RED ALERT! Tube amp popping! WTF!

[Ern Dog]

So I'm listening to John Coltrane's softer side when I start hearing this intermittent popping sound coming from my left speaker. The popping that sound similar to listening to old scratched records. WTF!?

I turned off the cdp and it continued. I checked the bias for my 4 power tubes and they were all in range. I replaced my left 12ax7 input and left 6SN7 and still didn't solve the problem. Any ideas what this could be? :confused:

[F1nut]

Bad tube in the pre amp.

[Ern Dog]

Bad tube in the pre amp.


I considered that, but the Modwright only uses one tube, so I figured if it was going out then the popping would be coming out of both speakers.

[nooshinjohn]

So I'm listening to John Coltrane's softer side when I start hearing this intermittent popping sound coming from my left speaker. The popping that sound similar to listening to old scratched records. WTF!?

I turned off the cdp and it continued. I checked the bias for my 4 power tubes and they were all in range. I replaced my left 12ax7 input and left 6SN7 and still didn't solve the problem. Any ideas what this could be? :confused:




this I why I like solid state:p


In all seriousness, good luck with solving your troubles, as I know how bad it sucks trying to get the listen on and something just don't sound right...

John

[F1nut]

The tube has two sections, one driving the right, the other the left. One triode can go bad while the other is still ok.

[SCompRacer]

Ern, all the SWL 9.0's I've seen have two tubes (5687's / variants), one for each channel. If equipped with the optional tube regulated power supply, the PS would have a single tube (5AR4 / GZ34), along with two 5687's for the R and L channel. Power down and swap the R & L channel tubes, see if the problem moves.

Just a FYI, Dan has a power supply upgrade taken from his flagship 36.5 pre for the 9.0 power supplies. It is well worth the investment. I did both my SWLP pre amp and Sony ModWright 9100ES. Check out this thread (http://www.audiocircle.com/index.php?topic=67802.0) at AC for details.

[george daniel]

Question,, have you recently replaced in tubes in your power amp?

[AudioGenics]

just a thought
bad capacitor that is discharging.

[george daniel]

If it is an ocassional pop,, it could be a cap,, as I had the same issue with a tubed pre,,changed the tubes ,no effect, changed the output coupling caps,, problem solved,, let us know what the culprit is,when you find it. Good luck.

[Ern Dog]

Ok, I'll swap out the tubes in my pre amp when I get home from work today to see if that fixes it. I have no clue how to swap out caps, but I'll ask more about that later if needed.

Scompracer: I read your link and am very curious how this upgrade would sound. How much does it cost?

[reeltrouble1]

well I think the guys have pointed you in the right direction, the popping is frequently causes as the tube degrades and becomes microphonic normally this takes a very long time (around 10,000 hours) however some tubes give it up early, which simply means time for a new tube.

now I am not recommending you do this, but if you took say a pencil and with the eraser tapped on the body of a good driver tube you would hear some pop/thumping, some tubes more some less.

RT1

[F1nut]

Ern, all the SWL 9.0's I've seen have two tubes (5687's / variants), one for each channel.

Thanks Rich, I thought they had 2 tubes.

[SCompRacer]

Ern, the power supply upgrade comes from his uber option for the 36.5 6H30 tubed pre amp, an external dual-mono tube-rectified and tube-regulated power supply. He uses a solid state version of the tube-voltage-regulation circuits for the upgrade.

Per Dan:

These dual-discrete voltage regulation circuits incorporate actual error amp technology and constant current sources, allowing for VERY tight voltage regulation.

It just means more nuance in the output. More meat on the bones. He is getting $400 to upgrade existing 9.0 power supplies. Check this AC thread (http://www.audiocircle.com/index.php?topic=66958.0) for pricing, or send an email to Dan.


Thanks Rich, I thought they had 2 tubes.


Jesse, you are most welcome and correct about having two tubes! While some designs do only use only one side of a dual triode per channel, Dan uses both sides per channel. This means a bad tube will definitely act the same when swapping from right to left channel. Unfortunately, that also means no extended tube life by swapping tubes from right to left to use the other half.

[Ern Dog]

Well, I swapped the L & R preamp tubes to see if the popping shifts to the other speaker and it didn't.

I also emailed Rogue Audio and they indicated that even though the bias meter shows the correct range, that one of the power tubes could be the culprit. So I'm in the middle of trading each one out, one at a time.

This is definitely one of the down sides to having an all tube rig. Tracking down which tube is going out is a PITA. I'm still new at this and this is my first time doing this, so I'm hoping it gets easier and less time consuming as I get more tube savy.

[Ern Dog]

Ern, the power supply upgrade comes from his uber option for the 36.5 6H30 tubed pre amp, an external dual-mono tube-rectified and tube-regulated power supply. He uses a solid state version of the tube-voltage-regulation circuits for the upgrade.

Per Dan:

These dual-discrete voltage regulation circuits incorporate actual error amp technology and constant current sources, allowing for VERY tight voltage regulation.

It just means more nuance in the output. More meat on the bones. He is getting $400 to upgrade existing 9.0 power supplies. Check this AC thread (http://www.audiocircle.com/index.php?topic=66958.0) for pricing, or send an email to Dan.

Schweeet! Sounds perfect for me. I'll have to add this to the never ending list of things to buy.

[AudioGenics]

have you isolated the impulse/pop in a specific channel ( left or right ) ?

[Ern Dog]

Ok, I figured it out. It was one of the power tubes in my amp.

Thanks for all the help guys.

[george daniel]

Good for you,, I had a similar situation,,new set of tubes,, I finally isolated the tube,put it on a tester,,upon warmup it would flash on-off-on--light turning a light on-off-on--turns out it was a bad cathode to grid connection,,after warmup,it would disappear,, kudos to Jim McShane, who promptly replaced it.What brand/type was it?

[reeltrouble1]

I have special things I do with tubes that flash on and off, I can show you but I can't tell you here.

RT1

[george daniel]

Ted,,I don't even want to respond to that,,the mental picture is ,,,,,I have no words,,,, :eek:

I've heard about the things that you do to the little 7 and 9 pinners.

[Ern Dog]

Good for you,, I had a similar situation,,new set of tubes,, I finally isolated the tube,put it on a tester,,upon warmup it would flash on-off-on--light turning a light on-off-on--turns out it was a bad cathode to grid connection,,after warmup,it would disappear,, kudos to Jim McShane, who promptly replaced it.What brand/type was it?


One of my tube dealers is named Jim too. 1st rate guy if were talking about the same dude (I don't know his last name). For power tubes I'm using 4 Tungsol 6550's. Shoot! this is going to cost me at least $125 for a quad on the 'Gon.