NBPK402 Posted March 1, 2015 Share Posted March 1, 2015 (edited) How about a pair of PPI amps... Edited March 1, 2015 by ellisr63 1 Quote Link to comment Share on other sites More sharing options...
NBPK402 Posted March 1, 2015 Share Posted March 1, 2015 Great thread.... This is the real reason for buying a power amp. Quote Link to comment Share on other sites More sharing options...
mkane Posted March 2, 2015 Share Posted March 2, 2015 2 Quote Link to comment Share on other sites More sharing options...
Fjd Posted July 8, 2015 Share Posted July 8, 2015 (edited) Many years ago there was an unusual class of tubes designed for the sweep circuits in tube-type TV sets that have substantially large reserve current capability; hence the name “sweep tubes” was coined. While sweep tubes are no longer made and some versions are getting much harder to find, there are examples that are still quite common. The sweep tubes can put out huge power levels and still have substantial reserve capability. Pete Millett’s Engineer’s amplifier [also known as a “Distortion-cancelling Push-Pull" (“DCPP”) amp], uses these unusual sweep tubes. If following Pete Millett's actual design, the DCPP amplifier is actually a 2-stage push-pull pentode design with the output stage biased so it will remain in Class A1 operations until somewhere over 10 watts where it then enters Class AB1. The input/driver stage uses a pair of 6CB6 pentodes in a differential amp configuration using a silicon CCS in the tail. In Pete's design, the output stage uses 12-pin compactron TV sweep tubes, such as the 6JN6 (no plate caps required) or 6JM6/6GV5 (plate caps are required), which have a 17.5 watt plate dissipation. Here is a link to Pete Millett's page where more information on the DCPP amp can be found. http://www.pmillett.com/dcpp.htm Several years ago when Pete Millett started to sell PCBs with his DCPP circuit, George of DIY Audio Tubelab fame, decided to test the upper limits for power in relation to these sweep tubes. George used a power supply that would generate 650 volts at 1.7 amps and plugged in his samples of sweep tubes. The amplifier generated 250 WPC in this configuration with a 2,500 ohm load. Not satisfied, he decided to wire both channels in parallel through a common OPT set for 1,250 ohms and lo and behold; this combination generated 504 watts at 5% distortion and 525 watts at clipping. I bought a PCB but had not done much in the way of putting together my parts list when I found a completed version of the DCPP amplifier come up for sale for slightly less than the parts would have cost me from my preliminary estimates. Here is my Pete Millet DCPP amplifier. My DCPP amp uses the 6JN6 sweep tubes for output and is nowhere near George’s 504 WPC. My amplifier does the 20 WPC that Pete originally designed it for; and at that output, the sweep tubes will probably last a few life-times at that abuse-rate. Edited July 8, 2015 by Fjd 2 Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted July 8, 2015 Share Posted July 8, 2015 Having spent many years in TV repair, I got to enjoy the beautiful glow of the horizontal output tubes! Those look really nice. Here's a link to an article which explains a bit about why they have gained some popularity in audio amplifiers: http://tetrode.co.uk/sweep.html Maynard Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 8, 2015 Share Posted July 8, 2015 I love to see Pete's Big Red board!!! George from Tubelab is a great guy, I haven't heard much from him since his move. I think he is still unpacking. If I remember correctly George was using a screen drive topology along with high voltage to achieve the amount of power he did. I have been toying around the idea of making an amp with sweep tubes but until I come across a whole box of unused specimens I will wait. Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted July 8, 2015 Share Posted July 8, 2015 I have been toying around the idea of making an amp with sweep tubes but until I come across a whole box of unused specimens I will wait. All the hams I know hoard the sweep tubes for linear amplifier service (and to think that I gave many away about 20 years ago!). In case you're interested though, Mike Marx still has the Phillips 6BG6GAs available at a decent price. I've used them in a number of designs and they are true battleships as he claims (equiv. to the 6L6GC). It might pay to grab some while he still has them: http://www.vacuumtubes.com/6BG6.html Maynard Quote Link to comment Share on other sites More sharing options...
Schu Posted July 9, 2015 Share Posted July 9, 2015 https://www.youtube.com/watch?v=7g6moBMa7ls Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 9, 2015 Share Posted July 9, 2015 That doesn't look dangerous! The 833 isn't something you throw 300 volts at, it's more like 1kV. Good info here: http://www.diyaudio.com/forums/tubes-valves/232484-midlife-crisis-my-833c-amp-build.html Seriously what an awesome time we live in.......magnets and miracles..........and seriously crazy amplifiers that bring the mad scientist out in all of us. Quote Link to comment Share on other sites More sharing options...
philly0116 Posted July 9, 2015 Share Posted July 9, 2015 Sorry, nothing to add, just saw "porn" and had to stop by. 2 Quote Link to comment Share on other sites More sharing options...
Schu Posted July 13, 2015 Share Posted July 13, 2015 (edited) Line Magnetic 41.2 212 Single Ended mono amplifier Line Magnetic LM-1 212 Single Ended mono amplifier with tungar filament supplies Tube complement: 805 x 4 (two as rectifiers), 300B x 1, 6SN7 x 2, 1 x 274BOutput Power: 20W SETOutput Impedance: 4, 8, 16ohms Edited July 13, 2015 by Schu 1 Quote Link to comment Share on other sites More sharing options...
Fjd Posted July 13, 2015 Share Posted July 13, 2015 Schu, some of us are just dying to see the covers off your Bel Canto REF 500M and the SC85 to show us some modern-amp porn. I've been trying to come up with something for this thread but none of my amps are really artistic. https://community.klipsch.com/index.php?/topic/146056-tube-art-what-lies-beneath/ 1 Quote Link to comment Share on other sites More sharing options...
justinsweber Posted July 14, 2015 Share Posted July 14, 2015 I've build a few 6T9 and 6LU8 tubes and loved the sound of the 6T9. Quote Link to comment Share on other sites More sharing options...
A1UC Posted July 16, 2015 Share Posted July 16, 2015 (edited) Sent from my iPhone using Tapatalk Edited July 16, 2015 by A1UC Quote Link to comment Share on other sites More sharing options...
A1UC Posted July 16, 2015 Share Posted July 16, 2015 Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
minermark Posted July 16, 2015 Share Posted July 16, 2015 (edited) Line Magnetic 41.2 212 Single Ended mono amplifier Line Magnetic LM-1 212 Single Ended mono amplifier with tungar filament supplies Tube complement: 805 x 4 (two as rectifiers), 300B x 1, 6SN7 x 2, 1 x 274B Output Power: 20W SET Output Impedance: 4, 8, 16ohms Wife came in last night when i was checking this picture out, what is that? she say's, room heater(s) dear. Told her they were Mono blocks a little bigger than she runs, her parting commet was get the house in Nevada done. Not that i would get these,(no wattage). got something from silicone valley in mind for later in life for that. Edited July 16, 2015 by minermark Quote Link to comment Share on other sites More sharing options...
Fjd Posted February 11, 2016 Share Posted February 11, 2016 A little change with a few pro amplifiers that recently joined the amp collection. Here are a few glamour shots and a little amp porn of the BGW 100B. Quote Link to comment Share on other sites More sharing options...
Fjd Posted February 11, 2016 Share Posted February 11, 2016 AB International Series 200 Quote Link to comment Share on other sites More sharing options...
Fjd Posted February 11, 2016 Share Posted February 11, 2016 (edited) Perreaux PMF 1150 B 100wpc . Edited February 11, 2016 by Fjd Quote Link to comment Share on other sites More sharing options...
ZEUS121996 Posted February 11, 2016 Share Posted February 11, 2016 ImageUploadedByTapatalk1437038191.732961.jpg Sent from my iPhone using TapatalkImageUploadedByTapatalk1437038639.036203.jpgImageUploadedByTapatalk1437038659.725791.jpg Great gear Rodney. IDK what else to say about it Mark Quote Link to comment Share on other sites More sharing options...
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