droning sound in R channel- possible damage from moving

[kip.duff]

As mentioned earlier, I did substitute "known-good" tubes at positions C and D after accidentally reversing them. Did not have a 12AU7- but did some research and determined a 12AT7 (which I had) would substitute as a temporary test in position D. Had a good Sovtek 6922 for position C. As mentioned, there was no improvement or change. At that time, I ordered an NOS Amperex JAN 7308 for jollies. That tube is supposed to be a higher spec 6922 with "lower noise and microphonics". It arrived today and I installed it. The main problem of the helicopter noise is gone. With no music and preamp volume all the way up, I could still hear very faintly the helicopter noise in both channels- probably no different than before this event. I did some input switching while listening to a stereo LP, and I could listen to the same separated instrument thru either channel. My ears are telling me there may still be some sound quality and db reduction in the R channel- but not sure. And- if that's true, it could be from other components in my system. I have a speaker testing microphone and will do detailed testing when I have time.

I'm not seeing a clear smoking gun here- unless I thought I changed the 6922 and accidentally reinstalled the bad one (which I doubt). One possible explanation is I noticed that all the tubes were difficult to remove/install. The tubes have been in place since the build in 2019- and I don't think any of them had gold pins. The new Amperex output tube had gold pins. Anyway, I need to get some more pin cleaning lube (can't remember what I used to have)- and scuff in all the tube pins. I would also like to say that the Amperex tube seems to have made a significant sonic improvement. I have just ordered an NOS Sylvania (branded Baldwin for their organs) 12AU7 off eBay for position D.

Do you have a recommendation for pin lube/cleaner?

Thanks so much for your help.

 

[Paul Birkeland]

I would definitely not put a 12AT7 into the regulator section.

For pin cleaning, you can insert a tube into a magic eraser to remove a fair bit of oxidation. Definitely do not use Deoxit though!

 

[kip.duff]

I would definitely not put a 12AT7 into the regulator section.

For pin cleaning, you can insert a tube into a magic eraser to remove a fair bit of oxidation. Definitely do not use Deoxit though!

I don't know what "Magic Eraser" is: I'll research.

No liquid lube?

 

[bucketofguts]

The "Magic Eraser" is also an excellent stylus cleaner used correctly when you get Eros sorted out. I sometimes use a scalpel to gently scrape the valve pins for really tough oxidation.

 

[kip.duff]

The "Magic Eraser" is also an excellent stylus cleaner used correctly when you get Eros sorted out. I sometimes use a scalpel to gently scrape the valve pins for really tough oxidation.

Any advice for the female connectors in the tube sockets?

 

[kip.duff]

I would definitely not put a 12AT7 into the regulator section.

For pin cleaning, you can insert a tube into a magic eraser to remove a fair bit of oxidation. Definitely do not use Deoxit though!

I believe I have used Deoxit in the past. What is the downside of Deoxit? These tubes were very stuck in their sockets. I'm thinking of using gold plated sockets on all future builds.

 

[Paul Birkeland]

Deoxit reacts with some common materials used for plating things like RCA jacks and tube sockets, and it will actually create more corrosion than what you had, and that corroded mess will be conductive.

 

[kip.duff]

Deoxit reacts with some common materials used for plating things like RCA jacks and tube sockets, and it will actually create more corrosion than what you had, and that corroded mess will be conductive.

It's possible I used Deoxit on original assembly believing it would be protection against corrosion and help conductivity

I'm gonna try Magic Eraser and some sort of reamer for the sockets. I've heard mention of small dental picks.

I would still like to use some sort of anti corrosive lube during installation after cleaning- maybe some light dielectric grease applied to the pins with a small brush.

During my 50 years as a mechanic, some of the biggest problems I've run into have been caused seizures and corrosion requiring very difficult extractions of sheared off bolts and destroyed spark plug threads. In the case of bolts in aluminum, if assembled dry, after a certain amount of years, the bolts will not come out without ripping the aluminum threads with them. This always happens after the expiration of the original warranty. I NEVER install a bolt or spark plug in aluminum without applying anti-seize paste to the threads.

 

[kip.duff]

The "Magic Eraser" is also an excellent stylus cleaner used correctly when you get Eros sorted out. I sometimes use a scalpel to gently scrape the valve pins for really tough oxidation.

"Magic Eraser": the Mr. Clean abrasive sponges? Dry- or with liquid?

 

[bucketofguts]

The original "Magic Eraser" straight from the box is dry to the touch. I will have to look on the box if it contains some kind of cleaning agent/ chemical. I have never put any substance on mine.

 

[2wo]

Just use it dry, for 9 pin tubes just push the pins in a few times.
Or if you have something like scotchbrite, it’s a great low tech solution

 

[kip.duff]

The original "Magic Eraser" straight from the box is dry to the touch. I will have to look on the box if it contains some kind of cleaning agent/ chemical. I have never put any substance on mine.

You're talking about the Mr Clean product? I ordered a variety pack: one of the variety is "Foamy": I guess that one has dried soap that foams up when wet. Don't think I'll be using that one.

But- anyway you guys are talking about the Mr. Clean pads, dry, I assume? Plunge the pins in and out of the pad.

 

[Paul Joppa]

You're talking about the Mr Clean product? I ordered a variety pack: one of the variety is "Foamy": I guess that one has dried soap that foams up when wet. Don't think I'll be using that one.

But- anyway you guys are talking about the Mr. Clean pads, dry, I assume? Plunge the pins in and out of the pad.

Yes.

It's a Melamine foam; there's a good article on Wikipedia. Originally developed as an acoustical absorber and thermal insulator. It is fireproof, but also a source of microplastic pollution. Works because the pores are extremely small but the material is quite rigid.

 

[kip.duff]

Yes.

It's a Melamine foam; there's a good article on Wikipedia. Originally developed as an acoustical absorber and thermal insulator. It is fireproof, but also a source of microplastic pollution. Works because the pores are extremely small but the material is quite rigid.

There was mention of use on stylus. Release tonearm from its stand and drag across the stylus from right to left using the the VTF downforce?

 

[bucketofguts]

Just raise and lower into ME. No side to side. Are you pulling out leg?

 

[kip.duff]

I did not word that properly. What I meant was drag the abrasive across the stylus in the same direction as the record moves in relation to the stylus. Back to front is probably a better description of the motion. This is a procedure recommended by Linn. In the case of Linn they provided and/or recommended a high quality fine grit sandpaper. I cannot remember the specifics – but I do remember that it was green.

 

[Paul Birkeland]

I would still like to use some sort of anti corrosive lube during installation after cleaning- maybe some light dielectric grease applied to the pins with a small brush.

During my 50 years as a mechanic, some of the biggest problems I've run into have been caused seizures and corrosion requiring very difficult extractions of sheared off bolts and destroyed spark plug threads.

This is a tube amp that lives in a climate controlled and very dry environment that doesn't experience wild temperature swings, so treating the sockets may be more of a hassle than it's worth.