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Old 3rd December 2007, 08:41 PM   #1
hnb2907 is offline hnb2907  United Kingdom
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Default Best output transformer for 300B

Folks,

I'm another one that's been bitten. Having thoroughly enjoyed modding a couple of valve amps, I'm not starting to think about designing my own. My current thought is 300B (or 2A3) single ended.

As I'm starting to price up components, can we have a straw poll of which of the 2 following transformers would be best?
1) Tamura F-475
2) James 6123-HS
...both seem to get good reviews.


What d'ya think?


Cheers,
Chris.
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Old 3rd December 2007, 10:54 PM   #2
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I think you should consider a few more transformers. There are lliterally dozens of SE transformers that would suit a 300b, some 3K and some 5k. The Lundahl range, O-netics, Bartolucci, Hammond, Rohrentechnik, Hashimoto, Silk, Tango, Audio Note. Tribute if you can wait.

Hit list would likely go:
Tribute
Tamura
Lundahl = James = Hashimoto = Tango = O-netics
Bartolucci = Audio Note
Electraprint
Magnequest
Hammond

You may want to set some money aside for interstages - also very important.
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Old 3rd December 2007, 11:18 PM   #3
kmtang is offline kmtang  Canada
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I would recommend Lundahl LL1620 or LL1623 OPT. I have tried the LL1620 in my 45 tube amp and it sounds great. The price is rather reasonable.


JOHNNY
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Old 3rd December 2007, 11:20 PM   #4
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I see a lot of custom toroidal 300B OPT's on eBay for whatever reason. If you're a gambler like me, that's the way I would go.
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Old 3rd December 2007, 11:38 PM   #5
hnb2907 is offline hnb2907  United Kingdom
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Quote:
Originally posted by andyjevans
I think you should consider a few more transformers. There are lliterally dozens of SE transformers that would suit a 300b, some 3K and some 5k. The Lundahl range, O-netics, Bartolucci, Hammond, Rohrentechnik, Hashimoto, Silk, Tango, Audio Note. Tribute if you can wait.

Hit list would likely go:
Tribute
Tamura
Lundahl = James = Hashimoto = Tango = O-netics
Bartolucci = Audio Note
Electraprint
Magnequest
Hammond

You may want to set some money aside for interstages - also very important.

Hi all,

Thanks for your replies, it's greatly appreciated.

I've already done a bit of shopping around for prices and reviews - that's 1 of the reasons why I'd already narrowed down to James and Tamura - the 2nd being I like the aesthetics of them.

Regarding the interstages, I was going to capacitively couple them to the front end stage instead - is this not a good idea?


Cheers,
Chris
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Old 4th December 2007, 12:00 AM   #6
rdf is offline rdf  Canada
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I took that bet and lost. Things might have changed since but it appears the SE models I bought a couple years back weren't air gapped. The low end rolled off below 200 Hz. Parafeed brought back the bass but didn't raise them above mediocre. I dropped them for generic A-V toroid power transformers (different application, not the right ratio for a 300b) which measured much better in parafeed. Not so much a matter of getting what you pay for since the A-Vs were salvage but of 'buyer beware'.
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Old 4th December 2007, 12:54 AM   #7
shooter is offline shooter  United States
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The James 6123-HS are very good for the price, it beats out the low end Tango, for some serious transformers you should also consider the custom wind transformers on a large amorphous core from Intact audio, you can set the gap on them and tune by your own ears, single secondary winding only on mine, each transformer weight over 10lb, not much in the look department, but they do sound wonderful.
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Old 4th December 2007, 03:09 AM   #8
arnoldc is offline arnoldc  Philippines
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I use a Tamura F-475 for my 45 and while you can use it for the 300B, you have to pick that operating point wherein you're not going to exceed the current limit of 45mA.

I'm now using James JS-6113HS and I'm very happy with the results. Real value for money, nice looking too. I'm using 3.5K tap.
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Old 4th December 2007, 05:14 PM   #9
kevinkr is offline kevinkr  United States
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My favs in a very limited field of comparison: Tamura F-5002 amorphous core 3K. They are exorbitantly expensive, but the amplifiers I built using them were the best I've ever done.
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