I'm curious if there is a measurable/audible difference besides the 'easy wire secondary' in the A series OPTs? Anyone with any experience or opinions (on this subject)?
There shouldn't be. They are basically replacing the old series with the new. If you don't need to switch impedance, go with the non "A" version since it's cheaper.
The easy wire solution means that on the 4R tap you will be only using half of the interleaved secondaries in the transformer. That makes the transformer more complicated or the HF phase response (important for NFB) is compromised. It best to use all secondaries. If you don't need easy windings buy the standard version. There is something on the Sowter website for their transformers:
OPTIONS We normally provide a single 8 ohm secondary or 4 separate secondary windings which can be arranged for loads of 16, 8, 4 or 1 ohms as shown in the tables below. Alternatively we can provide a single 4, or 16 ohms or 8 tapped at 4 ohms. Also we can provide twin 4 ohm windings which can be connected in series for 16 ohms or in parallel for 4 ohms. Tapped secondary windings will have somewhat increased losses, reduced HF response and reduced damping when the load is connected to a tap. This is particularly true when a 4 ohm tap on a 16 ohm winding is used. Please be sure to specify your preferred option if you wish to have a non-standard secondary option or a screen tap %.
OPTIONS We normally provide a single 8 ohm secondary or 4 separate secondary windings which can be arranged for loads of 16, 8, 4 or 1 ohms as shown in the tables below. Alternatively we can provide a single 4, or 16 ohms or 8 tapped at 4 ohms. Also we can provide twin 4 ohm windings which can be connected in series for 16 ohms or in parallel for 4 ohms. Tapped secondary windings will have somewhat increased losses, reduced HF response and reduced damping when the load is connected to a tap. This is particularly true when a 4 ohm tap on a 16 ohm winding is used. Please be sure to specify your preferred option if you wish to have a non-standard secondary option or a screen tap %.
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Kodabmx, Baudouin, thanks for the responses. Rather confirms what I thought, but nice to have assurances.
baudouin0 is correct about the way the coil will be different using only part of the winding, but generally it shouldn't be noticeable.
Since your name is prairieboy, I'm guessing you're in Manitoba or Saskatchewan? You probably won't find better pricing on the coils than from Hammond Push-Pull Tube Output Transformers - (1608 - 1620, 1645 & 1650 Series)
Not sure how the shipping is but it's usually cheap domestically.
Since your name is prairieboy, I'm guessing you're in Manitoba or Saskatchewan? You probably won't find better pricing on the coils than from Hammond Push-Pull Tube Output Transformers - (1608 - 1620, 1645 & 1650 Series)
Not sure how the shipping is but it's usually cheap domestically.
Good guess; Saskatchewan. And yes, I'm aware of A-1, though one needs to check shipping costs given that Digikey.ca would ship free.
The non-A series is still “easy wire” if you only use 4 or 8 ohm loads. Who uses 16 ohm speakers anymore anyway? Even with a guitar speaker cab you would put two 16’s in parallel.
jhstewart9,
I have some older Electra Print single ended 3k and 5k output transformers.
They have 4 identical secondaries.
1 Ohm
4 Ohm
9 Ohm
16 Ohm
. . .
Is what you can get. I wire them up for either 4 Ohms or 9 Ohms, and use All the windings.
Note:
with 4 equal windings, there is No 8 Ohm selection, it is 9 Ohms (not that important of a detail).
I have some older Electra Print single ended 3k and 5k output transformers.
They have 4 identical secondaries.
1 Ohm
4 Ohm
9 Ohm
16 Ohm
. . .
Is what you can get. I wire them up for either 4 Ohms or 9 Ohms, and use All the windings.
Note:
with 4 equal windings, there is No 8 Ohm selection, it is 9 Ohms (not that important of a detail).
I have some older Electra Print single ended 3k and 5k output transformers.
They have 4 identical secondaries.
1 Ohm
4 Ohm
9 Ohm
16 Ohm
. . .
Is what you can get. I wire them up for either 4 Ohms or 9 Ohms, and use All the windings.
Note:
with 4 equal windings, there is No 8 Ohm selection, it is 9 Ohms (not that important of a detail).
----------------------------------------------------------------------------
Got an amplifier you can shew us where you have done that?😀
They have 4 identical secondaries.
1 Ohm
4 Ohm
9 Ohm
16 Ohm
. . .
Is what you can get. I wire them up for either 4 Ohms or 9 Ohms, and use All the windings.
Note:
with 4 equal windings, there is No 8 Ohm selection, it is 9 Ohms (not that important of a detail).
----------------------------------------------------------------------------
Got an amplifier you can shew us where you have done that?😀
Jhstewart9,
Thanks for repeating exactly what I said.
I said 4 equal secondaries.
I said 9 Ohms.
Yes, some will still think they can get an 8 Ohm tap.
Thanks for repeating exactly what I said.
I said 4 equal secondaries.
I said 9 Ohms.
Yes, some will still think they can get an 8 Ohm tap.
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I was asking if you can shew us one of your amplifiers with an example of that kind of OPT used. So far don't see much of your work aside from a rough build on a previously used chassis a while back.🙂
I would also be tempted to move the plate supplies for the NTP off the input B+ and onto the second B+.
jhstewart9,
I would have to look up some very old photos.
I started into building and modifying vacuum tube amplifiers 'again' in 1996.
I published in Sound Practices and in Glass Audio.
Then I brought and showed amplifiers at all of the VSAC conferences,
and I gave a summary presentation at VSAC of my Glass Audio article.
At the last ever VSAC, I gave a 2 part presentation of single ended parallel 300B versus Push Pull 300B; with overheads and pictures, then a controlled listening session.
Perhaps if I get the time, I might put something up on one of these threads.
But I have much to do, and considering that many of my presentations and articles went largely un-noticed, I am not sure how much I want to cover old ground again.
I am constantly trying things that are new for me (maybe not for someone else).
I do have a life outside of time on this forum.
By the way, showing the old transformers that are no longer available, seems a little pointless to me.
Perhaps I will snap a picture of one of them that I have left, including the S1 F1, S2 F2, S3 F3, and S4 F4 wires.
I never used a switch to change the output impedance. I made the decision whether to wire it for 4 Ohms or 8 Ohms, and then left it that way.
If I ever do a 2A3 amplifier again, using the 3k Electra-Print 4-secondary transformer, I might put it up on this forum.
Oh, the only time I used new chassis was in the late 50s, and the 60s.
There is nothing wrong with an old used chassis (especially when it is used as a test bed for many different tubes, topologies, etc.)
I would have to look up some very old photos.
I started into building and modifying vacuum tube amplifiers 'again' in 1996.
I published in Sound Practices and in Glass Audio.
Then I brought and showed amplifiers at all of the VSAC conferences,
and I gave a summary presentation at VSAC of my Glass Audio article.
At the last ever VSAC, I gave a 2 part presentation of single ended parallel 300B versus Push Pull 300B; with overheads and pictures, then a controlled listening session.
Perhaps if I get the time, I might put something up on one of these threads.
But I have much to do, and considering that many of my presentations and articles went largely un-noticed, I am not sure how much I want to cover old ground again.
I am constantly trying things that are new for me (maybe not for someone else).
I do have a life outside of time on this forum.
By the way, showing the old transformers that are no longer available, seems a little pointless to me.
Perhaps I will snap a picture of one of them that I have left, including the S1 F1, S2 F2, S3 F3, and S4 F4 wires.
I never used a switch to change the output impedance. I made the decision whether to wire it for 4 Ohms or 8 Ohms, and then left it that way.
If I ever do a 2A3 amplifier again, using the 3k Electra-Print 4-secondary transformer, I might put it up on this forum.
Oh, the only time I used new chassis was in the late 50s, and the 60s.
There is nothing wrong with an old used chassis (especially when it is used as a test bed for many different tubes, topologies, etc.)
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I published in Sound Practices and in Glass Audio.
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No problem, I have all copies of Joe Roberts Sound Practices & Edward Dells Glass Audio & AudioXpress. So no need to find any photos, just let me know the name you were published under & dates of issues.
BTW, most of the rest of us have lives outside DIY too. Mine is 4.4 Acres & house we built 50 yrs ago. Just a little more than a hobby.🙂
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No problem, I have all copies of Joe Roberts Sound Practices & Edward Dells Glass Audio & AudioXpress. So no need to find any photos, just let me know the name you were published under & dates of issues.
BTW, most of the rest of us have lives outside DIY too. Mine is 4.4 Acres & house we built 50 yrs ago. Just a little more than a hobby.🙂
As I have said in this Forum before, I wrote in Sound Practices issue 10,
and I wrote in Glass Audio Volume 12 Number 5 2000 (the very last issue of Glass Audio).
After that, 3 magazines were combined into 1 by Ed Dell.
I only had one person over the years ask me "are you the one who wrote that article in Glass Audio?".
Except for spyware, I will do my best to remain semi-anonymous.
And . . . I am human, make many mistakes, I like many others have had many failures, not just successes.
and I wrote in Glass Audio Volume 12 Number 5 2000 (the very last issue of Glass Audio).
After that, 3 magazines were combined into 1 by Ed Dell.
I only had one person over the years ask me "are you the one who wrote that article in Glass Audio?".
Except for spyware, I will do my best to remain semi-anonymous.
And . . . I am human, make many mistakes, I like many others have had many failures, not just successes.