View Full Version : So, tell me about those valve amps..
steveinspain
10-10-2009, 05:52
Apologies for the title-theft but I would like to know a little about Valve amps.
Many years ago I had a Beard P100/P500 (?) pre/power amp - it was huge, weighed a ton, heated the house and cost a fortune to run in power and replacement valves - I lent it to a friend who still has it, and it seems I may have lost it forever, as he cannot afford to buy anything even half decent if I asked for it back. I used my Magnaplaner MGc1 speakers (think that is the model number 0 they were about 5ft tall and 2ft wide - not the baby ones). They are still in Mums attic, awaiting the day I can get them shipped down to me, as I loved the space and air they gave music, though loud'n'low stuff was not so good.
I then went to Naim and now have Avondaled Naim amps.
Living in a remote area, my chances of getting to listen to other equipment is very slim, which is good, as I have little money to burn, so can any of you tell me what I am missing, what might be good to try, should I ever spot a bargain, and are running costs and reliability a problem -both sides of the pleasures of owning would be good to hear !
Magna Audio
10-10-2009, 10:50
I had some nice MF A3 amps, bi-amping (9 years ago now!).
Cost back then ~£2k.
I borrowed a DIY tube amp and it blew the MF stuff into the weeds.
I Went on to build a DIY project amp called SoH (group of guys at work), semi pro ali cases, proper Lundahl audio output transformers, KT88's push pull, triode, class A, a massive mains transformer etc.
cost back then ~£500.
Spent a bit of time tube rolling but once tried most and got it just right I've left it. It's been in op now 7 years.
Apart from needing a 2nd PSU board (under estimated a bit at first) and as a result a few resistors suffering a bit of over voltage it's been completely reliable since that was sorted out. Been in constant use usually a few hrs every day or other day.
It is a bit special - I can fix it myself or draw on a few key members of the team if I am stuck.
It is totally quiet and drives all the speakers I've thrown at it with ease.
Much of the goodness is in the transformers - the iron work costs money.
Cheapo amps will skimp in that dept and sound will suffer.
Sound wise - I don't think there are many amps I'd swap it for TBH.
Tubes done well sound right to me ears. Perhaps the same would go for a mega buck tranny amp but I could not build and maintain that myself or tube roll!
Tubes used are 6SN7 Sylvania Brown bases as Drivers, Electro Harmonix KT88's as power tubes ~ 20W, which is ample.
A pal of mine (also built a SoH) recently build a EL34 based amp. Warm and tubey and lacks the precision and etched sound of the SoH.
Most stuff I've auditioned since (Krell, Copland, Naim) sounds congested and cramped or is very, very expensive. The recent show was pretty much tubes everywhere... They are in fashion.
Here's how it looks at night
http://theartofsound.net/forum/showthread.php?t=3110
More info and pics
http://home-and-garden.webshots.com/album/535523301vfXSDn
hope that helps.
The other biggy is TVC instead of active preamp!
I *think* I can say that the Maggies you have NEED OODLES of watts to make them come to life and I'd suggest one of the better pro amps such as the MC2 models to drive them economically and well.
From what I gather from comments on PFM and from Les himself (bless 'im), the Avondale implementation of the circuit Naim use is very much better behaved and has less distortion than the CB and Olive Naim product. If you have NCC200's properly set up and all the race tuned rectifiers and power supplies Les offers, you're more than half way to a valve-like purity of sound as it is - the old bolt-up 250 gave some EAR509's a very good run for their money way back in the late seventies.
You know, if the power amps are working well, you could consider a really good valve preamp such as one of the EAR ones or a Croft. As the amp circuit is a reasonably high impedance as I recall, the valve pre's should be fine IMO.
Just another alternative, as I don't know what the naim-like power amp referred to above is...
steveinspain
13-10-2009, 04:34
Thanks for the replies !
Speedy.Steve - how long do your valves last roughly ?
Can you tell me more about SoH - are the details available online ?
I have never built anything, but if I could afford the bits it might be fun to try....
DSJR - my amps are both fully Avondaled - a 160 and a 250, and from what little I know are 'race-tuned' with all Les had to offer when they were built and sound way better than they did as Naim amps - can you enlighten me a little more as to what EAR or Croft valve pre-amps to look out for ?
I got the maggies model number wrong - they are the MG1c, and I have never even tried them with anything other than the Beard - my curiosity is rising.....
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