DISCLAIMER: Vacuum tube circuits work with dangerously high voltages. Do not attempt to build circuits presented on this site if you do not have the required experience and skills to work with such voltages. I assume no responsibility whatsoever for any damage caused by the usage of my circuits.

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Monday, July 22, 2013

New Transformer Covers - Neue Trafohauben


Since my old supplier of transformer covers can't deliver any more, I decided to develop my own covers with a metal shop. This is the first prototype:

I get many inquiries for such covers. So I decided to not only use these for my amps and kits but also offer them individually. The first series production batch is still about 5 weeks away. As soon as they are available I will set up a web shop in which these will be offered along with other parts like power transformers and capacitors.

The covers will be made in 4 sizes : 

80*80*90 mm

Besides matte black, they will also be available in the other colors which can be seen on my amps: metallic white, graphite grey, dark blue and dark red. Other colors can be made on request. 

The surface of these covers is of very high quality and scratch resistant.

The transformer cover can be mounted to a metal plate with 4 3mm screws, which screw into threaded holes in the corners:

The corners on the top side are nicely rounded:

The covers will come with two different alternatives for this rounding. As shown above and with half the radius.

Another announcement will be made when the covers become available. If you have specific requirements or need larger quantities, please contact me.

thomas -at- vinylsavor -dot- de

Best regards



Da mein Lieferant für Trafohauben nichts mehr produziert, habe ich mich entschlossen meine eigenen Hauben anzubieten. Da ich viele Anfragen für solche Hauben bekomme, werde ich diese nicht nur für meine eigenen Verstärker und Bausätze verwenden, sondern auch einzeln anbieten. Die erste Serie erwarte ich in ca 5 Wochen und werde diese dann neben anderen Teilen wie Kondensatoren und Netztrafos in einem webshop anbieten.

Die Transformatorhauben werden in 4 Größen gefertigt:

80*80*90 mm

Die Fotos zeigen den ersten Prototypen in matt schwarz. Ausserdem wird es verschiedene Metalliclacke geben: Perlmutt weiss, Graphit Grau, Dunkel Blau und Dunkel Rot. Auf Nachfrage wären auch andere Farben möglich. Die Oberflächen sind sehr hochwertig und unempfindlich gegen Kratzer.

Die Befestigung erfolgt mittels 4 M3 Schrauben über Gewindelöcher in den Ecken.

Die oberen Kanten werden in zwei Rundungsradien angeboten. Einmal wie oben gezeigt und mit dem halben Radius.

Sobald die erste Serie verfügbar ist werde ich das hier nochmal bekannt geben. Für spezielle Anforderungen oder größere Stückzahlen nehme ich bereits Vorbestellungen an. Email:

thomas -at- vinylsavor -punkt- de

Viele Grüße


Saturday, July 13, 2013

Tube of the Month : The 5X4


This months tube is a rectifier tube, the 5X4:

This is a 'classical' rectifier as used in most tube rectified amplifiers. It has two diodes with a common cathode in one bottle. The rectifier is directly heated which means the filament is also the cathode.

The 5X4 was only made in ST glass as far as I am aware. That's why it is also called 5X4G. It has an Octal base. The pinout is shown on the left. It is typically used with a transformer with a center tapped secondary. The secondary connects to the plates of the rectifier and the center tap serves as ground. B+ is then derived from the center tap of the heater winding, or from either end of the filament. It can also be used in a bridge rectifier arrangement without center tapped secondary, if it is augmented by two additional diodes. These connect from the secondary ends to ground, cathodes to AC and anodes to ground. I mostly use TV damper diodes as rectifiers, that's why I have not used the 5X4 in any of my designs yet.

The reason why I am presenting it here in the tube of the month series is it's electrical equivalence to the very often used 5U4. It only differs in the pin out. 5U4 or 5U4G are often seen in the power amplifiers of 300B amplifiers. Hence they are commanding a hefty price. The 5X4 however is still largely overlooked. It typically costs a third or even less of the price of 5U4s.

Sockets which are wired for the 5U4 can be very easily rewired to accept the 5X4. While the plates of the 5X4 connect to pins 3 and 5, the 5U4 has the plates brought out to pins 4 and 6. The former has the filaments at 7 and 8 and the latter at 2 and 7.

The rectifier socket can even be wired such that it accepts both tube types. All that is needed are 3 jumpers which connect pins 3 with 4, 5 with 6 and 2 with 7.

The first photo above shows Rogers 5X4G made in Canada. Here some more details of this tube:

A Sylvania, made in USA:

A close up of it's ribbon filament:


RCA slightly changed construction details and printing over the years:

A close up of the filament of a RCA tube:

Availability of the 5X4 is still good. If your amp uses 5U4 rectifiers and you have difficulties finding replacements, consider modifying it to accept 5X4.

Best regards


Thursday, July 11, 2013

Only a few ELROG tubes left in stock


The ELROG tubes from the last batch which I got are moving fast. Feedback from some of the initial users of ELROG tubes can be found in the previous post. My own assessment of their sound can be read here.

I have two pairs ER845 left. Of the ER211 only two slightly used pairs are currently available. These have been used by me for measurements and characterisation. The tubes have not been stressed and only been operated within allowed limits for a few hours. The bases might have some slight scratch marks. Therefor these ER211 are available at a discounted price. Regarding warranty and return policy these will be treated like new tubes.

Due to summer vacation I will get the next batch not before mid August.

Email me if you are interested: thomas - at - vinylsavor - dot - de

Update:  All Elrog tubes are currently sold out. Place a preorder now to reserve your pair from the next production batch due to arrive mid August

Best regards


Saturday, July 6, 2013

ELROG sound reports


In the meantime several people tried the Elrog tubes and I received some feedback which I'd like to share.

Oliver tried a pair Elrog 845 in this amp:

These are his findings:

The Elrog 845 adds much more transparency and detail. Tonality appears more natural. Dynamics are explosive with the Elrogs which could even be too much for some people's taste.Tone colors are great.

Here a photo of Oliver's system:

Here the Elrog 845 in another famous amplifier:

It reportedly sounded very close to NOS RCA 845, which are impossible to find nowadays at any price

And remarks about the Elrog 211:

The sound is very natural and warm!

I got GE and RCA VT-4-C
But none can compete with ELROG211!
very detailed from high to deep bass, without any offensiveness.
Thomas Mayer is right : the tone of ELROG is a bit similar to 45!

Jürgen uses Elrogs in his very elaborate and extremely well built 211 mono amps:

Tango interstage and output transformers, 801 driver tubes, external power supplies. These are his findings:

The beauty of the 45
The magic of the 300B
The power of the 211

Marco uses Elrog 211 tubes in these 211 mono blocks

His findings:

The Elrog 211 tubes show a constructive outstanding care which translates into much better performance than other tubes of the same type.
In particular, if compared with the GE 211, the sound is certainly more dry and fast, without that this is a negative connotation.
On the contrary, these features result in a much better transparency, more silence between the notes and the ability to perceive in the full orchestral the sounds of lower intensity and in the background, as is the live music.
However this does not happen at the expense of full-bodied sound and tonal coherence, as high mid and treble ranges merge together to form a musical fabric perfectly blended.
Also add that the fluidity of the sound, the natural emission and the dynamics are considerably higher than what was found with the GE and the same applies to the provision of sound, for which, even in the most difficult passages do not feel any effort or tonal compression, quality that is very important in listening to the CD where you do not feel any more hardness orscreeching.
Finally, it seems to me that the output power is greater with these tubes, but it could also be a sensation due to less distorsion than that wich is present with 211 GE
The judgment is therefore very positive.
These valves, which I try with the monoblock of Thomas Mayer, do take a significant leap in quality to the amplifiers in which they are installed.

Thanks to all who shared their experience and photos!

I just received another batch 211 and 845 tubes. If you are interested to test these, I will send a pair for a deposit of the purchase price. After a 2 weeks trial period you can either keep the tubes or send them back for a refund (except shipping cost). All you are risking is the shipping charge.

Contact me by email if you are interested: thomas - at - vinylsavor - dot - de

Best regards


Thursday, July 4, 2013

Silver vs Copper


As mentioned in the previous post about the two DHT line stages, I built one with copper LL1660 output transformer and the other with the silver version. As promised a description of the sound differences.

Readers of my blog will have noticed that I am not much of a wire guy. I do use silver wire in many of my builds but haven't found it to make a huge difference. In transformers however the impact of silver is at least an order of magnitude more audible.

The more I use silver transformers the more I appreciate them. I already used silver MC step ups, line input transformers and silver LCR RIAA coils with success. In the recently built DHT phono stage the silver output transformer adds a remarkable degree of clarity and transparency to the sound, retaining all the qualities of the design. Not that the version with copper transformer sounds muddled in any way. The silver just lifts it up a level.

Silver often has the reputation to sound bright or even a bit harsh or just 'silvery'. This is not my experience at all. Transparent yes, but it retains all the tone colours of a design and in some cases even enhances them. Totally smooth and enjoyable sound.

This recent experience made me curious about the sound of a linestage which is in the works with the same silver line out transformer and a silver TVC. Stay tuned for reports on this.

Best regards


Tuesday, July 2, 2013

Two DHT Phono Stages


Just finished two phonostages with all directly heated triodes. Here some photos:

Both preamps share the same circuit which has already been presented here.

Also the internal construction is identical as shown here and here.

There is onlyone difference. The phono stage with the black covers uses a silver wound output transformer, the LL1660Ag.

Both preamps will be used with external MC step up transformers. Also the LCR RIAA will be in separate chassis.

The preamp with silver output transformer will be used with a silver MC step up transformer and the recently shown silver LCR RIAA.

Both preamps share the same sound character of all DHT amplification which has already been described here. The silver in the output transformer again make a remarkable difference. Stay tuned for a report on the sonic differences between the standard LL1660 and the silver version.

Best regards