TUBE QUESTIONS---- help needed

boston1450

I know nothing about tubes first of all. I stummbled on these units & have not so much as plugged them in yet. The tube unit is Stereophonic STA-24 & the tuner is Lafayyette-225. I have both original manuals & both are in very good cosmetic condition. The manual states 30 wpc ? I have some reading to do later & looking for any feedback before i power it up. Also i paid 25.00 for both. So did i pay too much ?

boston1450

Front panel

boston1450

Back panel is all taged by original owner

boston1450

I did some research & the guy i got it from (his father) was into Realistic everything & i think this is one of their brands from the 60's era. Figured id ask ?'s before i power it up & see if black smoke starts rolling

disneyjoe7

Flames are better

F1nut

If you have no idea when the last time the power amp was used, it should be brought up on a Variac.

tonyb

F1nut wrote: »

If you have no idea when the last time the power amp was used, it should be brought up on a Variac.

Absolutely, and that goes for most vintage stuff left in storage....which you see on Craigslist and Ebay constantly.

leftwinger57

Nice that everything is Dymo Labled for you.I also know nothing about tubes but if not in use for years just plugging it in could damage them hense the variac.Also you might as well have them tested if in fact your going to use the thing. You do come up w/ some interesting gear from time to time....

boston1450

Thanks. The guy said it was in use last fall. His father used it until he passed away. Thats all i know. He had one room that was full of electronics & boxes & boxes of tubes. All i could think about was.i wish i knew what tubes may be worth picking up

Msabot1

Hey..I think that 225 is an old short wave reciever..from the mid 60's..wow..haven't seen one of those in years..not sure about the amp though....

erniejade

25$ for both? heck the tubes inside are probably worth more then 25$ depending on what they are!

erniejade

Do a search for Stereo National sta-24

mhardy6647

That amp was a rather generic kit sold by several companies - you can see it, e.g., on page 27 at http://www.radioshackcatalogs.com/catalogs/1964/

boston1450

Well i know its not a top quality tube unit. But i will say this. It has some power & doesnt sound bad at all. I couldnt resist. Hooked er up & not bad for 25 smackaroos. Nice clean sound with tons of power fwiw.

tonyb

Lol.....just a tip from your Uncle Tony,

If your going to just hook them up and power on....vintage gear....taking that chance, always,always use throw away speakers at first. Never on your main rig. Unless of course you need a reason to buy new stuff.

mhardy6647

I don't disagree but there is a fine point to the previous comment. It is 100.000% absolutely true for a direct coupled amplifier - especially solid state amps (although also true for an OTL vacuum tube amp). In a direct coupled stereo amp, a shorted driver or output device can put the DC rail voltage right to the speaker output (e.g., maybe 30 to 60 VDC). That can cook a voice coil very quickly (don't ask me how I know this).

It would be much less risky with a capacitor coupled SS amp - or a transformer coupled SS or vacuum tube amplifier - simply because the coupling device would block DC (absent a shorted capacitor in a cap coupled amp, e.g.). That said, it IS still good advice.

As to expendable, test mule speakers - heck, that's what Radio Shack and Cerwin-Vega speakers are for! :-)

tonyb

LOL....YEPPERS, but truth be told most don't know the difference or even care to when shopping vintage stuff on the cheap. It's the old " ounce of prevention is worth a pound of cure" thing that everyone should abide by.

dromunds

mhardy, that's one heck of a radio shack catalog. Wonder how many McIntosh mono amps they sold? I even noticed they sold AR3 speakers, and electrostatics. And Thorens TD-124 TTs. That was a little before my time, but I remember being at a boy's camp in the summer of 1964 and this older (maybe 15-years-old!) counselor had a Singer (IIRC) battery operated record player, and he had the Beatles brand new 45, (must've been Hard Day's Night,) and also some Beach Boy 45's. I think the record player folded up when not in use.

cnh

Those early Shack catalogs sold just about "everything", all kinds of brands that were left behind as time passed.

25 dollars for what is probably a very passable tube amp from that time. How could you go wrong? Now you need some more appropriate vintage speaker to drive with those. I would not necessarily choose Polk Monitors as my "first" choice with tube amps? Older KLH, AR (vintage bookies) or Klipsch?

If I had that I'd put my KLH 17s on as soon as I knew it was safe! Or possibly Dynaco A25s? I'm definitely on the prowl for something similar for the old Kloss's, they're very smooth with a low powered tube amp!

I have no idea what tubes that unit uses, there are others here who can probably guess and make suggestions.

All I can say is what a STEAL, Randy!

Have fun! Enjoy!

cnh

dudeinaroom

Just to be on the safe side you might want to pop the bottom covers off and take a look at the bottom of the can capacitors (round kind of long things sticking up from the chassis, usually silver, sometimes have a black cardboard covering). IF there is any black or tan stuff coming out of them you are going to want to replace them. The black stuff will look kind of like rubber oozing out. The tan stuff will usually be hardened and will have a cement like appearance. Both of these are the signs of failed or failing capacitors.