The Other 13E1 SE-OTL

What people are working on at the moment
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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Tue Aug 06, 2019 2:10 pm

Yes, I've been very tardy with it - something to do with the time of year I think.

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Tue Aug 06, 2019 10:11 pm

Ray P wrote:
Mon Aug 05, 2019 11:36 pm
Tomorrow I just need to finish hooking up the switch and LED, check everything and put the lid on it.
Bugger! Did that except I couldn't find a resistor of the right sort of value for the LED current setting so still not fitted the lid! Collecting one from a mate on Thursday so tomorrow I'll move on to the remaining work for the amp chassis.

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Sat Aug 10, 2019 1:12 pm

Soldered the LED resistor into the power supply chassis this morning, checked all the connections are correct and secure, powered up, checked/tested, fitted the lid - job done!

Now for the amp chassis.

Cressy Snr
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Re: The Other 13E1 SE-OTL

Post by Cressy Snr » Sat Aug 10, 2019 2:29 pm

Ray P wrote:
Sat Aug 10, 2019 1:12 pm
Soldered the LED resistor into the power supply chassis this morning, checked all the connections are correct and secure, powered up, checked/tested, fitted the lid - job done!

Now for the amp chassis.
Switch-on getting nearer then. :D
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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Sat Aug 10, 2019 4:21 pm

Cressy Snr wrote:
Sat Aug 10, 2019 2:29 pm
Switch-on getting nearer then. :D
Yes, indeed Steve.

Inside of the power supply chassis;

Image

Pretty boring with the lid on;

Image

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Sat Aug 10, 2019 4:27 pm

Two PCBs in the first picture are;
  • top-right - One of Nick's mains DC blockers
  • bottom left - A K&K Audio switch on delay, turns on B+ transformer 60secs after front panel on/off switch is pressed (blue LED built into the on/off switch turns on when B+ powers up)

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Ali Tait
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Re: The Other 13E1 SE-OTL

Post by Ali Tait » Sat Aug 10, 2019 4:38 pm

Looking good Ray, very tidy as usual.
Image[/img]

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IslandPink
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Re: The Other 13E1 SE-OTL

Post by IslandPink » Sat Aug 10, 2019 5:02 pm

Interesting stuff. Also, so smart it's almost ... now.. what's the word ?
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Mon Aug 12, 2019 10:45 pm

Another step forward, I soldered up most of the parts for the driver PCBs today (sorry, not a great quality picture).

Image

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Mon Aug 12, 2019 10:49 pm

Showed the value of checking before soldering today; I had four resistors all look identical and all clearly labelled as 10K, the problem is that only three of them measured as 10K, the other is 1K! Something went wrong somewhere in the factory :roll:

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Paul Barker
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Re: The Other 13E1 SE-OTL

Post by Paul Barker » Tue Aug 13, 2019 9:59 am

You’re vigilance at this stage has saved us all from a thread fault finding it later which may have taken some time to zero in on.
I can do it right or I can do it now, but I can't do it right now.

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Sun Aug 25, 2019 12:21 pm

Bugger! I was hoping to get everything assembled today, and maybe powered up, but a momentary lapse in concentration has scuppered that plan - I soldered one of the small transisters in the Cathode current sinks to the wrong pads and don't have a spare. C'est la vie. :x :oops:

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Ray P
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Re: The Other 13E1 SE-OTL

Post by Ray P » Sun Aug 25, 2019 12:28 pm

As I'll be using my amp with my 15ohm Lowther's I want to experiment with the feedback as per Wolfgang's experience with his 6C33C build so I've soldered a couple of header pins to the feedback resistor pads so I can easily attach multiturn pots (20K) to find the sweetspot. Once found I'll whip out the pots and solder some decent resistors across the pins.
Last edited by Ray P on Sun Aug 25, 2019 2:06 pm, edited 1 time in total.

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Re: The Other 13E1 SE-OTL

Post by Cressy Snr » Sun Aug 25, 2019 12:47 pm

Ray P wrote:
Sun Aug 25, 2019 12:21 pm
Bugger! I was hoping to get everything assembled today, and maybe powered up, but a momentary lapse in concentration has scuppered that plan - I soldered one of the small transisters in the Cathode current sinks to the wrong pads and don't have a spare. C'est la vie. :x :oops:
Ahh...the birth pangs of bloody OTLs! Glad it isn’t just me. :)
It’ll be worth the hassle though.
Last edited by Cressy Snr on Sun Aug 25, 2019 12:52 pm, edited 1 time in total.
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Cressy Snr
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Re: The Other 13E1 SE-OTL

Post by Cressy Snr » Sun Aug 25, 2019 12:50 pm

Ray P wrote:
Sun Aug 25, 2019 12:28 pm
As I'll be using my amp with my 15ohm Lowther's I want to experiment with the feedback as per Wolfgang's experience with his 5C33C build so I've soldered a couple of header pins to the feedback resistor pads so I can easily attach multiturn pots (20K) to find the sweetspot. Once found I'll whip out the pots and solder some decent resistors across the pins.
Good idea.
As Wolfgang said, and I have subsequently found; the difference between optimum and non-optimum feedback levels is not subtle with these amps. In fact, with SEOTLS like these, any sort of change is very audible indeed.
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