Great Site! I look forward to participating!
I'm repairing one of these, and two outputs - one P, one N, have been replaced on one channel.
It worked for awhile and is now popping fuses ( + and - )
I was wondering what a good replacement would be?
These are substituted in now: PNP - Hitachi 25B655A
NPN - RCA 2N3772
The originals have been relabeled - Mondial - 027 9132N (NPN)
and - Aragon - 031 9132 N (NPN)
This is a nice amp, has 140v rails, serviceable, and built to last.
Thoughts on just running each channel with 6 outputs on each channel instead of 8?
I'm repairing one of these, and two outputs - one P, one N, have been replaced on one channel.
It worked for awhile and is now popping fuses ( + and - )
I was wondering what a good replacement would be?
These are substituted in now: PNP - Hitachi 25B655A
NPN - RCA 2N3772
The originals have been relabeled - Mondial - 027 9132N (NPN)
and - Aragon - 031 9132 N (NPN)
This is a nice amp, has 140v rails, serviceable, and built to last.
Thoughts on just running each channel with 6 outputs on each channel instead of 8?
Schematic
Would be nice. These are more simple amps compared to a lot of others I've seen.. There is a simple schematic available on here, but it's kindof a rough scan.. Every bit helps though!
Would be nice. These are more simple amps compared to a lot of others I've seen.. There is a simple schematic available on here, but it's kindof a rough scan.. Every bit helps though!
You wrote that both the output of the NPN and placed as a substitute and NPN and PNP. I think that Aragon has mj15003 and 15004 at output. Have you checked the resistor at emitter of driver transistor.
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These transistors say Japan on them.. The resistors are .33 , but 2 have been replaced with 2.2 ohm..
Gonna get into this today and pull these two odd transistors, check for shorts and try it out.
It may have been working, but became unstable and blew the fuses at high volume.. , we'll see..
Hopefully the Aragon guru's will chime in!
Gonna get into this today and pull these two odd transistors, check for shorts and try it out.
It may have been working, but became unstable and blew the fuses at high volume.. , we'll see..
Hopefully the Aragon guru's will chime in!
Found two shorted outputs (the hitachi and the oem one next to it).. removed the other substitute (RCA) and it sounds great now. - the RCA has less forward bias voltage when tested, so it does not match the others closely. about .1 volt less each way.. - Hopefully someone will chime in with some good matches..
I have successfully repaired a 4004mk2 that had one defect channel.
The defect channel had Toshiba 2SD424/2SB554 and the other (the working ) channel had Aragon labeled transistors.
After asking a lot of local experts from my network it seemed that several kinds (Aragon/Motorola/Toshiba) were in use throughout the lifetime of these amps.
Appearently even official repair centers allowed for one channel having one kind of transistors and the other channel having another kind.
After fruitless attempts of getting new genuine Toshibas, I settled for OnSemi MJ15003/15004.
I bought ten pieces of each and picked the ones that were closest to each other in Hfe.
These were even more closely matched than the Aragon transistors in the other channel.
I left the Aragon transistors in the working channel - if it ain't broke don't fix it - and I couldn't hear any difference or stereo-smearing or anything at all, even knowing there were two different kinds of transistors in the two channels.
I played on the amp for 6 months and then sold it on.
It is not the best sounding amplifier around, but it might be a good choice for difficult loading speakers ...and the design is just soooo sexy.
You could easily play it with 6 outputs instead of 8, but don't. This amplifiers claim to fame is the hefty output, so it deserves a correctly repaired, closely matched and well adjusted output stage.
Also check if it picks up noise. I had to add an output coil since it was picking up some EMC and slowly going into audible oscillation around 6-8kHz. Remember this amp is constructed before cheap SMPS mobile-phone chargers, wi-fi congestion and halogen spotlights.
The defect channel had Toshiba 2SD424/2SB554 and the other (the working ) channel had Aragon labeled transistors.
After asking a lot of local experts from my network it seemed that several kinds (Aragon/Motorola/Toshiba) were in use throughout the lifetime of these amps.
Appearently even official repair centers allowed for one channel having one kind of transistors and the other channel having another kind.
After fruitless attempts of getting new genuine Toshibas, I settled for OnSemi MJ15003/15004.
I bought ten pieces of each and picked the ones that were closest to each other in Hfe.
These were even more closely matched than the Aragon transistors in the other channel.
I left the Aragon transistors in the working channel - if it ain't broke don't fix it - and I couldn't hear any difference or stereo-smearing or anything at all, even knowing there were two different kinds of transistors in the two channels.
I played on the amp for 6 months and then sold it on.
It is not the best sounding amplifier around, but it might be a good choice for difficult loading speakers ...and the design is just soooo sexy.
You could easily play it with 6 outputs instead of 8, but don't. This amplifiers claim to fame is the hefty output, so it deserves a correctly repaired, closely matched and well adjusted output stage.
Also check if it picks up noise. I had to add an output coil since it was picking up some EMC and slowly going into audible oscillation around 6-8kHz. Remember this amp is constructed before cheap SMPS mobile-phone chargers, wi-fi congestion and halogen spotlights.
When I want to hear the difference in sound output transistors, bring on both channels the same signal and listen to what frequency deviates from the central vertical line. Stereo sound can not show the difference in sound because the left and right channels are not the same.
The Aragons are very sought after by audiofreaks who couldn't afford it back then, but IMO it is really just down to the looks.
Despite the many outputs and the heavy powersupply, the Aragon has a very sloppy bass.
Harman Kardon Signature 1.5 is of equal size but has a much much better sound and is often very cheap second hand. Super-tight bass and a more open sound.
Based on my personal experiences with having listened to them alot at the store I used to work at circa 1998, they don't hold up to the level of Mark Levinson, but they were significantly better than their Acurus cousins. I'd say they occupy a sort of grey area between NAD/Acurus/Arcam and Levinson/Krell. The general quality, appearance, and performance is on par with alot of "high end" stuff, but sound quality never quite reached that top level. They paired well with some interesting high end speakers, like the Eggleston Works Andra, but I remember them doing exceptionally poor with the big Apogee ribbons (to be fair, almost all the amps performed badly with those... probably why they never sold). We probably had them hooked up to Dynaudio Contour series speakers most of the time. I don't remember if they worked well driving the MBL 101D or not... I'm sure we tried them together at least once and I think a customer had one driving 101Cs for his system. We tried practically everything with everything at that store.
"the Aragon has a very sloppy bass."
Merely a sign of poor power supply bypassing.
Either the amplifier has none, or they need to be replaced. Try values around 22µF~100µF on each main filter cap.
Merely a sign of poor power supply bypassing.
Either the amplifier has none, or they need to be replaced. Try values around 22µF~100µF on each main filter cap.
Be careful to get a high current ground, make sure the input ground and feedback grounds are isolated from this point.
I find if you use a 470µF as a bypass you will need something smaller in parallel with that. Smaller values of film caps are good, but may need a small resistor in series with them to avoid oscillations from the inductance in the wires/traces.
I find if you use a 470µF as a bypass you will need something smaller in parallel with that. Smaller values of film caps are good, but may need a small resistor in series with them to avoid oscillations from the inductance in the wires/traces.
Based on my personal experiences with having listened to them alot at the store I used to work at circa 1998, they don't hold up to the level of Mark Levinson, but they were significantly better than their Acurus cousins. I'd say they occupy a sort of grey area between NAD/Acurus/Arcam and Levinson/Krell. The general quality, appearance, and performance is on par with alot of "high end" stuff, but sound quality never quite reached that top level. They paired well with some interesting high end speakers, like the Eggleston Works Andra, but I remember them doing exceptionally poor with the big Apogee ribbons (to be fair, almost all the amps performed badly with those... probably why they never sold). We probably had them hooked up to Dynaudio Contour series speakers most of the time. I don't remember if they worked well driving the MBL 101D or not... I'm sure we tried them together at least once and I think a customer had one driving 101Cs for his system. We tried practically everything with everything at that store.
Interesting comments,
I can remember hearing them driving a pair of mini grands , well the palladium mono blocs, not the stereo 4004, I heard the Palladium setup at Mondial and can tell you i have never heard Apogee's sound better and i have heard apogee's on many many occasion's. The 4004mk2 sounded better than their 8008's replacements.
Thinking back i remember tony saying those palladium's were not off the self units... 🙂
Thanks, never thought of them having sloppy Bass when new, my criticism back then was about their top end and they did have good drive ..
Very rare to have room to do so ......
Not following you , series resistor ...?
"Not following you , series resistor ...? "
Do you understand the difference between series and parallel?
Resonant RLC Circuits
Do you understand the difference between series and parallel?
Resonant RLC Circuits
follow up:
Indy Audiolabs still supports Aragon, and I was pleasantly surprised to get original aragon labeled outputs for a decent price.
The above comments about the sound are correct, in the grey area between mid-fi and very high end. I repaired another one since then, and it was a later model, more heavily biased. The sound was extra close to very high end. It was biased around 21 mv, while the first was around 15 mv.
Possible close to the heatsinks limit if not well vented..
More heat = better sound in this case.. lol
We will be seeing these around for a very long time!
Gotta love the trimmer resistors that have the gear reduction, talk about getting it just right - with the cover on and room temp all warmed up with no fans.
Indy Audiolabs still supports Aragon, and I was pleasantly surprised to get original aragon labeled outputs for a decent price.
The above comments about the sound are correct, in the grey area between mid-fi and very high end. I repaired another one since then, and it was a later model, more heavily biased. The sound was extra close to very high end. It was biased around 21 mv, while the first was around 15 mv.
Possible close to the heatsinks limit if not well vented..
More heat = better sound in this case.. lol
We will be seeing these around for a very long time!
Gotta love the trimmer resistors that have the gear reduction, talk about getting it just right - with the cover on and room temp all warmed up with no fans.
I don't like Aragon's use of an IC chip on the amp board. IC's are hit and miss in my experience..
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