Gents, I am not that skilled in managing discussion threads and I need to learn a few things so please give me some time to figure it out.
Here is the amplifier circuit, just in case. The SIT is KP802A. The trick is this thing is nowhere close to what is published in the datasheet (it even got the pinout wrong...). I am adding measured curves for one of the devices which is inside. The tube is 6N6P.
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A few resistors ended up adjusted for value during debugging and listening. No measurements have been done yet except the max power at 8Ohm - app. 25W and I checked that nothing wrong happens when it is clipping, attached.
Output transformer - Toroidy, the one for 6C33C.
Output transformer - Toroidy, the one for 6C33C.
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Is this case from an old appliance? Or purchased separately?
https://www.diyaudio.com/forums/tubes-valves/71300-photo-gallery-936.html#post6168802
Are these transformers manufactured in Romania?
https://www.diyaudio.com/forums/tubes-valves/71300-photo-gallery-951.html#post6217118
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El 84 Se Triode Wired
I finally got my El 84 Se Triode wired finished. About 1-1,5 w out to my Klipsch RF15 loudspeakers. Beautiful sound! Just about ONE Watt out and it is enough to fill my livingroom with music!! I think this must be the most musical amp who has been in my stereo systems. Sovtek el 84 and one E88cc from Philips.
I finally got my El 84 Se Triode wired finished. About 1-1,5 w out to my Klipsch RF15 loudspeakers. Beautiful sound! Just about ONE Watt out and it is enough to fill my livingroom with music!! I think this must be the most musical amp who has been in my stereo systems. Sovtek el 84 and one E88cc from Philips.
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stenak,
Nice job!
I love the painted chassis, and the wood ends.
And thanks for the pictures and the schematic.
You should ground one of the output transformer's secondary connections.
Safety First!
And put a 5 Watt 50k resistor across the first cap (220uF) in the B+.
That will bleed down the B+ when you power off the amplifier.
Use a bottom cover, with lots of holes in it for air flow.
Hopefully when you get the bottom cover removed, the bleeder will have discharged the B+ to a safe voltage.
Safety First!
Safety First!
Prevent "The Surviving Spouse Syndrome"
Enjoy the Music!
Nice job!
I love the painted chassis, and the wood ends.
And thanks for the pictures and the schematic.
You should ground one of the output transformer's secondary connections.
Safety First!
And put a 5 Watt 50k resistor across the first cap (220uF) in the B+.
That will bleed down the B+ when you power off the amplifier.
Use a bottom cover, with lots of holes in it for air flow.
Hopefully when you get the bottom cover removed, the bleeder will have discharged the B+ to a safe voltage.
Safety First!
Safety First!
Prevent "The Surviving Spouse Syndrome"
Enjoy the Music!
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Low power amps can be fun!
And simple too.
Do not forget to ground one end of the output secondary.
A True EL84 is a True Pentode (with a Suppressor Grid).
A True 6BQ5 is a True Beam Power tube (with Beam Formers).
Some manufactures mark EL84/6BQ5, or 6BQ5/EL84.
Now matter how similar the specs, it can not be both.
And simple too.
Do not forget to ground one end of the output secondary.
A True EL84 is a True Pentode (with a Suppressor Grid).
A True 6BQ5 is a True Beam Power tube (with Beam Formers).
Some manufactures mark EL84/6BQ5, or 6BQ5/EL84.
Now matter how similar the specs, it can not be both.
Hmmm. Interesting. I didn't know that. I'll have to look closer. Does it make a difference in sound? I'm a big fan of the 6AQ5, but I like the 6BQ5 too. Not sure I've heard a true EL84, certainly haven't rolled them.
That's not (at least entirely) correct.
There might be some rare wacky tetrodes labelled as 6BQ5, but the majority of 6BQ5 tubes are pentodes.
Is GE 6BQ5 true enough?
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Nice.Finished my SIT push-pull project. It is playing now and I am not sure I will be able to make something better than that so I may stop tryingThe circuit is unusual and the idea came in a conversation with one of the friends as a wild option for his PP output transformer: the phase splitter transformer is driven from both 'ends' - from the input signal and in phase from the output.
It looks like it is a thing to safely store money
TG,
I forgot that I was shown the GE data sheet that called the 6BQ5 a pentode.
Did you show that to me recently, or was that someone else?
My GE tube book calls the 6BQ5 a Beam Power tube.
A quick look at Franks tube pages shows both Pentodes, and ones that have Deflectors/Beam formers.
I would say that there would be no more difference in performance and sound (without negative feedback) between a 6BQ5 and EL84, versus from one manufacturer to another, versus from Beam Power construction and Pentode construction either.
6BQ5 and EL84 Plug and Play tube rolling.
I know the next time I get EL84 tubes, they will be JJ EL84 from Eurotubes.com
The 6AQ5 is quite a bit different than the 6BQ5 / EL84.
Not the same pin out.
Not the same specifications either.
Not for Plug and Play.
I forgot that I was shown the GE data sheet that called the 6BQ5 a pentode.
Did you show that to me recently, or was that someone else?
My GE tube book calls the 6BQ5 a Beam Power tube.
A quick look at Franks tube pages shows both Pentodes, and ones that have Deflectors/Beam formers.
I would say that there would be no more difference in performance and sound (without negative feedback) between a 6BQ5 and EL84, versus from one manufacturer to another, versus from Beam Power construction and Pentode construction either.
6BQ5 and EL84 Plug and Play tube rolling.
I know the next time I get EL84 tubes, they will be JJ EL84 from Eurotubes.com
The 6AQ5 is quite a bit different than the 6BQ5 / EL84.
Not the same pin out.
Not the same specifications either.
Not for Plug and Play.
6A3sUMMER,
No, that wasn't me.
Looks like it's the matter of definition mostly.
The funny thing is that the beam tetrode, being the 5-electrode tube, is the pentode by definition. And it wasn't named "pentode" just because Philips held the patent for the "classic" (i.e. with suppressor grid) pentode.
Older datasheets have a lot of confusion on that matter. I've seen some early 6V6-type tubes being called "pentode". I believe I've even seen the term "beam pentode" somewhere...
Another funny thing is that Philips/Mullard EL34 is the classic pentode, and the GE or Sylvania EL34 is the classic beam tetrode
No, that wasn't me.
Looks like it's the matter of definition mostly.
The funny thing is that the beam tetrode, being the 5-electrode tube, is the pentode by definition
. And it wasn't named "pentode" just because Philips held the patent for the "classic" (i.e. with suppressor grid) pentode.Older datasheets have a lot of confusion on that matter. I've seen some early 6V6-type tubes being called "pentode". I believe I've even seen the term "beam pentode" somewhere...
Another funny thing is that Philips/Mullard EL34 is the classic pentode, and the GE or Sylvania EL34 is the classic beam tetrode
Stereo 50w PPP 807 Class AB1 amp finished, see pics. OPT's wound by my mate in Oz, he also rather kindly sent me 12 NOS 807's still in tropical packing FOC. Bar a few finishing touches it's finished but needs different knobs and something doing with the top ali plate, try as I might I couldn't get it to shine up, the ali is some odd alloy. I did have one painted up, but screwed it up drilling holes in the wrong place, then ran out of paint.
This one was a bit of a roller coaster, I had it all working, then by a stupid mistake burnt out a winding on the mains tfmr, so out it came and I rewound it from scratch. Put rewound mains tfmr back in, amp played up big time, which to cut a long story short I fixed with a 2200p cap from one CCS zener reference to ground.
A few brief details... case old Pye Wheatstone bridge, teak or mahogany perhaps, OPT's 3k4 Z pri/8r sec - UL tapped (not used at present) stack 3 3/3" x 4" x 3 3/4" deep. Mains tfmr 625VA toroid, handwound by myself, overwound. CLC filter, 10 second delayed start, Rod Elliot hifi preamp front end into 6H8C common cathode triode gain stage into 6H8C LTP - CCS. Protection circuit - if any valve exceeds 140mA Ik relay cuts neutral of mains tfmr.
F response 1dB @ 20hz and 30khz, THD 0.6% @ 21.47v RMS 440hz, 0.5% @ 19.7v RMS 20khz.
Bit more tidying up & tweaking to do so forgive the odd stray wire and tacked in caps .
Andy.
This one was a bit of a roller coaster, I had it all working, then by a stupid mistake burnt out a winding on the mains tfmr, so out it came and I rewound it from scratch. Put rewound mains tfmr back in, amp played up big time, which to cut a long story short I fixed with a 2200p cap from one CCS zener reference to ground.
A few brief details... case old Pye Wheatstone bridge, teak or mahogany perhaps, OPT's 3k4 Z pri/8r sec - UL tapped (not used at present) stack 3 3/3" x 4" x 3 3/4" deep. Mains tfmr 625VA toroid, handwound by myself, overwound. CLC filter, 10 second delayed start, Rod Elliot hifi preamp front end into 6H8C common cathode triode gain stage into 6H8C LTP - CCS. Protection circuit - if any valve exceeds 140mA Ik relay cuts neutral of mains tfmr.
F response 1dB @ 20hz and 30khz, THD 0.6% @ 21.47v RMS 440hz, 0.5% @ 19.7v RMS 20khz.
Bit more tidying up & tweaking to do so forgive the odd stray wire and tacked in caps .
Andy.
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soundbrigade,
What did you mean about the 6P1P?
My 2 Soviet Data sheets both show:
Plates maximum is 250V
Screen maximum is 250V
The 6BQ5 / EL84 is 300V max on plate and screen.
Using a 6P1P to do Tube Rolling on an amplifier made for a 6BQ5 / EL84, will end up in maximum smoke.
(Plug and Pray, not Plug and Play)
The pinouts are totally different.
And the maximum voltages are totally different (to name a few differences).
Tube Rollers Beware.
What did you mean about the 6P1P?
My 2 Soviet Data sheets both show:
Plates maximum is 250V
Screen maximum is 250V
The 6BQ5 / EL84 is 300V max on plate and screen.
Using a 6P1P to do Tube Rolling on an amplifier made for a 6BQ5 / EL84, will end up in maximum smoke.
(Plug and Pray, not Plug and Play)
The pinouts are totally different.
And the maximum voltages are totally different (to name a few differences).
Tube Rollers Beware.
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