Crackling and hiss - Preamp tubes not seated right?
I've posted here before about the cracking and hiss I get from my Primaluna Dialogue Premium. It became very noticeable during listening last week, so I took another stab at trying to isolate it.
When the amp is on, but with out anything playing, I can hear a low hiss and an intermittent crackle - the volume knob does not effect it.
It was only happening in the right speaker, when I swap the speakers it stays, so I figure it has the be the amp.
I swapped the three preamp tubes in 1,2 and 3 positions with the tubes in 4,5 and 6 position and it moved to the other speaker, so I assume it's a preamp tube problem.
I swapped out the 6 Mullard CV4003 for the original stock tubes, and it's silent. That felt good to finally get ahead of the problem.
I started to swap back in the Mullards one at a time to see when the 'bad' tube appeared. Swapping into position 1 and 2 were good, but it came back on when I added a tube to position 3, so I went back down to positions 1 and 2, and it was there again! But it was silent before? Very frustrating. I went back to all 6 of the stock tubes and it's silent again.
So my question is this - could it be that the Mullards don't seat as well as the stock tubes, and there is some arcing and other interference getting through? Should I give the pins and sockets a cleaning? Any advice on how to do that? Maybe I need an adapter to go into the socket to seat the Mullards?
I also think this may be the source of some distortion I was hearing, particularly on piano at certain higher frequencies. Does anyone have any thoughts on that?
I was apprehensive about JJ tubes, I had read some posts about reliability. I retubed my Quicksilver Mid Monos with JJ EL 34, 12ax7, 6922 , and they have never sounded better. Incredible tone and huge soundstage .
I also put a JJ 6922 in my c-j Classic 2 SE but we'll see how long it stays quiet.... that thing eats tubes for lunch. So far so good, the stock EH tube and Gold Lions are the only ones that have lasted . None has sounded as good as the JJ 6922 . Many would argue the Gold Lion reissue is better , but the tone of the JJ has me hooked.
The CV4003 I purchased from Upscale were graded and matched and were their best tubes out of the lot. Four of the six tubes went microphonic within 4 months.
The Tube Audio Store tests every tube before it is sold and categorizes them so you know exactly what you are getting. The super low noise tubes are one or two in 100. Buying NOS tubes untested is asking for it. as you can see in this post.
For the price I paid for those 6 tubes, I would have been better off taking that money in 20 dollar bills and driving to the poorest area of town and give it away. I would have had more satisfaction
stereo5"I bought 3 Mullard CV4003 NOS tubes at a very high cost and both times , two of the three tubes went bad (noise) within 4 months"
NOS means "New Old Stock" and the vast, overwhelming majority of tubes so described are not new at all you can tell because they are sold in white boxes they are Old tubes that have been removed from old equipment!
Twice, I bought 3 Mullard CV4003 NOS tubes at a very high cost and both times , two of the three tubes went bad (noise) within 4 months. Uncle Kevyn at Upscale claimed the Rogue Cronus Magnum is very hard on tubes. After the second time of spending a small fortune for the 3 tubes, I gave up and went back to newly manufactured tubes.
Had the exact same problem with a Mullard CV4003 as the OP. The culprit is the tube. These tubes, which sound great...as another member posted, are getting on in years ( if they are NOS, which mine were). As such, i think they are not as ’durable’ as a lot of others. I sourced mine from a very well known tube supplier, yet one tube still had this problem. It is NOT the fault of the gear ( although the tube supplier always tells everyone that my preamp is hard on tubes....yeah right!).
Despite what I've read about JJ reliability, I decided to re tube with
JJ in my amps and pre and they have been rock solid so far and the tone
is perfect in my set up.
IMO/IME JJs are more reliable than any of the newer Russian made signal tubes.
I swapped the three preamp tubes in 1,2 and 3 positions with the tubes
in 4,5 and 6 position and it moved to the other speaker, so I assume
it's a preamp tube problem.
@stephenjess This is a solid indication that one of the three you swapped from left to right is the culprit. The thing is, when a tube is making crackling sounds, often it will be affected by physical handling- tapping on the tube can often make it stop- for a while. So I would swap the tubes one at a time! When the problem moves then you'll know which tube it actually is. Don't be fooled by it shutting up for a while- be patient.
I got the same problem with my quad 300b Gold lion , I bought them last year brand new, I decided to use them Feb 2019, last week I notice my left speaker does have crackling sound, When I replaced them with EH 300 B all back to quiteness, I will try to use all the tricks mention here, and rotate them, I think it will work...
I agree with Elizabeth, I've had same issue many times with newly purchased nos tube from very reputable dealers. If you take the tube and lightly tap tube pins on countertop, take tube out of amp tap the tube with a pencil it should clear up problem. If not there are other issues.
You can try taking 4-0 steel wool to the pins to clean them but I suspect your unit just does not like the Mullards. If you want the best tubes go here
http://www.tubeaudiostore.com/.
New Sensor makes some duds, regardless of whether they are branded Mullard, Tungsol. EH, etc... I have actually had better luck with EH tubes than any other brand made by New Sensor. Despite what I've read about JJ reliability, I decided to re tube with JJ in my amps and pre and they have been rock solid so far and the tone is perfect in my set up. Awesome tone, so good I don't want to mess with it . Prior to the retube I cleaned and tightened the tube sockets and it made a big difference and with new tubes both components are dead quiet. FWIW , I had two "Mullard" 12AX7 fail within 6 months and had a Tungsol 12AX7 go noisy after a few weeks. If they were real CV4004 , I would chaulk it up to the fact that NOS tubes have been cherry picked for years.... how many choice ones are left?
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