Best SE output transformer for 300b - shootout

[andyjevans]

I'm just the latest in many converts to the SE 300b sound. I have a LL1623/60 in my DIY amp driven by 46s and the following on the shelf:
LL1682/50
LL1620/80

I'm liking the sound of this, and would like to know how good it can get with output transformers.

I enclose a shootout below which suggested that there is better out there than Lundahl, but I need others to give me their listening experiences. So please join in this thread with your own experience, whatever the OPT is you have heard!

Andy Evans

__________________________________________________

Here is our Thailand shotout. (DIY Audio) We test on 2A3 first.
1. Tamura F-2007
The one that was installed on the chassis. Neutral, clear bass and good impact in LF. Detail and HF is fair.
2. Tamura F-7003
Connected for 5K. Sweet and pleasingly musical. It made female vocal more sweet and seem to be younger. Unfortunately, bass is not as clear as the F-2007 but good enough.
3. NY-15-3.5s
Same tone of F-7003 with a bit of added detail in the HF. The vocals are the same as F-7003. We 're surprised that NY-15.3.5s is so close to the F-7003, much more so than other series of the same brand.
4. Tamura F-5002
Superb detail. Vocal is very clear but not as sweet and pleasing as both permalloy transformers. Lacks the bass of all the above. But we have some magic.
5 LL1623
Very economic. Less detail and clarity than a Japanese trans. Bass is same as F-2007 with the same character, punchy and full. We didn't listen to this trans as much 'coz it worse than any Japanese transformer.
6. DIY trans 3k
Less clear than LL1623 but tonal balance is same. Nothing to talk about. We have to experiment much more.

After the first round we concluded the "sound of the core" made the difference. Hi-B give neutral and full bass with impact. Bandwidth is less than others. Permalloy adds something good to vocals. Less full and clear in the bass. Amorphous very detailed and clear with less impact of bass. Bandwidth is so wide.

Second round started with the VV52. We focused on F-7003 and F-5002 only. The result still the same but the owner of F-7003 said "I feel the detail of F-7003 was hidden somewhere"
So, we moved both OPT to the Spk terminal to use #35 SWG 20cm long of Spk cable and used 5 meter for HV cable from VV52 to OPT. Believe it or not, both OPT gained in detail and F-5002 showed more volume and clearer bass than the F-7003, even better than F-2007, I think. I thought this contradicted the idea that F-5002 has weak bass.

[andyjevans]

As an update I've been doing some searching and reaults seem to be that in ranking order something like this is reported:

1) Tamura or Tribute, amorphous or permalloy, e.g. Tamura
F-5000 series amorphous core
F-7000 series permalloy core
These are expensive, like 300GBP for amorphous and 200GBP for permalloy

2) Lundahl = James
James make some of the Tamura transformers according to reports. Lundahl make amorphous cores, so they should be contenders, and their ordinary range can be good, though no doubt some are better than others - some designs are quite old and some newer.

3)Bartolucci = Audio Note
Don't know much about these, for Barties around 300 Euros each http://www.audiokit.it/ENG/Frames/Introduction1.htm

4) Electraprint
5) Magnequest
6) Hammond

One interesting range is Silk from Thailand:
S-325 standard range = 138GBP
S-303 economy = £63
http://www.sacthailand.com/

Another is Hashimoto http://stores.ebay.com/Vintage-and-H...Audio-from-OBS
H-30-3.5S Cost $380
H-20-3.5U Cost: $225ea ($530 pair OBS)

Has anybody had experiences of Silk or Hashimoto, or indeed any of the others??

[sorenj07]

I've been discussing a wide-bandwidth OPT with Edcor . A 15W 3K version with an UL tap and 8 ohms out costs $60, plus $20 one-time only for the designing fee. These people seem to know what they're doing, they might be worth a shot! Especially at the price, I'd be interested to see what they can come up with.

[jlsem]

I recently did a comparison test between the Tango U-808, James 6123HS, and James 6157HS with a Loesch designed type '50 amp. For a similar price, the 6123HS was superior to the U-808 in every category. The 6157HS was superior to both in terms of distortion and bass extension (surprise surprise) albeit the 7K tap was used while the others had only a 5K max tap. The 6123 had better HF extension and somewhat clearer highs than the 6157, however.

John

[jlsem]

I've been discussing a wide-bandwidth OPT with Edcor . A 15W 3K version with an UL tap and 8 ohms out costs $60, plus $20 one-time only for the designing fee. These people seem to know what they're doing, they might be worth a shot! Especially at the price, I'd be interested to see what they can come up with.

It's been my experience that with a cheap OPT, you will end up with an amp that works, but not much more.

John

[Cobra2]

I would like to se some listening-reports from the Silk iron.

The amps and trafos are all measured, layout seems neat...
Prices are reasonable...
http://www.sacthailand.com/Transformer_TestOutput.html
http://www.sacthailand.com/Transformer_SilkWinding.html

Arne K

[sorenj07]

Originally posted by jlsem


It's been my experience that with a cheap OPT, you will end up with an amp that works, but not much more.

John

But has it been your experience with THIS cheap OPT - that is the question

And another thing. If you listened to it without knowing that it was cheap, it might sound altogether different

[jlsem]

But has it been your experience with THIS cheap OPT - that is the question

Well, maybe you could do a comparison test between it and some of the other transformers listed above and report on the results.

John

[andyjevans]

I've been discussing a wide-bandwidth OPT with Edcor . A 15W 3K version with an UL tap and 8 ohms out costs $60, plus $20 one-time only for the designing fee. These people seem to know what they're doing, they might be worth a shot! Especially at the price, I'd be interested to see what they can come up with.>>>

Have you asked about different core types - amorphous and permalloy, low nickel content (50%) and high nickel content (80%). It would be very interesting to see how they price these. If they could undercut other makers then they would be competitive. The same would be true of interstages. I'd definitely be interested in what they could offer in terms of superior cores.

Roports to me vary from "go for nickel, forget amorphous" to
"good Amorphous OT will give you more civilized sound, better HF and more rounded and dynamic LF. LF wouldn't be rather as solid as silicon steel cores, but more vivid. If you are rather a ROCK MUSIC guy, stay with SS cores, If more towards chamber music - go for amorphous. Don't forget, that amorphous core needs a lot of break-in-in time to show what it can deliver,"

Does anyone have experience with permalloy and/or amorphous?

[kevinkr]

I used Tamura F-5002 transformers in my commercial 300B SE amplifier line - flat out the best of several I have worked with.

Great overall performance, solid extended bass, great mid range detail and HF extension. Definitely the least compromised transformer I have used in my designs - note though that I have never really seriously compared them to anything else. Unfortunately I couldn't afford them for my personal amplifier..