Erik Mandaville Posted November 7, 2005 Share Posted November 7, 2005 An FIY if looking for some tube power at a great price. http://cgi.audiogon.com/cgi-bin/cl.pl?ampstube&1136498780 Erik Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 7, 2005 Author Share Posted November 7, 2005 Or a great-looking OTL from Atmosphere. I've read a few good reviews of this amp as well. Obviously I'm into the retro-tech sort of appearance. Erik edit: forgot the link http://cgi.audiogon.com/cgi-bin/cl.pl?ampstube&1134674695 edit2: Check the other items, too. There is a Dyna70 rebuild I would buy right now if I could. The prices for the level of craftsmanship and quality are very good IMO. Quote Link to comment Share on other sites More sharing options...
Piranha Posted November 7, 2005 Share Posted November 7, 2005 Thanks for the links. But I think I'll go ahead and keep my nosvalves.com VRD's. [] Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 7, 2005 Share Posted November 7, 2005 Never get rid of amps. You are just supposed to get more! [] Quote Link to comment Share on other sites More sharing options...
D-MAN Posted November 7, 2005 Share Posted November 7, 2005 Speaking of Mk III's, VRD's and such, I have a pair of these sitting in the closet (mine are all chrome, though). I had no idea at the time that these were pretty much modernistic Mk III's... made by a now-defunct company that did alot of after-market Dynaco stuff. DM Quote Link to comment Share on other sites More sharing options...
D-MAN Posted November 7, 2005 Share Posted November 7, 2005 pic 2 of the same thing Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 7, 2005 Author Share Posted November 7, 2005 Sure, no problem![] I'm going to keep my amps, too, but thought these might be of interest to some thinking about getting into very good quality tube amplification at a reasonable cost. Erik Quote Link to comment Share on other sites More sharing options...
D-MAN Posted November 7, 2005 Share Posted November 7, 2005 pic 3 w/cage Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 7, 2005 Share Posted November 7, 2005 D-Man, For a while Sound Valves had the surplus parts for the Dynacos. Then they rolled their own. Their ST-70 was a nice looking amp, and not too highly priced. But they are now defunct. Bruce Quote Link to comment Share on other sites More sharing options...
D-MAN Posted November 7, 2005 Share Posted November 7, 2005 Indeed. DM Quote Link to comment Share on other sites More sharing options...
Piranha Posted November 7, 2005 Share Posted November 7, 2005 Sound Valves, NOSValves? Hmmmmmmm............................????????????? [*-)] Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 7, 2005 Share Posted November 7, 2005 D-MAN, You have those sitting in a closet? That is crazy get them amps playing tunes. Craig Quote Link to comment Share on other sites More sharing options...
Marvel Posted November 7, 2005 Share Posted November 7, 2005 He should send them to me. They would go great with my Merlin I'm sure. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 7, 2005 Share Posted November 7, 2005 The only problem I see with these Mark III's is the guy used a lower voltage rating power supply can at only 500V. The original Mark III's biggest draw back was it chewed up the power supply filter cans and spit them out. The originals were rated at 525V which wasn't nearly enough even with a slow start 5AR4 rectifier. Now I'm sure the seller will say that is why he specs a 5U4 rectifier but in reality that will only net you 15V max drop in the B+(been there tried that). Then factor in the the 5U4 is a instant on rectifier that will slam the can with 540V or more instantly everytime you turn it on and this voltage will stay that way until the output tube heaters warm up the cathodes. Net result cathode stripping hell and early failure for the power supply. There is a much better approach to solving this problem but it cost more. Craig Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted November 7, 2005 Share Posted November 7, 2005 Sound Valves, NOSValves? Hmmmmmmm............................?????????????Rest assured, the name NOSValves had zero to do with Sound Valves. It's a strange coincidence though. kh Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted November 7, 2005 Share Posted November 7, 2005 Oh, it's nice to dream...someday... Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted November 8, 2005 Author Share Posted November 8, 2005 "Then factor in the the 5U4 is a instant on rectifier that will slam the can with 540V or more instantly everytime you turn it on and this voltage will stay that way until the output tube heaters warm up the cathodes. Net result cathode stripping hell and early failure for the power supply. There is a much better approach to solving this problem but it cost more." I have heard it said that as long as the rectifier is vacuum tube, one does not have the risk and subsequent problems of instantaneous in-rush current. That's not true, as you mention above. A couple of things that can be done at not too great an expense (just a little work) involve the installation of standby mode, which could be as simple as a switch installed on the center tap of the of the high voltage winding of the power supply transformer. IOW, B+ isn't applied to the plates (manually, by making the switch) until the fiilaments have warmed the tube. The correct thermistor can also be used on the power transformer primary winding, which will provide something of a soft-start feature. These are actually very effective, and are inexpensive. Erik Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 8, 2005 Share Posted November 8, 2005 Sound Valves, NOSValves? Hmmmmmmm............................?????????????Rest assured, the name NOSValves had zero to do with Sound Valves. It's a strange coincidence though. kh Yup you got that right. The name NOS Valves came from my previous drag racing internet name NOS440. Kelly came up with the idea of keeping the NOS and adding Valves. We thought NOSTubes would be to lame. Kelly came through with the Idea Valves. It sounded cool and left the door open if I decided to sell tubes or something. Craig Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 8, 2005 Share Posted November 8, 2005 "Then factor in the the 5U4 is a instant on rectifier that will slam the can with 540V or more instantly everytime you turn it on and this voltage will stay that way until the output tube heaters warm up the cathodes. Net result cathode stripping hell and early failure for the power supply. There is a much better approach to solving this problem but it cost more." I have heard it said that as long as the rectifier is vacuum tube, one does not have the risk and subsequent problems of instantaneous in-rush current. That's not true, as you mention above. A couple of things that can be done at not too great an expense (just a little work) involve the installation of standby mode, which could be as simple as a switch installed on the center tap of the of the high voltage winding of the power supply transformer. IOW, B+ isn't applied to the plates (manually, by making the switch) until the fiilaments have warmed the tube. The correct thermistor can also be used on the power transformer primary winding, which will provide something of a soft-start feature. These are actually very effective, and are inexpensive. Erik Sure the things you mention would help and can be done! But my question is why not fix the problem or at least install a can rated higher. This guy would rather save the $20 then buy a 525 volt can. He would also rather use a $5 5U4 then a proper 5AR4 that costs more and at least slows the voltage spike some and lessons its duration. Oh and were not talking in-rush current here were talking voltage spike big difference between voltage and current. The voltage spike is caused by a lack of current draw. With a 5U4 an inrush current limiter (thermistor) will do little good because there is no real substancial current being drawn on the B+ at start up these Thermistors work by current being drawn through them so no major current little effect. They work fine with a 5AR4 because it affords some time for the filaments to warm up before producing B+ so when the B+ starts rising the in-rush current limiter will kick in and slow the process even further. Its all about experience and testing and not being cheap. Craig Quote Link to comment Share on other sites More sharing options...
D-MAN Posted November 8, 2005 Share Posted November 8, 2005 D-MAN, You have those sitting in a closet? That is crazy get them amps playing tunes. Craig Craig, well maybe so. These got pushed out of the system by a Mc300. I haven't ever heard them on horns! sort of stupid, I know. I just haven't got the space for all of them at the same time. If they EVER need something, I'm sending them to you - you clearly have the expertise to deal with these orphans. DM Quote Link to comment Share on other sites More sharing options...
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