Advice for integrated tube amp that's been in storage

[SubWolfer]

Back in 2010 I bought a pretty nice integrated tube amp. Liked it a lot but then had acquired some mono amps and the tube amp was put away.

I covered it in plastic to keep out dust and it's probably been stored for at least 5 years or more.

It's a Mastersound Due Venti S.E.

So being as it's not vintage, would you say it'd be safe to hook it up to my CD player and a set of speakers and just power it up?

 

[Tinkerbelle]

I would suspect so if it has just sat unused and covered. It is not vintage and the tubes have not seen any life usage, so seems it should not have any appreciable deterioration from the time it was stored.

However, I would check that the tubes are all seated correctly in their sockets to be sure nothing loosened (or if there is possibility of another person in the house playing with it & moving parts). Also check that none of the tubes have gone to air from a possible knock or drop shock (the gettering would look white inside rather than silvered). If it is a fixed bias amp, check that bias is correct. When powering up, watch for anything unusual such as red-plating on output tubes.

 

[SubWolfer]

Thanks for the quick reply and great advice. I didn't think there would be an issue powering it up but thought I'd ask anyway, just to be sure.

It's a Saturday evening and I'm kind of itching to set it up. Is there an easy way to tell if it's fixed or auto bias?

 

[Alan0354]

Take a look at the inside to spot obvious problems, look at the big filter caps if they look swollen or spit the beans. Use dim bulb to power it up. If you have a variac, that would be even better.

I am new on this tube section, I don't know people use dim bulb here. It is very common in the SS section.

 

[SubWolfer]

Thanks, I guess it cant hurt to do a visual inspection.

What's a dim bulb? Are you referring a dimmer switch? I heard of using a variac (which I don't have) but I never heard of using "dim bulb."

Edit: doing a little research I discovered this amp is auto bias

 

[Alan0354]

Thanks, I guess it cant hurt to do a visual inspection.

What's a dim bulb? Are you referring a dimmer switch? I heard of using a variac (which I don't have) but I never heard of using "dim bulb."

Edit: doing a little research I discovered this amp is auto bias

Go to Solid State or DIY section here, everyone use dim bulb. Basically it's just put a light bulb is series of the AC line in, use a bigger bulb. If the amp have no shorts that draws a lot of current, the bulb will by very dim and the amp power up. If there is a short, the amp draw a lot of current. The bulb will light up bright and limit the voltage into the amp to prevent burning stuffs.

Go there, they even talk about how to build one or what not.

 

[SubWolfer]

So I read about the DBT. Very interesting, thanks for the tip.

You're right though, doesn't look like anyone is using a DBT with tube amps. Maybe it's only for SS?

 

[eiraved]

Mainly for SS, not so much for tubes. Make sure you have speakers hooked up, or a similar resistance load before powering up a tube amp.

 

[Alan0354]

Tubes use power for heating filaments, so it draws current, but if you use higher wattage bulbs like I suggested, it will still work. It the amp is normal, you might drop some voltage, it will still work. But if there is a short, it will still protect you.

 

[gadget73]

dim bulb testers are fairly common for resurrecting tube gear actually. It limits the current in case the filter caps are pooched. Unfortunately stuff with tube rectifiers won't give you much high voltage till you get somewhere about 80 vac in to the amp.