• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

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Russian chokes? Dr-5-008? Whats the current through them? Do they warm up?

Each is working at 50mA and are not warming up. "DR-5-008" means 5H 80mA


Interesting,

Are the EL34's in pentode, triode or UL ?

I like wood and tubes.. :)

Regards
M. Gregg

EL34's are in triode mode - 50mA/390V/-30V; Rk=560 Ohm


e88cc:

12mA/150v/-3,3v; Rk=270; Ra=15K
 
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forgotten tube

Hello All
I see alot of the contributors use alot of standard tubes, Ive built amps using EL34 and 6L6s and 6550's, hell I even did a couple KT66's.
But I got bored of the sound between some of these tubes, the EL34's are suprising sometimes, depending on how they are run, cold or hot! But I just wanted to mention that I havent heard anyone talk about the 8417.
This tube has the highest transconductance in a audio power tube than any other i know. Low capacitance also helps the range these tubes can handle. Did some research and these tubes were designed to be used as frequency motor drive controller.. I had and built many amps and this tube suprised me...got the bottom and mids of the EL34 and the sweet highs of the 6L6s in one package...unfortunatly this tube isnt made anymore, but hoping who ever bought the tooling from RCA will make them again... Anyway I enclosed a pick of my latest refurb, pair of Bogen MO200A's, these amps are awesome performers, specs on these things are 8hz to 50khz, and 200watts conservatively. So if you come across them get them... can be modified for 6550's by adding a extra gain stage.
 

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Disabled Account
Joined 2010
Hello All
I see alot of the contributors use alot of standard tubes, Ive built amps using EL34 and 6L6s and 6550's, hell I even did a couple KT66's.
But I got bored of the sound between some of these tubes, the EL34's are suprising sometimes, depending on how they are run, cold or hot! But I just wanted to mention that I havent heard anyone talk about the 8417.
This tube has the highest transconductance in a audio power tube than any other i know. Low capacitance also helps the range these tubes can handle. Did some research and these tubes were designed to be used as frequency motor drive controller.. I had and built many amps and this tube suprised me...got the bottom and mids of the EL34 and the sweet highs of the 6L6s in one package...unfortunatly this tube isnt made anymore, but hoping who ever bought the tooling from RCA will make them again... Anyway I enclosed a pick of my latest refurb, pair of Bogen MO200A's, these amps are awesome performers, specs on these things are 8hz to 50khz, and 200watts conservatively. So if you come across them get them... can be modified for 6550's by adding a extra gain stage.

Very nice,

I love the hot rod wheels :D

What about an inside shot? (do you have any)

Whats the switch on the top for? (input select)

Regards
M. Gregg
 
Sorry for the delay response, night shift this week...I do have inside shot I will post it when I get off my camera...the switch is the screen standby switch...it's more effective at not causing tube sickness or cathode stripping. It works very well, switching screens stops 90 percent of current so when you warm up tubes the cathode can heat before current can flow, and since there is a small amout of current flowing you wont weakin or oxidize the barium on the cathode...if anyone likes this idea make sure you use a bypass cap across the switch terminals so you dont get popping in speakers fron the contacts arcing. .1 to .47mf..also use a good size voltage rating 600 to 1000v..
The best standby is switching rectifier filaments, if you have tube rectifier..some use fast diodes for the quickness. I personally use diodes before the rectifier tube incase it shorts, tube rectifiers when short send ac to everything including the speakers and if you have old and expensive speakers this will be your saviour...ac will destroy almost evrything in the power and output stage including your precious speakers. word for the wise...John
 
I have to share this one amp with you since I get alot of questions from this one, I call it Little Gem, lets see if you can figure this one out, I this amp is more than what it seems and somebody out there probably can tell right away...outputs are scotts and power tranny is Chicago...sound is really unbelievable which has everyone questioning who heard it...I'll also give you a pick of the KT66...
 

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3C24 With 6em7 pre-driver class A2

Thought this may be a little more interesting than a standard pic, the sound quality is not the best with the camera that I have but it is just for fun anyway.
Sounds fantastic in person even with the Open Baffle test speaker.
Breadboarding for fun and pleasure.
Have fun watching...

http://www.youtube.com/watch?v=KXuDRDgEMek&feature=share
 
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Pics of the 3c24/6em7/0D3 SE A2

Here are some photos of the breadboard setup. It is, well... a breadboard test, not much for appearance. :spin:


The sound quality is superb to my ears, and I have made many many amplifiers past and present. Sounds on par with my 45 set, but much more power out to my ears. I do not have tools for testing output or harmonics, but it is crystal clear with Bach, and other jazz samples.

I have a 5973 UL se amp with James xfmrs throughout, and this 3c24 with antique opt is blowing it away also.
I will need to make connectors to disperse the heat better on the plate and grid.
The wire I am using on the plate right now is off a tv flyback, but the insulation is beginning to droop 1/2-3/4" up from the top of the tube, however the rest of the insulation is cool elsewhere. I am running 297v on the plate and 37v+ on the grid of the 3c24 and the opt pri. is @3k. I am using an 0D3 to regulate the plate of the power section of the 6em7 which is maintaining the pos voltage from the cath to the grid of the output. The HV PS is at 75mA for the circuit. I will have to draw up a schematic to post, as this is another circuit off the top of my head. They seem to work better when I design on the fly.:p And the white masking tape on the leads of the black cat is just for rigidittty, no other function.

Next up is the 826 RCA for output....:D
 

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Hi mitube ... it's a stupendous acheivement!

Am seeking for a easy built with affordable tubes to see me thru my twilight years.

We'll be delighted and thankful if you can come up with a schematic to share.

BTW, came a similiar one on the "audiophiletalk" forum.

Enjoy your fruit of success!

Thanks!
 
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:smash:
I have to share this one amp with you since I get alot of questions from this one, I call it Little Gem, lets see if you can figure this one out, I this amp is more than what it seems and somebody out there probably can tell right away...outputs are scotts and power tranny is Chicago...sound is really unbelievable which has everyone questioning who heard it...I'll also give you a pick of the KT66...

Guess nobody can see the indifferences with this amp...I call it Little Gem because it looks like a ordinary single ended amp...far from it..this little think has a output power of 24 watts a channel, if you look close at the tubes there is 2 7189s in one envelope so the amp is really push pull...6U8 in the front end, the first amp is pentode and the triode section is the phase inverter....power supply is diodes before the tube rectifier. This amp is definitly a performer it actually can drive my infinitys and moves the woofers with no problem. With a good effecient speaker this amp has alot gain and sound is excellent, and bass is really low and solid...highs are crystal..thats the scott outputs, anyone who has ever had a scott knows the quality of these trannies...happy building!!
 
Disabled Account
Joined 2004
6SN7 Push Pull

It was a grey, ordinary amp. It wanted a sex change....I said no way instead I gave him new clothes. Seems happier now. The sign warning high voltages is there for two reasons: to remind me this motherfkr gave me the shock of my life and to cover a rounded hole (changed my mind about using a tube rectifier). Oh yes there are two paint schemes there, can't decide which one I like less.
 

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Disabled Account
Joined 2004
I used this tube in my headphone ampl. for 300 ohms Sen.HD580.

Could you share the schematic? I also have RCA 6AS7's and I want to do something with them. Cathode followers, not SE. Yuk!

Hola "Cassiel"!

Cassiel is known for simply watching the events of the cosmos unfold with little interference. Which means I do little and when I do nothing changes.

Do you want to show us the inside and tell us more about the circuit?

Your wish is my command. It's the third amp I do with the same circuit but different tubes. First one was 5965+ 6V6's; second one 6SN7+EL84s; third one 6SL7+6SN7. Why am I doing such a thing, you may ask. Well, after building some Push Pull amps I finally found my favorite phase splitter circuit (a floating paraphase stolen from a Leben amp) so what I'm doing now is checking out different tubes. It's all about the circuit really, there are small differences between these tubes but all the amps sound great. This one didn't sound as good as the others. I wondered why, then I realized this one had a choke (Hammond) and the others didn't. Took the choke out (filter section) and that was it: now it sounds as good as the others. Everybody raves about chokes and LTP's with current sources.....well, NOT me. I don't need them, nor do I need special caps.

The heatsink is there for decorative purposes, so you guys don't have to see a black hole.
 

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