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Thursday, April 28, 2022

Tube of the Month : The G2504


This month we have a rather exotic rectifier. Meet the G2504.

The G2504 is a directly heated full wave rectifier tube. It is equivalent to the RGN2504.

The tube has a European 4-Pin B4 base. The pinout is shown on the left. Unfortunately not much technical data can be found about this rectifier. The information I found states plate to plate voltage 500 V RMS and an output current of 180mA. I couldn't find anything about operation with capacitor input or choke input filters, peak inverse voltage or voltage drop. Since I do not have any G2504 tubes myself, Josef from Vienna was so kind to lend me some to take photos. He sent two different version of G2504. Both made by Valvo. One with mesh plates and the other with more common solid plates. Lets have a look at them starting with the mesh plate version.

Some close ups showing the mesh structure of the plates:

Some more views:

When the filament is lit up it is nicely visible through the mesh plate:

Next we have the G2504 with solid plates:

Close ups:

Some more views:

Obviously the filaments are not as visible as on the mesh plate when lit up. Just the tips at the top show the glow:

Thanks to Josef for lending me these tubes!

Best regards


Thursday, April 21, 2022

10Y Line Preamplifier in Black


Some photos of the 10Y preamplifier which is used to drive the 'Black Beasts' 300B monos.

All black with red engravings.

All signal transformers are silver wound in this unit.

Some photos of the preamp in their new home:

If you are interested in your very own 10Y preamplifier. Contact me to discuss your needs.

Best regards


Saturday, April 9, 2022

The Black Beasts


A finished pair of Single Ended 300B mono amplifiers.

801A Drives 300B, interstage transformer coupled using silver transformers throughout.

Finished in all black for a sinister look.

And here some photos of the amps in their new owners home:

Since I am always reluctant to write about the sound of my amplifiers I am glad that their owner allowed me not only to use his photos but also to quote him:

I’m in complete bliss and awe of the Thomas Mayer amps…:)
I’m just starting to listen to the new set up, aka the Black Beast. The setting is temporary but doesn’t look too bad…:)
The added depth, texture, transparency, dynamic range, holographic feel, silence (like I haver never heard silence so dead and soothing),…

What an experience…
I must say, I did not expect this.
What an amazing gift Thomas…

And this remark after listening to the amps for a few days:

The funny thing about the amps, they’re so good, I don’t even have to go through my favourite albums, the reference albums, because this combo of line amp and mono blocks is so miles ahead of what I knew of sound, that I can listen to whatever album and be in awe of the listening experience. There’s no need of a reference album, the amps are that good. There’s no doubt, this is propulsing me in the upper and pure audio sphere…

The 10Y line preamplifier which is driving these amps will be featured in an upcoming post.

Stay tuned!

Best regards