What are these ?

[TheFinisher]

Hi gents,
Does anyone know what these could be ?they each have 1 input bnc coaxial and the black and red speaker type outputs
Someone said they could be fm signal amplifiers .

 

[jjasniew]

Why wouldnt they be audio? Perhaps a shaker drive. That there are two...maybe whomever built them likes BNC; thought it was a better connection than RCA (locking...)

 

[TheFinisher]

I hope you are correct

 

[TheFinisher]

 

[JMFahey]

A plain vanilla Class AB (presumably) Audio power amplifier.

Please show us:

* big blue capacitors rating

* power transistor labels and/or closeups

* voltage to ground present at those rail fuses.

You managed to post 6 pictures without showing significant data 😉

EDIT:I guess we´ll find a toroidal PT mounted to the bottom.

 

[TheFinisher]

Yes there is a toroidal transformer under the gold bit, thanks for your input it’s very much appreciated , hopefully these photos of the components will help .

 

[TheFinisher]

So do you think they are monoblock amplifiers?
If so I will test them tomorrow with a preamp and a sacrificial speaker or is that not advised?
Could they be any good ?

 

[adason]

Looks like standard hitachi amp, perhaps musical fidelity clone
Monoblocks for sure
Any good? Up to you to find out

 

[rayma]

Yes. Check for DC on the outputs first.

 

[JMFahey]

Looks well made, definitely not lacking on filtering 😉 , MosFet outputs in a simple elegant design, what´s not to like?

I bet they sound quite good.

Pawnshop find? Weird you didn´t know what they are.
Agree with Rayma´s suggestion about checking for DC first, even if "sacrificial" no speaker needs to be sacrificed 🙂

 

[rayma]

Yes, where did you get them? Much better than average DIY, great cabinets.

 

[jjasniew]

Yes, dig the workmanship under the cover. I like how the one resistor is held on Tektronix style standoffs, with the flush flat head screws in the sub-chassis wall.

Yes, where did you get them?

I second the question. Not that I'd be any future competition, but if I saw them in a thrift... My luck is I spend $5 for a bag of dead batteries and a charger, thinking they're lipo (cause of the charger) and after getting home, find they're nimh. Pay to suffer the disposal task...

 

[TheFinisher]

Thanks for the comments gents .
I saw them on a local auction website with minutes before they were due to end, the photo on the auction site wasn’t the best and I couldn’t see if the inputs were rca or not but I took a chance and bid and won at not a lot of money at all .
I will hook them up today after first checking for dc on the outputs .
I know very little about diy amps so I just hoped that they were in fact audio monoblocks ( someone said they were fm signal amps )
The attached photo is what I saw before bidding, the description said “ 2 x amplifiers “ .

 

[jjasniew]

I didnt notice before, but they're even designed in mirror-image! I know that's preferred in a speaker, but... It would be fun to meet whomever built them and like a kid ask them; why, why, why.

 

[TheFinisher]

Just opened up the other one , yes they are mirrored.

 

[TheFinisher]

Thankfully there is no voltage on the outputs ( if I’ve done it correctly)

 

[TheFinisher]

Is there anyway to know if these are class A or not ?
I do like class A .

 

[JMFahey]

Easy peasy: just listen at them .... if you like them, they are Class A




😉

 

[jjasniew]

Just power them on, if the heat sinks get hot, probably class A. No speaker required 🙂

 

[TheFinisher]

Just power them on, if the heat sinks get hot, probably class A. No speaker required 🙂

Cheers