How did Ken Fischer test his output transformers?

[Mark]

Hi

Does anyone know how Ken Fischer tested his transformers?

I have asked this question to a few people over the years and I usually get a glib reply. The story goes that Chris Merren showed Ken how to effectively test them.

What is the best way to test the specs of an output transformer?

I guess the idea is to know the tolerance of the supplied transformer.

Any thoughts?

Regards

Mark

[bepone]

i dont know how Ken Fisher did this but my method simple:
by clips fast connect them to some existing amp (where you previously removed wires from existing output transformer? )

other than connecting them to few kV voltage to see the leakage or breaks in the OT, there are some passive parameters where you can measure something but is not telling you anything about the sound, only you can assume or suspect something until you actually hear the sound from OT.

L primary inductance (i like hi level of L, so laminations with high permeability
Lp parasitic inductance (i like this number to be high - more than 10-20mH)
Cp parasitic capacitance (i like this number also high)
scope about B-H characteristic curve (narrow - wide)
Resistance of primary, secodary (compression)
Lamination type (smaller, bigger), A.core area (different approach for compression and clean trafos)

So if you measure them like above, you can form some opinion and expectations, and probably you will be close if those numbers are in your window based on personal experience ,and from other similar examples. And connect them to real amp to see how they behave.

[gktamps]

Mark, I wonder if Chris would share that knowledge if asked?

[RockinRocket]

I'm curious too.. It would be extremely hard and annoying to swap transformers in a Wreck.

Reject aka undocumented express has a circular hole on the power supply board cut out to access the 1 bolt that is other wise hidden. Wonder what the story is on this. Did the output need replaced and was the easy way to replace it or was this the easiest way to swap in and out the output for testing? I've seen 10 originals and this is the only one with access to the bolt,

[wpaulvogel]

I read that he would get the batch order and hook them to a donor amp and listen to each one individually. This is speculation though. I also heard he sent back the ones that didn’t make the cut. It’s thought that Welagon bought the whole lot of Ken’s rejects from Pacific.

[Mark]

Mark, I wonder if Chris would share that knowledge if asked?

I have asked him, but received no reply.

[Mark]

I read that he would get the batch order and hook them to a donor amp and listen to each one individually. This is speculation though. I also heard he sent back the ones that didn’t make the cut. It’s thought that Welagon bought the whole lot of Ken’s rejects from Pacific.

I didn’t hear this. As far as I know he bought them from Allyn Meyer.

[gktamps]

Yes, that was what I understood based on Jelle's posts elsewhere.

[wpaulvogel]

I read that he would get the batch order and hook them to a donor amp and listen to each one individually. This is speculation though. I also heard he sent back the ones that didn’t make the cut. It’s thought that Welagon bought the whole lot of Ken’s rejects from Pacific.

I didn’t hear this. As far as I know he bought them from Allyn Meyer.

Okay, that’s what it was. I couldn’t remember where he got them.

[Mark]

I can’t see Allyn or Jelle using subpar transformers. They both have made some great amps.

I will be getting a transformer rewound, I will ask the guy and see if he will tell me how to test and quantify output transformers.

[Reeltarded]

I think that Ken would tell you himself that he wasn't checking for normal tolerances but for a certain action and that is based on his idea of what perfection is.

He had a bunch on a shelf with notes like (brighter. darker. this one.)

He would tell you that if it sounds good, it is good. (and to replace it if you blow it up lol)

[rooster]

You guys are way off the mark as to how Ken tested the OTs. The story I heard from Gregg Levy is that Ken had 'a guy' who did the testing. By holding the various OTs in his hands and making the call. Not kidding. He was a local guy, a neighbor of sorts (who's name was never given to me), and someone who hung out at Ken's shop in NJ, along with Gregg, Chris Merren, John Mark (the current Trainwreck Co builder), and a few others. As things were explained to me, Ken enjoyed the company of people interested in guitar amps and liked having them in the shop to demo things and ask their opinions.

Anyway, back to the OT tester. How the particular tester was chosen apparently occurred when Ken became frustrated with the OTs that were arriving in ten count lots. Since the basic components were the same, apparently Ken started to think that the OTs held the key. Some amps sounded amazing and some amps sounded simply 'OK'. Perhaps in jest, or a belief that somebody might have a magical power, or just to past the time, he asked his friends in the shop to look over the new batch that would arrive and see if they could pick a 'winner'. As I heard it, everyone there gave it a go. However, in the end there seemed to be this one guy who was very consistent in his choices.

I know it sounds somewhat 'out there' but I've decided this story sounds very much like something that Ken would get into. I believe this story is true, you don't have to. As to returning the OTs to the manufacturer that didn't pass the test, haha, that is very VERY unlikely. What company that had a 'line card' on your particular OT design (that you had approved and previously accepted) would accept a return of, say 5 of 10 OTs? That's not going to happen.

[2tone]

While I can believe some of the voodoo aspects of Ken's techniques, I can stretch my imagination to accomodate this, in that certain people have different magnetic properties in their blood from iron levels, anion and cation levels etc, maybe these types could sense an interaction with their magnetic properties and the iron and core parameters in the OT. Stranger things have happened I am sure. However, in converstaions with Ken I know he actually jumpered in OT's to test them in existing amps. He was telling me about it, so I decided to jumper in three different OT's in my Rocket, and reported back to him.. But Ken also said many times the guy building the amp imparts part of his musical makeup in the amp!! Hard to believe, but he said rockers who built amps imparted a rock nature to the amp, and blues guys a more bluesy nature!..Sometimes ken pulls your leg, I know, but if you believe in some avant-garde idea that keeps being accurate, you tend to reinforce your theory.. Back to magnetism...I was told that some people could tell the sex of a fetus inside a mare by dangling a nail on a string above the rear of the horse. If the nail spins one way, it's a male, etc. I considered it hogwash, but I took a nail and string and tried it and got different directions of spin on different mares. I also dangled the nail above my hand, and by turning my hand right or left it would affect the nail spin..Again, maybe a magnetic blood-iron phenomenon, I dont know.. So maybe some people have sensitive enough reactions to bio magnetic fields to distinguish something as different, whether good or bad..

[Mark]

I certainly don’t know everything, but I did take some things Ken Fischer said with a grain of salt. I remember him says the Komet amps had red wire in them as it sounds better. I find that extremely hard to believe and an exercise in leg pulling.

Getting back to Ken Fischer, I had heard he had a method of testing transformers. I would have thought it would have been testing the parameters of the output transformers.

If anyone have ideas and suggestions on testing transformers, I would love to hear them.

[Reeltarded]

You could make a fixture and check response, but that takes gear and effort.

This is a Pacific testing video. No lie. It is Pacific.