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Tuesday, June 28, 2022

Tube of the Month : The VT127A


This months tube is another crazy specimen from the collection of Josef from Vienna : The VT-127A

The VT-127A is a directly heated transmitting triode with thoriated tungsten filament. Designed as VHF pulse oscillator. Josef uses it as output tube and operates it similar to a 211.

The tube has a weird bulb shape. The four rods protruding from the sides through the glass are the plate and grid connections. The two on the top connect to the plate and the two in the middle to the grid. The two pairs of connectors are in parallel. Filament voltage is applied through two rods coming out at the bottom of the bulb.

The first tube is made by EIMAC.

The filament runs at 5V and needs a whopping 10A current. Maximum ratings and typical operating conditions for continuous use are the same as those of the EIMAC 100TL.

Some close up photos of the tube:

Next we have a Gammatron VT127A:

Some photos with the filament lit up.

The tube in operation in an amplifier built by Josef:

Quite a beast of a tube! Thanks to Josef for providing the samples for this post.

Best regards


Thursday, June 16, 2022

SE 300B Mono Amplifiers ... How Do They Sound?


In April I shipped a pair of single ended 300B mono blocks along with a 10Y line preamplifier. 

Their new owner sent some feedback about their sound and allowed it to be published.

This is what he reported back:

This feedback took more time than expected, seeing that the sound has changed so much in the course of the first two weeks of use. At first the sound was a little closed-in, but after the first week they started opening up. Now, after two weeks of hardly being able to switch them off, the window into the music has opened wide! My expectations were naturally high, due to the quality and cost, though I have to say that the experience has far superceded my expectations.

First a few thoughts about the "sound". The extreme transparency and being extremely dynamic - combined with being extremely musical is something I find very unusual, since my experience usually finds a compromise of one or the other, that these components don't seem to have. 
I can listen to music for hours on end, and previously, with systems that are very detailed, dynamic and transparent, I become saturated, and able to end the listening session more easily. But now, after hours of listening to variously complex music at realistic volumes, there is no auditory fatigue whatsoever. Switching the system off becomes an impossibility. 

However, these terms and observations are somewhat irrelevant, seeing as how for me, all that really matters is the experience of the emotional content of the music . Being able to see the colours of sound, feel the texture of the music. In addition, experiencing that the music is communicating with me. That the content of the music is forcing me to listen, to pay attention to what it is trying to convey. Whether it is instrumental og vocal, they are equally capturing, and with a two way communication that I have never before experienced in a stereo system, only with live music. 

There seems to be a magical capacity of musicality, though I believe that the "magic" in reality can be explained as a combitation of extremely well suited tubes and their positioning in "perfect"  circuits, as well as an unwillingness to make compromises in the power supply (ref. the wheight and size of the components... stereo 300B... 80kg+). 

Being able to "harvest" the historical event of the original performance of music and having it be available at any given time is for me the ultimate goal of musical reproduction and uniquely apparent in these components. 

From the first e-mail corresponence concerning my needs and preferences to the continous updates during production and finally unpacking of the boxes, it has been so enjoyable that I would easily repeat it just for the positive experience.

And here some photos of the amps and preamp in his home:

So far the amps have been used with the standard Elrog ER300B. I recommended to enjoy the amps for a while and then experience yet another jump in sound quality with the TM300B tubes.

If you are interested in getting your own 300B amps or 10Y preamp built, drop me an email.

Best regards


Tuesday, May 31, 2022

Tube of the Month : The 3C24


This month we have another rather unusual tube. The 3C24:

The 3C24 is a transmitting tube developed for Class B audio amplifier or modulator use or for Class C RF amplifier or oscillator service.

It is a directly heated triode with thoriated tungsten filament on an UX4 4 pin base. Only the two larger diameter base pins are used for the filament connection. The grid is brought out of the side of the tube and the plate on top. This provides good high voltage insulation for the max plate voltage of 2kV. The filament operates at 6.3V and consumes 3A. The tube is rather small for a transmitting tube with an overall height of about 11cm including base and top pins and only 6cm height of the glass bulb and 3.5cm diameter. For all technical information please refer to the EIMAC data sheet. The tubes shown below are kindly provided by Josef from Vienna who has a good collection of some crazy tubes.

Starting with a 3C24 in military packaging made by North American Philips Co. (Norelco). 

The tube also has the military type number VT204 printed on the base.

The plate and grid connections:

A 3C24 made by Lewis Electronics:

Another Lewis 3C24 in different packaging:

The next one is from a rather unusual brand.

I never came across this brand name before.

The tube bears the HK (Heinz Kaufmann) logo which to my knowledge was a rebrander.

And lastly an EIMAC 3C24:

Due to the structure of the tube with the plate enclosed on the top, only some glow at the bottom is visible when the tube is in operation:

A shot from below where the unique filament and grid structures are visible. The filament is a spiral around a central rod with the grid as cylindrical cage around it.

I hope you enjoyed the tube of the month presentation. Thanks to Josef for lending the tubes to me.

Best regards