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Best 2a3 PP OPT.
Best 2a3 PP OPT.
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Old 1st June 2012, 03:55 PM   #11
Yvesm is offline Yvesm  France
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Hi Andy,

You may ask to my friend Charly to wind this one for you.
"charlydoria at free dot fr"
Feedback highly welcome.

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Old 1st June 2012, 06:00 PM   #12
JimW is offline JimW  United States
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Hi Salectric,
I think you could do a search of this forum for pp 2a3 and find it. I am not sure what the exact title of the thread was, I saw the schematic, printed it, and built it a year or so later. Lot of threads floating around re paraphase, can be made to work pretty well by adjusting resistor values in the voltage divider to get ac balance.
Yes, I thought the hammond offered acceptable performance, but is bettered by the other manufacturers mentioned. We always recommend boutique grade parts in these threads, don't we. If you have no basis of comparison, the hammond sounds pretty good, and to squeeze the extra performance, the wallet has to be opened widely! As an aside, my pp2a3 began life as a pp 300b, but I could never get it quiet enough (2-2.5 mv), and I didn't really need much power, so I converted it to 2a3.
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Old 1st June 2012, 06:57 PM   #13
vuki is offline vuki  Croatia
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Here is mine 2a3PP - complete project with some measurements. AOT40 is really good transformer and the price is OK - about $350 for a pair. It could be good option for you because it's EU made and the shipping price would be low.
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Old 2nd June 2012, 01:45 PM   #14
dennis h is offline dennis h  United States
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Which level O'Netics OPT'S do you have ?
Please read this Quote from Budp...


Yes these are O-Netics transformers, but the ones found at C3 Amps and Rhodes are only for guitar amps. Anyone can PM me, I will shift you over to my private email when you do, but a PM is always welcome.

As for differences..... hmmm.... Our level one OPT's are likely to be 3 to 4 times the amount of retained signal information, over anything you have heard. Their FR and phase are flat from 20 to 40kHz for both PP and SE at any power level, including up to hard saturation at 20Hz. They will not oscillate and their impedance curve down in the sub sonic realm is very flat, while phase and frequency response roll off very smoothly. Compared to say, a Lundahl 1620, they have slightly but noticeably more distortion, are not as dynamic in transient response, are roughly as clear in tonality and timbre but will have more internal information to note and transient structures. Of the two, I like the 1620 slightly more.

When O-Netics level 3 is in the picture, the low level coherent signals are completely retained, so hall resonances, deeply buried musical signals etc are made clearly apparent. They have another 2 times the information content of level one and provide a complete ease to all sounds, regardless of their complexity or amplitude. Compared again to a 1620 they are slightly softer in presentation, just as clear tonally and transiently, are as vivid, but do leave the Lundahls sounding faintly cartoon like when it comes to deeply complex music, such as Cantate Domino on XRCD or a 24/192 rendering of Carmina Burana, from a live stage production. I wont go into tape or LP's here, but you can expect the same differences with those sources.

These comparisons come from Gary Pimm's system, using his second generation Tabor SS amp, with plug and play interstage and output transformer connections. None of this should be taken as faulting the Lundahl 1620, these are fabulous output transformers, Lundahl and I have just taken two different paths and thus offer different strengths.

Please note that these are very small differences and are really only available from speakers that can exceed the typical downward dynamic limit pointed to by Meyer Sound, of about 40 db below average signal levels, typical with modern dynamic speakers. Ribbon based systems and CD / LeCleach horn systems will provide greater downward dynamic range, as will any EnABL'd dynamic speaker system.

My previous statement about purchasing less revealing transformers still stands. Unless you really do have a very revealing speaker system (and of course we all are certain we do!) there is no real reason to spend from $150 to $600 per output transformer. Even if an exquisite level of signal retention and expression into your listening room is your eventual intention, I would still suggest you utilize under $100 apiece OPT's for all of your development and system proofing work, including hum and noise reduction. Then, spend your money on high resolution speakers, output transformers, speaker cables and signal sources, in that order.


This is from the choosing a opt thread, #63 or #67...
dennis h
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Old 2nd June 2012, 03:43 PM   #15
andyjevans is offline andyjevans  United Kingdom
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I have level 1. I completely agree with Bud - I've compared his transformers to Lundahls and he's absolutely right. the Lundahls are kind of more 'square'. the O-netics are softer and more detailed. More musical to me and definitely my preference. Better on classical orchestral music in particular, though right across the board really.
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Old 2nd June 2012, 05:50 PM   #16
zigzagflux is offline zigzagflux  United States
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My limited experience has been exactly the opposite with Level 1's. Both in sound and measurement, the Lundahl was the obvious winner. Distortion skyrocketed above 10 kHz over 1/2W-1W range, whereas the Lundahl held its ground up to around 3W. This was a Karna 300B, however, for what it's worth.

For interstages, a similar experience, but a magnitude more drastic. The O-Netics couldn't hold phase shift balance at all, even at 1 kHz. Get the series/parallel configuration right with the LL1692A (took some experimentation) and balance was good past 25 kHz.

I don't get too concerned when people opine different audible experiences; we all hear with our brains, which are all different. But the measurements made no lie, and fortunately for me I was able to hear what the scope was telling me.
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Old 2nd June 2012, 06:42 PM   #17
andyjevans is offline andyjevans  United Kingdom
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I should say that my most critical listening was done with a O-netics SE transformer versus LL1620 and LL1623 in SE. I did do some listening to the PP O-netics OPT against some PP Lundahls but it was a while ago so I can't be so certain of that. So I'm being a bit general in my comparisons. I do find O-netics musical and detailed in general, and it's my daily listening 2a3 PP amp.
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