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tamura f-7000 series

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#2
I've considerable experience with the amorphous core F-5002, and have encountered the F-7000 series in a customer amplifier. These transformers are very good, certainly amongst the best I have ever worked with. EIFL is a good source - all of the F-5002 I used in my amplifiers came from this source along with some custom built Tamura power transformers.
Highly recommended.

Edit: Since you live in Italy you might also want to consider Bartolucci, in my experience (limited) they have also been excellent. They have an extensive line of SE transformers, and I think you will find one of their higher models to be comparable in quality to the Tamura.
 
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#3
Tamura F5000 series

Hi Kevin:

I still have a pair that I used in an amp a while ago. Great highs/mids - actually amongst the very best. But bass was mushy, ill defined. I think the design lacked proper inductance to handle lows properly.

Mind you, the bass problem is relative to the fantastic highs and mids, I could easily live with them for a long time. But, having heard some things which cover the full bandwith, well it is hard to go back.
 
#4
kevinkr thanks but after tre mail at eifl no answer....😕

Jon "having heard some things which cover the full bandwith," can you explain better ? 😉

if you have inused pair 5003...send a pm 😉
 
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#8
Jon Ver Halen said:
Hi Kevin:
<snip>

But bass was mushy, ill defined. I think the design lacked proper inductance to handle lows properly.

<snip>
Click to expand...

Not necessarily, there are so many things that can go wrong in amplifier design starting with the use of cathode biased output stages, high impedance power supply design (likely with CLC or CLCLC type supplies and tube rectifiers), and the speaker's dependence on high damping factor for good bass performance.

Substituting that OPT with something else with no further changes and getting a much better result might be proof that the transformer itself was the culprit, short of that, and without seeing the schematic or knowing more about the particular design it is hard for me to know.

My experience with the F-5002 and some limited experience with the F-7000 series stuff leaves me wondering if there isn't more to the story. Mushy bass is not the impression of bass performance I have gotten with any Tamura output transformer I've used.
 
#11
nicoch46 said:
Jon "having heard some things which cover the full bandwith," can you explain better ? 😉
Click to expand...

Of course. The full answer revolves around the fact that transformers get designed to cover a specific bandwidth, and that bandwidth is reduced when you deal with the airgap meant to prevent saturation with an SET. The traditional Japanese designs, like Tamura, optimized the mids/highs. The Magnequest designs of old were more optimized for lows/mids, with a slight reduction in the highs.

The more recent Magnequest para-feed designs do not require an airgap, and therefore have a wider frequency response - so the whole audio band is covered evenly and very nicely. Dave Slagle of Intact Audio has a different approach, using a secondary winding to avoid the need for parafeed. Both, to my ears, are superior to the Tamura (if you get their Nickel core designs).

As they say, YMMV, but this is what my ears tell me.
 
#12
glad to know some info on dave opt , you try nikel no am rigth ?
I have an lcr riaa from him on the way....😉

As I use supravox in OB I give up under 40hz ,with LL at 5k the bass kick and very solid at last for me... but I search more on mid/higth ie ambient detail,3d sound stage and so on...
 
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#13
kevinkr said:
Not necessarily, there are so many things that can go wrong in amplifier design ........

My experience with the F-5002 and some limited experience with the F-7000 series stuff leaves me wondering if there isn't more to the story. Mushy bass is not the impression of bass performance I have gotten with any Tamura output transformer I've used.
Click to expand...



Agree totally. Be Yamamura was a supremo of 211 SET amps. They were sonically in a different league to virtually anything else. I had one at home on loan for a few years. Bass, deep, clearly defined and with fearsome dynamics was present in totally correct balance with the remainder of the frequency range. Plus it played music! Many people much preferred them to the original Ongaku. Incidentally, most of them used ex German Airforce Telefunken 211/VT4 tubes.

Be used Tamura transformers throughout. THere are some of these amps in Italy, though I will be surprised to hear of one for sale other than when some owner dies!
 
#14
nicoch46 said:
hi kevin , looking around the 5000 series is more critial to use as you write is not plug and play opt 🙂

5002 have lower induttance 18H vs 25H of 7002, this can be one ?
Click to expand...

That's the minimum guaranteed primary inductance at 100mA of plate current (the rating of the transformer) at typical plate currents of 60 - 80 mA it is significantly higher. I found bass performance of the F-5002 to be very good in my 300B SE fixed bias, fully regulated commercial product. Power was down considerably less than -1dB at 25Hz, and more importantly the distortion was not significantly higher. (The amplifier managed 4% THD at around 10Wrms - a good result I thought.) I inferred the primary inductance based on the -3dB point, but no longer remember or can find the information but I was surprised by the result at the time. (Tamura was conservative)

FWIW I am still using a variant of this design with custom OPTs and it has stood the test of time well.. Listening to it right now in fact.

Closer to home though Bartolucci makes some really fine transformers, probably the equal of the Tamuras and I would definitely check them out. Not exotic in your home market perhaps, but here they are respected and regarded to be in the same general league as the Tamuras by some in the know. (They're pretty obscure here.)
 
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#15
Bartolucci is very near me , very good trafo ,but from what I read the sound can be the same as my Lundahl ie focus in the bass/mid bass , and I don't see AM or permalloy ,price is not low !good source for custom pw trafo 😉
in this class can be interesting hashimoto good price

I thinks the 5000 serie is better then 7000 , but the 7000 is more compatible , cost a bit less ,at last for simple bulding boys 🙂
 
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#17
Hi Guys
How much burn in time is required to hear at least 90% of f7000 series potential?
I have f7002 and with 50hrs of burn in but they still sound pretty much on the bright side, not dark and sweet like i was expecting ;-)

Can i expect significant change over the time?

I've got F2004 fully burned in for a comparison and these are very clear, extended but definetely not bright.
 
#18
From my experience with F7002 it is an excellent transformer right from the start.
Its nature is never on the bright side, as SET with RE604 it is dark romantic with a super sweet voice, bass may be not as good as F2004 but still good enough compared to other trannies.
This is an excellent design, maybe impedance mismatching within the circuit or some other fault? Every component has its own sound, so to use unknown components may lead directly into the field of hazardous sounds.
It becomes better over time, but dont expect to change its nature, just more refined.
To change trannies in the same amp doesnt work if you are looking for superior sound.
Try to optimize the circuit for one given trannie, not changing one important component at the end. So maybe the circuit is optimum for F2004 but doesnt suit F7002?
 
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