Luxman L-85v Integrated Amplifier

[Jojo]

It actually looks pretty much original, right down to the 45 year old dust, the odd spilled drink etc.

You mention hum. Is the hum common to both channels or just one? Is it dependant on volume setting or does it remain constant? Does the tone bypass/defeat function change the hum level?

The original Nippon Chemicon black electrolytics are usually pretty reliable, however Lux has glued several of the large ones down and corrosion of the leads under the capacitors is a very common issue. There is one that has a significant lean on it- it could be OK, but it could also be the rubber seal swelling and lifting the cap. Those old caps have their vents on the base, not the top like modern caps. I have arrowed the one I don't like the look of.
View attachment 181118
Down the track, you need to have the four red arrowed components replaced with twin diode strings (2x1N4148). They are an epoxy 'blob' varistor diode and they are failure prone. When they become intermittent, the amp will go in and out of protection and then possibly fail altogether.

The Lux L-81 is a great vintage integrated amplifier- very beautiful to look at, nicely made and very reliable. They are also worth a lot on the 2nd hand market. Enjoy!

@restorer-john Hello, thank you for you response ! I will try to be understable in english...
"It actually looks pretty much original, right down to the 45 year old dust, the odd spilled drink etc." Good to know i guess. The spilled drink thing does not seems to be a problem since the amp is working fine with. Idk where it comes from. Looks like someone tried acetone or something hard on cleaning.

"You mention hum. Is the hum common to both channels or just one? Is it dependant on volume setting or does it remain constant? Does the tone bypass/defeat function change the hum level?"
The hum is constant, botch channels, in the tweeter (2,5k --> 13,5k is the frequency band for this driver). Independant of volume knob. This little hum was always here. It's only when i turn on "speakers" A or B, not before (logical, right). I've read that this amp seems to not be grounded good in some of your responses and in some words from @sabristol. Could it be just this ?

"The original Nippon Chemicon black electrolytics are usually (...) I have arrowed the one I don't like the look of."
Thanks a lot for this explanation. Very interesting even if i'm not an electrician (really far from it )
So you would change this one cap if you had this amp right ? I'm thinking that if i change one i change them all... They are like 45years old. I'm not sure how it will affect the sound if i put some audio caps from now. The two big caps may be need to be replaced too, 63V 6800uf if i follow what i've seen for this amp on the internet, almost everytime they lack of uF capacitance.

"Down the track, you need to have the four red arrowed components replaced with twin diode strings (2x1N4148). They are an epoxy 'blob' varistor diode and they are failure prone. When they become intermittent, the amp will go in and out of protection and then possibly fail altogether."
Thanks a lot for this information. Very usefull to know.
I've seen several persons talking about the different diodes on this amp - like https://www.audiovintage.fr/2014/02/23/luxman-l81/
I think i don't have the skill/electrical knowledge to do it unfortunally ; i will try to find a local shop to do it for me. Cause i don't wan't to damage the amp since it is still working (all the tone/bypass are working).

I would like to compare this amp "fixed" and class d from nowadays (hypex etc.) just to see how it performs. I guess it's worst on THD and everything, but this thing surprised me cause everything seems "here", in the room with me. I want to keep this baby alive !

 

[Jojo]

I just add some pics (sorry for double post) - I was speaking about transistors, one channel is sylvania EGC 2**. Is this original too ?
And again, i'm so glad i found ASR. What a forum

 

[restorer-john]

I'd like to see those Sylvania replacement OPTs replaced with NOS, but, considering the originals are from 1977 (date code), it would be a bit hard to find genuine ones.

If it works well, I say leave it alone, as apart from the replaced OPTs, she looks fantastic.

Hum in the tweeters sounds more like residual noise to me. The vintage Luxs have some of that.

 

[Jojo]

I've seen some NEC OPT's in l-80 or l-80v on the internet. As far as i undestand (or missunderstand), the important thing is to keep electrical propertys of the NOS one, right ? So i don't know if the EGC280 is a good replacement and i'm not sure about what was the reference one on l-81... Same as the other channel ? (Hitachi)
--- So, someone actually changed opt's in this amp... but when ? i will never know ! Kind of mysterious. ---
I found "MJ15003G" and "MJ15001G" being an equivalent of hitachi ones but i'm not sure about it since i don't have the knowledge to verify it myself with the values.


I will follow your consideration knowing what you did on those amps. Yes i think it wasn't so much used because it seems to still have a lot of power for a 2x45w amp. I'm a bit surprised of your phrase saying "she looks fantastic" ; you mean interior components health ?
It seems kind of a very nice bid for 30€.
So now I want to :
- change the bulb light. This is P711 - P710 right ? Need to find the good voltage or led replacement with resistor, idk...
- Put new diodes 1N4148
And i would like to know if the 2way power plug need to be changed for a 3 way plug (I'm in France, i would like to have the "earth" on the plug to).

​

​

 

[restorer-john]

I have several lux's in my collection, including two L81s. They used either NEC it Hitachi finals. I can give you the numbers, but several alternatives were used for service, none being Sylvanias.

 

[Jojo]

It does not rassure me to know that... Yes if it don't take too much time to you, some alternatives names are always good to take.
Thanks.
( i hope it's not disrepectful to post my questions on this thread ; i could start a new one but they seems like "brothers amps" and pretty rare so i finally put my askings and photos here so it feed this thread with something relied on the l-85v)
One photo of some NOS (nec) ones

 

[Pineapple Dave]

This is a project I did last year - a mid 70s Luxman L-85v refurbishment with a re-engineered output stage.
View attachment 114355

The output stage PCBs were damaged in the early 1980s I've I had this amp kicking around since then. After 30 years, I eventually decided to try designing and building some replacements based on the Bob Cordell and Douglas Self books. After numerous attempts I ended up with:
View attachment 114359

Here are the finished PCBs fitted:
View attachment 114360

I thought this forum may be interested some of the tests I've put it through using the QuantAsylum QA-401 and QA451.

Frequency Response
Happy with the FR, although I could roll off the bottom end a little earlier.
View attachment 114358

THD v.s. Power
Happy with the results as better than OEM spec. It's odd that the left channel distorts earlier though and suspect this is due to output transistors. May change the left hand pair to see if that is the problem.
View attachment 114361

Intermodulation Distortion
This is worse than the OEM spec, but suspect I'm not comparing like with like. The QA-401 uses 19k and 20k, whereas I expect the OEM test was at significantly lower.
View attachment 114362IMD

Output Impedance
This seems a bit high as, if I understand this correctly it makes damping factor a paltry 8/0.35 = 23.
View attachment 114372

My first post on here so I'd appreciate some constructive feedback!

Nice, would you happen to sell a pair of your pcb's. maybe a part list and walk thru diy assembly instructions?

 

[Northernlight]

Hi all, new member to the forum here.

I have just picked up an L-85v which the seller tells me has been recapped and serviced. I have given it a test run and it does sound very good indeed but I noticed that it is rather ‘loud’.

Ie, even on the first volume notch it is fairly audible in my lounge setting. I’m used to slightly more subtlety in being able to have quietly in the background when the family are around so this came as something of a surprise.

Can anyone let me know if this is something normal with these amps or if there’s some form of adjustable gain that I can tinker with?

Many thanks!

 

[Doodski]

Hi all, new member to the forum here.

I have just picked up an L-85v which the seller tells me has been recapped and serviced. I have given it a test run and it does sound very good indeed but I noticed that it is rather ‘loud’.

Ie, even on the first volume notch it is fairly audible in my lounge setting. I’m used to slightly more subtlety in being able to have quietly in the background when the family are around so this came as something of a surprise.

Can anyone let me know if this is something normal with these amps or if there’s some form of adjustable gain that I can tinker with?

Many thanks!

Use the attenuate switch at the front panel.

 

[Northernlight]

Thanks, I had thought the function of that was more as a mute but that does now make some sense!

 

[Northernlight]

Hi again all, having given this amp some time with my various music formats I have to conclude that it’s a very sweet sounding unit (even if I haven’t really gone into the nth degree with the rather complex tone controls!).

The only thing that doesn’t work is the power on led above the main volume control. Does anyone know if this is an easy item to source and replace?

Thanks

 

[Jojo]

Hi again all, having given this amp some time with my various music formats I have to conclude that it’s a very sweet sounding unit (even if I haven’t really gone into the nth degree with the rather complex tone controls!).

The only thing that doesn’t work is the power on led above the main volume control. Does anyone know if this is an easy item to source and replace?

Thanks

Idk if it can help, but i have the l-81, i think it's the same light bulb. It was not working until i "cleaned" the components inside of the amp. It's working again since this day. So i guess dust was the problem in some way.