Japan famous tranformers

[CJ]

Tamura XFMR

https://groupdiy.com/threads/tamura-transformers.74204/

Very good iron, lowest loss of any transformer I have tested, Jensen 4:1 output is close second.

B-H curve is the best way to test for loss, the area inside the curve represents loss.

 

[Tubetec]

Any guesses as to the way its wound CJ ?
Obviously two bobbins , each with primary /secondary bi-fi wound ?

 

[abbey road d enfer]

for example, this is a tangoo transformer, has anyone come across this?

I can see that it's heavily sandwiched; I can only think of McIntosh for such a complicated xfmr. No wonder it's expensive.

 

[Gold]

I pulled a bunch of Tamura TD-1W/P-1379 600:600 output transformers from a quad stereo receiver from the 1970's. It was built as more of a pro audio unit than a consumer audio device. I also got some incredibly cool edge VU meters from that unit which I used in my DAOC compressor builds.

The P-1379 have two coils on the primary and secondary. No Screen. I'm no transformer guru but what i tested them for frequency response and distortion they measured very well. I can't remember the specifics. They also sounded great.

I have some other Tamura transformers. The P-599 looks like it may be an input transformer. It has a single winding for primary and secondary and a screen connection. I haven't tested those.

I also have a few Z96/ 1-423-189-11. They are 7KΩ to 10KΩ. A single coil for primary and secondary. The 10K side has a center tap. The 7K side doesn't. There is a scree connection. I haven't tested these.

 

[tomislavkn]

Hi,

does anyone have any info about TamRadio OT-373 transformers? They are, as far as I know, Tamura but cannot find any info on them. They are used in Toa RX7 mixer.



Thanks

 

[CJ]

just do some testing, figure out turns ratio, measure dcr, measure pri inductance, frequency response, phase shift if you have a dual trace scope, then if you want, you can try and see if it matches someting in a Tamura catalog which i do not know if they exist,

that's gonna be an OEM private label on that thing. Toa been around since 1934, wow.

 

[C12VR]

Just discovered what is nominally a very interesting mic input--150/200/300 to 100K!!!! with FR 20-20k!!! (maybe down a few db at 20k)
Tamura TKS 27
The question is firstly, whether 100k is just a random nominal figure and the actual turns ratio is much lower, and secondly, whether the FR is anywhere close to flat out to 20k.
Not cheap, (saw a pair go for $100 on a japanese site, but the going rate seems to be at least $250 a pop) but given the prices for vintage iron that can approach these specs, if it works even close to as well as it claims it might be worth looking into. Of course, you can always wait around for Peerless 4622; about 300 seems to be going rate.

 

[terry setter]

Ah, but the question is "what do you like to hear?", not "what looks good in specs?" I've just spend several days measuring 17 different mic output transformers and there is one thing that I have found to be true, we don't like flat FR, non-ringing output transformers as much as we do those that impose a "signature" on the sound. If you want clean, try looking at a Lundahl "C" core LL1940 (9:1 ratio). If you want personality, AMI transformers have it, but you have to be careful that you don't flush your low frequency response when going for the excitement of those higher frequencies imparted by designs that were created to sound very "transformer-y". ESPECIALLY the ones wound on smaller cores. Crimson makes very good transformers, most of which are cheaper than their better-known competitors.

Lundahl makes the 1538 and 1538XL (5:1 ratio) which they stipulate as being intended as a mic input transformer. They measure pretty dang well.

 

[CJ]

300 to 100 k is 1 : 18 turns ratio. High but not outrageous

V76 input is 1:30 turns ratio using 7 chambers on one bobbin

 

[C12VR]

300 to 100 k is 1 : 18 turns ratio. High but not outrageous

V76 input is 1:30 turns ratio using 7 chambers on one bobbin

true, but nonetheless exceptional for a modern transformer, at least if it performs well up to 20k. Also, i think it's 1:22 at the 200ohm and 1:26 at 150ohm. Only comparable is the cinemag 9994. Maybe that's a safer bet, but probably not cheaper anymore. Last I checked in 2020 it was like 140. With all the transformer manufacturers raising prices these days, it's probably even worse. Not that it isn't worth it.
Crimson is indeed a bargain, if you can ever get ahold of someone. Called 10 times over a month, emailed just as much, and not so much as a whisper.

 

[abbey road d enfer]

Ratio doesn't tell the whole story.
A ratio of 1:30 is quite common for moving-coil cartridges, but only because the nominal primary impedance is very low (typically 1-10 ohms).
The limiting factor is the inductance of the secondary, which, combined with parasitic capacitance, defines the HF behaviour.
Reducing the primary inductance, whilst preserving ratio, is a cheap but effective solution for extending HF response, at the detriment of LF.
It's all a matter of compromise. For a 150r source, the inductance should not be less than 5H @20Hz, which generally means 2H @1kHz (remember that inductance is frequency dependant for iron cores).
For a 1:10 xfmr, the resulting HF secondary inductance is about 100H, which means a reactance of about 10 megohm.
It is commonly acknowledged that it's the upper limit for standard manufacturing techniques.
For higher secondary inductance, sophisticated methods must be employed, deruved from RF techniques, such as sandwiching and chambering. These are very costly because they involve multiplying the number of windings and splices.
Some xfmr manufacturers reduce primary inductance, which results in some LF loss, and allows them to either publish better HF specs or decrease their manufacturing cost.

 

[C12VR]

Ratio doesn't tell the whole story.
A ratio of 1:30 is quite common for moving-coil cartridges, but only because the nominal primary impedance is very low (typically 1-10 ohms).
The limiting factor is the inductance of the secondary, which, combined with parasitic capacitance, defines the HF behaviour.
Reducing the primary inductance, whilst preserving ratio, is a cheap but effective solution for extending HF response, at the detriment of LF.
It's all a matter of compromise. For a 150r source, the inductance should not be less than 5H @20Hz, which generally means 2H @1kHz (remember that inductance is frequency dependant for iron cores).
For a 1:10 xfmr, the resulting HF secondary inductance is about 100H, which means a reactance of about 10 megohm.
It is commonly acknowledged that it's the upper limit for standard manufacturing techniques.
For higher secondary inductance, sophisticated methods must be employed, deruved from RF techniques, such as sandwiching and chambering. These are very costly because they involve multiplying the number of windings and splices.
Some xfmr manufacturers reduce primary inductance, which results in some LF loss, and allows them to either publish better HF specs or decrease their manufacturing cost.

Yes, but doesn't the nominal impedance and FR spec imply suitable inductance?
Tamura is not well know among Western audio guys but as CJ points out, with the line transformer, they can be very high quality. They are also no strangers to the esoteric winding techniques required for exceptional audio transformers.
Of course, it is quite possible that the transformer isn't intended for microphones, but then why did they manufacture a dedicated MC transformer in the same product line?
I'm no longer interested in it anyway. Too rich for my blood.

 

[Gold]

but then why did they manufacture a dedicated MC transformer in the same product line?
I'm no longer interested in it anyway. Too rich for my blood.

The Tamura MC transformer I have my eyes on is the one made for the Denon DL103. I have a feeling the cartridge was designed with this transformer in mind. The DL103 is a high output MC. With a 1:8 or 1:10 (I forget off the top of my head). It magically transforms the level and impedance to present the load the DL103 wants to see with an MM preamp 47KΩ termination. They are way expensive on the bay.

 

[C12VR]

The Tamura MC transformer I have my eyes on is the one made for the Denon DL103. I have a feeling the cartridge was designed with this transformer in mind. The DL103 is a high output MC. With a 1:8 or 1:10 (I forget off the top of my head). It magically transforms the level and impedance to present the load the DL103 wants to see with an MM preamp 47KΩ termination. They are way expensive on the bay.

Yes, loads of mu shielding on those things. Good quality, evidently. Once the audiophiles get wind of anything, it instantly becomes unobtainable. Hell, you can't even get one of those old plugin transformers without wading through an ocean of "GREAT FOR MC STEP UP!"

 

[abbey road d enfer]

Yes, but doesn't the nominal impedance and FR spec imply suitable inductance?

There are many ways to get nominal impedance with different inductances. It depends on how the designer choses to optimize things.
At midrange, which is usually where nominal impedances are defined, the actual inductance is almost irrelevant (within limits, of course).
You can make a 200:10k xfmr with a 2H primary or a 10H primary, because at mid fequencies, the load is dominant.
The difference between the 2H and the 10H will be noticeable at VLF, where one could drop by about 1dB and the other by 0.1dB.
There is also a good probability that the HF response of the 2H is better than the 10H, unless specific and costly precautions are taken.
.

 

[AUDIO FREQ]

300 to 100 k is 1 : 18 turns ratio. High but not outrageous

V76 input is 1:30 turns ratio using 7 chambers on one bobbin

Hi Cj, how do you calculate turns ratio?

I have an Tamura GA80071 transformer id like to use inside a Presonus Eureka as an Mic Pre Input transformer. A friend sent me 2 transformers in the mail to play around with.

One is the Tamura GA80071 and the other is a smaller (cuter) Tamura GA8027. I know nothing about them aside from the fact they came out of a Yamaha mixer PM1000.

 

[abbey road d enfer]

Hi Cj, how do you calculate turns ratio?

Turn ratio is the square root of the impedance ratio. Conversely impedance ratio is turn ratio squared.

I have an Tamura GA80071 transformer id like to use inside a Presonus Eureka as an Mic Pre Input transformer.

The Presonus preamp is transformerless, optimized for low impedance source. Putting a step-up xfmr in front may result in the preamp seeing too high a source impedance, which is not good for noise performance.

A friend sent me 2 transformers in the mail to play around with.

One is the Tamura GA80071 and the other is a smaller (cuter) Tamura GA8027. I know nothing about them aside from the fact they came out of a Yamaha mixer PM1000.

The PM1000 xfmr is a low ratio (1:3 voltage ratio, 1:9 Z ratio) so it may be suitable.
Now, what do you expect from this experiment?

 

[AUDIO FREQ]

Turn ratio is the square root of the impedance ratio. Conversely impedance ratio is turn ratio squared.

The Presonus preamp is transformerless, optimized for low impedance source. Putting a step-up xfmr in front may result in the preamp seeing too high a source impedance, which is not good for noise performance.

The PM1000 xfmr is a low ratio (1:3 voltage ratio, 1:9 Z ratio) so it may be suitable.
Now, what do you expect from this experiment?

Just experimenting and learning to be honest. I bought it non-functioning for parts and to learn/experiment on. It does have a transformer on the input. I have the schematic if you'd like to see.

 

[abbey road d enfer]

Just experimenting and learning to be honest. I bought it non-functioning for parts and to learn/experiment on. It does have a transformer on the input. I have the schematic if you'd like to see.

The existing transformer is a very good one (Jensen 11K8). I don't believe you can expect improvement from the xfmr that comes from a PM1000.

 

[AUDIO FREQ]

The existing transformer is a very good one (Jensen 11K8). I don't believe you can expect improvement from the xfmr that comes from a PM1000.

Mine doesn't have a Jensen in it. It's an unlabeled generic transformer, according to Chad from Presonus. They stopped putting Jensens in them after the MP20.