Forums - Print Page

Forums
https://www.decware.com/cgi-bin/yabb22/YaBB.pl
AUDIO FORUMS >> General Discussion and Support >> Volume loss at warm up.
https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1521644477

Message started by Archie on 03/21/18 at 16:01:17

Title: Volume loss at warm up.
Post by Archie on 03/21/18 at 16:01:17

I noticed something odd last night. I powered up my audio chain: TT-ZMC1-ZP3-CSP3-ZROCK2-ZMA-HR1 and immediately started listening to music. About 1/3 way through the first side, I noticed a loss of volume equivalent to one or two clicks of the CSP3 outputs. I then bypassed the CSP3 and ZROCK2 but other than a loss of density, the volume stayed the same. So, these two components don't seem to be the issue.

Does anyone have an idea what could cause this? I'm thinking it might be tube related but it happened on both channels. My sound quality wasn't affected. I think I've been having this for a while but I've never caught the moment before, I just had a sense that things weren't as loud as when I started listening.

Any suggestions before I start swapping tubes?

Title: Re: Volume loss at warm up.
Post by Lon on 03/21/18 at 17:54:35

Puzzling. . . . In someways this is similar to how my Taboo Mk IV seems pre-warm up and warmed up. It's thicker and richer and slower for the first half hour to hour and then opens up and blooms and can seem a bit louder as a result, though it's not, it's just more dynamic and quick. But you would be noticing that in your amp for some time and it wouldn't be something that starts happening. . . .

Title: Re: Volume loss at warm up.
Post by Archie on 03/21/18 at 18:21:11

Unlike your Taboo getting louder with warm up, I lost volume.

I'm wondering if it has something to do with the Russian 6N5P tubes I recently started using. I'll be listening more closely going forward. To me it makes sense that it has to do with heating of something either in the ZP3 or the ZMA. I haven't changed the ZP3 tubes recently so my guess is the ZMA.

Title: Re: Volume loss at warm up.
Post by Lon on 03/21/18 at 18:33:19

Actually I just wrote my post wrong, it appears less loud warmed up because it opens up and becomes less "compressed sounding."

It may be that tube. I bought 8 and so far have used one a few weeks in the Taboo Mk III with headphone use, and I put that tube in the Taboo Mk IV and listened via speakers yesterday. . . and took it out today. Just a bit too crisp for my system.

Title: Re: Volume loss at warm up.
Post by Archie on 03/21/18 at 18:43:25

If that tube, then would it just be a characteristic of that tube or a faulty tube? Maybe Steve would know?

Title: Re: Volume loss at warm up.
Post by Lon on 03/21/18 at 19:10:49

Likely a fault in that tube if it is the tube. . . .

Title: Re: Volume loss at warm up.
Post by Archie on 03/21/18 at 23:56:51

Lon, I asked Steve and here is his reply:

Quote:

It is characteristic of a tube that tests bad to work momentarily until it warms up, so my money is on a tube. Probably one in the phono stage.

Steve

So, good call. I'll check these tubes first since they were NOS at best. It's always a tube! Except, when it's not. :-?

Title: Re: Volume loss at warm up.
Post by Lon on 03/22/18 at 00:36:35

Steve knows. . . let us know what you discover.

Title: Re: Volume loss at warm up.
Post by maddog07 on 03/22/18 at 18:07:12

I had a JJ 6CA7 in my Torii that exhibited very similar symptoms. It didn't sound "bad", it appeared to be lit up the same as the others, it just had less gain/volume from the channel it was in after the amp had been on awhile. This symptom gradually became worse. Since there are two of these tubes in each push-pull channel of a Torii, I didn't have a way to tell which one of the pair - I don't have a tube tester. The way I figured out which one was bad, was with an infrared temperature thermometer gun (cheapy from Harbor Freight works great)... powered up and running 3 of the 6CA7's were within 20 degrees of each other, and one was a 100 degrees cooler... that was the bad tube.

Title: Re: Volume loss at warm up.
Post by Archie on 03/22/18 at 19:50:42

Maddog, that's interesting. Now I'm wondering about my output tubes on the ZMA. I have the meters though and they are still rock solid. I'll have to watch at startup to see if one lags.

I've changed some tubes in my ZP3 but so far I haven't found the culprit.

Title: Re: Volume loss at warm up.
Post by Archie on 03/23/18 at 16:42:26

I've changed all the tubes in the ZP3 and I'm still getting the volume drop. I even turned of the ZMA for an hour or two while leaving everything else on but when powered up and warmed up the volume remained constant. I've got a couple more tests to try but so far, I'm still perplexed. Next, I'll play a CD and leave the ZP3 off. If I don't get a volume drop then that should narrow it down to the ZP3, even if it's not a tube.

Title: Re: Volume loss at warm up.
Post by Archie on 03/24/18 at 18:07:18

After changing every tube in my ZP3 and CSP3 with no apparent effect on the volume loss, I changed the output tubes on the ZMA and I think I may have found the culprit. While the bias of the existing outputs remained rock solid, when I switched tubes, the left channel was WAY off whereas the right channel was almost spot on. So, my preliminary conclusion is that one or both of the left channel tubes were getting tired. I'll see if this is in fact correct over the next few days. In the meantime, does anyone have a lightly used quad of 6P3Ss that they tried but want to sell? A quad from Cryoset would be prefered.

Title: Re: Volume loss at warm up.
Post by Archie on 03/25/18 at 18:40:09

Okay, I finally figured this out. First, I must have had a brain cramp when I first "isolated out" the CSP3 and ZR2. In fact, I had only taken the ZR2 out of the chain. It turns out that I'm having CSP3 issues. It has something to do with the headphone jacks since the loss of volume is exactly the same as the loss when headphones are plugged in and the speakers are left playing. I noticed, months ago, an issue with my left channel with headphones but I ignored it since headphones are never used. I had also noticed an occasional crackle at start up in the left channel speaker but I attributed this to a tube. I'm now convinced that this is not a tube issue but rather something inside the CSP3. I'll likely be sending it in for service. In the meantime, I'm running direct from the ZP3 into the ZR2 into the ZMA and I don't miss the CSP3 at all -- the ZR2 gives so much weight on it's own.