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May 31, 2020, 06:47:48 AM

Author Topic: S.E.X. amp seconde hand  (Read 567 times)

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Offline oguinn

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Re: S.E.X. amp seconde hand
« Reply #30 on: May 23, 2020, 09:02:19 AM »
Oh lord, thank you: I am in the learning mode now.

Will do the measurements again.

We were all new at this at one point in time or another. I still mess at least one thing up per build.
Jameson O’Guinn

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Online mwgrient

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Re: S.E.X. amp seconde hand
« Reply #31 on: May 23, 2020, 09:03:56 AM »
 :)

Offline Oyvindk

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Re: S.E.X. amp seconde hand
« Reply #32 on: May 23, 2020, 12:11:39 PM »
Hi.
I buildt this amp 6 years ago and recently sold it to mwgrient. I am not an experienced amp-builder, but it worked fine all the time I had it. If anyone is interested, here is the building process documented (in Norwegian, but with many pictures)  link was not allowed, but google  “
hifisentralen Bottlehead Single Ended eXperimenter's kit“ and the thread should appear.

I listene to the amp for two hours (no issues) before it was double-boxed and shipped. Obviously, something must have happened during shipping, and therefore my first suspicion would be (besides damaged tubes, which was  ruled out) a bad solder joint, as Doc B mentioned.

The amp is wired for 8ohm output as I mainly used it with horn speakers.

Online Paul Birkeland

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Re: S.E.X. amp seconde hand
« Reply #33 on: May 23, 2020, 03:52:49 PM »
So far there isn't any indication that there's an issue with the build.  It could simply be some external interference. 
Paul "PB" Birkeland

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Online mwgrient

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Re: S.E.X. amp seconde hand
« Reply #34 on: May 23, 2020, 09:59:35 PM »
I have tried to eliminate interference. Other room, divert power cable and wall-plug. Shutting down the computer. Nothing.

I can hear music, but when the volume is turned off, de loud signal is back. I will try to install the noise eliminator.

Online mwgrient

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Re: S.E.X. amp seconde hand
« Reply #35 on: May 23, 2020, 10:57:11 PM »
Here is a link to my amp, with a sample of the sound it gives true my headphone left channel.



regards, Marco.
« Last Edit: May 23, 2020, 10:58:57 PM by mwgrient »

Online mwgrient

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Re: S.E.X. amp seconde hand
« Reply #36 on: May 24, 2020, 01:49:30 AM »
Hi all, I have soldered the sockets lower than they where soldered. And re-soldered all the ground wires/points again and again. There is no oscillation anymore!
Only a faint hum when I connect my headphone; It is also there when the volume is turned down//closed.

Offline Tom-s

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Re: S.E.X. amp seconde hand
« Reply #37 on: May 24, 2020, 02:20:08 AM »
Glad it worked out!

I have soldered the sockets lower than they where soldered.

To further explain to others on this forum.
What you've done here is relocate the grid stoppers closer to the socket pins (1,4) of the tube as a preventive measure for oscillation.


Now enjoy it!
Let us know how you like the SeX 2.1!

Online Paul Birkeland

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Re: S.E.X. amp seconde hand
« Reply #38 on: May 24, 2020, 06:15:06 AM »
Oh man, that's quite a noise! 
Paul "PB" Birkeland

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Online mwgrient

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Re: S.E.X. amp seconde hand
« Reply #39 on: May 24, 2020, 07:21:01 AM »
Yeah! It is still not quiet, but doing a lot better now. Pffiew!

I would like to replace the potentiometer, jack socket and RCA terminals.

Does someone know where to get the distinctive Bottlehead knop?

Online Paul Birkeland

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Re: S.E.X. amp seconde hand
« Reply #40 on: May 24, 2020, 07:32:28 AM »
I would like to replace the potentiometer, jack socket and RCA terminals.
Why?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Online mwgrient

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Re: S.E.X. amp seconde hand
« Reply #41 on: May 24, 2020, 07:41:03 AM »
The RCA sockets are fried, at least one. And do not look nice anymore. My fault!
The potentiometer gives noise at the end of the volume (almost open wide)

The big black knob is not detachable since the screw is broken that will hold him in place.

Online Paul Birkeland

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Re: S.E.X. amp seconde hand
« Reply #42 on: May 24, 2020, 07:45:51 AM »
The potentiometer gives noise at the end of the volume (almost open wide)
This is a function of the high input impedance of the amp, not the pot itself.
The big black knob is not detachable since the screw is broken that will hold him in place.
Hmm, you'll have to maybe melt it off then to get it off. 

https://no.mouser.com/ProductDetail/Eagle-Plastic-Devices/45KN014-GRX?qs=EiTGd8sy9OrVz4TOJLy7AQ%3D%3D
Paul "PB" Birkeland

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Offline Deke609

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Re: S.E.X. amp seconde hand
« Reply #43 on: May 24, 2020, 08:24:11 AM »
you'll have to maybe melt it off then to get it off. 

 A really small diameter extractor bit might work - and then you'd be able to use the knob again, provided you can find or make a replacement set screw. Failing that, I'd drill it out with regular bit made for metal.

cheers, Derek
Derek
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Offline Doc B.

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Re: S.E.X. amp seconde hand
« Reply #44 on: May 24, 2020, 05:46:45 PM »
Ever tried to melt one? I have not, but I think maybe they are bakelite and won't melt.
Dan "Doc B." Schmalle
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