Let's hope someone is still paying attention to this thread.
I'm trying to gather the parts to build a Luxman clone of model 5M20.
Main problem is, of course, all active part types have to be replaced with available ones.
Now I'm trying to make groups of substitutes for each bipolar, and which modern part can be used. This will probably affect the sound of the final amp, but there's little that can be done about it. Particularly with the tools we DIYers have.
Comparing datasheets and check that minimum specs are equal or better is the fist step.
I will list some of the parts and what replacements could work better.
That is if someone is following this. So please tell me if you are around.
I'm trying to gather the parts to build a Luxman clone of model 5M20.
Main problem is, of course, all active part types have to be replaced with available ones.
Now I'm trying to make groups of substitutes for each bipolar, and which modern part can be used. This will probably affect the sound of the final amp, but there's little that can be done about it. Particularly with the tools we DIYers have.
Comparing datasheets and check that minimum specs are equal or better is the fist step.
I will list some of the parts and what replacements could work better.
That is if someone is following this. So please tell me if you are around.
Hi Carlmart, I have just come across this thread.
Did you have any luck in sourcing modern equivalents for 2SA968B/2SC2238B by any chance?
Best I have found so far are 2SA1859/2SC4883 and Profusion have suggested 2SA1668/2SC4382, which have a lower ft
I should add that I am not too bothered about package or pin configurations
Did you have any luck in sourcing modern equivalents for 2SA968B/2SC2238B by any chance?
Best I have found so far are 2SA1859/2SC4883 and Profusion have suggested 2SA1668/2SC4382, which have a lower ft
I should add that I am not too bothered about package or pin configurations
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Yes I know and many thanks for suggesting.
Am waiting to see if I can find a closer equivalent before commiting!
Hi Sajti,
Thanks for that, but these are unfortunately obsolete, what I am seeking is a modern in-production equivalent.
Not worried about package or pin type, want to avoid obsolescence! So much good stuff is no longer available!
The pair 2SA1859/2SC4883 is what I used on the LTSpice simulations, and the results were excellent.
Let's hope the listening results are similar to those in the original amp, which were rather tricky transistors. They needed a 220R base resistor, with 220p cap in parallel.
With the new transistor you can use just a 10R base resistor and no cap. They did on other Luxman models from that family.
Simulation improved a lot after that change.
Hi Carlmart and Sajti,
Many thanks for your assistance here, much appreciated.
Looks like TTA/TTC004B is the closest match on paper, but I shall order 2SA1859/2SC4883 aswell and try both. Carlmart - you have Spice models for these? Could you share please?
They will be part of a Luxkit Avance Z504 rebuild I am undertaking, I have a standard one to compare results with.
Above transistors will drive 2SA1386/2SC3519 output devices, which replace the original 2SA1215/2SC2921, which are also now obsolete!
Paul
Many thanks for your assistance here, much appreciated.
Looks like TTA/TTC004B is the closest match on paper, but I shall order 2SA1859/2SC4883 aswell and try both. Carlmart - you have Spice models for these? Could you share please?
They will be part of a Luxkit Avance Z504 rebuild I am undertaking, I have a standard one to compare results with.
Above transistors will drive 2SA1386/2SC3519 output devices, which replace the original 2SA1215/2SC2921, which are also now obsolete!
Paul
.MODEL 2SC4883A_kq npn (Bf=140 Ikf=100 Is=600f Vaf=100 Rb=1.7 Re=105m RC=0 Rco=6 Ibc=150f Vo=30 Gamma=250n Cje=1.2n Cjc=72p Tf=875p Vtf=1.2 Itf=1 Qco=8p Nk=1.2 Br=2 Var=22.9 Ikr=36 TR=85n Xtb=0.34 Xtf=1.36 Vceo=180 Icrating=2A mfg=Sanken)
.MODEL 2SA1859A_kq pnp (Bf=162 IKF=10 Is=500f Vaf=300 Rb=0 Re=0 Rc=90m Rco=3.25 Ibc=150f Vo=120 Gamma=22n Cje=1.5n Cjc=72p Tf=1.9n Vtf=1.9 Itf=1 Qco=8p Br=2 Ikr=10 Var=23 Tr=188.8n Xtb=0.138 Xtf=5 Vceo=180 Icrating=2A mfg=Sanken)
.MODEL 2SA1859A_kq pnp (Bf=162 IKF=10 Is=500f Vaf=300 Rb=0 Re=0 Rc=90m Rco=3.25 Ibc=150f Vo=120 Gamma=22n Cje=1.5n Cjc=72p Tf=1.9n Vtf=1.9 Itf=1 Qco=8p Br=2 Ikr=10 Var=23 Tr=188.8n Xtb=0.138 Xtf=5 Vceo=180 Icrating=2A mfg=Sanken)
druidaudio,
It's interesting that you are working on a Z504. That seems like a very good amplifier.
I simulated both the Z504 and its predecessor, the M120.
Interestingly enough, the M120 specs (THD) are better than the Z504's. I plan to modify an amp I have, which has the same stages architecture as the M120, to convert it.
Of course none of the active parts would be the same, so I resist to call it a clone really.
If you want the simulations for both I can upload them here.
It's interesting that you are working on a Z504. That seems like a very good amplifier.
I simulated both the Z504 and its predecessor, the M120.
Interestingly enough, the M120 specs (THD) are better than the Z504's. I plan to modify an amp I have, which has the same stages architecture as the M120, to convert it.
Of course none of the active parts would be the same, so I resist to call it a clone really.
If you want the simulations for both I can upload them here.
Here are the sims for THD, measured at maximum output and for 20KHz.
I wish they were better, like on other recent amps.
If you want to, have a look at a thread of mine where I simulate other Luxmans. THD is much more better at all frequencies.
www.diyaudio.com/forums/solid-state/318909-luxman-clone-clone-6.html
I also simulated a dual bjt input on both M120 and Z504, and the results were very good.
As you can see, I am not using the DC servo on the Z504, as Luxman shows on the manual.
I wish they were better, like on other recent amps.
If you want to, have a look at a thread of mine where I simulate other Luxmans. THD is much more better at all frequencies.
www.diyaudio.com/forums/solid-state/318909-luxman-clone-clone-6.html
I also simulated a dual bjt input on both M120 and Z504, and the results were very good.
As you can see, I am not using the DC servo on the Z504, as Luxman shows on the manual.
On what amp?
Digikey seems to stock the TO3-P Sankens, so at least they are legit. What about matching?
It’s my own design. CF topology, 60-120W depending by supply voltage.
I get the output devices from Profusion, drivers from Digikey. I use 2SC6145/2SA2223 for the higher power version.
I match the output devices for hfe+Vbe.
Sajti
I'm curious about Vbe transistors matching, so I found two interesting threads here:
MJL3281 Vbe matching
Parallel output transistor matching
http://www.cappels.org/dproj/xstrmatch/Transistor_matching.html
On the second is suggested that:
"Output BJTs are usually not matched as VBE is very consistent, just use sufficient emitter degeneration for current sharing (0.2-0.6 Ohms will do usually)"
For smaller transistors, like those cascoding an LTP or used as pairs on a VAS, matching might perhaps bring distortion improvements.
The setup using just a zener seems simple enough to give it a try.
Parallel output transistor matching
MJL3281 Vbe matching
Parallel output transistor matching
http://www.cappels.org/dproj/xstrmatch/Transistor_matching.html
On the second is suggested that:
"Output BJTs are usually not matched as VBE is very consistent, just use sufficient emitter degeneration for current sharing (0.2-0.6 Ohms will do usually)"
For smaller transistors, like those cascoding an LTP or used as pairs on a VAS, matching might perhaps bring distortion improvements.
The setup using just a zener seems simple enough to give it a try.
Parallel output transistor matching
