LSS blew the fuse...

[ifailedshapes]

So, as much experience as I have with tube amps, this is the first time I've actually had a problem. The power light flickered for a second, then the amp totally lost power. I knew it had to be the fuse, and yup, I was right. I removed the power tubes, and one of them is obviously scorched inside, and after reading the manual, I guess shorts are one of the most common tube problems.

Now to my question: I don't know anything about cathode-biased amps, and I'm wondering if there are are particular rules I need to be aware of for tube replacement. I have a friend with a set of JJ's he is willing to let go of, but seeing as how they would be second-hand, there's no guarantee they would be matched for my amp. Again, with cathode-biasing, is this even an issue?

I'm going to be doing a lot of online research tonight, so hopefully I can answer my own question, but I'll gladly accept any advice you guys have to offer.

 

[screamingdaisy]

Cathode bias amps are self biasing. The stock tubes are relabeled EHX if it makes any difference to you. I have a set I'll send out with the slip cover. No cost as I don't have an EL84 amp any more.

 

[ifailedshapes]

Wow. Thanks, man. Nothing makes me quite as happy as free.

 

[plan-x]

You should get matching pairs of tubes. But it isn't absolutely neccesary to run the amp. I will just sound better. It might stress the circuitry more also.

 

[thom]

Hi

Although the LSS is cathode biased I would still exercise some caution when changing tubes. The guy I go to for JJs, (my favourite new production EL84), supplies tubes to Mesa specs. I once bought a set of military grade Sovteks from elsewhere and these were slightly red plating when I put them in the LSS. I am currently using a set of NOS Philips which are very nice sounding and holding up really well; the LSS can eat new production EL84s for breakfast.......So if you're using tubes not specifically spec'd for a Mesa amp I would just keep an eye on them for the first 1/2 hour or so just to check they're not getting too hot and you should be good to go.

How are you liking the LSS compared to the Stiletto? I would love to try a Stiletto!

 

[ifailedshapes]

Okay, thanks for the info, guys. What you have said affirms what I found in my research. Now for another spin:

Do you guys have preferred brands of EL84s? I see JJ's in plan-x's signature, but is that because of tone, reliability, or both? My friend thought he had JJ's, but they ended up being Sovteks. I'm still going to take them off his hands because he's giving me a very fair price and it will give me something to compare against, especially when screamingdaisy's tubes get here. (Thanks again for that, btw.)

I watched a video comparing 4 brands of EL84s, and while YouTube videos and MacBook Pro speakers are not audiophile-quality, I couldn't tell a difference between the 4.

 

[ifailedshapes]

Hi

Although the LSS is cathode biased I would still exercise some caution when changing tubes. The guy I go to for JJs, (my favourite new production EL84), supplies tubes to Mesa specs. I once bought a set of military grade Sovteks from elsewhere and these were slightly red plating when I put them in the LSS. I am currently using a set of NOS Philips which are very nice sounding and holding up really well; the LSS can eat new production EL84s for breakfast.......So if you're using tubes not specifically spec'd for a Mesa amp I would just keep an eye on them for the first 1/2 hour or so just to check they're not getting too hot and you should be good to go.

How are you liking the LSS compared to the Stiletto? I would love to try a Stiletto!

Thanks for the info. Much appreciated.

The Stiletto has a great clean channel. Really, it's amazing how warm and round it is for being an EL34 circuit. The dirty side just wasn't my cup of tea. It's not that I didn't enjoy the sounds coming out of it; it's just that at this stage in life I can only afford to have one amp, and the Stiletto wasn't what I wanted to hear everyday.

The LSS, as you know, also has a great clean channel, but it has the added bonus of a great onboard reverb. I love a little bit of 'verb in my cleans, so I'm just thrilled right now. The LSS can't get anywhere near as distorted as the Stiletto, but the tonality of the LSS is a much better match for me. I don't want to make any statements yet as to how I will use it, but I'm leaning towards setting channel 2 as a grittier version of channel 1, therefore giving myself two base tones two work with - one being as clean as possible, and one having just a hair of distortion for that touch-sensitive blues vibe. I really get my rock and roll overdrive sounds from my Fulldrive anyway, but I discovered that channel 2 has some awesome sounds in it, so I will be experimenting a lot.

 

[thom]

[/quote]I'm leaning towards setting channel 2 as a grittier version of channel 1, therefore giving myself two base tones two work with - one being as clean as possible, and one having just a hair of distortion for that touch-sensitive blues vibe. I really get my rock and roll overdrive sounds from my Fulldrive anyway, but I discovered that channel 2 has some awesome sounds in it, so I will be experimenting a lot.[/quote]

That's exactly what I am doing at the moment. I have a couple of fuzz pedals and a couple of Wampler drive pedals, all of which I use on Ch' 2, set for just a bit of grit. Works great. I am not gigging at the moment but if I was and could get to crank it, then I could easily see myself using it without any pedals, as it's such a great sounding amp. Enjoy!

 

[plan-x]

JJ's are made in the Slovak Replublic. I got mine from the Euro tubes dealer in Oregon. They are tested and matched. The difference from the Mesa tubes was the JJ's sound better, and have a longer life. Mesa tubes were dull sounding in the in my LSC. I'm not a big Chinese tube fan in my LSC. JJ's are good current production tubes.

 

[ifailedshapes]

So I put my friend's used Sovteks in today with a new fuse, and they don't sound bad at all. The only sour note (besides my mistakes, of couse ) is that my rectifier tube took a dive. The serial number of my amp is such that I didn't expect this problem. At least I can play in the 30 watt mode for now.

 

[litespeed]

Put a NOS rectifier tube in there and you should be all set....the stock 5Y3's in the LSS are junk,Dealt with the same problem myself....Good luck....The LSS is an amazing amp....

 

[Jared Purdy]

So I put my friend's used Sovteks in today with a new fuse, and they don't sound bad at all. The only sour note (besides my mistakes, of couse ) is that my rectifier tube took a dive. The serial number of my amp is such that I didn't expect this problem. At least I can play in the 30 watt mode for now.

That is so interesting, and unfortunate for you. I had an LSS that I eventually returned to the store as it kept blowing rectifiers and fuses (4 or 5 in 5 weeks). I recently had a newLSS loaner for a night from a local store and it did the same thing within about an hour. I started thinking that maybe it was the wiring in my 100 year old house, some of which is new, and some of which is knob and tube, though the circuit board is new and to spec. When I had my last LSS I tried a Sovtek for a while but pulled it as I was worried about voiding the warranty if anything happened. It was such a downer, as I really loved the sound of that amp, but the blowing of rectifiers and fuses was too much, especially for an amp that costs that much. I would love to hear a technical explanation for this. I am about to get another LSS, and I have purchased a decent surge protector (in the event my house's electrical is the problem). If the same problem arises, I will likely buy NOS tubes or try the Sovtek again as all of the rectifier tubes that blew were Mesa branded.

Have you continued to have the same problem?

 

[ifailedshapes]

Between moving and starting a new job, I haven't even played in about a month. I can say that I haven't blown anymore tubes or fuses since that first bout, and I think the problem was that my daughter pulled one of the tubes halfway out. I haven't bothered to replace the rectifier tube yet. It might be a while for that because I really like the sound in 30 watt mode.