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Offline borism

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output coupling capacitor
« on: June 14, 2017, 07:39:06 am »
Hi,

I have finally started putting together my Eros kit. First, a shout-out to Josh who has somehow managed to get all the right little parts and in the right number into the kit.

My question is regarding the outside foil orientation of the output coupling capacitors (for upgrading purposes). I assume they should be connected to the low impedance side of the circuit. What terminal numbers does that translate into and why?

Thanks!
Boris

Offline Sugar Man

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Re: output coupling capacitor
« Reply #1 on: June 15, 2017, 03:10:35 pm »
Not sure if this helps, but I asked this on the Stereomour II forum.  Make sure to read all the way through, because there was a bit of confusion (all caused by me)

http://bottlehead.com/smf/index.php?topic=9124.0
Mike "Stein" Ayotte

Current Gear:

Stereomour II w/ Jupiters and JJs
Rega RP6 w/ Audio Note IQ3 (MM)
Eros w/ Mundorf Silver Oils
Blumenstein Orcas and Subs

Paraglows (retired)
Quicksand
Quickie w/ PJCCS

Offline borism

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Re: output coupling capacitor
« Reply #2 on: June 16, 2017, 11:02:42 am »
Well, I've completed the amplifier. It passed all resistance and voltage tests and is currently playing - beautifully as I may add - in my system.

I have solved the outside foil capacitor question to the best of my ability, concluding that the low impedance terminals are numbers 9 and 10. They are connected to ground through the 47K resistors.

Here are a few pictures of my build.

The base is bubinga wood.

Boris

Offline Caucasian Blackplate

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Re: output coupling capacitor
« Reply #3 on: June 16, 2017, 11:37:06 am »
It's kind of funny, those terminals are generally the lowest impedance to ground, but you could plug your Eros into a load that's much less than 50K, then things get switched around.

Is that the stock alder base dyed/stained, or custom wood?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline borism

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Re: output coupling capacitor
« Reply #4 on: June 16, 2017, 11:46:25 am »
Thanks, it is a custom bubinga base I made to complement my Bottlehead system consisting of Stereomour, Crack and now Eros.

Boris

Offline Caucasian Blackplate

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Re: output coupling capacitor
« Reply #5 on: June 16, 2017, 11:49:10 am »
That's a nice looking trio!

Yeah, I was going to implore you to share the details of how you could get alder to look like that!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline borism

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Re: output coupling capacitor
« Reply #6 on: June 17, 2017, 04:14:33 am »
I am also wondering if there are any sonic benefits in upgrading the 0.1 uF capacitors on the shunt regulator board. I have some Russian FT-3 teflon capacitors sitting around.

Let me know what your experience is.
Boris

Offline Paul Joppa

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Re: output coupling capacitor
« Reply #7 on: June 18, 2017, 01:08:27 pm »
I recall a long time ago hearing an improvement with the 0.056uF FT-3 caps. Worth a try if you can find room for them.
Paul Joppa

Offline borism

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Re: output coupling capacitor
« Reply #8 on: June 19, 2017, 03:46:39 am »
Thanks Paul! I'll probably try it out. At this point I've put in some Telefunken EF86s and am enjoying the sound.

Boris

Offline borism

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Re: output coupling capacitor
« Reply #9 on: Today at 03:42:35 am »
One, hopefully, final step for this Eros build was replacing the electrolytic cathode bypass with film caps (Jantzen, 82 uF) and the 0.1 uF shunt board capacitors with same value Russian FT-3s. I was happy that everything fit and the amplifier works. I will need some time to hear if there is any detectable sonic benefit to this.

However, what a fun project!
Boris