Tango Transformers

Hi!

Readers of my blog probably realised that I like to use the japanese made Tango transformers a lot. In fact I have been using them since the first years when I started to develop and build tube amplifiers. So I decided to dedicate a post to them.

Tange transformers have a long history which spans back at least into the 1970ies, as far as I know. Originally Tango was a branch of Hirata Electric which is a big japanese corporation. There is a story that Mr Hirata himself initiated the transformer winding department since he was into tube amplifiers. When he retired the new management decided to close the department since it was not profitable enough and did not fit to the core business of the company. If this is true or just a myth, I don't know for sure. When the transformer winding business was shut down, the employees who worked in that department did a buy out and founded a company of their own which was called ISO-Tango.

This happened around the year 2000. Tango transformers were not available for a year or two but then ISO Tango entered the marked again with a reduced portfolio of models. As with everything which is not available any more, legends spread claiming that the 'original' Hirata-Tango transformers were superior in performance to the later ISO-Tango models. I used both extensively and cannot confirm this. I had been as happy with the ISO models as with the former Hirata transformers.

In June last year ISO Tango sadly announced that they will shut down their business. Different reasons have been mentioned why they decided to close the operation. Shrinking market share, lack of profitability especially in export markets due to the strong Yen exchange rate or simply the fact that the employees are way past the retirement age and decided to give it a rest.

Luckily I got a chance to place a last order to fill up my stock. Apparently ISO-Tango received many last time orders after the news. Since they planned to stop the operation in September it was not sure if I would receive my order. But the employees of ISO-Tango carried on until January this year to full fill each order which they received in June. This is the strong japanese spirit and commitment. A spirit which I learned to appreciate a lot over the many years I dealt with partners from Japan. During the time from September to January I received one lot after the other until my order was complete:

The photo above shows my stock which contains not only ISO-Tango models but also some which had been wound under the Hirata roof. Most of them new, some have been used and dismantled from old amplifier projects. This does not contain all models Tango made but just those which I mainly use in my projects.

The row of large transformers in the back are the fabulous X10S output transformers for single ended 211 amplifiers as used in the recently finished 801A/211 mono blocks. The four similarly sized transformers in front of them are X2.7S output transformers for single ended 300B amplifiers. Then there are 4 FC30-3.5S outputs, also suitable for the 300B. I also used these with the 6CB5a. The four rows in front of those are a bunch of XE20S output and NC20F interstage transformers. The XE20S is a versatile transformer which can be configured for impedances from 2.5 to 5k Ohm. Thus they can be used with a wide range of tubes. I used them with 300B, 2A3, 45 and 6CB5a. In fact it is my favourite output transformer for the 45. I have used them with the NC20F for example in 45 amps with DHT drivers or in no compromise implementations with the 6CB5a.

The small transformers in the front are M757 single ended output transformers with primary taps for 5 or 7k. More about this one later on. On the left side is a mix of older transformers for example some from the FW series which used a different core (the ones with black covers). There are also different small interstage transformers, chokes, line out transformers and the exquisite EQ600P LCR RIAA networks. The two small ones at the very right are EQ2L. These contain the inductances for 600 Ohm LCR networks.

I like the finish of the Tango transformers a lot, especially the grey hammer tone varnish:

Hirata-Tango transformers sometimes also came in black and a hammer tone white. But ISO only made the grey hammer tone finish.

Let's have a look at some of the transformer types in detail. First the humongous X10SF output transformer:

The connection terminal:

A 10k output, usable for transmitting tubes like the 211 or 845 or any other tube which needs 10k loading. It even has a tap for screen connection for ultra linear circuits with pentodes. Besides the usual 4, 8 and 16 Ohm output taps it also has one for 6 Ohms. This is one of the best output transformers for the 211 tube.

Another type from the 'X' series is the X2.7S, designed specifically for the 300B:

It has the same size as the X10S, it is only a bit smaller. It also has the additional 6 Ohm output tap:

ISO reduced the model line up when they started. But they made many of the older types on custom order if requested. Custom wound transformers got a 'S' label followed by a 4 or 5 digit number. In this case the X2.7S was reborn as S-2595.

There are different labels used for the different series transformers. Most transformers came with the label separately so that the user can decide himself if he wanst to use it or leave the transformer unlabelled. Only the 'X' series had the large square label with the wave T:

Next is the FC30-3.5S, smaller than the two above but still an impressive size:

One of my favourite output transformers, the XE20S:

Despite being classified as 'universal' type which can work with a variety of tubes it has great performance. The different primary impedances are obtained simply by using different secondary taps.

Another very interesting output transformer was the H5S which was only made under the Hirata roof:

This is a small output transformer with 5k primary. Due to the small core it has limited primary inductance so the low frequency end does not extend as far as with the larger cores. It was meant for midrange/tweeter amps in active systems. Such amps only need to reproduce midrange and/or highs. So it was optimised for that. But it could still be used full range. For example with certain speakers which use a single full range driver the low frequency roll off is not really noticeable. The secondary taps extend up to 32 Ohms. Ideal also for headphone amps. This transformer had a unique round label:

ISO-Tango developed a successor of this transformer called M757 here in comparison with the H5S:

The M757 has primary taps for 5 and 7kOhms and secondaries only for 4, 8 and 16:

Here a size comparison between XE20S and M757:

Of course there are also great interstage transformers in the line up. My favourite is the NC20, which got renamed to NC20F by ISO. This is still one of the very best interstage transformers out there and I used it a lot already. Here the connection terminal of the ISO version:

The Hirata version:

The Hirata NC20 always came with the label already attached:

While the NC20 was made both in grey hammer tone and black, the NC20F was only finished in grey. These are quite big interstage transformers, they are the same size as the XE20S.

Like all Tango transformers, the NC20 was delivered with a very good data sheet:

Other famous and popular interstage transformers are the NC14 and NC16:

The Hirata versions were offered in hammer tone grey or white.

Both have split primaries and secondaries which can be wired in series or in parallel. This offers many different uses. The NC14 is meant for use with tubes with lower plate resistance. The NC16 for higher rp tubes and it is a 1+1:2+2 while the NC14 is 1+1:1+1. When used with low rp tubes the NC16 could even be wired 1:4. These interstages came in the same small housing like the M757.

It is not clear why these are marked as input transformers. Although they can be used as such, their main application is interstage transformer with DC on the primary. There are 'real' input transformers as well, like the NN-6:

Lineoutput transformers, here the NP8 as used in my UX201A Sound Processor:

Besides transformers Tango also made a variety of chokes:

Yet another different label on these:

Among my favourite Tango products is the EQ600P which contains an entire 600 Ohm LCR network:

These came in the same housing as the NC14 and NC16 transformers. I only saw the EQ600P in white. Besides this there is also the EQ2L, which just contains the 1.8Hy and 45mHy coils. The resistors and capacitors had to be added externally. The EQ2L is a bit shorter in size. Here the EQ600P and EQ2L in comparison:

There had been many more types as those shown here. Of course a whole range of push pull output transformers, more interstage transformers, a MC step up, many different chokes and also power transformers.

There are indications that the brand will be carried on by a new company, but details are not available. If the same types will be produced with the same winding techniques or if just the brand name will be bought is not known yet. With my stock I can offer amplifiers with Tango transformers for a few more years.

But what is the alternative when the stock is used up? There will certainly be a life after Tango. There are other manufacturers who offer the same and maybe even better quality (albeit at a price). I already stocked some alternatives. The company Hashimoto has developed a line of transformers which pretty  much resembles part of the Tango range. In fact most of their transformers match the Tango models in specs and size remarkably close. Their A-305 interstage transformer for example seems to be a promising replacement for the NC20:

The Hashimoto is shown on the left and the NC20 on the right. Finish of the housing is perfect on these. Here the connection terminal:

Another japanese transformer manufacturer with a great reputation for excellent sound quality is Tamura. They offer a wide range of products at different price levels. Here a single ended output transformer:

The build quality of these is exquisite, but comes at a price. They recently introduced a budget range with flying leads instead of a connection terminal:

Tamura is famous for their amorphous core transformers. I have never been too fond of amorphous cores, but I will give these a try:

These also have exceptional build quality and a beautiful finish:

I will build some amplifiers with these various alternatives during this year and evaluate the sound differences.

I would like to thank Mr. Iwasaki, president of ISO-Tango and his entire staff for the marvellous products they made for the tube audio community during the last decades and especially for their commitment to quality and performance. The audio world would be poorer without Tango.

Best regards

Thomas