Remember These?

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steve s
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Re: Remember These?

Post by steve s » Sat Nov 23, 2019 12:11 pm

jack wrote:
Fri Nov 22, 2019 9:53 pm
Interesting. My understanding of NFB is that it relies on a constant180° phase shift, so if the DUT is not phase linear across the working bandwidth (which pretty much no power amp is), distortion will be introduced....

Phase linear amps are very specialised and expensive...
Morgan agreed when I had a good chat about power supplys contaminating the signal through multiple valves connected to it.
we also agreed feed back was similar in effect.. It cancels or alters the original signal.. But by how much is amplifier dependant...So it's not a guide to how good an amp sounds.?
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Nick
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Re: Remember These?

Post by Nick » Sun Nov 24, 2019 11:53 pm

Just thought, the talk of 180 is maybe confusing matters. For feedback to be useful, there needs to be effectively 0 deg phase shift between the input and output in the range of frequencies of interest, the feedback is then compared to the input. Its the act of comparison that gives the illusion of 180 deg being involved. What it actually is is a - sign.
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Ray P
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Re: Remember These?

Post by Ray P » Sun Jan 12, 2020 8:45 pm

Cressy Snr wrote:
Fri Nov 22, 2019 10:35 pm
I’ve done a lot more work on the OTL, than I’ve documented in this thread, and a year is the longest I’ve kept my attention on a project.
Hi Steve when you come to rework your 13E1 amp would you be interested in the PCBs I was going to use for mine before I switched back to using 6SN7s? I need to declutter.

I thought they might be interesting to you because they include my (untested, but as per the schematic) clone of the K&K Audio constant current sink - the rest is as per schematics IIRC. The two halves of the input/driver valves can be powered seperately by just removing a wire link so they'll work well with your multi-stage power supply arrangements. If you want the Mundorfs we can work something out otherwise, I'll whip them off and you can have the boards for the cost of the postage?

Image

No problem if they're not of interest - just thought I would ask before recyling them.

Ray

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jack
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Re: Remember These?

Post by jack » Sun Jan 12, 2020 9:06 pm

Ray, are those boards 2oz or 1oz?

I only ask as the 13E1 heaters are 5.2A at 6.3V, so for a 1oz board that'd be a minimum of about a 8mm or 310mil trace and half that for 2oz...

It's a lot of current for a PCB... Wire jumpers?
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Nick
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Re: Remember These?

Post by Nick » Sun Jan 12, 2020 9:20 pm

I only ask as the 13E1 heaters are 5.2A at 6.3V
I don't think the output valve heater circuit is on that PCB just the driver stage.
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jack
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Re: Remember These?

Post by jack » Sun Jan 12, 2020 9:24 pm

Nick wrote:
Sun Jan 12, 2020 9:20 pm
I only ask as the 13E1 heaters are 5.2A at 6.3V
I don't think the output valve heater circuit is on that PCB just the driver stage.
Ah!
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Ray P
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Re: Remember These?

Post by Ray P » Sun Jan 12, 2020 9:47 pm

Nick is correct Jack, the 13E1 sockets are 'off-board' - the PCBs have the input/driver stages precedng the 13E1 but then also have the output caps and current sinks 'after' the 13E1.

Anyway, 13E1 filaments are 26V @ 1.3A or 13V @ 2.6A. You may be thinking of 6C33Cs, which are 12.6V @ 3A or 6.3V @ 6A?

Cressy Snr
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Re: Remember These?

Post by Cressy Snr » Sun Jan 12, 2020 10:23 pm

Ray P wrote:
Sun Jan 12, 2020 8:45 pm
Cressy Snr wrote:
Fri Nov 22, 2019 10:35 pm
I’ve done a lot more work on the OTL, than I’ve documented in this thread, and a year is the longest I’ve kept my attention on a project.
Hi Steve when you come to rework your 13E1 amp would you be interested in the PCBs I was going to use for mine before I switched back to using 6SN7s? I need to declutter.

I thought they might be interesting to you because they include my (untested, but as per the schematic) clone of the K&K Audio constant current sink - the rest is as per schematics IIRC. The two halves of the input/driver valves can be powered seperately by just removing a wire link so they'll work well with your multi-stage power supply arrangements. If you want the Mundorfs we can work something out otherwise, I'll whip them off and you can have the boards for the cost the postage?

No problem if they're not of interest - just thought I would ask before recyling them.

Ray
Hi Ray, You’ve already sent me two of the boards with the K&K CCS clone incorporated, but thanks for the offer. :)
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Ray P
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Re: Remember These?

Post by Ray P » Mon Jan 13, 2020 6:32 am

Ah, forgot that Steve. :oops:

These ones are populated (sans Mundorfs). Anyway, I'll see if any one else is interested otherwise they'll go into the box for the recycling centre.

Max N
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Re: Remember These?

Post by Max N » Mon Jan 13, 2020 8:06 am

Hi Ray
Is there a link to the circuit anywhere?
They might be just what I need for something I am working on
Cheers
Max

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Ray P
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Re: Remember These?

Post by Ray P » Mon Jan 13, 2020 8:26 am

Max N wrote:
Mon Jan 13, 2020 8:06 am
Hi Ray
Is there a link to the circuit anywhere?
They might be just what I need for something I am working on
Cheers
Max
Hi Max, below is Steve's schematic that I used for setting out the PCB;
steves circuit.png
Apart from the anode resistors for the 6H30pi halves it doesn't include any power supply parts (my PS was different, lifted straight from my Transcendent 300B SE-OTL) and has the K&K current sink instead of the TL783 (though you could use that if you wanted). Obviously the Septal socket parts are off-board. The tube socket is a teflon type, soldered to the PCB - I designed it as the means of mounting the board and clamping the socket to the chassis top plate. I must emphasise that I've never used/tested the boards, though Steve has been using an earlier version (sans K&K current sink) in his build that this thread is about.

Ray

Max N
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Re: Remember These?

Post by Max N » Mon Jan 13, 2020 7:42 pm

Thanks Ray, I’m just trying to figure out if I could adapt them a bit.....

Max N
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Re: Remember These?

Post by Max N » Mon Jan 13, 2020 11:35 pm

Hi Ray
The circuit I want to try is too different so I’ll pass, but thanks for the offer. Hopefully someone else can use them. They’re nice boards. Would be a shame to recycle them.

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Ray P
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Re: Remember These?

Post by Ray P » Tue Jan 14, 2020 6:13 am

No problem Max.

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