbook for how to design transformers to see if what you want is sensible. For a given core and winding, there is a Power/THD vs Frequency factor which is constant.
eg if you want 1% THD at 10W 20Hz, the same transformer will give you 1% @ 40W 40Hz and 160W 80Hz. etc. It is a 6dB/8ve relation. Whether the amp attains this is up to the rest of the circuit but these are the transformer LF limitations.
Use this to find out what power 30Hz transformer you need for 20Hz at your specified distortion and power. If it turns out to be physically bigger than the Sowter, you know what you need in terms of $$$
And Ultra-linear helps the "rest of the circuit" achieve your LF power, take advantage of your huge transformer at higher frequencies, flatter frequency response bla bla.
eg if you want 1% THD at 10W 20Hz, the same transformer will give you 1% @ 40W 40Hz and 160W 80Hz. etc. It is a 6dB/8ve relation. Whether the amp attains this is up to the rest of the circuit but these are the transformer LF limitations.
Use this to find out what power 30Hz transformer you need for 20Hz at your specified distortion and power. If it turns out to be physically bigger than the Sowter, you know what you need in terms of $$$
And Ultra-linear helps the "rest of the circuit" achieve your LF power, take advantage of your huge transformer at higher frequencies, flatter frequency response bla bla.
You may like from ogonowski.eu i build this amp and it sounds fantastic (to my ears).
I know relatively little about OPTs but I knew that after reading the first NGO reply that got real old, real fast! 😉
What's required here is a time machine to go back to the 80s when these transformers were $50/each.
The Z-565 is supposedly the "be all and end all" of output transformers, but it's not what I want in this case. Fine for most, not for me.
Not begging. I have money and there are options.
Two? Different topics help people find information.
They are ... in China, which I haven't ruled out completely.
So I should make a snap decision, and settle for low quality and/or not what I want, for a long-term project, just to satisfy others?
I'll have to ask them if they have end bells or if they make open frame transformers only. On the website I only see open frame, but they may be able to add end bells.
Fortunately, I have found multiple options. Thanks to everyone who helped.
Not begging. I have money and there are options.
Two? Different topics help people find information.
They are ... in China, which I haven't ruled out completely.
So I should make a snap decision, and settle for low quality and/or not what I want, for a long-term project, just to satisfy others?
I'll have to ask them if they have end bells or if they make open frame transformers only. On the website I only see open frame, but they may be able to add end bells.
Fortunately, I have found multiple options. Thanks to everyone who helped.
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Thanks. I will contact them to see what options they have that might fit my needs. I did find some others on their web site pictured with end bells, so maybe they do use them when requested.
My first choice is the relatively large 25 watt models from Primary Windings. However I can't order them until my power transformer arrives in 3-6 weeks. I'll have to position the PT as far back as possible on the chassis and then take careful measurements to see if I can get the Primary Windings OPTs to fit. If I can get them to fit it will only leave a few millimeters to spare. They are large, almost as big as the power transformer, which is fine if I can fit them. It would be a beast of a little amp with all of that big heavy iron sitting on top. I would like it. Maybe add carrying handles to it. 🙂
My backup choice is Thermionic Lab. They are very friendly and helpful, and they can do various sizes that they say will perform as I want.
While I wait for the power transformer so I can take precise measurements with it installed, I have a lot of satin black paint work to do. Can't do anything without a chassis, and it has to be all black.
Am I picky? Yes. I have built two amplifiers this year, have a third from years ago, and am building two more right now. One of them will become my "forever" amplifier I hope. Perhaps this one. I certainly do not need five, and I have high hopes for this one.
My first choice is the relatively large 25 watt models from Primary Windings. However I can't order them until my power transformer arrives in 3-6 weeks. I'll have to position the PT as far back as possible on the chassis and then take careful measurements to see if I can get the Primary Windings OPTs to fit. If I can get them to fit it will only leave a few millimeters to spare. They are large, almost as big as the power transformer, which is fine if I can fit them. It would be a beast of a little amp with all of that big heavy iron sitting on top. I would like it. Maybe add carrying handles to it. 🙂
My backup choice is Thermionic Lab. They are very friendly and helpful, and they can do various sizes that they say will perform as I want.
While I wait for the power transformer so I can take precise measurements with it installed, I have a lot of satin black paint work to do. Can't do anything without a chassis, and it has to be all black.
Am I picky? Yes. I have built two amplifiers this year, have a third from years ago, and am building two more right now. One of them will become my "forever" amplifier I hope. Perhaps this one. I certainly do not need five, and I have high hopes for this one.
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One thing to remember is that the Hammonds are rated +/- 1db at 30hz maximum power output. As the wattage output drops, the low
frequency response improves greatly. At one watt output, 20hz is easily attainable, but also depends upon the rp of the output tubes.
The above Hammond response is generally given considering a beam power tube, with high rp.
Very important is the rp of the output tubes. Triode rp is generally much less than pentodes/tet/beam power tubes.
For instance, a KT88 operated as a triode has ~600 ohm rp (without current feedback, cathode grounded),
a 300b is similar. As such it does not take much primary inductance to achieve flat response to 20hz, or lower.
A pentode/tet/beam power tube requires much higher primary inductance.
A low rp triode tube generally has a higher FR than generally stated, depending upon internal capacitance of the
tube, stray capacitances, and internal losses in the OPT (leakage inductance, distributed capacitance etc).
Proper frequency balance of the OPT is quite important. It can be bass heavy or high frequency heavy.
cheers
pos
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Excellent information. Thanks! 🙂
It is pentode, not triode, and no ultralinear connection. One schematic says 10k and one says 8k. If I have to err, I'd like to err on the side of bass-heavy. I can't stand systems with weak or light bass, especially at low volume where the natural preference is to want more anyway, as with artifical "loudness" controls.
I think after doing a scale drawing that Primary Windings 25 watt 8k will fit with 2 mm to spare. Is 8k ideal given this scenario or is another value more appropriate?
I'm learning. Thanks to those who are helping. I do appreciate it.
A beautiful sight if I got all measurements correct. The power transfomer winding is horizontal (parallel to the amp) while OPT windings are vertical (up and down in relation to the amp). This is the way they are oriented now, and packed almost as tightly, with no problems. The extra space needed for the Primary Windings transformers is gained by leaving off the metal housing that goes over the stock transformers, which are half the size.
It is pentode, not triode, and no ultralinear connection. One schematic says 10k and one says 8k. If I have to err, I'd like to err on the side of bass-heavy. I can't stand systems with weak or light bass, especially at low volume where the natural preference is to want more anyway, as with artifical "loudness" controls.
I think after doing a scale drawing that Primary Windings 25 watt 8k will fit with 2 mm to spare. Is 8k ideal given this scenario or is another value more appropriate?
I'm learning. Thanks to those who are helping. I do appreciate it.
A beautiful sight if I got all measurements correct. The power transfomer winding is horizontal (parallel to the amp) while OPT windings are vertical (up and down in relation to the amp). This is the way they are oriented now, and packed almost as tightly, with no problems. The extra space needed for the Primary Windings transformers is gained by leaving off the metal housing that goes over the stock transformers, which are half the size.
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It's usually considered good practice to have the PT laminations at right angles to the OPT lams.
Primary windings will likely be costly to ship as they are in the UK. Just sayin'.
By the way, the Hammond 1650F (7.6K, 25 watts) is 90mm wide versus the one shown in your drawing's 86mm. Might just fit in a pinch.
https://www.hammfg.com/electronics/transformers/classic/1608-1650
S.
Primary windings will likely be costly to ship as they are in the UK. Just sayin'.
By the way, the Hammond 1650F (7.6K, 25 watts) is 90mm wide versus the one shown in your drawing's 86mm. Might just fit in a pinch.
https://www.hammfg.com/electronics/transformers/classic/1608-1650
S.
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Duly noted if a fourth or fifth option is needed.
Shipping cost is fine. Not too bad actually. I calculated it with the shopping cart.
Windings are still at right angles from the OPTs to the power transformer whether the OPT laminations are rotated 90 degrees from the power transformer or not. OPT's are wound vertically, power transformer is wound horizontally. Winding orientation controls magnetic field not the laminations if I understand correctly. That issue was raised several times. Correct me if this info is wrong. I'm always learning. They come configured like that and seem to work fine. I found these illustrations in some reference book somewhere as I was looking into this issue. Spacing the left and right OPTs farther apart might be ideal, but the narrow chassis is something that I really, really want.
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I understand, your welcome NGO.
Here is a little more information, attached, that you and others can use when contacting, or providing personalized
info for any, or customized OPT. It comes from the RCA Radiotron Designers Handbook, 1960.
cheers and all the best.
pos
The lams also indicate winding direction. Either rotate the OPTs or the PT in your drawing. I've seen amps where the OPTs bookended the PT and all were very close (EG. Leak Stereo 20) and the PT was 90 degrees to the OPTs. No magnetic interaction as far as I could hear. If you are using a choke in the power supply these can sometimes radiate or pick up AC. If you are very, very careful and temporarily wrap the choke in electrical tape, it's possible to "tune" the choke live for the position of minimum interference. This has worked for me on a couple of occasions.
S.
S.
How so? The windings are 90 degrees regardless of the lamination direction. This has been discussed many times, but no guarantee that those who discussed it were correct. So much to learn. We all start somewhere.
Here are the winding orientations in my current amplifier, which I love dearly even with the small Chinese OPTs, horizontal vs. vertical windings:
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