First of all congratulatios for this great forum with those wonderful threads and ideas . I would like to introduce to you , my new tube power amplifier ( its not complete yet , but soon it will be ) , wich is an OTL Circlotron topology with the PL36 tubes . I use the following tubes for each channel , one EF184 or EF183 for the input stage / phase spliter following by one PCC85 as first differential gain stage following by two PCL82 as second differential gain stage ( the triode sections ) and the pentode sections as cathode follower to drive easely the output tubes wich is 10 PL36 five per each rail . Here is some fotos .
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Impressive...
It's quite a bit of glass - can't wait to hear your impressions on how this baby sounds !
It's quite a bit of glass - can't wait to hear your impressions on how this baby sounds !
Nice job. I like the use of the PC card as a strip line for the outputs. If you run this in or near class A I hope it doesn't oscillate on you. You may have to move the stopper resistors closer to the socket connections. Also the filaments might do a little better powered from the center tube, or even end-to-end, to equalize voltage.
Yes you have right , the grid stopper resistors its better to be closer to the tubes , but in this case the driver stage have very low output resistance because it is a cathode follower and will minimeze any unwanted effect . The filaments of the PL36 is 25V 0,3A for each one and the 5 tubes need 1,5 A wich is not heavy current , but i agree with you that it is better to connect it like you say if we have tubes like EL36 or El509 or other tubes wich have big reguirements of currents . In the past i use to connect every tube filaments with sepsrate cables , in this amp i do it for simplicity because there is too many tubes .
I don't think it will oscilate i have built another one OTL amp with 12 PL36 per channel , futterman topology with the same build philosophy and dosen't oscilate at all , the frequency response was high 195 Khz -3db .
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Very nice project.. 🙂
How do you protect your speakers?
ie what type of protection (crowbar)?
Regards
M. Gregg
How do you protect your speakers?
ie what type of protection (crowbar)?
Regards
M. Gregg
Is this you?
otl amp.handmade with 12 PL36 tubes per channel . - YouTube
If it is, then its very nice ,,, 🙂
Regards
M. Gregg
otl amp.handmade with 12 PL36 tubes per channel . - YouTube
If it is, then its very nice ,,, 🙂
Regards
M. Gregg
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Yes it is my first OTL , i build it back in 2004 , still playing good right now with many modifications over the years . I dont't use any kind of protections , I DON'T recomend this to anyone for safety reasons , but the amp has no proplem till now .
Well I hope you are arround here for a while because I like the amp..
What kind of coupling capacitors do you use or do you DC couple?
Welcome to the forum...
Regards
M. Gregg
Thank you a lot Gregg , I use Philips / BC MKP capacitors , sounds good to my ears , MKP 378 or 379 series , maby the 336 2 too .
This is the second video . PL36 Handmade Output transformerless tube amplifier by D.Argiannis - YouTube
Sounds very clear..what power output do you get from these tubes..?
In the comments to the video you say this is a variation of the futterman..what is the variation from the scheme?
Regards
M. Gregg