6C33C SE-OTL Project

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Wolfgang
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#76 Re: 6C33C SE-OTL Project

Post by Wolfgang »

There should be price for best looks and perfection! Maybe at the next Owston meeting?
Chapeau, Ray! Incredibly aesthetically pleasing.

Wolfgang
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Dave the bass
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#77 Re: 6C33C SE-OTL Project

Post by Dave the bass »

Pfffffttttttt......shoddy!
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Ray P
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#78 Re: 6C33C SE-OTL Project

Post by Ray P »

Dave the bass wrote: Sun Nov 04, 2018 8:55 am Pfffffttttttt......shoddy!
What took you so long!
Sorry, I couldn't resist!
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pre65
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#79 Re: 6C33C SE-OTL Project

Post by pre65 »

Ray P wrote: Sun Nov 04, 2018 12:06 pm
Dave the bass wrote: Sun Nov 04, 2018 8:55 am Pfffffttttttt......shoddy!
What took you so long!
He's getting old. :lol: :lol: :lol:
The only thing necessary for the triumph of evil is for good men to do nothing.

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IslandPink
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#80 Re: 6C33C SE-OTL Project

Post by IslandPink »

That really is smart though, impressed.
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Ray P
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#81 Re: 6C33C SE-OTL Project

Post by Ray P »

I'm gonna pause this project after following Steve's breadboard adventure with 13E1 valves.

I have purchased a pair of 13E1s and my plan is to adapt this project to utilise them, for which I'll start a new thread.

I may return to the 6C33C project in the future.
Sorry, I couldn't resist!
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Ray P
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#82 Re: 6C33C SE-OTL Project

Post by Ray P »

Again, more Owston affect, but I've decided that I will resurrect this project - I may as well use all the parts I've gathered as there was no interest in someone taking them off my hands. It'll be interesting to compare the 6C33C and 13E1 - the amps won't be identical (slightly different driver stages for example) but I'll be able to get a feel for them. First I'll get the DSD decoder and 13E1 amp projects finished.
Sorry, I couldn't resist!
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Ray P
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#83 Re: 6C33C SE-OTL Project

Post by Ray P »

A question for the panel if I may...

This evening I was looking through the various parts I've collected/built for this project to see what I need to take it forward and it got me wondering if I could build it as an alternative 13E1 by just substituting a pair of them for the 6C33Cs in the ouput stage? To a numpty layman like myself the 13E1 and 6C33C don't seem to be worlds apart.

I know Steve had pleasing results with the 6CG7 (the 9pin version of the 6SN7) in his 13E1 build, albeit substituting for the 6H30pi in his own driver circuit and at a lower voltage (about 165V IIRC) - the 6C33C driver uses a Broskie Aikido Cascade arrangement running at 350V.

Below is the 6C33C build schematic that Wolfgang developed and the question is 'can I just drop in 13E1s to this circuit in place of the 6C33Cs?' (ignoring the heater aspects as they're easily dealt with).
6C33 OTL.pdf
(159.88 KiB) Downloaded 321 times
Attachments don't seem to be working correctly at the moment so I'll try again shortly.
Sorry, I couldn't resist!
Wolfgang
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#84 Re: 6C33C SE-OTL Project

Post by Wolfgang »

I don't think you will face any problems. The original circuit (6SN7/6C33)has enough input sensitivity and gain.
It depends of course also on the amount of NFB you are planning to use.You can always adjust the 13E1 B+/idle current to your needs which should be easy as it has a lot of reserves to play with.

As you anyway plan to use the Maida regulators for the driver stage you can easily replace the 300k/1k5/4k7 network with a simple resistor bypassed with a cap which would add some extra gain. I think you can find such a configuration even in Broskie's original posting of this circuit.
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Ray P
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#85 Re: 6C33C SE-OTL Project

Post by Ray P »

Thanks Wolfgang.
Sorry, I couldn't resist!
brommermartin
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#86 Re: 6C33C SE-OTL Project

Post by brommermartin »

I have one channel up and running :D for testing.
Image
The 6c33c is set at 387ma with 3,3ohm set R ,grid -34 and anode supply 155,5v .
In a couple of days I hope to build the stereo version on a piece of chipboard.
The only thing that scares me are the delicate 16 ohm AER md1 units as there is no proper output protection :cry: :cry:
Could this be a useful option ?
https://www.diyaudio.com/forums/group-b ... ay-gb.html

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Dave the bass
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#87 Re: 6C33C SE-OTL Project

Post by Dave the bass »

A toilet roll and clip leads!

Try DIY ethic!

Like!
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Wolfgang
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#88 Re: 6C33C SE-OTL Project

Post by Wolfgang »

The only thing that scares me are the delicate 16 ohm AER md1 units as there is no proper output protection :cry: :cry:
Could this be a useful option ?
https://www.diyaudio.com/forums/group-b ... ay-gb.html
The output DC protection is the cap. If it can handle B+ in case of a tube failure the speakers should be ok.

It takes a while to get those XRK boards. 4 weeks at least.But they would certainly disconnect the drivers in case of DC at the output (connected after the cap, in case of cap failure). They have been tested with 100V max. If you want to use them for higher voltages the SSR should trigger a mechanical relay so that it is only exposed for a very short time to higher voltages in case of a catastrophic tube/cap failure.
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Mike H
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#89 Re: 6C33C SE-OTL Project

Post by Mike H »

Dave the bass wrote: Wed Oct 23, 2019 9:22 pm A toilet roll and clip leads!

Try DIY ethic!

Like!
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Image
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
brommermartin
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#90 Re: 6C33C SE-OTL Project

Post by brommermartin »

Oke :wink: I have found A pair of Kemet /Rifa 6800uf 160vdc at a local dump shop for 8 euro a piece :D
Hopefully they sound as good as they look :mrgreen:
If all goes wrong the speakers should be safe !
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