It does reasonably well with Metallica on 96db speakers. It makes an honest 8 WPC with the KT88's in it. I must admit that the best amp I have to play Metallica is not one of my own. I took one of Pete Milletts DCPP amps and hot rodded his 18WPC design to 125 WPC. Play that through my 96 db speakers and its like having Metallica in the living room.....only louder.
I was up against the railing in the fromt of the pit at a Metallica concert during the Load tour. No home stereo can do justice to the Pyro. You feel the heat on your face when it goes off. James got a bit too close......
Looking at the underside wiring in this picture:
http://vacuumtubeart.files.wordpress.com/2008/10/dsc01742.jpg
I traced the phase inverter circuitry. The 3 octal sockets at the bottom have the two channels of phase inverters on the outside sockets, and the input tube stage for each channel is split across the center socket. All are 6SN7 pinouts. The four output stage sockets above have 6L6 pinouts.
The phase inverter wiring is identical with Fig. 6.19 of Morgan Jones "Valve Amplifiers" 3rd ed. page 402, except the P.I. cathodes have individual resistors to ground, instead of being combined into one. No build-out resistor to equalize the Zo of the outputs is used. (was standard comercial practice to skip this according to M. Jones)
So the verdict is: standard floating paraphase inverters. Tuning probably consists of adjusting one of the P.I. grid summing resistors going to the 2nd triode (pin 1) of the inverter for balance since there is no balance pot. Someone with better color rendition on their monitor may be able to make out the resistor values better than I.
The value of the plate load resistors (particularly the one from pin 2 to B+, but looks like the two load resistors are identical, ie pin 5 R to B+ also) might be of interest since the floating version of the P.I. sums the 2nd harmonic (even harmonic) from both tubes (see N. Crowhurst "Understanding Hi-Fi Circuits" page 85), rather than partially cancelling them as in the non-floating P.I. (page 80 Crowhurst). An unusually low load R value on pin 2 would enhance 2nd harmonic generation.
Somewhat odd that 6SN7 is used on some designs, and 12AU7 is used on others for the P.I.. 6SN7 being quite linear. I would think that a 12AT7 might be a more preferred floating P.I. tube here to generate SE sound signature from the even harmonics, if that is the secret goal.
http://vacuumtubeart.files.wordpress.com/2008/10/dsc01742.jpg
I traced the phase inverter circuitry. The 3 octal sockets at the bottom have the two channels of phase inverters on the outside sockets, and the input tube stage for each channel is split across the center socket. All are 6SN7 pinouts. The four output stage sockets above have 6L6 pinouts.
The phase inverter wiring is identical with Fig. 6.19 of Morgan Jones "Valve Amplifiers" 3rd ed. page 402, except the P.I. cathodes have individual resistors to ground, instead of being combined into one. No build-out resistor to equalize the Zo of the outputs is used. (was standard comercial practice to skip this according to M. Jones)
So the verdict is: standard floating paraphase inverters. Tuning probably consists of adjusting one of the P.I. grid summing resistors going to the 2nd triode (pin 1) of the inverter for balance since there is no balance pot. Someone with better color rendition on their monitor may be able to make out the resistor values better than I.
The value of the plate load resistors (particularly the one from pin 2 to B+, but looks like the two load resistors are identical, ie pin 5 R to B+ also) might be of interest since the floating version of the P.I. sums the 2nd harmonic (even harmonic) from both tubes (see N. Crowhurst "Understanding Hi-Fi Circuits" page 85), rather than partially cancelling them as in the non-floating P.I. (page 80 Crowhurst). An unusually low load R value on pin 2 would enhance 2nd harmonic generation.
Somewhat odd that 6SN7 is used on some designs, and 12AU7 is used on others for the P.I.. 6SN7 being quite linear. I would think that a 12AT7 might be a more preferred floating P.I. tube here to generate SE sound signature from the even harmonics, if that is the secret goal.
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You're braver than I, Don. The plate resistors look like 560k on my screen, which seems awfully high. Maybe the "secret" to their "sound" is early rolloff or slew limiting. 😀 The tuning resistors, if that's what they are, seem like yellow-something dark-yellow.
Hey Dude, I was talking about Steve (the student) and Lance (the teacher), not you. The comments were based on what each of them has said.
Man, that is like telling a pilot he does not know what he is talking about because you watched 'Top Gun'! There are guys on here that know a lot about electronics, and high voltage tube stuff in particular. They have said what the dangers are. I am not one of those guys (that knows a lot about electronics). I do know who to listen to on this forum and I take their advice seriously. The law is something I know a little about, and your views on the liability of these guys is just plain wrong.
"You're braver than I, Don. The resistors look like 560k on my screen, which seems awfully high. Maybe the "secret" to their "sound" is early rolloff or slew limiting. 😀"
😀 Well, from Steve's comments on low global feedback, I figured they were trying to preserve some effect. But maybe the OTs used are not up to Hi-Fi bandwidth and have to be early roll-off protected. Less harsh sounds that way too.
😀 Well, from Steve's comments on low global feedback, I figured they were trying to preserve some effect. But maybe the OTs used are not up to Hi-Fi bandwidth and have to be early roll-off protected. Less harsh sounds that way too.
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Good for you. I was doing the same thing last night. The amplifiier is definitely the red "firecracker" with 6550's in self bias. I was going for the entire circuit and then post it here. 😀 However, the wiring is such a gawd-awful scrambled rats nest, I got fatigued. There is also shadows to contend with, but I came up with the paraphase inverter too. There's is a thin copper buss wire that snakes around between the two rows of sockets that seems to be grounded at several points along the way. So there's no single point ground. I've got most of it sketched out, but I don't have any schematic drawing software so it'll have to wait till I feel like redoing it neatly. And even my new LED flat screen has trouble with the resistor colors, but I can make out some of them.
No your wrong, it's based on New York law and used as an example anyone could see.
You really do know very little about law, look it up yourself.
You really do know very little about law, look it up yourself.
You can be my wingman, chrish...
On a more serious note, and address to the general audience and not chrish, I do have to put forward my own opinion that these guys are being treated unfairly. AND, to beat them up on safety is a little ridiculous, as a lot of dodgy things have been put forward on this forum by senior members in the past. Yes, I do agree that the statements they have put forward do need to be challenged, on performance claims, most certainly safety, and historical facts, but that was a few pages ago and this turned turned into bullying a long while back.
"However, the wiring is such a gawd-awful scrambled rats nest, I got fatigued. There is also shadows to contend with, but I came up with the paraphase inverter too. There's is a thin copper buss wire that snakes around between the two rows of sockets that seems to be grounded at several points along the way. So there's no single point ground."
Yep, I was having trouble deciphering too. Fortunately the two channels are there to compare between. Was fun detective work, puzzle solving. Maybe instead of crossword puzzles, we should post wiring mazes each day for members to solve.
Yep, I was having trouble deciphering too. Fortunately the two channels are there to compare between. Was fun detective work, puzzle solving. Maybe instead of crossword puzzles, we should post wiring mazes each day for members to solve.
Since when did New York law apply to Canada?
Man, I am not going to give you a lesson in tort law here. This is an area I do have qualifications in. If you think you know more, that is fine. I am not going to argue the point with you any more. The other contributors have apparently grasped the legal and moral issue with Steve (and perhaps Lance and his other apprentices) selling dangerous products.
I hope my behaviour is not bullying. I tried to post some links to sites that demonstrate how to safely ground your gear while avoiding ground loops, and posted to Amazon link to 'Building Valve Amplifiers' to explain the construction and lead dress issues...
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Spelled "bubala", it's a Yiddish (Jewish) word, traditionally used by Grandmothers, that references children.
Kinda reminds me of a Fringe episode, where it's better just to hide in the "other dimension" so there's no chance of being attacked.🙂
jeff
Well , I see two resistors 470K two 2K2 and two 560K around the phase spliter , the cathode resistors is seperate and connected to ground , I can go further , but I think the smart guys already understand why this circuit claimed to be low distortion , but not so low as mentioned .
Interesting threads...but if you even are considering debating safety issues then its a given that your not safe. It is a topic that should not be a grey area or even open for debate
"Well , I see two resistors 470K two 2K2 and two 560K around the phase spliter , the cathode resistors is seperate and connected to ground , I can go further , but I think the smart guys already understand why this circuit claimed to be low distortion , but not so low as mentioned . " --- Dimitris AR
Since the two cathode currents are phase inverted, I wonder if one could combine the two cathode resistors to a CCS tail, and if that would buy anything. Morgan Jones mentions the common resistive tail version (3rd ed. page 403), but says the V2 feedback overwhelms the balancing effect.
One can only go so high on the plate loads to get linearity before slew limiting or HF roll-off occurs.
Since the two cathode currents are phase inverted, I wonder if one could combine the two cathode resistors to a CCS tail, and if that would buy anything. Morgan Jones mentions the common resistive tail version (3rd ed. page 403), but says the V2 feedback overwhelms the balancing effect.
One can only go so high on the plate loads to get linearity before slew limiting or HF roll-off occurs.
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So unusual Amps eh...
I had a look at this steve White website and that guy has made a LOT of amps!
Anyhoo I am a noob and keeping to the topic this pic here:
I love this layout! Looks wonderful. I am guessing a layout like this is fine if you structure your build to suit.
Other amp designs look only to serve the best circuit layout rather than good aesthetics.
Is there a perfect compromise? Can the above amp be made with this aesthetic layout and still be wired to the best standard?
I had a look at this steve White website and that guy has made a LOT of amps!
Anyhoo I am a noob and keeping to the topic this pic here:
An externally hosted image should be here but it was not working when we last tested it.
I love this layout! Looks wonderful. I am guessing a layout like this is fine if you structure your build to suit.
Other amp designs look only to serve the best circuit layout rather than good aesthetics.
Is there a perfect compromise? Can the above amp be made with this aesthetic layout and still be wired to the best standard?
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