Hi All, I have been following this thread since it started. I am just now finishing up a GM70 SET amp so now I am starting to think about building a 6C33C SET amp. I found a PTX last night in my stash and it is a 350-0-350 with 12.8v legs, 6.3v legs, and 5v legs. It came from a Conn organ that had lots and lots of tubes to drive.
I have two issues that I could use help with
1. I do I know if the 12.8v legs will drive 2 6C33C tubes
2. I am a metal sculptor and I have a wild chassis built already that I would like to use. That being said, what would be the smallest (physially) OT I can buy for the amp?
Here is a pic of the chassis with my John Hogan amps that I sold. I would put the output tubes, driver tubes, and output transformers on top and the power supply on the bottom....or visa versa fit it works out better.
I have 2 6D22S dd rec tubes, the PT, 2 new steel boxes made to fit the upper and lower chassis, and all the chokes for the PS.
I am still trying to figure out what scheem to use.
I have two issues that I could use help with
1. I do I know if the 12.8v legs will drive 2 6C33C tubes
2. I am a metal sculptor and I have a wild chassis built already that I would like to use. That being said, what would be the smallest (physially) OT I can buy for the amp?
Here is a pic of the chassis with my John Hogan amps that I sold. I would put the output tubes, driver tubes, and output transformers on top and the power supply on the bottom....or visa versa fit it works out better.
I have 2 6D22S dd rec tubes, the PT, 2 new steel boxes made to fit the upper and lower chassis, and all the chokes for the PS.
I am still trying to figure out what scheem to use.
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@DJN,
You might want to contact mr. Ari Polisois, he makes a very special breed of OPT called the SC-OPT, which in fact houses both OPT's on one core.
Since you are limited to existing housings, which to my taste are great looking, this could be just what you are looking for.
Polisois audio amplifiers and transformers: designing and building audio amplifiers and output transformers
Ari's designs are somewhat controversial, but if you always follow the beaten track, you will never discover something new
You might want to contact mr. Ari Polisois, he makes a very special breed of OPT called the SC-OPT, which in fact houses both OPT's on one core.
Since you are limited to existing housings, which to my taste are great looking, this could be just what you are looking for.
Polisois audio amplifiers and transformers: designing and building audio amplifiers and output transformers
Ari's designs are somewhat controversial, but if you always follow the beaten track, you will never discover something new
Thanks Midlife. I sent him a note for the dimentions. They just might work. Cheers.
@DJN,
You might want to contact mr. Ari Polisois, he makes a very special breed of OPT called the SC-OPT, which in fact houses both OPT's on one core.
Since you are limited to existing housings, which to my taste are great looking, this could be just what you are looking for.
Polisois audio amplifiers and transformers: designing and building audio amplifiers and output transformers
Ari's designs are somewhat controversial, but if you always follow the beaten track, you will never discover something new
Hi,djn!
You can check Your transformer for:
1. Heating for each 6S33S is 12,6v/4A, or 6,3v/7,5A.
2. 6S33S works good with Uanode-cathode = 190-210v.
3. Your main transformer has 350-0-350 v, after filtering will more than 400v, that is very big and not suitable.
Cheers!
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OK, thanks Azazello. The transformer is not marked but I got the reading with a multi meter. I think if I used a choke input out of the PTX I would get it down to the 210v range. It also has 300v legs before the 350v legs so I can use those as well.
How can I tell how much amps the 12.6 legs will handle without data on the TX???
How can I tell how much amps the 12.6 legs will handle without data on the TX???
Banned
Joined 2002
@djn
Below an earlier post that might grab your attention:
Hi all,
I stumbled across this thread and thought I would read it to find if anybody else had maybe built the same amp I did. I can not recommend this direct coupled design highly enough. I notice K.A.B is familiar with this amp.
About 4 years ago after much research and correspondance with the designer,
Ari Polisois, I built his DCMB ( direct coupled modulated bias ) amp with 6SN7as driver and with the 6C33C cathode direct to ground, made possible by using 2 power supplies and using an output trannie of my own design, the details of which are with the transformer company that wound the bobbins for me. I chose an input impedance of 1000 ohms which in practice worked well and allows me to use 4 to 8 ohm speakers. We once paralleled 4 ohm speakers for a party !
At the time some friends and I decided to build with the 6C33C, each choosing a different design. 2 were built with cap coupling, 1 Loftin White dc as appeared in Glass Audio magazine and mine
The first 2 sounded really good compared to other contenders, EL34 SE, KT66 etc. The Loftin White was way better but everybody agreed,some reluctantly, that mine sounded exceptional and the comparison ground to a halt. That is we did not need to go back and listen again to any others.
The excitement grew and it became a case of trying different speakers. Old Quad electrostatics sounded better than I had ever heard them and had the owners jaw on the floor !
The amp was bought by a friend and has been in daily use for three years. I intend building another when circumstances change. This thing grabs any speaker and makes it sound good, with a delightfull midrange and involuntary involvement with the music. Conventional amps sound boring, constipated and lifeless. No washed out thin wimpy sound here, this has a ballsy sound that puts a smile on your face and gets feet tapping. In other words MUSIC
Ari was very helpful when I emailed him on many occasions. His design can be found googling SIMPLEX DCMB
Regards Charles
Below an earlier post that might grab your attention:
Hi all,
I stumbled across this thread and thought I would read it to find if anybody else had maybe built the same amp I did. I can not recommend this direct coupled design highly enough. I notice K.A.B is familiar with this amp.
About 4 years ago after much research and correspondance with the designer,
Ari Polisois, I built his DCMB ( direct coupled modulated bias ) amp with 6SN7as driver and with the 6C33C cathode direct to ground, made possible by using 2 power supplies and using an output trannie of my own design, the details of which are with the transformer company that wound the bobbins for me. I chose an input impedance of 1000 ohms which in practice worked well and allows me to use 4 to 8 ohm speakers. We once paralleled 4 ohm speakers for a party !
At the time some friends and I decided to build with the 6C33C, each choosing a different design. 2 were built with cap coupling, 1 Loftin White dc as appeared in Glass Audio magazine and mine
The first 2 sounded really good compared to other contenders, EL34 SE, KT66 etc. The Loftin White was way better but everybody agreed,some reluctantly, that mine sounded exceptional and the comparison ground to a halt. That is we did not need to go back and listen again to any others.
The excitement grew and it became a case of trying different speakers. Old Quad electrostatics sounded better than I had ever heard them and had the owners jaw on the floor !
The amp was bought by a friend and has been in daily use for three years. I intend building another when circumstances change. This thing grabs any speaker and makes it sound good, with a delightfull midrange and involuntary involvement with the music. Conventional amps sound boring, constipated and lifeless. No washed out thin wimpy sound here, this has a ballsy sound that puts a smile on your face and gets feet tapping. In other words MUSIC
Ari was very helpful when I emailed him on many occasions. His design can be found googling SIMPLEX DCMB
Regards Charles
I have, but there are two versions of the OPT one called SC-OPT and OPT are two separate they are very large, approximately 18x15x11 cm with a weight of 6.6 kg each the second version, called SCC-OPT and have two channels on the same core. It weighs less and is obviously having a better frequency range.
I have the first option and am very satisfied how it sounds the only problem is that the amplifier is very heavy. Today I had probably built with SCC-OPT but it may be the next time I build a new amplifier.
Here are one of my SC-OPT
Anders
Can You measure aprox. diameter of wire for 12,6 v and 6,3 v on the tap?
Current, aprox. 2,5 - 3A, across 1 sq. mm /sorry for bad english./
Or connect resistor 3 ohm/5-10 wts for a while and measure U on the taps. If is 12,...v
it is suitable coil.
Than connect the same resistor to taps 6,3 v and measure, if is 6,...v it's suitable.
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Thanks Azazello. I will do that. This transformer was in an organ that had over 50 tubes in it and the 12V legs powered all the heaters so it should have enough amp draw capability to handle the 6C33C heaters.
If not, I have room on the lower chassis for a second PTX.
I was surprised that the 6C33C tube is not that expensive compared to my KR300B tubes. I could buy 15 6C33Cs for the what I paid for the KRs.
If not, I have room on the lower chassis for a second PTX.
I was surprised that the 6C33C tube is not that expensive compared to my KR300B tubes. I could buy 15 6C33Cs for the what I paid for the KRs.
Banned
Joined 2002
How much bass do you need djn ?
I've tried my DCMB amplifiers on different speakers I have not lacked any bass yet with SCC-OPT should the bass go deeper and suit bass maniacs better.
This amplifier is very sensitive but feels very powerful even it only has 15 Watts I use my DCMB to a pair of back-loaded horns with a sensitivity of approximately 95-97 dB I dont miss any bass. One of the speakers I have tried my amplifier on is a pair of OB with 2x Alpha15 and Viston B200 everybody there were sitting with a big smile on their faces. I know that there will be no problems at all with to drive your woofers.
Anders
I've tried my DCMB amplifiers on different speakers I have not lacked any bass yet with SCC-OPT should the bass go deeper and suit bass maniacs better
.This amplifier is very sensitive but feels very powerful even it only has 15 Watts I use my DCMB to a pair of back-loaded horns with a sensitivity of approximately 95-97 dB I dont miss any bass. One of the speakers I have tried my amplifier on is a pair of OB with 2x Alpha15 and Viston B200 everybody there were sitting with a big smile on their faces. I know that there will be no problems at all with to drive your woofers.
Anders
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Thanks Azazello and Anders. My woofers at the Lambda TD 15M in ported cabs. I am driving them now with a Adcom 30wpc amp and don't even have it turned up past 1/4 volume to match the 1.5wpc Zen amp that drives my horns.
This is good to hear. I am going to order the SCC-OT as I am space limited on the chasses.
This is good to hear. I am going to order the SCC-OT as I am space limited on the chasses.
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