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Best SE output transformer for 300B - shootout
Best SE output transformer for 300B - shootout
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Old 18th October 2007, 12:20 PM   #21
kevinkr is offline kevinkr  United States
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Best SE output transformer for 300B - shootout
Hi Thomas,
I think it is good that you are making transformers, and I, and many others want to hear about that. Was just suggesting you provide a link to your pictures and information, rather than posting it all here..

Some day I may even be a potential client, you just never know.

I ended my business in the early 2000 time frame, but in my limited experience both Tango and Tamura offered performance levels not really available here in the USA - at least at that time.

I no longer have all of the details, but found that the F-5002 in normal use at 60-80mA in my amplifier design met or exceeded all of the performance specifications Tamura provided. Unfortunately at the time I did not have access to an AP, so I had to use my Amber 3501 and did a series of measurements at various plate currents, frequencies and power levels. While I no longer have the data, but I do clearly remember that it easily exceeded its specifications, particularly in regards to primary inductance. (I wasn't too surprised as Tam Radio specifies things very conservatively.)

One of the things I wondered is how you actually measure the performance of your transformers? Do you drive them with a representative source impedance similar to the rp of the tube it is going to be used with, and in addition with a dc current superimposed that equals the operating current? I know you have an AP so that helps quite. When I test I usually use a circuit similar to what will be driving it in the application..
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Old 18th October 2007, 02:52 PM   #22
tube-lover is offline tube-lover  Hong Kong
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hi kevin,

very nice to discuss with U in here.

I fully agreed for your comment about 5002.

HF & atmosphere was really very good which compare to normally OPT ( HI-B)

Vocal also smooth too.

5002 is a success product but looks it birth period amorphous production is not in high mature condition. price of core was expensive & crystalline looks still in micro crystalline or super micro crystalline only. Nano crystalline was promoted & mass production on recently time.


5002 was very good. If U use full range speaker. But if u use large size woofer large than 12' inch woofer. LF will little weak.

that's why I combine & test different method for amorphous core & hope the bass maintain fast detail but deeper & less phase shift.

Hashimoto winding method was very good but combine with tango X series winding can improve & air gap mst good fit with thin copper sheet.

this is part of my experience. I really hope can discuss with U too.


thx

thomas


hashimoto method I was reference for this.

Click the image to open in full size.
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Old 23rd October 2007, 02:25 AM   #23
Norelco is offline Norelco  Philippines
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which better? Silk or James OPT for 300B
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Old 4th November 2007, 03:23 AM   #24
tube-lover is offline tube-lover  Hong Kong
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in my opinion, al not good.

If budget averiable, choose Tamura F7001 or 2 ( 2a3 or 300B)
F2007. Tango X-3.5S or tailor made model NY-15-3.5S.

U will love them!


thx

thomas
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Old 4th November 2007, 07:06 AM   #25
analog_sa is offline analog_sa  Europe
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The before and after break-in distortion presented by Thomas seems really startling. Improvement of several hundred percent? I have never seen such measurements done by anyone else. Are they typical?
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Old 29th March 2009, 02:05 AM   #26
mb-de is offline mb-de  Germany
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>>Are they typical?<<

In my experience with amorphous core inductances in measurement applications, rather not.

Usually such changes point towards flawed manufacturing or handling process of the cores themselves, creating the necessity to "reset" them magnetically - just the same way one has to "reset" the magnetic properties of permalloy/mu-metal after mechanically forming (bending, cutting, pressing, drilling, ...) it by annealing it in a hydrogen atmosphere...

Regards,

mb-de
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Old 29th March 2009, 06:02 AM   #27
korneluk is offline korneluk  United States
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Quote:
Originally posted by 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
John,
can you provide a link or info on the Loesch 50 amp?
TIA,
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Old 12th December 2009, 07:24 PM   #28
mb-de is offline mb-de  Germany
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Quote:
Originally Posted by Norelco View Post
which better? Silk or James OPT for 300B
Properly used, I prefer the James JS-6123HS (settin 3,5 kOhms to 8 Ohms).

This will hold up to a Tango XE-20S in similar settings.

Both do not stand a chance against the Tango X30-3,5S (better overall balance) or X-3,5S (way superior in the low frequency regime, no surprise, if you take the core size into consideration).

In check, all of these loose - for my ear AND for my testkit - against the Tamura F7002 (again unsed 3,5k:8R)... cleaner, dryer, more controlled, more low level detail...

That one gets a run for its money from the Lundahl LL1623AM-PP in parafeed (used with setting 3k or 5,6k:8R), if you happen to find a good 120..300 Hy choke which has a good frequency response and will have to stand 80 mA DC (160 mA peak) without saturation, and in must be very wide-band.

Best regards,

mb-de
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Old 12th October 2010, 03:05 AM   #29
gmant123 is offline gmant123  Argentina
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Best SE output transformer for 300B - shootout
Default Better OPT

Hello everyone.
I wish change my James 6123 for other OPT with better overall performance, Wich OPT suggest me?

Thanks in advance..

Alberto.
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Old 12th October 2010, 04:08 AM   #30
TerryO is offline TerryO  United States
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Lest we forget, another source of excellent OPTs are those from O'netics. The company's designer, Bud Purvine (BudP) is also a member of diyAudio. There are several very well known amp designers that have used and recommended these.

Disclaimer: I consider Bud a friend, so I may be biased, but I believe that his transformers are right up there with the very best.

Best Regards,
TerryO
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