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In Reply to: Re: Made the call posted by John Chleapas on February 28, 2007 at 20:52:42:
Yeah, thanks for letting me know the 45s are better. :-}
Follow Ups:
Paul you just might like the sound of the 300b DRD more than the 45 amps. We all hear things very differently. The Welborne 300b is one very fine sounding amplifier. Your speakers make it the better choice for you. I did find the Herbie's 300b tube dampers were a nice addition to the TJ 300b mesh plate tubes in my amps. I would dearly love to try a pair of new production WE 300b tubes in my Welborne 300b DRD amps. Many in the know write that the current ones sound even better than the NOS ones that can sell for up to $3K a pair. That makes their current price tag of ~$1200 a pair new seem like a bargain. If the tubes last for what is it 40,000 hours that makes them the real bargain over the long run. Good luck! John
IIRC, the 40k hour tube life is specified for the 300V plate, 60mA (57mA?) operating point; a classic operating point I believe, which is little used in these times of maximising power. Higher operating points (as in the DRD) will decrease tube life, relative to lower.Cheers
Raymond
Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
The WE data sheet says: "The life of the tube at maximum operating conditions will be shorter than at the recommended conditions." That data sheet (at least the copy I have) does not specify "maximum" or "recommended" conditions, except for the maximum plate voltage (450v), plate dissipation (40 watts), and maximum current (70mA fixed bias, 100mA cathode bias).I have also some scans of the STC 4300B (CV1452 Special) data sheets - the British specs for the same tube, which mark all the operating conditions as "maximum" where the plate voltage is 450v. 400v or less is not so marked, and the maximum plate dissipation in the unmarked conditions is 32 watts (400v at 80mA). I have always taken that to mean the life at no more than 32 watts, no more than 400v, and no more than the maximum plate current, would be the widely quoted 40,000 hours.
I believe I've read somewhere the expected life at 40 watts dissipation and/or 450v would be half, i.e. 20,000 hours.
I've never seen an authoritative WE-published expected lifetime number for this tube, though the above numbers are widely quoted. If anyone has an authoritative reference, I'd be delighted to learn of it!
Ron has written that the ss rectified DRD amps are a bit harder on the output tubes. He admits the ss rectifed versions put more stress on the output tubes at the initial start up Vs. the tube rectified versions. I wonder if converting my ss 300b DRD amps to tube rectified would cure this problem? This is because they do not have the soft start feature the tube rectified versions have. I would like to find out how hard it will be to turn my ss rectified 300b into a tube rectified version? While Ron states in writing he prefers the sound from the ss rectified version I was amazed at how much better sounding my tube rectified 45 DRD amps became when I swapped in a GZ37 replacing the Sovtek rectifier it came with stock. My only amplifier that I used prior to the Welborne DRD ss rectified ones are my Klimo push pull EL34 mono amps. They sound simply amazing to my ears. But for bang for the buck sound quality it is very hard to beat the Welborne DRD amplifiers. John
Ron has developed and his DRD amps; he has his preferences. Well experienced others prefer tube rectification for the DRD-type topologies, despite the advertised advantages of the SS approach.As for conversion, I think this has been posted previously, but not sure which forum. I am surprised a slow start-up facility has not been integrated into the amplifiers original design.
Regards
Raymond
Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
preferring the 300B versions of his amps (in his demo systems), at least for the big $$$ versions. You made the call and won the battle. Sit back and enjoy your music - You have an awesome device for reproducing music. You are indeed fortunate.Cheers
Raymond.
Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
Not necessarily. My DRD's are both SS rectified. They are close enough in quality that the amp I favor depends not on the associated equipment but which room I use them in. In the smaller room, where I listen nearfield, I like the DRD45's better - they have a more intimate sound that suits listening in a close environment. In the larger room, I prefer the DRD300b's - and this isn't volume dependent. They just sound better at the 3 meter listening distance. Both are great.
if you're tied to the Zu Druids, so enjoy your new amps and don't look back! They'll sound great.
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