Hello everyone,
I have recently came across a nice little amplifier from Goldmund - model SRA. It's a stereo 2x50W audio amplifier with a very nice sound. One thing that struck me was it's physical size - about 30cm x 30cm x 6cm ! The manufacturer uses a design approach in which the bandwidth/slew rate of the amplifier is very high (for an audio amp) and he calls it a JOB circuit.
It's small, it looks cute, but it's no little cosmetic piece whatsoever. It's a very musical and pleasant amplifier that costs about $1500 (surprisingly higher end price for such a size
).
I did a search and found out that the JOB was first made by http://www.jobsys.com and Goldmund used it under license apparently.
Also, on the http://www.goldmund.com site you can see internal pictures of this little amplifier. 2 output power transistors (mosfets ?) per channel and little more. The heatsink is very small, and when I tested it myself, I could touch it no problem, it wouldn't hurt my fingers.
I'm not an electronics wizard but I do understand a little of it. Each designer has it's own approach to solve a problem but this thing, coupled with the sound quality I heard and the reviews I've seen seems to go against what I've seen designed - big class A amplifiers dissipating generous amounts of heat, or fast amps like the Stochino and others which have more complex circuitry than this one seems to have at first sight, etc.
Anyone ever investigated these kind of amplifiers and came out with some ideas of what is being used ? I was kind of amazed that I searched and couldn't find any discussion on the topic on this forum
Relevant links :
http://www.jobsys.com/
http://www.jobsys.com/jobstereodoc.htm
http://www.goldmund.com/old/phlib.html#secr
(inside pictures of the SRA amplifier, scroll down)
Best regards to all,
K.
I have recently came across a nice little amplifier from Goldmund - model SRA. It's a stereo 2x50W audio amplifier with a very nice sound. One thing that struck me was it's physical size - about 30cm x 30cm x 6cm ! The manufacturer uses a design approach in which the bandwidth/slew rate of the amplifier is very high (for an audio amp) and he calls it a JOB circuit.
It's small, it looks cute, but it's no little cosmetic piece whatsoever. It's a very musical and pleasant amplifier that costs about $1500 (surprisingly higher end price for such a size
I did a search and found out that the JOB was first made by http://www.jobsys.com and Goldmund used it under license apparently.
Also, on the http://www.goldmund.com site you can see internal pictures of this little amplifier. 2 output power transistors (mosfets ?) per channel and little more. The heatsink is very small, and when I tested it myself, I could touch it no problem, it wouldn't hurt my fingers.
I'm not an electronics wizard but I do understand a little of it. Each designer has it's own approach to solve a problem but this thing, coupled with the sound quality I heard and the reviews I've seen seems to go against what I've seen designed - big class A amplifiers dissipating generous amounts of heat, or fast amps like the Stochino and others which have more complex circuitry than this one seems to have at first sight, etc.
Anyone ever investigated these kind of amplifiers and came out with some ideas of what is being used ? I was kind of amazed that I searched and couldn't find any discussion on the topic on this forum
Relevant links :
http://www.jobsys.com/
http://www.jobsys.com/jobstereodoc.htm
http://www.goldmund.com/old/phlib.html#secr
(inside pictures of the SRA amplifier, scroll down)
Best regards to all,
K.