Bringing up a found Mono tube amp for the first time

[Mark W.]

I managed to luck into a cute little Voice of Music 8810 Mono 5watt amp today (see this thread for photo's and details) I even got two copies of the instructions and schematic.

http://audiokarma.org/forums/showthread.php?t=172614

Anyway once I have the proper adapter and I can plug the Mic. from the same find into it. I want to try it out.

So since it is unknown how long this little amp has been sitting in the dark I need to know the best way to bring it up without smoking it.

I have in the past glanced over any number of posts talking about using light bulbs as a stepped Varic to introduce power to the amp at a reduced rate allowing things to get used to the juice. BUT since I had no need of it I never paid close attention. I have a couple of base mount bulb sockets around here somewhere.

Well now the last thing I want to do is damage this amp. SO can someone tell me how to rig up a Light bulb Varic so I can find out if this little guy works.

I know the 12ax7 is the preamp tube. Doe that make the 6V6 the power tube and the 6X4 a rectifier type tube?

I'm about to have a number of 12ax7's so if need be I should have no trouble replacing that.

Kind of excited about trying out this little Voice/ Harp/ Guitar amp and the Turner Microphone. pretty sure the Speakers I got will work they look fine.

Be fun to get this all cleaned up. Karaoke anyone???

[DENNYDOG]

As far as I know your right on about what the tubes are for. I'm pretty sure there is a sticky in the tubes forum for the light bulb variac along with other info about bringing the juice back you might not thought of asking.

Denny

[Tinkerbelle]

Take a look at this article. It gives a pretty good run down of everything you need, including pics of a light bulb set-up.

http://antiqueradio.org/dimbulb.htm

Good luck with the new amp!
Christine

[gogofast]

Well now the last thing I want to do is damage this amp. SO can someone tell me how to rig up a Light bulb Varic so I can find out if this little guy works.

I know the 12ax7 is the preamp tube. Doe that make the 6V6 the power tube and the 6X4 a rectifier type tube?

very nice mic set up you scored there!
you're right about the tube designation. i haven't tried the light bulb (poor man's variac) myself, because i usually just replace all the main caps before i even plug anything in, and that's what i feel you should do, too. the unit you have should be very simple with just a handful of caps. good luck playing with it!:thmbsp:

[gearhound]

Yeah, I'm about ready to recap a 12 watt mono PA amp I found at a yard sale.
I'm gonna order from a Canadian on-line vendor called Just Radios....BIG inventory of caps and the prices look fair.
I ordered a few new tubes from Tube Depot (JJ 6ca4 & two Tung Sol 6V6GT's).
Good luck with your recap!!

Steve

[Tinkerbelle]

Doe that make the 6V6 the power tube and the 6X4 a rectifier type tube?

Yes; they are relatively common & inexpensive tubes so should have no problem getting replacements if needed. The 6X4 full wave rectifier is also called EZ90.

[yamahammer]

i built this worked well for me http://audiokarma.org/forums/showthread.php?t=41523&highlight=poor+mans+variac

[soundmotor]

I checked the thread where you show all the gear.

I love finding stuff that the original owner optimized to his specific task.

Here, he needed an easily portable PA rig.

And, you saved it from the inevitable trash can.

What a cool find!

[Mark W.]

From talking to the guy that sold it this gear was bought in the mid to late 50's and used clear into the late 70's So someone got their moneys worth out of the investment. I still haven't brought the larger speaker in from the pickup I need to see what might be inside it.

I think since it is such a simple little amp that maybe I'll use it a refresh project before I attempt any work on my Scott 233 this winter.

I will go ahead with the light bulb variac to see if it powers up as is. But I doubt I will run it more then a couple minutes.

Trying my damest to figure out a place and way to display this. Maybe this winter when I get my office remodeled I can find a way to show it off.

[gogofast]

Yeah, I'm about ready to recap a 12 watt mono PA amp I found at a yard sale.
I'm gonna order from a Canadian on-line vendor called Just Radios....BIG inventory of caps and the prices look fair.
I ordered a few new tubes from Tube Depot (JJ 6ca4 & two Tung Sol 6V6GT's).
Good luck with your recap!!

Steve
i've used their stuff a few times now mainly due to low price and superb customer service, but when i got 'em, they were rather very light in weight compared to other electrolytic caps of same values - such as sprague atoms. i haven't used the gear with those long enough to really figure out their performance, but somehow i have a feeling that i'd wanna spend a few more $$ for better caps....but i really don't know what to think of it yet.:scratch2:

[robert1]

I managed to luck into a cute little Voice of Music 8810 Mono 5watt amp today (see this thread for photo's and details) I even got two copies of the instructions and schematic.
Anyway once I have the proper adapter and I can plug the Mic. from the same find into it. I want to try it out.

So since it is unknown how long this little amp has been sitting in the dark I need to know the best way to bring it up without smoking it.


this was a commonly used amp for the "Companion" Accessory for VM stereo & Binural tape recorders that were made from 1957 to 1963. the "companion" Accessory was a cabinet that was identical to size & color of the tape deck cabinet itself & also encased the 8810 amp, a 6x9 speaker & high frequency driver. the cabinet also had space to store reels of tape & other accessories as well. i have serviced many of these amps & are very familiar with them.
as for powering it up, Don't. Don't power it up at all, not until you take it apart & replace the filter capacitors & the Bumblebee capacitors that are in it.


I have in the past glanced over any number of posts talking about using light bulbs as a stepped Varic to introduce power to the amp at a reduced rate allowing things to get used to the juice. BUT since I had no need of it I never paid close attention. I have a couple of base mount bulb sockets around here somewhere.


you are just wasting your time going that route. you would be just better off just changing the capacitors before doing anything else.
the one thing i know is that VM sourced all of their capacitors from Cornell-Dublier & used the cheaper grade capacitors.


I know the 12ax7 is the preamp tube. Does that make the 6V6 the power tube and the 6X4 a rectifier type tube?


the 6V6 is a Audio Output Tube. yes, the 6X4 is the rectifier


I'm about to have a number of 12ax7's so if need be I should have no trouble replacing that.


you will probably find that all of the original tubes are ok


Kind of excited about trying out this little Voice/ Harp/ Guitar amp and the Turner Microphone. pretty sure the Speakers I got will work they look fine.
Be fun to get this all cleaned up. Karaoke anyone???

you may be disappointed as there is not that much gain on low or medium line levels. you still may have to add another pre-amp or mixing console