May 2003

The AVVT 300BSL Output Valve

Review by Thorsten Loesch
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  In December 2001 I published a test of overall nine different types of 300B valves, or should I say 300B compatible valves in that they fit the same socket as the 300B and have at least notionally identical electrical parameters. Missing at that point in time where two makes of 300B that had proven near impossible to obtain within the UK for testing.

One of them were the valves designed and manufacturer by Alesa Vaic, sold under the AVVT brand and the other where the valves designed and produced by the late Dr. Kron, sold under the KR Brand. While the KR Valves have remained elusive for me, due to the good offices of Bjorn Steenback I had a chance to test a brand-new pair of AVVT 300B SL in the recent month.

This test of the AVVT 300BSL should be seen as a continuation of the original 300B Test and I would strongly recommend to read the other test first to get an idea of the context. While my system has changed appreciably between the original test and now, I have retained samples of most of the valves originally tested and hence the actual comparisons are still valid, both relatively to the Valves previously tested and to the test of the AVVT 300BSL. I have also retained the format originally employed, to keep the continuity.

This valve has been around for a while and in fact as I write this it is in the process of being replaced by the "Reference" Series using a “Nickel Block” Anode and other improvements. While I have previously described the build quality of the TJ valves as outstanding, these AVVT Valves raise bar a few notches higher. The entire Valve feels immensely solid; the workmanship on the structures inside is quite outstanding.

When it came to sound, this valve also delivers the goods amazingly well. Compared to my personal "reference", the TJ Mesh Anode Globe 300B, the AVVT valves sounds somewhat brighter, yet this is absolutely smooth with no grain or edge. To compensate the thusly highlighted treble the AVVT valve also seems to have more weight and impact in the lower registers. In those areas the AVVT is clearly ahead of the TJ, only when it comes to the midrange fades the Magic and the TJ 300B is ahead. The AVVT shows a highly resolved midrange, accurate tonal colours but it just misses the tough of "magic" the TJ brings to the proceedings. That said, either TJ or AVVT are clearly, to me personally, the best currently available valves that plug into a 300B socket without changing circuits. Whereas the TJ highlights the Midrange and adds a touch of fairy dust to everything, the AVVT tends to be stronger at the very extremes of the sonic range and it presents music in a way that is a little more cerebral, a little more restrained than the TJ.

However all this is swings and roundabouts, I could happily live with either the TJ or the AVVT. The current production WE 300B makes a strong showing in a close third place, in my list at least.

Comparisons to the lesser 300B’s from Valve Art, Sovtek, Svetlana and JJ Electronics clearly put all of these notably behind the top three, arguably at a lower cost too, you get what you pay for. The AVVT 300B SL joins my personal list of outstanding 300B Valves and is certainly worth the extra outlay, just as the WE and TJ are.

Which Is The Best?

That will depend upon your preference and system context. The AVVT would be my first choice if I felt my system would need help at the frequency extremes, the TJ if I wanted to add a touch of magic and the WE, well, it’s WE, what more is there to say.

Overall 90
Tonality 90
Bass 95
Midrange 85
High-frequencies 90
Resolution 95
Soundscape /Imaging 90
Fit and Finish 100

System Used For Audition:

Source Analogue:

Acoustic Solid "Solid One" turntable, with a number of Arms and Cartridges including Origin modified RB-250 & Goldring Elite, SME 3009 & Denon DL-103, Rega RB-300 & Goldring Elite/Denon DL-103, Ortofon RS-212 special with SPU-GTE Pickup

Source Digital:

Philips LLH-1000 (Marantz DA-12) DAC, with TDA1541 and synchronous upsampling (or you can say oversampling if you like) to 176.4kHz. The DAC has been fully restores with all electrolytic capacitors replaced and is fitted with Burr Brown OPA627 Op-Amp’s. A modified Pioneer DV-505 DVD player drives the DAC as transport.

Preamplifier Phono:

DIY phonostage, EQ600 LCR RIAA equalization from Stevens & Billington, TX-103 MC Step-up transformer from Stevens & Billington, Siemens E810F special quality valves;  Powersupply with only high performance Ansar film capacitors, GZ34 rectifiers, 9 chokes….  

Preamplifier Line:

Passive Linestage based around the TX-102 Magnetic Volume Control Transformer from Stevens & Billington functionally similar Kits are available from DIY HiFisupply and Bent Audio, a finished unit from MF Audio UK.

Power Amplifier:

DIY HiFiSupply Billie Amplifier Kit, heavily modified using WE 437A driver to grid choke loaded 300B, WE 274A rectifier, several added power supply chokes, power supply with only high performance Ansar Film Capacitors and signal path with a Silver/Mica coupling capacitor, no electrolytic capacitors except heaters

Loudspeakers:

Tannoy Corner York copies build in 1-inch solid wood by a sadly departed friend, using C37 lacquered Tannoy Monitor Red 15 Inch coaxial drivers, 95dB/W/m, 15 ohm impedance, 25Hz to 20kHz in room, closest current equivalent is the UK/Europe/Japan only Tannoy Canterbury, not the somewhat inferior North America only Tannoy Churchill

Room correction:

Behringer Ultracurve 8024 Digital equaliser