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#1 |
diyAudio Member
Join Date: Aug 2001
Location: Sweden (Mora)
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Hi,
Irrational as it might be, I´ve become interested in Circlotron amps lately. I have a big stash (40+) of 6S19 tubes, 20 noval sockets and some interesting power transformers (two 2x6V 50VA toroids for the heaters and four 68V 100VA EI transformers for the floating output stage rails). Some questions: Can an OTL circlotron output stage operate in class AB? Would 95V rails be waaaaayyy to low (using 8 x 6S19 per channel*)? Is a tube or a solder joint goes south, would it mean the end for my speakers? * With 4x6S19/rail, ie 8/channel I should get a peak current capacity of about 1,2A which should give almost 6Wrms @ 8R. |
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#2 | ||||
diyAudio Member
Join Date: Jul 2005
Location: North East
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![]() ![]() As one side of Circlotron lowers it's current it hits rock bottom. Not 0 (400uA) but in this post ![]() Quote:
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![]() ![]() ![]() Well, theres my 2C |
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#3 | ||||
diyAudio Member
Join Date: May 2005
Location: USA
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#4 |
diyAudio Member
Join Date: Aug 2006
Location: Taxland, New Jersey
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Any of you guys want the Atma-Sphere MA-1 diagram? (6AS7s) Email me.
Victor |
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#5 |
diyAudio Member
Join Date: Aug 2006
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Circlotrons are also interesting me lately, OTL or not. I'm sure it's common knowledge to most members here, but it was only last week that I became aware that Wiggins = Electro-Voice and that they marketed transformer-coupled circlotron amplifiers from 15-100W. Given that the output impedance is 1/4 of that used in push-pull, these should be awesome sounding amps. (Anyone have/heard any of these?)
I recently exchanged email with Robert Turnbull, operator of this site: http://www.audiocraftworks.gr/gr/pag...circlohist.htm in an attempt to verify the OPT impedance for the A30 (uses 6BG6G or 1614) as I was considering constructing from the design - well either that or Al Stewart's circlotron circuit (AudioXpress, May 2002). Sooner or later I've gotta put together a transformer-coupled circlotron and an OTL. (So much time, so little money..) Roky, I think the tube you're referring to might be more commonly known as a 6C19. From what I've read it's like half a 6AS7 (ie single section) but I don't know how the ratings compare. Victor, I have the MA-1 circuit as well. Do you know how to go about adjusting the bias and balance pots? |
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#6 | ||
diyAudio Member
Join Date: Jul 2005
Location: West Virginia panhandle
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As a side note I saw my first tube instantly and violently shatter last night. It was one of the 6S19P's. I must admit that is was a totally dumb blonde mistake on my part that caused it though. I had been testing some Bendix rectifier tubes so I had the filament wires soldered to pins 3 and 6 of the 9 pin socket. All other connections were made with clip leads, which I removed. Without thinking I plugged a 6S19P into the socket and switched on the power supply. The tube instantly popped sending glass fragments all over the place. After using a lot of bad language, I figured it out. Pins 3 and 6 are both plate connections on the 6S19P. My old Fluke power supply probably cranked 10 to 20 amps into that dead short. The weakest link was the wire that goes through the glass from the pin. As the wire vaporized it must have built up some serious pressure inside the glass, causing violent destruction.
__________________
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before...... |
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#7 | |
diyAudio Member
Join Date: Aug 2006
Location: Taxland, New Jersey
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http://www.joule-electra.com/index2.htm CarlyBoy, I've never owned that MA-1 but would think that the DC balance is set to provide the least DC offset (differential) between the upper and lower sections as measured at the output. The bias adjustment sets the operating level of the output tubes since the driver is DC coupled to them. This level is 750 mA per side, or 125mA per tube. |
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#8 |
diyAudio Member
Join Date: Jan 2002
Location: Tyrone Ga. U.S.A.
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I have been thinking about using a few of those 6c19pi tubes
in a circlotron to. As you see I already have a few tubes mounted. I already have the 4 transformers for the 4 floating power suplies. I bought some 110-230v autoformers that i was able to convert to 110v to 130v transformers. One of these is in the picture. |
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#9 |
diyAudio Member
Join Date: Apr 2007
Location: Sofia
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#10 |
diyAudio Member
Join Date: Aug 2001
Location: Sweden (Mora)
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Thanks guys for helping me out with some answers!!
(Just for clarification: I´m not Roky Erickson, this is Roky: http://en.wikipedia.org/wiki/Roky_Erickson) 440mA at 95V on the plate is better than what I estimated by looking at the datasheet. According to this Pout might end up much higher than expected. |
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