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Re: New Toroid Output Transformer Marketed?
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97555&th=23773#msg_97555
gofar99 wrote on Thu, 21 March 2024 21:56
Hi Pos, hummm. 200KHZ , 150, 100 why and I really would rather audio trannies in my designs not reach that far. As is most seem to hit about 70K at only a minor drop from pass band.
I actually design into the amps a frequency limiting measure to prevent them form going past about 35K. IMO only noise and possible EMI out above that. When I order custom trannies (most of my projects have them) I specify flat pass band from 20HZ to 25KHZ with a smooth roll off one octave on either end. Must be able to handle that at the full output that I specify and not saturate at the currents I plan on using.
Thus far this has been a successful concept as the amps using them measure to those limits. To be sure the math and design issues are better left to the pros. Also the trannies I get this way are significantly larger, heavier and to a certain extent more costly. The weight and size are roughly double a typical off the shelf trannies. I do not use toroids for outputs, only standard designed ones.
Hi Go,
I just mention the high frequency response (FR) because of the extremely tight coupling/low leakage reactance toroids are known for.
As you have, one could certainly limit the high frequency response (FR) other ways, such as a simple low pass filter, and yet allow for other who wish the higher FR as well.
Tighter coupling, higher FR means more inner detail. I can't remember how much, but back in the 1980s when I worked in the -1db at 200khz vs -1db at 150khz range, and there was definitely a sonic difference.
I don't think there would be any problem making the toroid outputs double the weight of typical toroids I have seen. I wanted better low end anyway, and a larger core would be nice.
It is just a thought, and would appreciate more input from anyone.
cheers and thanks Go.
pos]]>positron2024-03-22T15:53:34-00:00Re: New Toroid Output Transformer Marketed?
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97553&th=23773#msg_97553
gofar992024-03-22T02:56:42-00:00New Toroid Output Transformer Marketed?
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97548&th=23773#msg_97548
I have heard that the weakness of the OPTs was the small core, thus
saturation due to imbalance of output tube plate currents.
I remember seeing the impressive high frequency response of their transformers.
What do you think of the idea of OPTs with much more core material
to over come the bass weakness?
There would probably be some loss of high frequency response,
but from 200khz to 150khz or even 100khz, would that be a problem?
Do you think there would be a market?
cheers
pos
]]>positron2024-03-21T04:14:51-00:00Re: Update on Previous Info on Oddwatt Amp issue
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97476&th=23750#msg_97476
Excellent info. Thanks for the update. SUPER important for Oddwatt owners.
]]>Wayne Parham2024-03-03T14:43:25-00:00Update on Previous Info on Oddwatt Amp issue
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97474&th=23750#msg_97474
gofar992024-03-03T02:35:17-00:00Re: Demagnetizing Tung Sol 6550, Penta KT88s
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97463&th=23551#msg_97463
positron wrote on Tue, 21 February 2023 22:45
After more testing/auditioning, I prefer the Pentas over the
Tung Sols. I find the new Tung Sols are still zingy in the highs.
The Pentas are just slightly fuller compared to the Tung Sols.
That is it for now.
Cheers
pos
I am eating some crow now. I just checked and the new Tung Sols (gift years ago) I have been using needed to be demagnetized again. The JJs not so. There is also a difference in the midrange I think I like better with the JJ KT88s.
cheers
pos
]]>positron2024-02-27T03:44:08-00:00Re: Class A, AB1, B, C Operation/Modes
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97384&th=23559#msg_97384
Santa Fe (about 8000 feet) caused them issues. ]]>gofar992024-01-25T02:31:12-00:00Re: Class A, AB1, B, C Operation/Modes
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97350&th=23559#msg_97350
gofar99 wrote on Mon, 18 December 2023 20:20
Hi, Somehow I missed that you had responded recently. Anyhow two things come to mind...one class B PP is only useful IMO in modulating AM ham radio transmitters. Class A and AB are quite suitable for high fidelity reproduction. My preference is class A triodes and class A with U/L if pentodes are used. My experience has been that AB operation seems to change the sound somehow that I can't measure but can hear. On another note the fact that the guy mentioned ignored the truth and insisted in the incorrect information seems to be a thing that many others have been doing in the media and dare I say politics.
Hi Bruce,
I have been testing some tubes and found the new Tung Sol 6550 and
Penta KT88 are my reference in PP AB1 operation. I am running ~29 watt
plate dissipation on each tube (~70ma idle), which may be high enough to account for the natural.
(Both type tubes were given to me as a gift years ago.)
Anyway, the transparency of my system is at least 1 part in 4.1 million,
so extremely transparent (polypropylene power supplies) and ear extremely sensitive. Using 20log, that is -132 db.
It allows me to hear real, natural instruments and all the back round at the venue on the recording. But it took some 43 years, off and on to accomplish. If I mentioned this before, please accept my apology.
The extreme sensitivity of the ear is probably why you were able to hear
and not measure. I have tested other brand tubes, and sonic changes did
occur if I remember correctly.
Anyway, if one is in central Illinois, please feel free to pm me, love
to show the work I am doing.
cheers
pos
]]>positron2024-01-17T03:32:11-00:00Re: Class A, AB1, B, C Operation/Modes
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97266&th=23559#msg_97266
gofar992023-12-19T02:20:52-00:00Re: Class A, AB1, B, C Operation/Modes
https://audioroundtable.com/forum/index.phpindex.php?t=rview&goto=97259&th=23559#msg_97259
I am just not sure how many are intentional.
I know of a YT video where some "obsessive" gent
uses PA quality Class B operation effects, with
outlandish nonsense, to attack high fidelity
Push Pull quality. (Push pull can sound perfectly
accurate in Class A or AB operation.)
I explained his errors filled explanation broke the
laws of science, but 8 months later he is still pushing
the error filled video. Interesting indeed.