LSS - Couple of Issues - rattle and crackle/sound loss

[Jim_Cross]

Hi guys,

I bought a Lonestar Special 1x12 on eBay last week. Firstly, it sounds beautiful - what a great amp! However, there are a couple of issues which I need to sort out before a gig on Friday!

1. There's a rattle which I'm pretty sure is coming from one of the EL84s. I can hear it when I tap the top of the amp, and again when I tap one of the tubes when it's in place. Is the best bet to remove the tube, tap it and see whether it rattles? If it does, is there a guide anywhere to retubing the LSS?

2. Occasionly there seems to be a crackle, the sounds starts to drop out, then it comes back. I can't be 100% sure that it's the amp - it could be the guitar, cable or the amp. However, it seems odd that it's only started to happen since I started using the LSS. Any tips on tracking this down, or has anyone had a similar problem before? I've tried shaking the guitar, cables etc, and haven't managed to reproduce it like that.

Cheers!

Jim

 

[thom]

I would retube if it was me. LSS is cathode biased so you should be OK. If in doubt buy Mesa El84s, or tell your supplier you want Mesa compatible tubes. I would also consider getting a couple of pre amp tubes and try swapping out to see if the crackle goes away. Another thing to try tube wise, is swapping the EL84s around and use use the 15, (or 5) watt setting. In this setting only two (or one) power tube is functioning so if you have a bad power tube this would be a way of proving that by a process of elimination. The manual tells you which tubes are used in each power setting. You can eliminate the rectifier tube from the equation by setting the amp at 30 watts so try that as well and see if the crackling/weird stuff stops.

In my experience this kind of thing is usually due to bad tubes and with a bit of thought and trial and error you can usually find the culprit.

 

[djw]

I would retube if it was me. LSS is cathode biased so you should be OK. If in doubt buy Mesa El84s, or tell your supplier you want Mesa compatible tubes.

Picky detail, but isn't the LSS fixed bias like the LSC? Pretty sure it is... in which case you do need to be conscious about what you put in there, if for no other reason than for you to end up with something that sounds decent not too cold (for tone's sake), nor too hot (for tube lifespan's sake). You could play it safe and get Mesa-branded/approved tubes, or talk to a knowledgeable tube dealer and let them know what you have.

 

[Jim_Cross]

Thanks for the suggestions guys!
Unfortunately I'm not going to have a chance to get hold of the new valves before the gig. Given that I've had the problem occur in 5w mode, and maybe 15w mode, and I'll only be use 15w for the gig, I'm going to try swapping the two outer EL84s with the two inner EL84s, spray the pins with contact cleaner, and keep my fingers crossed! That way if it is a bad power valve it should be one that isn't used after switching them.
I'm still not convinced it's the amp. I played a lot last night - early on it happened a few times so I decided to start eliminating things. I took out the tuner and 1 lead and didn't hear the problem again for the next hour. Thinking I'd narrowed it down to the tuner or lead I played through the tuner and possibly dodgy lead into another amp for another hour and the problem didn't occur. It would be a lot easier to track this down if it happened more frequently!

 

[twally]

From what you have described it's a tube issue. Most likely an EL-84 power tube or 5Y3 rectifier tube-although I wouldn't rule out a pre amp tube.

You have a good plan switching the power tubes. This is the most likely culprit. If you still hear the sounds in 30 watt mode you know you have nailed the issue-a power tube.

JMHO,

TW

 

[Jim_Cross]

I managed to get a full revalve set delivered in time (the Watford Valves standard gain set), started taking out the old valves and quickly found the culprit for the rattling - two of the preamp valve covers are missing their rubber washers that sit between the valve cover and the chassis!
Now I need to run around trying to find a similar washer!

 

[thom]

I would retube if it was me. LSS is cathode biased so you should be OK. If in doubt buy Mesa El84s, or tell your supplier you want Mesa compatible tubes.

Picky detail, but isn't the LSS fixed bias like the LSC? Pretty sure it is... in which case you do need to be conscious about what you put in there, if for no other reason than for you to end up with something that sounds decent not too cold (for tone's sake), nor too hot (for tube lifespan's sake). You could play it safe and get Mesa-branded/approved tubes, or talk to a knowledgeable tube dealer and let them know what you have.

I wouldn't call that 'picky detail' at all. It's a very important distinction. The LSS is cathode biased however. There has been some debate about this on this forum. In a previous thread someone posted a link to an interview with Randall Smith which quotes him saying that the LSS is cathode biased. Also if you look at the product descriptions on the Mesa web site, pretty well all the amps have the 'fixed bias for maintenance free operation' blurb, except for the LSS. I also posed the question over on the gearpage, and a couple of techs confirmed that it is cathode biased.

 

[Chester]

Thanks for the suggestions guys!
Unfortunately I'm not going to have a chance to get hold of the new valves before the gig. Given that I've had the problem occur in 5w mode, and maybe 15w mode, and I'll only be use 15w for the gig, I'm going to try swapping the two outer EL84s with the two inner EL84s, spray the pins with contact cleaner, and keep my fingers crossed! That way if it is a bad power valve it should be one that isn't used after switching them.
I'm still not convinced it's the amp. I played a lot last night - early on it happened a few times so I decided to start eliminating things. I took out the tuner and 1 lead and didn't hear the problem again for the next hour. Thinking I'd narrowed it down to the tuner or lead I played through the tuner and possibly dodgy lead into another amp for another hour and the problem didn't occur. It would be a lot easier to track this down if it happened more frequently!

Good detective work Jim - I always went to tubes as the source of crackle or sound loss until I learned to check cables first. They are too often overlooked as a source of interference and signal loss in the chain, and I have now invested in the best I can find to avoid degredation. FX and connections can be the obvious offenders, followed closely by the instrument cable, but I overlooked the speaker cable as a source of tone drain for too long

Short length Monster Studio Pro 1000's fixed that for me - bomb proof so far 8)

 

[Sebber]

On the crackling: does it still happen when you hard bypass the FX loop?