Re building Metaxas Solitaire Amplifier

[bobby1945]

I have a pair of Metaxas Solitaire Amplifiers that drive my Infinity Kappa 9 speakers
The amps were sent to a reputable Perth electronic service outfit ,but were deemed unserviceable by the technician.
The amps in question were revealed on the techs' Hall of Shame
https://liquidaudio.com.au/hall-of-shame/
So I have decided to rebuild myself , but the question is - Is it a Bridge too Far for a novice to undertake?
I have plenty of time at my disposal as I'm retired .
Any comments would be gratefully received.
Thank You.

 

[andyr]

I have a pair of Metaxas Solitaire Amplifiers that drive my Infinity Kappa 9 speakers
The amps were sent to a reputable Perth electronic service outfit ,but were deemed unserviceable by the technician.
The amps in question were revealed on the techs' Hall of Shame
The Hall of Shame is the only page dedicated to exposing bad hi-fi repairs
So I have decided to rebuild myself , but the question is - Is it a Bridge too Far for a novice to undertake?
I have plenty of time at my disposal as I'm retired.
Any comments would be gratefully received.
Thank You.

In short:
1. yes, it's a helluva task for a self-described 'novice' to undertake - irrespective of how much time you have available!

You may end up after lots of time and money spent ... with an unusable piece of junk.

2. The amp is on the "Hall of Shame" list for a reason; why do you think that 're-building' it - even if it was well within your sphere of competence - will correct the things that were the cause of its promotion to the HoS?

Sorry.

There are plenty of other amps that will drive your Kappas well and be reliable.

Andy

 

[Worldie]

To the best of my knowledge, Metaxas amplifiers are single-stage designs, and these are sub-optimal. On a fundamental level, an audio power amplifier should have at least two stages of gain.

 

[as_audio]

To the best of my knowledge, Metaxas amplifiers are single-stage designs ...

Whatever this means, the amplifier in question has a traditional multi-stage topology.

Did the OP manage to do the repair ?

 

[stocktrader200]

It looks like an easy layout to repair.
When removing dead transistors you can carefully cut each pin and remove individually so that the board is not damaged.
If one output transistor is dead all should be replaced on that channel.

 

[planet10]

an audio power amplifier should have at least two stages of gain.

Don’t tell that to Nelson.

dave

 

[planet10]

I am a novice as well… i look at these and say, what can i sub in that works and will use the existing chassis and power transformer.

dave

 

[as_audio]

But it can be fixed. Will add a schematic later.

 

[as_audio]

MAS Metaxas Solitaire Power Amplifier Schematic added, sorry for bad copy

 

[as_audio]

Tried to upload another schematic in different form, from official Metaxas
brochure, it is pdf (PDF-1.5), error message "Image file type is invalid" ..

 

[Bonsai]

I have a similar ‘hall of shame’ story. About 3 yrs ago I was on a hifi show with my amps and the organiser gave me an ‘upgraded’ Oppo CD player - top model at the time. It was being modded by some local guy to apparently improve the sound by inserting in a kluged digital PSU board. It hummed like hell and of course everyone looked at my gear. We quickly found the source. He had used Block EI transformer and some cheap 3.3 and 5 V regs. The transformer was placed right over the analog output circuits. I plugged my personal Oppo 103 in - problem gone. The shocking thing is, he was charging nearly £1000 for the ‘upgrade’ on top of a player that was selling for well over £2000 at the time.

 

[as_audio]

This amount of money obviously was an upgrade in his professional life.

 

[as_audio]

..