Lonestar special loss of volume

[dor21combe]

Hi Guys got my lonestar special yesterday, amazing sound, beautiful tone, thought i was on a winner considering some reports ive read. Today i was playing at 5w when the volume droped considerably and the sound became very distorted. Any advice why this may have happened.

Thanks

 

[94Tremoverb]

I'm not sure which tubes are used in the two low-power modes - if the one that's used in 5W mode is NOT one of the two that's used in 15W mode (but obviously will be in 30W), then it's probably a bad power tube... it could be shorting which will bring down the power and make it sound distorted. (In 5W mode two are actually on, even though only one is amplifying the signal - it could be either of these.)

Maybe someone who has one of these amps can tell you which tubes are on in which modes. If it's the *same* tubes in 15W and 5W modes, it's not likely to be a power tube. You could find out by pulling either the inner or outer pair and seeing if the amp works in either low-power mode. Don't try the 30W mode with only two tubes in, it may be safe but it may not, depending on how the biasing is done.

 

[screamingdaisy]

Sounds like a bad power tube. Tubes are fragile by nature, it's why Boogie waranties them for 6 months.

Normally the power tubes are paired up as inner and outers; ie, if the power tubes are laid out 1-2-3-4 numbers 1 and 4 are the outer pair while 2 and 3 are the inner pair.

In 5w mode the amp uses one tube from the inner and one tube from the outer pair. One is the actual tube being used, while the other is being used as a dummy load to balance the output transformer. Unfortunatly, I don't know which two tubes are used in 5w mode. You could try powering up the amp while looking at the tubes to see if one of the tubes redplates (you'll see the normally grey plate structure on the tube glow like a toaster element), if you see this power down the amp and replace that tube with a new one.

note: purple/blue haze is normal, and there is a small heater at the top of the tube that's supposed to glow... it's the large plate structure that fills most of the tube that you're watching to see if it heats up and goes red.

 

[dor21combe]

Thanks Guys for you advice. I'v contacted the store who are now waiting to hear from Mesa, hopefuly they will send out new valves.

Thanks

 

[dor21combe]

Sorry Guys Just one more question does anyone know where i can get a Nos 5v4 in the UK.
Thanks

 

[94Tremoverb]

Watford Valves have some.

http://www.watfordvalves.com/products.asp?search=5v4

These guys are pretty good for most NOS types.

(The Harmas aren't NOS and I would probably avoid the cheap Russian ones even though they're old, by the way...)

 

[212Mavguy]

Watford Valves have some.

http://www.watfordvalves.com/products.asp?search=5v4

These guys are pretty good for most NOS types.

(The Harmas aren't NOS and I would probably avoid the cheap Russian ones even though they're old, by the way...)

Haven't been to their site lately, but the Harma el84 Russian tubes I saw them using a couple years ago are about the beefiest built el84's out there, they are relabeled Panno 6p14p-ev, mil stock fo sho... Those tubes are rated for 7189 voltages, have a thicker, leaded glass bottle, they also are rated for 5000 hours, try to find another el84 with that kind of life ratings...were originally designed as a low frequency pentode, they have a massive cathode, the getter halo has three supports, (!) and more girth to their tone than most el84's. They do a nice, fat dirty tone. Beefier than the Sovteks Mesa used.

Have a matched quad in my Mav and they have several hundred hours on them. Have not modded the bias section in that amp to adjustable bias, got lucky. They feel a lot heavier in the hand than any other el84 out there. They need a full minute to warm before socking the b+ to them due to their massive cathode.

NOS 5v4ga might be found on eBay.com UK site. They are easily found in US site. Have had great luck with GE, Sylvania, and Westinghouse relabeled Sylvania in that tube type.