Mesa now says to use solid state rectifier in LSS

[rabinnh]

For the second time, my LSS fuse blew, smoke out the back, and some damage. Turned out to be the rectifier tube, which was from Mesa and was only in the amp for a little over a month.

My amp tech is Mesa certified. When he spoke to the factory they told him the LSS can't handle the "newer rectifier tubes", and that Mesa now suggests using a solid state rectifier.

I'm not the suspicious type, but this sure sounds like a cop-out to me. A quick search reveals that the LSS has had issues with blown fuses and rectifier tubes for years. Are the new ones really so electrically different (and the amp so sensitive) that a newer 5Y3 will cause the amp to blow, but one made 5 years ago is just fine?

I have the solid state rectifier in there but the amp's personality is completely different. it sounds harsh instead of the beautiful warmth that I loved about the amp.

I'd really love to hear opinions from people with tube amp experience.

 

[screamingdaisy]

It wouldn't be the first time Mesa's been stung by tube manufactures dropping their quality. Around 2006-2008 Mesa amps were getting a reputation for being unreliable. People thought it was because Mesa was dropping their build quality to keep up with demand, but it was because New Sensor changed the specs on the EHX 12AX7 they were using and it was burning out in the V3 position of the Dual/Triple Rectifiers. They now use JJ ECC83s.

Mesa originally had issues with the stock 5Y3 blowing out and they changed something in the circuit to compensate for it. Every amp built after a certain date (this was years ago) has the modification built into it. If yours is one of the ones with the mod (I forget the serial number it happened at, but a search should reveal it) and it's blowing new production tubes then I'd be inclined to believe Mesa.

FWIW... the solution to the rectifier issue was to buy a NOS 5Y3. They were better built back in the day.

 

[rabinnh]

Thanks for the response. Mine has the mod, installed by my tech as directed by Mesa a number of years ago.

Any idea of a good source for NOS 5Y3s?

 

[screamingdaisy]

https://www.kcanostubes.com

 

[mixsit]

FWIW my LSS (2009 approximately), went through two of them right off. Also some resistors burned and had to be up sized, but IIR that was a separate issue. Tech -shoot, that's Shane / Tube Sonic may as well give'em a bump! :>) ..got me a pair of NOS, I'm still running solid on the first one.
Coming from, gadds, many years of zero trouble on a Pearce, that to say the least was a shaky return to tube amps'.

 

[rabinnh]

Mesa recommends a mod "not guaranteed to forestall trouble" that involves cutting a trace and putting in a resistor. I had a bad cell phone connection, but from what I can gather the 30 watt setting uses a solid state rectifier and the 5W and 15W settings use the 5Y3. The mod and the resistor shunt off some of the current to the solid state rectifier in 5W and 15W settings to prevent over current conditions through the tube.

I figure I'll try that mod along with the NOS tubes (I bought 3 1970-72 JANs) and see how that sounds.

Thanks for the feedback and sharing your experiences. I've loved the sound of this amp for years, and the sort of "sterile" sound I'm hearing now changes the character quite a bit.

rabinnh

 

[Authorized Boogie]

Using an NOS 5Y3 (the amp was designed around the JAN Phillips tube) is certainly a good way to go, and we've also had good results with the new JJ 5Y3. The Russian and Chinese tubes just aren't built up to par. For those who want a one-time purchase, lifetime product and don't want to pay for a NOS tube - the Weber Copper Cap is a fantastic solution. Thanks!

 

[utop]

I have an early Lss with the current reduction mods done but it still blows Mesa branded 5Y3´s. About a year ago i purchased a JJ 5Y3 and since then i have had no problems with the amp.
I usually run it on 15 w setting so i´m using the tube rectifier all the time. Just wanted to support what Authorized boogie is saying, that a JJ 5Y3 seems to work well. (and they are cheap too)
If you are having trouble finding NOS tubes try a JJ.
Cheers
Utop

 

[rabinnh]

Well, I bought 3 NOS 5Y3 JAN tubes (to have 2 spares). I have back the tone I fell in love with. Don't let anybody tell you that a solid state rectifier sounds the same. With the tubes it's not nearly as harsh, seems like better sustain, all around sweeter. I did have to turn the volumes knobs up a bit to get the same level, but that's fine.

Go with the NOS 5Y3s if you run into this. No comparison.

 

[rabinnh]

And for laughs:

http://www.mesaboogie.com/tubes/rectifier-tubes/5Y3.html

Advertising it for the LSS, and telling my tech on the phone that it's likely to fail.

 

[Authorized Boogie]

And for laughs:

http://www.mesaboogie.com/tubes/rectifier-tubes/5Y3.html

Advertising it for the LSS, and telling my tech on the phone that it's likely to fail.

Not the JJ 5Y3 that we are currently using - they have proven to be very reliable.

 

[rabinnh]

I'm glad to see a response from Mesa, and I mean that sincerely.

So I'm puzzled; is the tune on the Web page which specifically names the LSS a JJ? If not, why advertise it for the LSS?

My tech was told by the Warranty dept to use a solid state rectifier "because modern rectifier tubes are not in spec for this amp". Alternatively, a mod could be done so that a resistor could be inserted between the 5/15w tube rectifier and the 30w solid state rectifier "but there are no guarantees". This was not 3 weeks ago. This was in response to me replacing the 5Y3 with the rectifier tube on the page in my previous post - bought directly from Mesa. 6 weeks later not only did the fuse blow, but smoke came out of the back, I had $175 in damages, and an amp in the repair shop. The previous 5Y3 had been in there for 8 years without issues until it finally started making "other" sounds.

So I would really appreciate clarification; is the information above (which is also directly from Mesa) correct, or is it safe to use a Mesa bought 5Y3 for the LSS?

I say this as a Mesa aficionado. I simply adore the sound of my LSS and I was devastated with the sound after inserting the SS rectifier. I would have sold it if that were my only choice. While it was in the repair shop, I practiced through my backup amp, which is a Subway Rocket (see, I love Mesa).

Honestly looking for the bottom line here.

Thanks,
rabinnh

 

[Authorized Boogie]

The bottom line is that any vacuum tube can fail. That said, the Russian 5Y3 that were available for years were not as robust as the JAN Phillips 5Y3 the amp was designed around and had a higher than average failure rate...and the current JJ 5Y3 has, so far, proven to be a very reliable alternative. We did some in-house testing on the Copper Cap, and it has the exact same voltage drop that mimics a 5Y3 - and only after Doug West approved the tonality - we began to recommend it as an alternative that is fail-safe. I hope this helps!