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Holden and Fisher transformers

S

smithy

pfm Member
Do they still exist?they seem to be well regarded historically ,Quantum 202 does that have a H+F transformer ?
 
As far as I know, they stopped transformer production a few years ago, shame really, apart from the hum (looseley wound for low interwinding capacitance) they are good, I'm lead to believe that the Avondale transformers are good also in case you need one (they don't hum apparently).

:)
 
Unfortunately your right, they did stop production which is a shame, they was very good indeed!
I use a pair of Holden and Fishers, they are totaly quite in use
 
Can't say I've compared if they improve the sound over other types, all I know is that my H&F's are mechanically quite where as a couple of other types I tried had some slight mechanical buz, mine was also free so it made sense to use them:)
 
these supermumetal toroids are for power supply, audio note of course swear by nickel content transformers if not toroids. These are almost unheard of in the uk. But I have my contacts. The winding needs to be done by yourselves and i understand these are ex military units. I will be winding one up to compare with Avondale toroids - once i have completed moving home. Unfortunately all my anticipated projects will have to remain anticipated for the next month or so.
The toroids i have at present are about 6" in diameter total area I will need to calculate at a later date.

If any one is interested now or after i have tried them i can get prices.
Luke
 
Quantum 202 is a weedy little power amp

You really want the 207DA - Much better !

Will compete quite comfortably with anything Naim make
 
audiojoy said:
these supermumetal toroids are for power supply, audio note of course swear by nickel content transformers if not toroids. These are almost unheard of in the uk. But I have my contacts. The winding needs to be done by yourselves and i understand these are ex military units. I will be winding one up to compare with Avondale toroids - once i have completed moving home. Unfortunately all my anticipated projects will have to remain anticipated for the next month or so.
The toroids i have at present are about 6" in diameter total area I will need to calculate at a later date.

If any one is interested now or after i have tried them i can get prices.
Luke
Click to expand...

Supermumetal has very high incremental permeability at low fields, but saturates quickly. This makes it excellent for small signal transformers, as you can get the needed winding inductance from a smaller number of turns, so the interwinding capacitance and the stray inductances are all small, giving a very wideband transformer. Large current levels will lead to non linear bahaviour.

Very wide bandwidth is a disadvantage in a power transformer - it just lets more interference through, and the power density needed can easily saturate something like mumetal.

Now, I don't have the full details on these cores, but would need to see worked numbers to be convinced that they would be good for mains power.

If they are 6" in size, they might make a fantastic output transformer for a valve power amp output stage - it would have to be a push pull one, as there is no air gap in a toriod, and so a SET would just saturate the core, negating the advantage of the mumetal.
 
thanks for that piglets had not appreciated any of that,but as i am more into the black art of hifi, i will let the final decision be my ears. It will be interesting to see if practice proves theory wrong or the other way round.

Luke
 
Transformer design is one of the well understood bits - there isn't a lot of empirical black art left there.

Note that a badly saturating core will heat up, so make sure there is a thermal cutout built into the design for safety. It could also put lots of interference back onto the mains, so make sure that you test it in a properly instrumented and filtered test set before connecting direct to the mains.

The Wikipedia article has a reasonable introduction to the basics of Transformers. See http://en.wikipedia.org/wiki/Transformer
 
Thanks piglet for that perhaps i have on this occasion let myself get ahead of myself. Will ensure adequate safety proceedures are followed when testing. Will let you know the results as soon as i have them

Luke
 
PigletsDad said:
Supermumetal has very high incremental permeability at low fields, but saturates quickly. This makes it excellent for small signal transformers, as you can get the needed winding inductance from a smaller number of turns, so the interwinding capacitance and the stray inductances are all small, giving a very wideband transformer. Large current levels will lead to non linear bahaviour.

Very wide bandwidth is a disadvantage in a power transformer - it just lets more interference through, and the power density needed can easily saturate something like mumetal.

Now, I don't have the full details on these cores, but would need to see worked numbers to be convinced that they would be good for mains power.

If they are 6" in size, they might make a fantastic output transformer for a valve power amp output stage - it would have to be a push pull one, as there is no air gap in a toriod, and so a SET would just saturate the core, negating the advantage of the mumetal.
Click to expand...

My findings exactly........
 
Supermumetal is so expensive that even if it were to be successful in driving circuits with a few VA's requirement this part of the thread would really be an academic exercise anyway.

Theory is fine but the ultimate test is in the listening. Measurements and listening trials often bare no relationship to one another.

LES whats happened to the circuit diagram for the pre regulator i bought from you??
 
Hey guys I have a pair of Kinergetics KBA-202 mono's and am in need of a Holden&Fisher transformer for the pre-amp board. The transformer is marked ser#148369 Type F1088, input is 120v and it has 5 outputs any ideas thanks
 
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