Attention tube heads!

LessisNevermore

I was given a small, old tube phono pre. I have searched high and low, but can't identify it.

I did find the exact one on ebay, it looks like this, there were no details about it in the sale ad.


Mine came in a small box with only a paper label picturing the pre, and letters AMD. There is also an AMD sticker on the back of the unit. The case is stamped Japan.

Anyone ever seen this, or can estimate it's age? I'm sure it's of no great quality, but I'm curious to find out more about it.

Thanks.

mhardy6647

Those were sold under various brand names by many distributors, including Lafayette (e.g.). I believe that Shure was the progenitor of this design. It dates to the 1960s and is probably at least as good as the Bellari one tube phono preamp in current production.

As a weird aside, in the late 1990's, a company called ASUSA ("Antique Sound USA", apparently a US licensee or subsidary of Antique Sound Labs of Japan) made a preamp in kit and assembled form that was virtually identical to these little Japanese phono preamps).

George Grand

These little factoids and bits of trivia balance out your dump finds.

LessisNevermore

mhardy6647 wrote: »

Those were sold under various brand names by many distributors, including Lafayette (e.g.). I believe that Shure was the progenitor of this design. It dates to the 1960s and is probably at least as good as the Bellari one tube phono preamp in current production.

As a weird aside, in the late 1990's, a company called ASUSA ("Antique Sound USA", apparently a US licensee or subsidary of Antique Sound Labs of Japan) made a preamp in kit and assembled form that was virtually identical to these little Japanese phono preamps).

Thank you very much!

So, it's decent, then? Cool, ya gotta love a freebie!

mhardy6647

Decent (look at what they go for on popular on-line auction sites).

Would benefit from new power supply electrolytics fo' sho' (and it might absolutely need new ones). Do you have a Variac to bring it up to operating voltage slowly? If not, you might want to consider building a "poor man's Variac"... which is nothing but a light bulb in series with one leg of the mains power... you vary the wattage (and thus the series resistance) of the light bulb to vary the input voltage to the amplifier. Doing this will allow the four-decade-old electrolytics to reform (if they're not totally dried out and "bad", which they may or may not be).

I will check some old catalogs and post whatever info I can find on phono preamps like this one.

In the meantime, here is information at "The Vinyl Engine" on the Shure stereo preamp. You'll need to register to access the downloads, but it's free and it's a great site if you have any interest in records/turntables, etc.

http://www.vinylengine.com/library/shure/m65.shtml

LessisNevermore

Would a dimmer switch give me the same results as using a Variac? I do have access to a Variac, but it's a guy I'd rather not owe a favor to......If you're pickin up what I'm layin down.:D

Thanks again for your help.

mhardy6647

Negatory, good buddy :-( A dimmer uses an SCR (TRIAC) to chop the AC waveform; not the best way to reduce voltage to an AC device (except an incancescent light bulb... and even then...).

I read your vibe re your Variac connection...

Hold that thought; back in a minute with some links (with any luck) on quick and dirty light bulb testers.

EDIT: Here ye go...

http://antiqueradio.org/dimbulb.htm
http://audiokarma.org/forums/showthread.php?t=41523&highlight=poor+mans+variac

(FWIW, I have all the bits collected to build one of these, even though I have a Variac... go figure...)

mhardy6647

some schtuff about dimmers.

http://www.ubasics.com/node/12/print
http://www.epanorama.net/documents/lights/lightdimmer.html

mhardy6647

The ASUSA PP-1 preamp. Not quite as identical as I thought; it's got three tubes :-)

Face

You would think they could have come up with a better name.

LessisNevermore

I appreciate your taking the time to track all this down! It's quite an education, to say the least.

I will built the dim-bulb tester, as I too, already have all that stuff collected in rubbermaid tubs. I have a friend who has 2 MC30's and 2 MC60's that are in need of it as well. (or so he tells me...after reading some of those links, I think he has some spent caps. lol)

Now to find time to get this done!

Thanks again.

mhardy6647

Face wrote: »

You would think they could have come up with a better name.

I just lol'd.

Perhaps they considered poopoo-1?

mhardy6647

LessisNevermore wrote: »

I appreciate your taking the time to track all this down! It's quite an education, to say the least.

I will built the dim-bulb tester, as I too, already have all that stuff collected in rubbermaid tubs. I have a friend who has 2 MC30's and 2 MC60's that are in need of it as well. (or so he tells me...after reading some of those links, I think he has some spent caps. lol)

Now to find time to get this done!

Thanks again.

ooh, the MC-30 is a heck of an amplifier!! (not that the MC-60 is a slouch, either) Either should be easy to restore and well worth the time, effort, and expense. Those are amplifiers for the ages...