[gerado]

Damn
Now Im almost as obsessed to find the noise as if its on my own GK

Brad have you opened the hood of the GK while playing and with an insulated probe pushed down at various points on the IC board? If its a loose joint/component it may just go away if you bend the board slightly and at least give you a clue what you should be looking for. Also wiggling any of the wires inside .

(I know I have taken the real high tech approach here  )

[PSP]

I haven't had any trouble with my GK-1, but I can vouch for the effectiveness of Caig Pro-Gold for cleaning contacts (there is also a De-Oxit for cleaning "ordinary metal" (i.e., not gold) contacts).

8+ years ago I had a problem with intermittent contacts:
http://db.audioasylum.com/cgi/m.mpl?forum=cables&n=11129&highlight=Thorens+Pro+Gold+PSP&r=  The Thorens headshell is still absolutely quiet, and I've never had to apply a second treatment of Pro Gold.

Be sure to wipe off any excess liquid.  I expect that this is especially important given that the tube sockets get so hot.

Peter

[RonR]

Brad,

PM me your address and I'll send you a pair of Valve sockets as supplied by Hugh.

Cheers,

Ron.

[andyr]

Brad,

PM me your address and I'll send you a pair of Valve sockets as supplied by Hugh.

Cheers,

Ron.

Aah, but did Brad already use tube sockets supplied as part of the GK-1 kit or buy his own?

Regards,

Andy

[AKSA]

Thanks Guys,

And particularly Ron, that was very kind of you!

Brad, keeping truckin' on......

Hugh

[Builder Brad]

Ron,

You are a star, I was just about to order some replacement valve bases. My GK1 is standard with the bases as supplied by Hugh.

All of this fiddling has got me all twitchy and looking for something to tweak!, and as I did not have the parts to sort out the GK1, I have now added the 1uf Auricaps to my AKSA55 - and that now has a problem! but thats another story/post.

PM on its way RON

[Builder Brad]

Hugh,

I will try to keep on the straight and narrow, unfortunately everything seems to be going wrong. I have now damaged my AKSA55.

Brad

[jules]

aagh Brad, the gods of audio tweaking certainly aren't on your side at the moment. You clearly have to do a lot more of it to get your hand back in  .

Given what you've said earlier it does sound as though you're on the right path replacing the valve base but, a question ... you said you leave the GK-1 on and you said the tubes feel loose in the base. I suppose it could just be time/heat that's caused the problem but is there any reason that your GK-1 could be getting too hot, thus accentuating the problem? Would improved ventilation help next time around?

Jules

[AKSA]

Brad,

You should be proud of your failures.....  they are the benchmarks of ultimate success, and without them, there is no achievement.

Learn to recognise the tombstones in the silicon crematorium, look for smoke.  Behind every smoky device, there is a story, a cost, and a well earned lesson.  We learn by mistakes rather than triumphs, welcome to the school of silicon knocks!!

Cheers,

Hugh

[Builder Brad]

Hi Jules,

I have considered playing with the layout of my GK1 in order to get the tubes o the outside, you do have a point as the tubes currently sit in a realtively closed in area with minimal ventilation - and they are horizontal!

Hugh,

Wise words, I just dont want to make all the mistakes, having said that the silicone is relatively cheap its those Seas drivers that would of really hurt!

Brad

[stvnharr]

Hi Jules,

I have considered playing with the layout of my GK1 in order to get the tubes o the outside, you do have a point as the tubes currently sit in a realtively closed in area with minimal ventilation - and they are horizontal!

Hugh,

Wise words, I just dont want to make all the mistakes, having said that the silicone is relatively cheap its those Seas drivers that would of really hurt!

Brad

Brad,
The quicker you make all the mistakes, the quicker that you learn.
This has often been my modus of operation.
At least with the GK-1 I'm only train ride away from the doctor.  Although once it went bad on the train when I was coming to show it off to the doctor.
Just keep at it, it's never fatal.

Steve

[Builder Brad]

The saga continues........

Big Thank-you to Ron for kindly sending me a spare set of valve bases.

I have now replaced what I thought was the faulty base and the sound is still there, although slightly attenuated and it seems to only happen when I power the GK1 and then it settles down. It really sounds like the mains in-rush on really large torroids, with the added LF content that moves the woofers on my Orions almost to their max excursion. The only time it disapeared was when I fitted the 1uf Auricaps in the C19 position. I have resoldered all of the joints near the valve bases, just in case, and am stuck again!

Could this be caused by the PS caps? As I have a working 1/2 of the amp I have a few options to test this out.

Brad

[AKSA]

Brad,

Are you absolutely sure with the sub-out test that this is the tube only?

If yes, then the next port of call would be the phase inverting transistor, the MPSA42.  Resolder all the joints.....

BUT, it does sound thermal.  This points to the tube, or its power supply.  Swap out the power caps, that might reveal something.

If NO, then the next issue to address would be the SS section.

Hugh

[Builder Brad]

Thank-you Hugh,

I have already resoldered the transistor, so I will look at the PS caps as sugested. What is really frustrating is that the tube section of the GK1 is so simple, there is so little to really investigate and yet this has taken up so much time! the output from the SS section is ok - my money is on the PS!

I am about to order some parts from RS Components, could you advise on replacement PS caps for the GK1 that are comparable, or better, that the std parts, please?

I would normally go with the Panasonic FM or FC, but am open to alternatives.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=capacitors

Brad

[AKSA]

Brad,

They would be fine, I use United chemicon, 120uF 315VW.

What is intensely frustrating is that if I had the freakin' thang on my workbench I could probably identify the problem in minutes.

However, before you go that route change C20, the 4.7nF 100V cap on the phase inverter.  It's cheap and it might just be the problem....

You have replaced C19?  Another to consider is C22, the 22nF filmcap which drives the drone cathode follower.  That too is cheap, where the filter caps are all quite pricey and I would not think are gone south anyway.

Hope this is helpful,

Hugh

[Builder Brad]

"What is intensely frustrating is that if I had the freakin' thang on my workbench I could probably identify the problem in minutes."

that does not make me feel any better!!!!!!!!

thank-you for the sugestions, on a + note with all the practice I have now got under my belt, de-soldering and replacing components is no big deal now.

Brad

[AKSA]

Brad,

Be kinder to yourself......  I designed the friggin' thang, so if I couldn't fix it, I'd be a right idiot.....  this is supposed to be my area of expertise, and I can't do it very well by remote control, I am very sorry.

Hugh

[Sparks]

Brad,
Whilst I have been following this thread off and on, I just had a complete read thru of the whole thing.  I've had quite a few abnormalities myself in the GK-1.  I don't recall you mentioning it, but do you have music in the one channel with the noise?  The noise you described sounds to me like a bad solder joint somewhere. You also mention some difficulty with soldering, and I think you may have some of that worthless lead free stuff that flows poorly wicks up poorly and makes crummy joints.  While that might not be the problem, it's not helping either.  You need to find some way to isolate the offending part or joint.  If you are certain that the issue is in the tube stage, and you've replaced the tube sockets, then swapping ONE part from the good channel to the other should eventually locate the issue.  This may sound very time consuming, but look at how much time you've already spent on this.  The random search for an easy solution has not worked.  I would start at the rca connections at the output and work backwards up the circuit.  If you don't want to swap out parts, just get new parts and or something.  But you need a systematic way of going thru this, or I think it will plague you forever. OR, you can just forget about the tube stage.  Your ears will adjust to the ss in a few seconds and you'll be fine.

Steve

[AKSA]

Hi Brad,

Good advice Steve, thank you!  A few more tips, hopefully useful:

#1  If the problem only shows after some period of playing, then it's likely thermal.  First port of call:  the tube, and surrounding solder joints.
#2  Piecemeal replacement, component by component, is best if you choose the 'hit 'n miss' approach, which is forced upon you now.  Replacing two things at a time does NOT reveal which was causing the problem.
#3  Don't overlook power caps on the HT supply, particularly C18.  We have up to 210V in this supply, the caps are large, and they are under heavy ripple stress.
#4  Be very sure to pinpoint the problem in the tube section, NOT the SS section.
#5  There are carbon grid stoppers on the tube;  R22 and R30.  Occasionally carbon resistors can fail, giving symptoms you describe.

Hope this points you along the way.....  I'm sorry you are having problems.

Cheers,

Hugh

[stvnharr]

Brad,
Steve

I became Sparks for a post.

Steve