As this is still an M-05 thread : the Luxman is one of few amplifiers i have seen with ventilation slots in 3 plaines.
Amazing that forced ventilation can enable full class A operation of a 6-device output stage at that level.
Anyone who has lifted a 100 pounds of M-05 knows how incredibly hot that thing gets.
Amazing that forced ventilation can enable full class A operation of a 6-device output stage at that level.
Anyone who has lifted a 100 pounds of M-05 knows how incredibly hot that thing gets.
You're right. The good channel is heating a lot. With all this heat, I'm asking me how long the output transistors can be good to get best sound.
I had a Classe DR3B class A amplifier. When I changed the output transistors, the sound changed dramatically. I suppose that heat finish to alterate semiconductor characteristics so they become worn with time.
Jacco, did you heard this amplifier ? I would like to know if the sound is marvelous. If it is sounding like a Krell, I will not love it. About my taste, the Krell is sounding like an amplifier with a lot of negative feedback. I love relax sound (tube like ?)
Thanks
Marc
I had a Classe DR3B class A amplifier. When I changed the output transistors, the sound changed dramatically. I suppose that heat finish to alterate semiconductor characteristics so they become worn with time.
Jacco, did you heard this amplifier ? I would like to know if the sound is marvelous. If it is sounding like a Krell, I will not love it. About my taste, the Krell is sounding like an amplifier with a lot of negative feedback. I love relax sound (tube like ?)
Thanks
Marc
Depends on the Krell model.
The M-05 ranked among amps like Threshold S300 series and Conrad Johnson's Premier 4 if you're into tubes (also a 100 watts amplifier, EL34 tubes).
I've heard the Luxman on electrostats, that amplifier can drive anything and is never harsh imo.
Just as good or better as the price comparable models by Accuphase, Stax, or Mark Levinson of those years.
Definitely more attractive than a bunch of other SS amps for someone who enjoys the tube-bouquet, marvelous beast.
The M-05 ranked among amps like Threshold S300 series and Conrad Johnson's Premier 4 if you're into tubes (also a 100 watts amplifier, EL34 tubes).
I've heard the Luxman on electrostats, that amplifier can drive anything and is never harsh imo.
Just as good or better as the price comparable models by Accuphase, Stax, or Mark Levinson of those years.
Definitely more attractive than a bunch of other SS amps for someone who enjoys the tube-bouquet, marvelous beast.
Banned
Joined 2002
id love to see one 
Mr. jleaman,
Here you go sir ...follow this link, but don't blink.
The M-05 is a nice sounding amplifier, not a Krell sound that I can remember. They run so hot that the green outputs turn gray / brown. The old grease needs to be shaved off, or use a strong solvent as I do.
It is pretty as well.
-Chris
Here you go sir ...follow this link, but don't blink.
The M-05 is a nice sounding amplifier, not a Krell sound that I can remember. They run so hot that the green outputs turn gray / brown. The old grease needs to be shaved off, or use a strong solvent as I do.
It is pretty as well.
-Chris
I just got another M-05
This one will not be a party to repair. An idiot placed 120 vac across both speaker output terminals. It comes from an insurance company.
The output transistors and drivers are charcoaled. Some great fun for winter is coming.
When I was talking about a Krell amplifier, I talked about a KSA100.
Marc
This one will not be a party to repair. An idiot placed 120 vac across both speaker output terminals. It comes from an insurance company.
The output transistors and drivers are charcoaled. Some great fun for winter is coming.
When I was talking about a Krell amplifier, I talked about a KSA100.
Marc
Marc,
Then the service manual has a misprint.
The NJM dual opamp in the schematic is a type used for DC-servos, and as it is connected in parallel with the freq. compensation and NFB components in the feedback line from output to the matched JFET input pair it is for DC-purposes.
VR201 is connected between an input of one of the NJM opamps and 2 regulation fets of the power rails for the opamps.
By adjusting VR201 the DC output voltage of 1 of the 2 opamps changes.
The first opamp is the active DC-servo, the second the static DC control.
The class A bias for the M-05 is adjusted with a Vbe multiplier at the driver stage, like any other normal power output stage, by trimpot VR204.
The 2SK146 matched N-channel JFET input pair is ok if the cold channel is playing music
Unless you are a very static prone person and touch its legs with your fingers it's not that easily destroyed.
Which is a good thing because these are hard to source and expensive. Always were, but now that they are obsolete you'll bleed if you need one. I know some places that still carry the lower V grade but an BL or a GR grade is trickier. Unless you're a longtime parts scavenger like me, you'll need to find substitutes for 2 out of 3 active parts in the M-05 if they are broken.
Even the successor of the 2SK146, the 2SK389, has become obsolete. I just bought 100 of those for my retirement.
So no touchy !
The M-05 was succeeded by other M models, from the 60 watts M-06 to the 250watts M-10. I lost count after that, maybe Chris knows which is the current M number.
The M-08 was like a revamped M-05. Same kind of topology, a similar 6-device output stage, and 100 watts in class A, but with even more attention to detail.
MSRP of the M-08 was $15.000 overhere and a well serviced one will do $5000 with ease.
Means retail price of an M-05 re-issue would costs a multitude of the price i mentioned in the email i sent you.
An M-05 is a collectors item overhere, market value of a nice one is positioned under the M-08. You are lucky to source these babies so easily.
20 years poorer and in your luxurious shoes, i'd be a reconditioned M-05 dealer.
(aren't the big amplifier feet i received from ApexJR a sight for sore eyes)
Then the service manual has a misprint.
The NJM dual opamp in the schematic is a type used for DC-servos, and as it is connected in parallel with the freq. compensation and NFB components in the feedback line from output to the matched JFET input pair it is for DC-purposes.
VR201 is connected between an input of one of the NJM opamps and 2 regulation fets of the power rails for the opamps.
By adjusting VR201 the DC output voltage of 1 of the 2 opamps changes.
The first opamp is the active DC-servo, the second the static DC control.
The class A bias for the M-05 is adjusted with a Vbe multiplier at the driver stage, like any other normal power output stage, by trimpot VR204.
The 2SK146 matched N-channel JFET input pair is ok if the cold channel is playing music
Unless you are a very static prone person and touch its legs with your fingers it's not that easily destroyed.
Which is a good thing because these are hard to source and expensive. Always were, but now that they are obsolete you'll bleed if you need one. I know some places that still carry the lower V grade but an BL or a GR grade is trickier. Unless you're a longtime parts scavenger like me, you'll need to find substitutes for 2 out of 3 active parts in the M-05 if they are broken.
Even the successor of the 2SK146, the 2SK389, has become obsolete. I just bought 100 of those for my retirement.
So no touchy !
The M-05 was succeeded by other M models, from the 60 watts M-06 to the 250watts M-10. I lost count after that, maybe Chris knows which is the current M number.
The M-08 was like a revamped M-05. Same kind of topology, a similar 6-device output stage, and 100 watts in class A, but with even more attention to detail.
MSRP of the M-08 was $15.000 overhere and a well serviced one will do $5000 with ease.
Means retail price of an M-05 re-issue would costs a multitude of the price i mentioned in the email i sent you.
An M-05 is a collectors item overhere, market value of a nice one is positioned under the M-08. You are lucky to source these babies so easily.
20 years poorer and in your luxurious shoes, i'd be a reconditioned M-05 dealer.
(aren't the big amplifier feet i received from ApexJR a sight for sore eyes)
Attachments
I checked the 2sc1904 which are attached to the heatsink. They are ok. What's the problem if the relay (RY202) have one or both contacts that doesn't work ?
The bias of the faulty chanel can be adjusted at a maximum of 50 MV and it is supposed to be set at 110mv. This voltage is taken at the 0.22 ohm at output transistors.
thanks
Marc
The bias of the faulty chanel can be adjusted at a maximum of 50 MV and it is supposed to be set at 110mv. This voltage is taken at the 0.22 ohm at output transistors.
thanks
Marc
You'll have to check with a DMM if Q210, Q211, and C204 are still ok.
Relay RY202 is for thermal protection, if the heatsinks become too hot the relay will shut down the bias by bypasssing the Vbe multiplier and the pre-driver bases to ground.
With the relay activated you may hear sound if the left contact sticks but it won't be pretty, and only with high volume setting.
If both contacts remain in position the bases of Q213 and its counterpart are connected to ground all the time and you won't hear a thing.
The "counterpart" probably should be Q212, C207 is printed twice on the schematic.
Q213 reads like a Mitsubishi 2SA1364, if it is the other pre-driver Q212 should be 2SC3444.
They both should have an awkward looking case, called SC-62 in Japan and X-90 elsewhere.
I can not imagine the line from the relay to the top pre-driver to connect at the crossing of 202 and ground, this schematic looks to contain several miss-prints too. Calling Anatech ?
Relay RY202 is for thermal protection, if the heatsinks become too hot the relay will shut down the bias by bypasssing the Vbe multiplier and the pre-driver bases to ground.
With the relay activated you may hear sound if the left contact sticks but it won't be pretty, and only with high volume setting.
If both contacts remain in position the bases of Q213 and its counterpart are connected to ground all the time and you won't hear a thing.
The "counterpart" probably should be Q212, C207 is printed twice on the schematic.
Q213 reads like a Mitsubishi 2SA1364, if it is the other pre-driver Q212 should be 2SC3444.
They both should have an awkward looking case, called SC-62 in Japan and X-90 elsewhere.
I can not imagine the line from the relay to the top pre-driver to connect at the crossing of 202 and ground, this schematic looks to contain several miss-prints too. Calling Anatech ?
Hi jacco,
The manual does have misprints, but I normally ignore the mistakes when working on a circuit. I really ought to have corrected the problems when I was working on one.
Yes, RY202 shuts down the entire shooting match. RY201 is something I'd rather trace due to possible schematic errors. It may speed up the DC correction during start up as a guess.
Aside from technician blunders, I normally see heat related issues with these. Transistor junctions can go intermitten open and the solder joints need attention. Everything on the heatsink is normally cooked past usefulness on top of that.
So if you have low bias, but signal, start by making sure all the protection transistors check okay (Q222 ~ Q225). Check Q210 and Q211 for leakage as well. Just thinking out loud. All the leds are lighting up, right?
-Chris
The manual does have misprints, but I normally ignore the mistakes when working on a circuit. I really ought to have corrected the problems when I was working on one.
Yes, RY202 shuts down the entire shooting match. RY201 is something I'd rather trace due to possible schematic errors. It may speed up the DC correction during start up as a guess.
Aside from technician blunders, I normally see heat related issues with these. Transistor junctions can go intermitten open and the solder joints need attention. Everything on the heatsink is normally cooked past usefulness on top of that.
So if you have low bias, but signal, start by making sure all the protection transistors check okay (Q222 ~ Q225). Check Q210 and Q211 for leakage as well. Just thinking out loud. All the leds are lighting up, right?
-Chris
I worked in the amplifier this afternoon. I measured the bias of each output transistors and they seems very different. The dc offset is also unstable. I begin to think that the output transistors are perhaps the problem. Mismatch and DC offset which fluctuate are perhaps enough to try new transistors.
The 2SA1302 / 2SC3281 sold by many places seems to be now counterfeit parts. Genuine Toshiba 2SA1943 / 2SC5200 seems to be a lot easier to find and are near equivalents. The input capacitance of the newer part is lower 200 Pf instead of 270 Pf.
Is it a good idea to use 2SA1943 / 2SC5200 ?
Is lower input capacitance = oscillation risks ?
About sound quality, will they be as better as original 2SA1302 / 2SC3281 ?
What's the best place to buy them in North america (or other good place) ?
Thanks a lot
Marc
The 2SA1302 / 2SC3281 sold by many places seems to be now counterfeit parts. Genuine Toshiba 2SA1943 / 2SC5200 seems to be a lot easier to find and are near equivalents. The input capacitance of the newer part is lower 200 Pf instead of 270 Pf.
Is it a good idea to use 2SA1943 / 2SC5200 ?
Is lower input capacitance = oscillation risks ?
About sound quality, will they be as better as original 2SA1302 / 2SC3281 ?
What's the best place to buy them in North america (or other good place) ?
Thanks a lot
Marc
True,
only a few sell genuine Toshiba old numbers, but for real steep prices. All others sell fakes.
The 2SA1943/2SC5200 are decent but you'll have to be carefull not to buy fakes either.
In your case i'd go for OnSemi MJL4302/4281.
These are 230 watt devices, better capable of handling the heat level in the M-05
Fast ones too, and they are easily obtainable for realistic prices.
Or, go for OnSemi replicas of the 2SA1302/2SC3281=> MJL1302/MJL3281. A bit cheaper than the 4000 series.
The original first series 2SA1302/3281 were 150 watt devices.
Later stage production was capable of 200 watts. The 200 watt power figure of the MJL1302/3281 will also have lower die temperatures at the prescribed bias level.
only a few sell genuine Toshiba old numbers, but for real steep prices. All others sell fakes.
The 2SA1943/2SC5200 are decent but you'll have to be carefull not to buy fakes either.
In your case i'd go for OnSemi MJL4302/4281.
These are 230 watt devices, better capable of handling the heat level in the M-05
Fast ones too, and they are easily obtainable for realistic prices.
Or, go for OnSemi replicas of the 2SA1302/2SC3281=> MJL1302/MJL3281. A bit cheaper than the 4000 series.
The original first series 2SA1302/3281 were 150 watt devices.
Later stage production was capable of 200 watts. The 200 watt power figure of the MJL1302/3281 will also have lower die temperatures at the prescribed bias level.
Hi Marc,
On Semi is making the MJL1302 / MJL3281 under license from Toshiba. Their newer outputs sound fabulous. No worries about the sound quality. There was never a complaint about the MJ15022 ~ MJ15025 parts either for sound quality. TO-3 though.
Really, too much worry about brand names going on.
-Chris
On Semi is making the MJL1302 / MJL3281 under license from Toshiba. Their newer outputs sound fabulous. No worries about the sound quality. There was never a complaint about the MJ15022 ~ MJ15025 parts either for sound quality. TO-3 though.
Really, too much worry about brand names going on.
-Chris
Marc,
Ssang Yong can build an engine under license, that doesn't make it a Merc.
The 2SA1302, 2SA1943 and MJL1302 are all different devices.
Japanese semiconductor manufacturers base their production solely on demand from the Japanese market. If the local demand level does not justify continueing production of an item it is taken out. There are plenty of Japanese semiconductors that were replaced by lesser ones because of changes in the Japanese audio industry. Wish i had been more prudent in the past and bought twice as many parts every time.
The 2SK146 in your M-05 is a prime example. There is nothing like it anymore, and probably never will. That device was pretty expensive when i bought them while it was a regular production device. Now you pay at least 6 times as much, if you can find them.
Question is : would you rather risk using inferior parts you paid top dollar for to rebuild a classic car and keep the original flaws, or use affordable aftermarket parts and build a more reliable car ?
A lot of the amplifiers from that era were not constructed with longevity in mind. Japanese manufacturers in particular had/have the urge to minimise parts and production costs wherever they can. Especially with class A amplifiers and output stage cooling more than one Japanese manufacturer had a hand of going for undersizing and designing for high temperature levels. Some made that decision over and over again, despite market feedback to be more prudent. Several Japanese (class AB) amplifiers are notorious for this minimalise state of mind.
If i had your M-05 i would rebuild the output stage with heavy duty OnSemi's. (despite me having all the parts to keep it fully original)
But then, i'd toss a Chevy V8 in a Range Rover instead of retaining the crummy original engine. I'd never buy a Tifosi model.
Ssang Yong can build an engine under license, that doesn't make it a Merc.
The 2SA1302, 2SA1943 and MJL1302 are all different devices.
Japanese semiconductor manufacturers base their production solely on demand from the Japanese market. If the local demand level does not justify continueing production of an item it is taken out. There are plenty of Japanese semiconductors that were replaced by lesser ones because of changes in the Japanese audio industry. Wish i had been more prudent in the past and bought twice as many parts every time.
The 2SK146 in your M-05 is a prime example. There is nothing like it anymore, and probably never will. That device was pretty expensive when i bought them while it was a regular production device. Now you pay at least 6 times as much, if you can find them.
Question is : would you rather risk using inferior parts you paid top dollar for to rebuild a classic car and keep the original flaws, or use affordable aftermarket parts and build a more reliable car ?
A lot of the amplifiers from that era were not constructed with longevity in mind. Japanese manufacturers in particular had/have the urge to minimise parts and production costs wherever they can. Especially with class A amplifiers and output stage cooling more than one Japanese manufacturer had a hand of going for undersizing and designing for high temperature levels. Some made that decision over and over again, despite market feedback to be more prudent. Several Japanese (class AB) amplifiers are notorious for this minimalise state of mind.
If i had your M-05 i would rebuild the output stage with heavy duty OnSemi's. (despite me having all the parts to keep it fully original)
But then, i'd toss a Chevy V8 in a Range Rover instead of retaining the crummy original engine. I'd never buy a Tifosi model.
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