Valve based audio

Ahrens Audio
This long running vintage audio dealer started manufacturing valve amplifiers at around the turn of the century, by popular demand they claimed. The products are all power amplifiers, the cheapest was the Ec Push-Pull Stereo model that pumps out a moderate 9.5w into 8ohms, slightly more upmarket is the wonderfully named Audio Amplifier, it's a single ended model that uses either EL34 or RS 282 valves. Top of the Ahrens Audio range was the plain silly Model I which is built around 30 Siemens Be valves (yes 30, not a typing error), price reflected this, I gather, and the fact that the Be was already out of production for a couple of decades when the Mode I was designed.

Antique Sound USA
Had a line of high end amps including the PA-4 preamplifier and the PA-2 line preamplifier, the A-8 80 watt mono block, but the one amp that got the most kudos in its day was the A-4 stereo power amplifier, it used EL-34 and was often likened to the old Dynaco D70. Earlier the company also had a range of cheaper models that included an integrated amp called 103 one owner has more info on that model here the 102 and 108 were apparently similar. Their best remembered amp is the K-2003 a single ended triode amp with only a 2x4 watt output, got great reviews but obviously will only work with very sensitive speakers, an old review of it can be found here. Note that the company supplied their products both as kits and fully built and while the build quality of the assembled models was excellent the quality of the kits will obviously vary upon the skills of the assembler, keep that in mind when you are investigating a second hand buy of one of those amplifier, Also this company should not be confused with Antique Sound Laboratory.

Amalgamated Wireless Australasia Ltd. (AWA)
Made a series of amplifiers intended for PA use in the 50's, these often found their way into the home hi-fi market especially on the second hand market. One of their models was the PA 826, a 30 Watt mono model based around the KT-66.

Audio Innovations
Made the Series 1000 preamplifier in the early 90's , a well regarded mid end preamplifier that featured a MM stage.

Audio Research
You can find an user review of the D-76 power amp from the early 80's here, that is I believe a design with symmetrical outputs at 2x75w.

Beam-Echo Ltd.
Made a small range of amplifiers starting in 1954 with in the late fifties and early sixties, these were designed by G. Lawson (of Lawson & Parsons) and were considered to be some of the best designs of their day. Amongst the amps the company made were the DL7-35 30w monoblocks, the SP-21 preamp, the SPA-21, an early stereo integrated amp that featured EL-84 output valves and pumped out around 12 watts. Has a switchable power supply so it can be used in any part of the world. A budget version of the 21 was also available as the SPA-11 that turned out around 6w.

Has a small range of high end amplifiers including the DL7-35 monoblocks, SA-50 stereo power amp and the SP-21 line preamp. They also make a limited edition preamp/monoblock amplifier combo called 301 that may or may not be still available.

Had quite a range of amps, the most commonly seen unit is probably the CSV-13 integrated unit from the early 60's. Output tubes were EL-84's, and there are separate speaker outputs for 4/8 or 15 ohms and a specialised output for Braun or Quad electrostatic loudspeakers.

Charles Amplifiers Ltd.
British valve amplifiers believed to have been in production from 1946 to 1951 although this is not for certain, there were probably three models made all in all but we only have information on 2 of them; the Concerto a 12 watt amplifier that features 8 triode valves plus an AC rectifier valve, priced at 27 pounds & 10 shillings in 1948 and a smaller 5 watt push-pull amplifier with negative feedback that was called the KI, that featured 7 valves in total and was sold for 17 gns., or in kit form where it retailed for 13 gns.. Both amps had output transformers that offered taps with 15, 7 and 3 ohm impedance outputs, phono and radio inputs and bass and treble controls but in addition the Concerto had a 2 level bass boost available.

These amps are rare, and notable for a number of reasons, these are integrated amplifiers in the modern sense while at the time most amplifiers were power amplifiers since they were intended either to hook radios to a larger loudspeakers or like the products from Quad Electroacoustics et. al. were actually designed for PA systems and were commonly not shipped with output transformers but rather you got them wound to match your speakers and in the case of PA applications the transformers actually came with the speakers, not the amps. The Charles Amplifier models had an especially flexible phono input that could accommodate anything from a radio level (line level) signal from a crystal pick-up, any sort of magnetic cartridge or even a moving coil pickup, but the support for MC's is interesting since they were as rare as hens teeth at the time in the UK, being a specialist and expensive import form Denmark (Ortofon). In other words the Charles Amplifier products are probably the first UK examples of such specifically designed as home hi-fi amplifiers making the company one of the first hi-fi companies in the UK.

Cyrus Brenneman Audio
Made "Cathode follower" amplifiers in and around the turn of the century, in fact apparently right up to 2003, both pre and power amps, and the power amps were available as push pull or single ended, you can find a review of their Cavalier integrated here.

Golden Tube Audio
This company had a reputation for making fairly inexpensive but well designed amplifiers, at the least compared the norm. In 1997/98 they introduced the SE-845 direct heated triode monoblock capable of pumping out 20w of Pure class A, it uses a 6SL7 in input stage, 300b as a driver and an 845 in the output stage, the SE-85 and SE-200 push-pull amps, both used EL 34, the SE-200 is a monoblock and uses 6 of them to deliver 200w but the stereo SE-85 uses for of them to deliver 2x85w. At around the same time they also bought out a couple of preamps, the SEP-2 and SEP-3, both were single ended triode pure class A affairs and were basically the same unit but the more expensive SEP-3 had an external power supply with valve based rectification, slightly improved circuit and the DC phono preamp built in as standard. Older models included the SI-50 and the SI-50 MkII integrated amps that gave you 2x50w, they are push pull class AB units that use 4x EL34's but have a true class A preamp, the MkII was introduced in 99 to fix reliability and usability problems and it retailed for around USD 1000 to 1300 when new, while it had only three inputs you could add the optional DC phono stage to it as well, note that the original model had a fan but the MkII did not and they shared one innovative feature an auto biasing circuit that used fuzzy logic, here is an old PR blurb for this amp and the scematic for the power modul can be seen here. The SEP-1 preamp that features balanced outputs in addition to the norm, could be bought with an optional battery powered DC phonostage that retailed for USD 100 when new and was considered to be something of a bargain,the SEP-1 was reviewed in issue 30, 1996 of Audio.

The SE-40 power amp is one of the best loved valve based amp from the 90's, it was introduced in 1993 or so and is a 2x40w class A parallel single ended unit that could be bridged in to a 80w monoblock, it offers excellent sonics especially in the midrange although it suffers a little in the bass like so many valve based amps. It also suffers from some reliability problems resulting from the use of lower spec parts than are really needed for the task, which is surprising considering the overall build quality of the amp, there is nothing wrong with the basic design of it, it's just a matter of replacing some of the parts with better spec units in particular the power resistors and is not an expensive or a difficult upgrade, you could also get a version called SE-40SE that had better valves, transformer and other parts and contained minimal circuit modifications in order to accommodate those parts, the original retail price of this model was around USD 1400 while the standard was around 1100, note that SE versions after 1997 had an improved output transformer as well. The USA based company Soniccraft sells scematics and offers upgrade kits for this model, those upgrades are mostly reliability related, the Australian company Trevor Lees Audio however offers an upgrade kit that is designed to improve the sound by reverting it to revision 1 of the amp and replace some of the same under powered parts (rev. 1 is very rare), and finally it was reviewed in issue 30, 1996 of Audio. The SE-100 was a follow up to the SE-40 introduced in the latter half of the 90's, it's basically an 2x 100 w version of the 40 (200w if bridged) and has the same basic topology with class AB attained with 10x EL34 pentodes, the power supply is a 600w thorodial and the list price was basically 2x se40's (£ 1780 in the UK). The SE-300B was a single ended amp from the company that was introduced at around the same time as the SE40 but for some reason never got the press or users that the push-pull variant had, it's a single ended pure class A 300B, no feedback based unit that delivered 2x7w and had a valve rectified power supply and balanced inputs, an improved SE-300B MkII and SE-300 MkIISE versions were introduced in 1996 that had 2x9w with list prices of UK £ 1495 and 1730, the SE version features oil filled capacitors. Unusually for valve based amps all their pre and integrated amps that we have seen came with remote controls.

Greenwave Audio
Had a small line of very good looking valve amps, but we lost our info on them, if anyone out there has that info or has saved the pages from the company's (now defunct) homepage we would welcome if you would send us a line.

Jefferson Electric
This company made a 60 and 120 watt amps in the 30's, more information on this page, these 2 were more intended for radio usage than audio but they could be used in audio application and the company was cery active in the audio market in the 30's.

A line of valve amplifiers from the Mexican company Margules in the fifties and 60, these were intended as much for home audio as for PA usage.

The PF 91 monoblock is something of a classic in the UK.

Silvaweld Audio Lab.
Despite being only in existence for about 10 years the company managed to make quite a number of models, note that the company manufactured a number of product in versions that were specifically made for their German distributor Black Forest Audio, these are marked with the initial BFA after the model name and are usually better specified than the stock models, sometimes considerably so but were when new up to 50% more expensive.

Silvaweld pre-amplifiers

One of the more successful designs amongst their preamplifiers was the SWC-450, it appears to have been introduced fairly late in the lifetime of the company or in 2003/4 or thereabouts. It is a mid/high end line stage with a valve based amp stage and the BFA version had a list price of 1500 euros in mid-Europe although it typically sold for less and the stock version is believed to have retails for closer to 1000 euros. Although expensive for such a simplistic amp it got better reviews in general than some of the more expensive models from the same company. More info can be had from a review by Positive Feedback

Silvaweld had introduced another line level pre-amplifiers around 1998 in the form of the SWC-550

The SWC-1000 was the company’s top of the line preamp and is believed to have been introduced in 1997 or thereabouts and came in at the least 4 variants. It features transformer coupling using a nickel-alloy transformer, the normal version of the amp uses a high quality 31 step attenuator for volume control but the SWC-1000R variant comes with remote control and thus uses a version of the attenuator that is digitally controlled with 56 discrete steps, although supposedly having a lower specification the difference is slight or not audible according to reviews, also the R version has no knobs, all controls on the front facia are buttons which makes it slightly more unwieldy to operate without the remote control. The SWC-1000 is a 2 box design with the power supply in a separate housing,that unit utilises a 300B as a voltage regulator.

Silvaweld SWC-1000/SWC-1000R technical specifications
Channels : 2. max gain : 20 dB. Input impedance : 100 kOhms. Output impedance : 200 ohms. Maximum output voltage : 50v ohms. Frequency response : 5Hz to 100kHz +/-3dB*. Harmonic distortion : 0.02% @ 1kHz*. Signal to noise ratio : -95dB A-wheighted. Attenuator : 31 step with solid silver contacts . Remote control : Yes (R v.)/No (Normal v.). Voltage : Single voltage, different spec units shipped to each country (230v, 110v etc.). Size : 500 x 130 x 320 mm (WHD). Weight : 15kg. Valves used : Signal chain : 4x $17A and 2x 6DJ8/Power supply : 300B, 5AR4 and EF86. RRP : 6000 Euros/6000 USD ca 1999.

Silvaweld SWC-1000RC BFA technical specifications
Channels : 2. max gain : 20 dB. Input impedance : 100 kOhms. Output impedance : 200 ohms. Maximum output voltage : 50v ohms. Frequency response : 5Hz to 100kHz +/-2dB*. Harmonic distortion : 0.02% @ 1kHz*. Signal to noise ratio : -100dB A-wheighted. Attenuator : 31 step with solid silver contacts. Remote control : Yes. Voltage : Available in a 230v version only. Size : 480 x 130 x 340 mm (WHD). Weight : 17kg. Valves used : Signal chain : 4x $17A and 2x 6DJ8/Power supply : 300B, 5AR4 and EF86. RRP : 9000 Euros ca 2005.

Silvaweld OLT Tube Reference 100 technical specifications
Topology : Output tranformer less single ended push-pull. Channels : 1. Power rating : 100w into 8 Ohms, 120w into 16 Ohms. Inputs : 1x Line level unbalanced. Input sensitivity : 1v. Outputs : 1x loudspeaker. Output impedance : 4, 8 or 16 ohms. Frequency response : 5Hz to 50kHz +/- 1dB. Harmonic distortion : Less than 1% @ 1w. Signal to noise ratio : -100dB A-weighted. Damping factor : 10. Negative feedback : -8dB. Voltage : Single voltage, different spec units shipped to each country (230v, 110v etc.). Size : 480 x 200 x 380 mm (WHD). Weight : 25kg. Valves used : 4x 6C33C, 3x 7119 and 1x 6U8A. RRP : 11,0000 Euros per pair ca 2004.

Vaic Audio

The company sold 4 basic models of single ended triode amps available all in all in 7 variations, these were built around thermionic valves from AVVT and they were designed by Cesare Sanavio and built by his company Mastersound, the Vaic Audio amps should not be confused with amplifiers sold with the Vaic Valve brand but these were predecessors to the current KR Audio Electronics products. The Vaic Audio amps were all very expensive at the time they were produced and thus are rather rare, especially so outside of Europe were they were sometimes bordering on being outrageously expensive, their usage of valves from AVVT that were as much new compatible designs as they were improvements meant that they were some of the most powerful SET amps ever made and thus allowed you to use them with low-efficiency speakers unlike most SET amps and in comparison to similar high power Japanese SET’s, seemed almost cheap.

The 300B Stereo is an integrated single ended amplifier that we have not been able to find the exact specifications for but it is broadly similar to the Mastersound Compact 300B except that the VV valve allows it to give out quite a bit more power than what the currently shipping variant. It and all of the other amplifiers from the company featured custom made transformers, valve rectification in the power supply, pure Class A operation without the use of negative feedback.

The other integrated model from the company was available in 2 versions 32B Stereo and the 52B Stereo but again the specifications are lost in time except that we seem to remember that the 52B Stereo model used a AVVT AV520B output valve and pumped out 2 x 30w, the only difference between the two was the output valve and thus the output wattage rating, so the 32 model probably used the AVVT AV320B and did 2x 20+w. These two amps are very rare, even more so than the 300B stereo which is not a common model at all. If you have the specs at hand we would appreciate an E-mail, both variants of this model live on in the Ayon 52B/62B series and in that line there are also models not dissimilar to the power amps below.

The other models from the company were Mono power amplifiers and as far as we know the company never offered a preamplifier. The cheapest monoblock from the company was the Classic 32B Mono that featured a single AVVT AV320B and put out about 20 to 25w, the Classic 32B is also the most common product you will see on the second-hand market, it had an RRP of 12900 euros for a pair in 2002 and was reviewed in issue 45 of German magazine Image Hifi and that magazine issue can be bought on the net. The Classic 52B Mono is the same model as the 32B but delivered 30w due to the use of a AV520B valve.

The Reference Line from the company was their top Reference 32B Mono is a double triode single ended model that used 2x AVVT AV320B valves and put out 40w, Reference 52B Mono is a double triode single ended model that used 2x AV520B valves and put out a whopping 55w, in some countries this was specified as 50w for reasons unknown. Stereo Times reviewed the unit and you can read that review here, but at the time the RRP was 19800 USD for a pair and in 2000 it actually crossed the 20k threshold. There was a version of this amp shown that uses the VV620B valve and had a rating of 60w but as far as we know it was never shipped with a Vaic Audio brand name on it but did show up as a Ayon Audio product.

Vaic Audio Reference 32B & Reference 52B technical specifications
Topology : Dual single ended triode, pure class A without negative feedback. Channels : 1. Power rating : 50w or 55w RMS – 100w peak (Reference 52B) 40w RMS 100w peak (Reference 32B). Inputs : 1x line level unbalanced cinch, 1x balanced line level XLR. Input impedance : 55kHz. Outputs : 1x loudspeaker. Output impedance : 2 to 8 Ohms ohms. Frequency response : 5 Hz to 100 kHz +/-2dB. Signal to noise ratio : Better than 98dB. Valves used : 2x AVVT AV520B (Ref. 52B) or 2x AVVT AV320B (Ref. 32B), 1x AVVT VV8B and 1x 6SNG7T. RRP : 19,800 USD (1999).

YS Audio
The company holds out an informative page on some of their older models, apart from the models lited there other notables are the The Music that was available in Mk1 and Mk2 variations.

Made a valve based "signal enhancer, you can find a couple of old reviews here and here.

© 1993 - 2013 Ólafur Gunnlaugsson, all rights reserved.

The site was last compiled on Sun Nov 10 2013 at 9:15:00am