Hi tiefbassuebertr
Greetings can you share schematic of electronics australia 800watt/ch.I have been searching for this since a long time
the last magazine in the one with the girl in the car if its possible.(there is a typing mistake in my last post d.c. voltage 70-0-70)
warm regards
Vedmitra Sharma
Greetings can you share schematic of electronics australia 800watt/ch.I have been searching for this since a long time
the last magazine in the one with the girl in the car if its possible.(there is a typing mistake in my last post d.c. voltage 70-0-70)
warm regards
Vedmitra Sharma
Hi vedmitraa
I don't think Tiefbassuebertr has any details beyond what he found on the net and posted images of here.
I don't recall EA publishing designs more than 300W/8R however. Perhaps someone would like to correct me
and give an issue/date reference, since SILICON CHIP magazine holds the archives of EA magazine and will
sell facsimilies of the article instalments for about $10 ea, same as for old articles from their own publication.
See Silicon Chip website for details
I don't think Tiefbassuebertr has any details beyond what he found on the net and posted images of here.
I don't recall EA publishing designs more than 300W/8R however. Perhaps someone would like to correct me
and give an issue/date reference, since SILICON CHIP magazine holds the archives of EA magazine and will
sell facsimilies of the article instalments for about $10 ea, same as for old articles from their own publication.
See Silicon Chip website for details
You are right.
Unfortunately I haven't this magazine. Here in Germany I have the possibility to search and find old issues from each exist vintage electronic magazine (from Germany) at libraries of universities (University Library). I think, in Australia this is also possible.
Perhaps one of the members from there can check out this.
Try to ask in this matter also there:
http://sound.westhost.com/contact.htm
rode@sound.au.com <rode@sound.au.com>
Maybe Rod know more exactly details in this case.
Last edited:
Girl in the car? There could be more than one of those issues... I have all the published Electronics Australia mags on my shelves. Can you give a range of years? I can have a look through them. I don't think EA published any designs for 800W, but it may be possible to upscale.
That's unusual, there is no PCB published in the articles. Maybe it was only ever for kit construction, and not for DIYers to roll their own.
Oops, the articles ran over 3 issues, not 2. I have added July 1986 (with PCB) in a new version (3) of the PDF:
http://dl.dropbox.com/u/44941643/Playmaster-60-60-v3.pdf
6.79 MB, 25 pages, scanned at 150 DPI, 256 greyscale
Copyright Federal Publishing 1986-1987
Reproduced for the purposes of fair research non-commercial use
http://dl.dropbox.com/u/44941643/Playmaster-60-60-v3.pdf
6.79 MB, 25 pages, scanned at 150 DPI, 256 greyscale
Copyright Federal Publishing 1986-1987
Reproduced for the purposes of fair research non-commercial use
For what it's worth I built a Playmaster 60-60 in my teens and used it for several years. It sounded very detailed but somewhat harsh and uncomfortable to listen to. I went through many diy speakers trying to improve my sound system until I finally worked out it was the amp that was the problem...
I never could get the quiescent current to stabilise in the output stage either (even with the MJE340 substitution), it would slowly keep wandering up and up.
Years later when I knew more about amp design and electronics in general I checked for oscillation with a friend's 'scope and the thing was prone to instability for sure. But eventually I worked out that the way to stabilise the quiescent current was to change the 4 x parallel 1R emitter resistors on each output device to 4 x 2R2. The higher emitter ballast resistance seemed to bring about thermal stability. Didn't do anything for the sound though.
Interestingly, I recently built the SC Studio 350 which is based on the same topology (finally proving to myself that I am mad), but with proper PCB design. It sounds excellent - none of the harshness or discomfort evident. Just goes to show how critical implementation is to the success of an amplifier design.
Anyway I'd pull the transformer out for re-use and dipose of the rest thoughtfully if you are picky about sound quality
I never could get the quiescent current to stabilise in the output stage either (even with the MJE340 substitution), it would slowly keep wandering up and up.
Years later when I knew more about amp design and electronics in general I checked for oscillation with a friend's 'scope and the thing was prone to instability for sure. But eventually I worked out that the way to stabilise the quiescent current was to change the 4 x parallel 1R emitter resistors on each output device to 4 x 2R2. The higher emitter ballast resistance seemed to bring about thermal stability. Didn't do anything for the sound though.
Interestingly, I recently built the SC Studio 350 which is based on the same topology (finally proving to myself that I am mad), but with proper PCB design. It sounds excellent - none of the harshness or discomfort evident. Just goes to show how critical implementation is to the success of an amplifier design.
Anyway I'd pull the transformer out for re-use and dipose of the rest thoughtfully if you are picky about sound quality
Not necessarily so. I built the 60/60 in 1987. The circuit is yet another in a long line based on the Hitachi Mosfet app. notes from way back around
1979 and these were long time favourites in the EA and Silicon Chip stables until the late 1990s with the adoption of Self's "blameless" RCA Lin model.
Ten years ago, I resited the Vbe multipliers onto a T03 output case via a short cable and that sorted the apparent drift due to the long thermal path
between sensor and heatsource. The real problem was that the bias setting was too low and with faster "feedback", you could adjust it with impunity
up to the limits of that rather small heatsink. IIRC, about double the recommended bias nailed that gritty crossover artefact that was so irritating
up to that point. Mine is well up to the mark for late 1980s domestic amplification now.
At the time, strange Motorola copies were beginning to appear and friends who also built the amplifier used some suspicious parts. Genuine MJ15003/4
were near $10 each, so you can appreciate the motive. They both had serious stability problems but I never learned their solutions or if they were
successful.
'Dunno about the C-core transformer though - a bit light-on and with enough stray magnetizing force to "pop" the steel case on start up!
1979 and these were long time favourites in the EA and Silicon Chip stables until the late 1990s with the adoption of Self's "blameless" RCA Lin model.
Ten years ago, I resited the Vbe multipliers onto a T03 output case via a short cable and that sorted the apparent drift due to the long thermal path
between sensor and heatsource. The real problem was that the bias setting was too low and with faster "feedback", you could adjust it with impunity
up to the limits of that rather small heatsink. IIRC, about double the recommended bias nailed that gritty crossover artefact that was so irritating
up to that point. Mine is well up to the mark for late 1980s domestic amplification now.
At the time, strange Motorola copies were beginning to appear and friends who also built the amplifier used some suspicious parts. Genuine MJ15003/4
were near $10 each, so you can appreciate the motive. They both had serious stability problems but I never learned their solutions or if they were
successful.
'Dunno about the C-core transformer though - a bit light-on and with enough stray magnetizing force to "pop" the steel case on start up!
Interesting - wish I'd known to try those things at the time.
Even then I knew enough to throw away the crappy steel case that Jaycar supplied and put it in a nice anodised aluminium rack case. The C-core t/f seemed good to me - no mechanical hum, and I recall reading that EA had tested it and found it had a lower radiated field than an equivalent toroid.
Other than that I think Jaycar had (have) a lot to answer for as the quality of components supplied was probably half the problem. These days if I buy kits I discard the components supplied and use the PCBs only (which I think are probably 1/8th oz copper and not too flash anyway...)
Even then I knew enough to throw away the crappy steel case that Jaycar supplied and put it in a nice anodised aluminium rack case. The C-core t/f seemed good to me - no mechanical hum, and I recall reading that EA had tested it and found it had a lower radiated field than an equivalent toroid.
Other than that I think Jaycar had (have) a lot to answer for as the quality of components supplied was probably half the problem. These days if I buy kits I discard the components supplied and use the PCBs only (which I think are probably 1/8th oz copper and not too flash anyway...)
That's probably fair comment for the state of the DIY market then. It was always geared to the low cost, budget end of the market since that still is what the majority of DIY enthusiasm is all about. Though if you thought Jaycar product was substandard, you should have seen what others were supplying! It's not saying much but Jaycar's were the best audio kit versions available for these and ETI's popular designs in their more expensive "blueprint" versions, at least.
'This was at the end of the popular wave of 1970-85 DIY electronics, here in Oz. It marked a return to simpler models from EA. Within a couple of years, both major magazines supporting DIY had fallen on lean times, were subsequently restructured and sold.
'This was at the end of the popular wave of 1970-85 DIY electronics, here in Oz. It marked a return to simpler models from EA. Within a couple of years, both major magazines supporting DIY had fallen on lean times, were subsequently restructured and sold.
Vedmitra,
Found it. The January 1984 issue of Electronics Australia has a girl in a car on the front cover and contains a review of the Perreaux 5150B 800W/Channel amplifier. As expected in a review, no schematic is supplied, although it states there are 6 pairs of TO-3 output transistors per channel and +- 130V power supply rails. I've scanned the article:
1.27 MB, 5 pages, scanned at 150 DPI, 256 greyscale
Copyright John Fairfax & Sons Ltd 1984
Reproduced for the purposes of fair research non-commercial use
http://dl.dropbox.com/u/44941643/Perreaux5150B-800WPowerAmpReview-EAJan1984.pdf
I can tell you for a fact that no Perreaux amplifier schematic was ever publsihed in that magazine. The schematic would be a commercial secret.
Playmaster 300W amplifier
It is a basic design intended for subwoofers and uses some very old parts but many similar and larger design amplifiers have been posted here over the years. However, the only thing in common with the 60/60 amplifier is the magazine originally publishing it.
It would be sensible to start a new thread to discuss any modifications to such a different amplifier and leave this thread for the OP topic so people find the relevant material when searching it.
It is a basic design intended for subwoofers and uses some very old parts but many similar and larger design amplifiers have been posted here over the years. However, the only thing in common with the 60/60 amplifier is the magazine originally publishing it.
It would be sensible to start a new thread to discuss any modifications to such a different amplifier and leave this thread for the OP topic so people find the relevant material when searching it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.