Owen Posted May 20, 2007 Share Posted May 20, 2007 I have a student who has one of these. I have no idea what it is apart from it's full of creamy valve goodness, hugely heavy and has 2 pre-amps - one normal Trace and one valve pre with no EQ just gain. I have Googled to no avail. Anyone throw any light on this? TIA. Quote Link to comment Share on other sites More sharing options...
Kiwi Posted May 20, 2007 Share Posted May 20, 2007 Oxblood has been working on a VA350 which he bought off OBBM Quote Link to comment Share on other sites More sharing options...
obbm Posted May 20, 2007 Share Posted May 20, 2007 If I remember correctly the VA400 is effectively the same as the VA350. Circuit diagram is [url="http://www.britishaudioservice.com/schem/Series%206/VA350%20&%20Hexa%20Head.pdf"] here[/url] Quote Link to comment Share on other sites More sharing options...
Oxblood Posted May 21, 2007 Share Posted May 21, 2007 The VA350 and VA400 are extremely similar, but I understand that there are some interesting differences, the main ones being that apparently the VA400 has an Ultralinear output stage (i.e. the screen grids are run from special taps on the OPT primary) and in order to squeeze out the extra watts, it runs the output valve anodes at a frankly scary 730 Volts. Consequently, the VA400 has a reputation for wearing out power valves very quickly, unless they're rugged enough to take it. Fortunately the Sovtek 6550WE are tough enough, and reasonably priced. Re. the PDF file: anyone working on a VA400 should be aware that the power amp circuit diagram shown in that document is actually the one for the VA350, and contains at least one inaccuracy: in the diagram, the screen resistors are shown as 22 Ohm, when in fact they should be 220 Ohm. To the best of my knowledge, no accurate diagram of the VA400 is known to be publicly available. Not even its designer, Clive button, has one! Quote Link to comment Share on other sites More sharing options...
Owen Posted May 22, 2007 Author Share Posted May 22, 2007 Thanks y'all I knew that there was a repair diary floating around, I just could not find it. It looks like Oxblood's VA 350 but with a GP12 pre as well. He is thinking of flogging it but I think I will try and persuade him to get it serviced and use a decent speaker (he has an EV 18" in a W horn thing) and then see how he feels about it. Of course there is the downside that it is stupid heavy. Quote Link to comment Share on other sites More sharing options...
Oxblood Posted May 22, 2007 Share Posted May 22, 2007 [quote name='owen' post='4339' date='May 22 2007, 01:57 PM']Thanks y'all I knew that there was a repair diary floating around, I just could not find it. It looks like Oxblood's VA 350 but with a GP12 pre as well. He is thinking of flogging it but I think I will try and persuade him to get it serviced and use a decent speaker (he has an EV 18" in a W horn thing) and then see how he feels about it. Of course there is the downside that it is stupid heavy.[/quote] Whereabouts are you, owen? I'm in East London. If it were possible, I'd be very interested in having a look inside the beastie, if only to educate myself properly as to the differences between it and the VA350. Quote Link to comment Share on other sites More sharing options...
Owen Posted May 22, 2007 Author Share Posted May 22, 2007 [quote name='Oxblood' post='4466' date='May 22 2007, 04:44 PM']Whereabouts are you, owen? I'm in East London. If it were possible, I'd be very interested in having a look inside the beastie, if only to educate myself properly as to the differences between it and the VA350.[/quote] Up in Bangor, North Wales. Bit of a trek! Quote Link to comment Share on other sites More sharing options...
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