Hi AJ: you wrote:
:::Yes I'm well aware of this, with SE you cannot lose the cap. And your argument is valid (but to be frank I find it uncalled for to say something like 'awe ... spooked by a cap').:::
I actually intended the "awe.... spooked by a cap" in a playful, tongue-in-cheek manner. Apologies for the offense you found in the expression. I had no intent to offend at all.
However, I could soapbox this--- another term I've used in the past is
"capacitoritis"--- transformers have tons of little "hidden" capacitors in them. Resistors have inductance. Capacitors have resistance (very little) as well as some inductances in them.
R,L, and C are the three basic building blocks of electronics. I don't find any one of them to be "evil", "undesirable", "sub-optimum" or etc in-and-of-themselves (generis).
Hence--- I sometimes picture the "age of innocence" wherein someone ascribes a valuation to one of these building blocks--- sort of in an "innocent" manner--- perhaps reflecting an erroneous view based on a prevailing attitude or viewpoint that itself tends to be transitory over time. Go back some years and the moreso dominant view was to eliminate from the signal path whenever and wherever possible transformers themselves --- for all the "evils" that allegedly they embodied. So, over time--- these notions come and go.
I find it more useful to carefully study and recognize the roles and\or functions that each of these building blocks (R, L, & C) can bring to the enterprise.
So, again--- I was not pointing to you personally--- with my intended tongue-in-cheek response but rather I was trying to address (for the umpteenth time) the mistaken notion that only parafeed has a capacitor in the signal path.
But, I'm probably getting in even deeper--- so at the risk of offending any further--- please accept that what I said was meant good naturedly.
:::Not too unreasonable I think if you're going to spend a lot of money on an OPT with the possibility that you don't like the sound of the design topology.:::
Again--- if I may--- take for example SRPP (or pick any other "topology")--- was real popular at one point (say early nineties based on some articles in SP)--- then became unpopular--- sort of like dresses go in and out of style--- my take on topologies is that most (if not all) can be done well or done poorly. Part of is in the designers understanding of the topology, the selection of parts, the selection of layout, the selection of specific operating points--- along with any hunches or insights that the designer\builder may bring to the table. I've heard SRPP arrangements that were quite good--- and some that were quite poor sounding.
Same goes for parafeed vs series feed. Each can be done well. On paper PF offers a host of technical advantages IMO. However, this does not mean you cannot build a great sounding series fed SE amp.
Making choices--- btwn series feed and parafeed--- as well as two thousand and four hundred and twelve different circuit topologies that could be implemented--- can be paralyzing--- and I don't have any sure fire way to narrow this down a whole lot myself--- other than gaining your own listening experiences over a period of time.
I can feel the water up to my chin now--- but all of this (what I am writing) is meant to be liberating---- to open or expand horizons not shut down or limit choices.
If you have an interest in learning more about PF-- check out many of the posts on this forum as well as Bottleheads. If you want to appeal to published reviews--- check out many of the positive glowing reviews of sevral of the PF amps that Gordon Rankin has built over the years.
Again--- with the optimization of design, materials, and layout--- there can be many paths to musical nirvana (from a particular subject's POV).
::::The FS-100PF was a parallel feed output transformer
Can I understand correctly that it is no longer available?:::::
correct. It was built as a limited edition transformer and has been sold out for quite some time.
:::OK, so let's assume I'm willing to go parafeed. What are the options and prices?:::
If your willing to adjust\optimize your operating points for the EXO-050 output trans--- Jim Dowdy uses this PF output in his GM 70 amps. But it has a five K primary impedance---- and hence you might have to adjust your tubes operating parameters to make for a good match.
Otherwise--- I thought I said in my first response to you--- that I had (on my own) done a fresh design at your operating points---- 7,000 ohms and 100 madc as an conventional airgapped series fed output transformer.
And overall I liked what I saw on paper. As a rough estimate--- as a custom ouptut--- given it's size and complexity and the materials I would use--- I would estimate that these would cost about $750 a pair.
For info on our EXO-050 please refer to our catalog at
www.magnequest.us
thanks Arend Jam--- if I've managed to pee-O you even further then send me an email and I would be happy to call you and smooth things over---- I've seen you post on the Asylum for a long time--- and actually have always had a good vibe about you personally. So none of this was or is intended to be rude or impolite.
MSL
Builder of MagneQuest™ & Peerless™ transformers since 1989
