45,
I still have some of Jack Elliano's Electra-Print Audio Very Good Single Ended output transformers.
~ 3k and ~ 5k primaries, two of each impedance.
They each have 4 identical secondary windings.
I can not find them at the moment, I think they are interleaved with the primary (Perhaps S, S, P, S, S; or P, S, S, S, S, P).
Doing S, P, S, P, S, P, S, P is very intensive and expensive, but perhaps that is why Jack no longer builds those versions.
All 4 secondary windings are always connected.
Connect them properly, and you get:
A 1 Ohm, 4 Ohm, 9 Ohm, or a 16 Ohm Single output tap (only 1 impedance per connection scheme).
It is all in how you do it that counts.
The 4 secondary winding versions are no longer available. Too bad.
If any of you readers think your speaker is 8 Ohms, then please do an impedance test of it, from 20Hz to 20,000Hz and get back to us with the test results, this thread will work fine for where to post your results.
The 9 Ohm connected version, and the 4 Ohm connected version of Jack's transformers will work just fine (after you measure your 8 Ohm speaker to find whether to use the 9 Ohm connection or the 4 Ohm connection.
I might be interested in selling those transformers, but for many of you in certain locations, the shipping cost is not cheap.
Have fun designing, building, and listening!
I still have some of Jack Elliano's Electra-Print Audio Very Good Single Ended output transformers.
~ 3k and ~ 5k primaries, two of each impedance.
They each have 4 identical secondary windings.
I can not find them at the moment, I think they are interleaved with the primary (Perhaps S, S, P, S, S; or P, S, S, S, S, P).
Doing S, P, S, P, S, P, S, P is very intensive and expensive, but perhaps that is why Jack no longer builds those versions.
All 4 secondary windings are always connected.
Connect them properly, and you get:
A 1 Ohm, 4 Ohm, 9 Ohm, or a 16 Ohm Single output tap (only 1 impedance per connection scheme).
It is all in how you do it that counts.
The 4 secondary winding versions are no longer available. Too bad.
If any of you readers think your speaker is 8 Ohms, then please do an impedance test of it, from 20Hz to 20,000Hz and get back to us with the test results, this thread will work fine for where to post your results.
The 9 Ohm connected version, and the 4 Ohm connected version of Jack's transformers will work just fine (after you measure your 8 Ohm speaker to find whether to use the 9 Ohm connection or the 4 Ohm connection.
I might be interested in selling those transformers, but for many of you in certain locations, the shipping cost is not cheap.
Have fun designing, building, and listening!
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The number of wires out does not necessarily reflects how the transformer is really made, especially regarding the primary where normally windings are in series. Connections are done internally as well. The only commercial transformers I know without internal connections are some Lundahls like LL1627, 1623 and the others of that series but most OPT's do have internal connections.
S,S,P,S,S is technically the same as S,P,S and I doubt the Electra Print are that simple as this would result in high leakage inductance and rather limited frequency response. The bare minimum I would say is P-S,S-P-S,S-P but maybe it's more like S-P-S-P-S-P-S or even 5P and 4S.
S,S,P,S,S is technically the same as S,P,S and I doubt the Electra Print are that simple as this would result in high leakage inductance and rather limited frequency response. The bare minimum I would say is P-S,S-P-S,S-P but maybe it's more like S-P-S-P-S-P-S or even 5P and 4S.
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45,
Those older SE transformers from Jack Elliano were specifically made for four different connection schemes, in order to do two things:
1. Use all secondary windings for all output impedance selections.
2. Make the same transformer capable of being able to have 4 different output impedances (one setting at a time).
I used both the 3k and 5k primary versions, and used both versions wired for 4 Ohms, and for 8 Ohms.
Worked good for me. 45, 2A3, 300B.
I even did measurements on those bare/naked output transformers, using the $50,000 Rohde & Schwarz Vector Network Analyzer and $10,000 Calibration Kit that I had access to, years ago.
I also used Lundahl interstage transformers. I was never able to tame them properly, they always had "ringing"; maybe just a function of my circuits.
Right or wrong, they had 1/2 of the primary and 1/2 of the secondary over one air gap, and the other 1/2 of the primary and the other 1/2 of the secondary over the other air gap.
Series connection (primary and/or secondary); parallel connection (primary and/or secondary), they sounded good.
But they did not look very pretty in the various measurement tests I did on them.
I no longer use those Interstage transformers.
I never had Lundahl output transformers to try.
I no longer build SE amplifiers; I design/build various forms of push pull:
Phase Inverter stage to output stage
Self Inverting Output stage
Fully Balanced from input to output stage plates.
The only way I will ever consider to try a Lundahl output transformer is if it is specifically made for push pull.
Just my experiences.
Your Mileage May Vary
Those older SE transformers from Jack Elliano were specifically made for four different connection schemes, in order to do two things:
1. Use all secondary windings for all output impedance selections.
2. Make the same transformer capable of being able to have 4 different output impedances (one setting at a time).
I used both the 3k and 5k primary versions, and used both versions wired for 4 Ohms, and for 8 Ohms.
Worked good for me. 45, 2A3, 300B.
I even did measurements on those bare/naked output transformers, using the $50,000 Rohde & Schwarz Vector Network Analyzer and $10,000 Calibration Kit that I had access to, years ago.
I also used Lundahl interstage transformers. I was never able to tame them properly, they always had "ringing"; maybe just a function of my circuits.
Right or wrong, they had 1/2 of the primary and 1/2 of the secondary over one air gap, and the other 1/2 of the primary and the other 1/2 of the secondary over the other air gap.
Series connection (primary and/or secondary); parallel connection (primary and/or secondary), they sounded good.
But they did not look very pretty in the various measurement tests I did on them.
I no longer use those Interstage transformers.
I never had Lundahl output transformers to try.
I no longer build SE amplifiers; I design/build various forms of push pull:
Phase Inverter stage to output stage
Self Inverting Output stage
Fully Balanced from input to output stage plates.
The only way I will ever consider to try a Lundahl output transformer is if it is specifically made for push pull.
Just my experiences.
Your Mileage May Vary
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Yes, the 4 secondary impedances scheme is the same used by Sowter 1/4/9/16 R. That is possible for both SE and PP. Having 2 or 4 secondaries also allows you to do cathode fbk for some secondary impedances (symmetric connection to serve both cathodes of the PP output stage) as well. With SE you can always apply cathode fbk for any secondary impedance.
Lundahls ITs are a little bit of nightmare I agree. I have one pair of 1635s that are extremely good a picking parasitic capacitances.. They never performed as they claim. In the best case I was able to get 15 KHz -1 dB.....
As I said many times, Lundahls appear to have fixed winding scheme for each family of transformers and so some are more optimal than others within a certain family. This is regardless of PP or SE. My favourite ones are LL1627, LL1682 and LL1688. The 1627 is the only one of the three that has no internal connections from what I can see. The 1688 is not a champion of frequency response but it gives the DIY'er a lot of options that are normally very expensive. It is not cheap by any means but it is a bargain when taking into consideration all the options it offers.
Lundahls ITs are a little bit of nightmare I agree. I have one pair of 1635s that are extremely good a picking parasitic capacitances.. They never performed as they claim. In the best case I was able to get 15 KHz -1 dB.....
As I said many times, Lundahls appear to have fixed winding scheme for each family of transformers and so some are more optimal than others within a certain family. This is regardless of PP or SE. My favourite ones are LL1627, LL1682 and LL1688. The 1627 is the only one of the three that has no internal connections from what I can see. The 1688 is not a champion of frequency response but it gives the DIY'er a lot of options that are normally very expensive. It is not cheap by any means but it is a bargain when taking into consideration all the options it offers.
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Yes, 6H30 driver and 45 power tubes PP-to-PP. They satisfy the load requirements pretty well in terms of source impedance and secondary capacitance. Worse for the other configurations. This variant of 1635 is the one usable with 5mA DC current (130H primary inductance) for SE-to-SE as well but in that case it barely gets to 10KHz..... It's a good IT at low frequency and is affordable but that's it. The fact it has very specific source/load requirements to work decently is a weak point. A few years back there were not many options but over the recent years things have changed. Today I would never buy it.
The same issue happens for most of their input transformers when there are competitive options that are quite the opposite. Take for example (in ascending cost) the Jensen JP-11 series, the Sowter 1475, 8540, 6093 or Hashimoto. They work fine with a variety of sources and do not necessarily need Zobel networks. This is a very relevant advantage. Possibly even the Hammond Studio Grade are like that but I have not tried them. Only heard good reports.
For phase splitting Sowter are the best I have tried, even better than Hashimoto regarding distortion figures at high frequency.
The same issue happens for most of their input transformers when there are competitive options that are quite the opposite. Take for example (in ascending cost) the Jensen JP-11 series, the Sowter 1475, 8540, 6093 or Hashimoto. They work fine with a variety of sources and do not necessarily need Zobel networks. This is a very relevant advantage. Possibly even the Hammond Studio Grade are like that but I have not tried them. Only heard good reports.
For phase splitting Sowter are the best I have tried, even better than Hashimoto regarding distortion figures at high frequency.
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Similar experience of mine, which I had reported on a few years back in these forums. Lundahl IT's were the worst of their product line; multiple resonances that could never get tamed by zobel networks. In my view, if you like what you hear but hate what you measure it is confirmation that your ears can deceive. However, in the case of Lundahl IT's I could hear what I was measuring. Unlistenable. I would say their input transformers did pretty well. Guessing the core designs and winding configurations were significantly different.
To date the only remaining transformer still in use is a LL1689AM/PP which is in service as my 12B4A differential preamp output transformer. It does just fine - no resonances and decent 0.005% distortion with zero feedback. I believe I could improve on it with a different xfmr but haven't bothered.
I would second a similar experience with Onetics. Less resonance-prone, but a complete breakdown in magnitude/phase balance with a PP-PP differential design. Sounded like it measured.
Monolith has solved all my problems, and not going elsewhere until they give me a reason to.
To date the only remaining transformer still in use is a LL1689AM/PP which is in service as my 12B4A differential preamp output transformer. It does just fine - no resonances and decent 0.005% distortion with zero feedback. I believe I could improve on it with a different xfmr but haven't bothered.
I would second a similar experience with Onetics. Less resonance-prone, but a complete breakdown in magnitude/phase balance with a PP-PP differential design. Sounded like it measured.
Monolith has solved all my problems, and not going elsewhere until they give me a reason to.
IMHO, it's not strange. Controlling stray capacitances is not easy and the transformer construction and winding scheme do not help for sure. IT is a completely different best respect to OPT and multi-configurable approach is more a problem than an advantage. Attractive on paper but not in reality. In fact, if you ask them what they would recommend between the LL1635 and another model of their range, they will suggest the other model 99% (if this is appropriate for your use). I believe the LL1635 is among the first models they introduced (if not the first).
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Spot on, extracted from LL1635 datasheeet:
"NOTE: LL1635 is not suitable for SE to PP interstage. For this application we suggest transformer LL1660 or LL1660S"
"NOTE: LL1635 is not suitable for SE to PP interstage. For this application we suggest transformer LL1660 or LL1660S"
There are tricks to design more universal grade of interstage transformers, such as the employment of screen windings, where their purpose is to trap the capacitance within the intended sections and not let it migrate between primaries and secondaries, where awful resonances can occur, especially in physically distant sections. I've designed SE to PP and SE to SE universal transformers with many wiring options. But this there is more labor and cost.
We were discussing the 1635 for PP to PP and SE to SE which is what it's been made for. For example, a fully bifilar transformer like the Monolith Magnetics IT2 is miles ahead but still it is not suitable for phase splitting. As 50AE says there are different ways to do things but they get more expensive....
I have now learnt to do bifilar transformers for myself and so for me it's cheaper to get a high performance IT with fixed configuration PP-to-PP or SE-to-SE. I only wish I could find EI Radiometal laminations (or similar 49-50% Nickel with high saturation induction) but best grade M6 works really well anyway.
So far I have found nothing that beats the Sowter 1475 or 6093 for phase-splitting with very low distortion across the full audio range and because they are relatively affordable I have not even tried to do something similar.
Now I think we are bit off topic.
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Hello all, i have been tested Trancsendars 10 watt, Edcors GSXE, Softone RW20, James 6123. Now thinking to buy Hashimoto H-20-3.5U or Monolith Magnetics Summit S - 9. Please help me to choose. Thanks.
Could you tell us what you thought of those 4 OPTs and which were your favourites? Did you try them out in equipment and listen to them?
Softone RW20 was clear low distortion and best 3D, Then James 6123 these was ok, Trancsendars 5k 10 watt good bass but not so much 3D, and Edcors GSXE was last. All same circuit.
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