All rights of photos and text reserved. Usage of photos or text from my blog on other websites or for any other purpose only with prior permission. If you want to use any material from my blog please contact me by email.

Sunday, August 7, 2022

Deutsche Elektronenröhren Manufaktur GmbH 6th Anniversary


Today we are celebrating the 6th anniversary of making ELROG tubes at Deutsche Elektronenröhren Manufaktur.

In August 2016 Deutsche Elektronenröhren Manufaktur was founded and acquired all assets and brand rights of Elrog Elektronenröhren GmbH & Co KG. The initial range of ER211, ER845 and ER300B was substantially improved in design and materials and continued to be produced under the new firm. Each year new tubes were introduced and the portfolio is now 18 types strong, of which 14 types are for general sale and 4 are exclusively produced for Thomas Mayer amplifiers.

The latest additions are a molybdenum plate version of the ER801A called ER801A-Mo and a TM801A which captures the sound qualities of a 46 in a tube with 801A specs, similarly to the TM300B. And a molybdenum version of the TM300B, called TM300B-Mo.

Yes, this means there are 4 variants of ELROG 300B tubes now.

And three variants of ELROG 801A tubes:

All these are fully compatible with old production 801A tubes and can be used in applications designed for 10, 10Y, VT15, VT25A, 1602, 801, 801A or VT62.

The new 801A variants have already been tested by some customers. Here are their impressions.

The first used the TM801A in his silver 10Y linestage which drives silver TM300B monoblocks.

These are his impressions:

It feels like whatever the TM magic is, it works very well…:)

It really 3Dimensonalises the sound. To me it’s like a Leica lens compared to other lenses. Leica optics makes the images to be more 3D and buttery. It has enhanced micro-contrast. It’s not romantic, but the perfect balance between sharp and still humane/warm. You can touch the soul of your subject, without being overly analytical and loosing the mystery of you subject. 
Now change Leica with TM and subject with recording…:)

So, now I need another pair for the monoblocks…:)

Next the impressions of a customer who compared the ER801A-Mo and TM801A as driver tubes in his monoblocks which are equipped with TM300B

I listend to both ER801A-Mo and TM801A as driver tube in 300B SE power amps with TM300B as output tube.
The power amps are directly driven from a DCS DA-Converter with Aurender music server. No vinyl all digital.

The short summary of my impression is easy: The Mo is the refined and optimised variant of the already high resolution ‘regular ER801A’ while the TM801A is the ideal partner to the outstanding sound quality of the TM300B.

More in depth description: The Mo not only does everything a bit better that the 'regular tube’ but its convincing resolution, openness and rock solid presentation is immediately apparent…and this without any aggressiveness. It impressively suits listeners with a preference for resolution and detail.
The character of the TM801A is more subtle she demands full attention to be able to enjoy its extraordinary finesse and underlines the quality of the TM300B perfectly.
The comparison to a very good wine is not far fetched. In both cases connaisseurs and hedonists get a treat and are rewarded.

Both the TM and Mo offer for different preferences the optimum especially in combination with the TM300B. The developers of these tubes must have extraordinary knowledge and experience.

This is my translations of his comments here is the original version for the german readers:

Sowohl die Elrog 801A Mo als auch die Elrog TM 801A wurden als Eingangsröhren
in Kombi mit Elrog TM 300B in den Endstufen 300SE gehört. Die Endstufen wurden
direkt von einem DCS Wandler angesteuert; als Quelle diente ein Aurender Musikserver -
also kein Vinyl, sondern alles Digital.
Die Kurzfassung meiner Wahrnehmung klingt ziemlich simpel. Die Mo ist die verfeinerte,
optimierte Variante der ohnehin schon auflösungsstarken „normalen Elrog 801A“, während
die TM 801A die kongeniale Partnerin zu den außergewöhnlichen klanglichen Qualitäten
der TM 300 B erscheint!
Im Einzelnen macht die Mo nicht nur etwa alles einen Tick besser als die „Normale“,
sondern ihre bestechende Auflösung, Offenheit und felsenfeste Darstellung springt
sofort ins Ohr…und zwar ohne jegliche Aggressivität. Damit spricht sie Hörer mit Vorliebe für Auflösung und Detailwiedergabe in beeindruckender Weise an!
Der Charakter der TM ist da subtiler. Sie fordert sozusagen volle Aufmerksamkeit, damit
man ihre wirklich außergewöhnliche Feinheit und ihren Klangfarbenreichtum genießen
kann…das hat fast unheimliche Finesse und unterstreicht und unterstützt die Qualität
der TM 300B perfekt! Der Vergleich mit einem besonders guten Wein ist vielleicht
gar nicht so weit hergeholt…in beiden Fällen werden Kenner und Genießer angesprochen
und belohnt!
Beide, TM und Mo, bieten für die jeweils klanglichen Vorlieben vermutlich das Optimum
ab ! Und das insbesondere in Verbindung mit der TM 300B. Die Entwickler dieser Röhren müssen über außerordentliche Kenntnisse und Erfahrung verfügen…..
Gratulation und Respekt!

More reviews of the TM801A will follow. Stay tuned!

Above our 'big boys'. Below our rectifiers:

Our triode with the least demand is the ER50:

This tube shows how tricky it is to decide about new tube developments. We had many requests to bring out this tube but actual demand turned out to be too low for continuous production. I occasionally get asked about the 2A3. We did contemplate to bring an ER2A3 to market and even developed some working prototypes:

But the thoriated tungsten filaments used have a different thermal behaviour than oxide coated filament which results in more residual hum when AC heated. Since the vast majority of 2A3 amps are AC heated and typically used with high efficiency speakers we decided against selling these. Thoriated tungsten filaments are giving all our tubes their signature sound and we would not want to bring out an oxide coated filament 2A3 like all others on the market. Restricting their use in DC heated amps would reduce their demand to less than that of the 50. So sorry no ELROG ER2A3.

But there are already ideas for other new types to introduce.

I'd like to thank the staff of Deutsche Elektronenröhren Manufaktur GmbH for their continuous passion and hard work and to all users of ELROG tubes. Without you audio tube production in Germany would not be alive.

Best regards


Friday, July 29, 2022

Tube of the Month : The RV218 / RV258


Here are two more triodes borrowed from my friend Josef in Vienna to show them to you. The RV218 and its successor the RV258.

These are two very old directly heated triodes made in Germany. The RV218 was introduced in 1928 and later replaced by the RV258.

They have a peculiar base which - contrary to most tube bases - is female. This means they do not have pins extruding from the bottom but connector jacks which conveniently fit 4mm banana plugs. They were intended as audio amplifier tubes. They are directly heated by a thoriated tungsten filament which runs at 7V and needs 1.1A of current. Some data sheets list slightly different filament voltages. I have seen 7.2V and even 7.5V. The filament power is actually close to that of the 801A or 10Y. The amplification factor of 7 and plate resistance of 3500 Ohms are quite similar to the values of the 801A as well. The RV258 is an uprated version which can handle up to 800V on the plate and 32W dissipation. The large metal collars of the bases have an additional jack for a grounding connection for shielding purposes. Interesting and long forgotten tubes. Due to their scarcity probably hardly used in any amplifier nowadays. As always let's have a look at the plate curves which I took from the RV218 with the tracer:

The grid lines are spaced in 5V steps. The plate voltage is on the horizontal axis, 50V/step and the plate current vertically at 5mA/step.

And now some photos of the two specimens Josef lent me, starting with the RV218

This tube was made by Siemens.

A few close ups:

Next the RV258, made by Telefunken:

And some fotos with the filament lit up:

Hope you enjoyed the presentation of these old gems. Stay tuned for more samples from Josef's collection.

Best regards


Friday, July 15, 2022

The All Silver D3a Differential Phono Preamplifier


Just finished a D3a differential phono stage with all signal transformers, plate chokes and LCR coils in silver.

This phono stage will be used together with previously finished 10Y differential line preamplifier and 300B mono blocks

To house all the components needed the signal unit has to be 6cm longer than the usual standard size.

The power supply unit is in the usual 40cm long portrait chassis.

View from the top:

These are all the silver wind goods used in this phonos stage:

Some impressions of the construction process:

Power Supply:

The phono stage is meant for use with MC cartridges. It has both XLR and RCA in and outputs.

Best regards