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AU-D907 LIMITED vs 919

GrisPato said:
I understand, but with Bdent you pay $ 22 for 4pc, with ampslab $30 for 20 pc.
Was just a suggestion ;).
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Until the ideal replacements come along from mouser or digikey and am able to order only 4 then I guess I will not do anything.
Thanks
 
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Well, I could easily hear the difference when I swapped the substitute driver transistors I had used in my AU-X1 back to the correct and original types namely 2SC2238 & 2SA968, take from that what you will. :smoke:
 
Hyperion said:
Well, I could easily hear the difference when I swapped the substitute driver transistors I had used in my AU-X1 back to the correct and original types namely 2SC2238 & 2SA968, take from that what you will. :smoke:
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I think this is because the NMC/NMA1012/1216 were not as fast as the 2SC2493/2SA1068(N). And that's why Sansui went with the Toshiba 2SC2238/2SA968 as driver transistors.
 
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GrisPato said:
I think this is because the NMC/NMA1012/1216 were not as fast as the 2SC2493/2SA1069(N). And that's why Sansui went with the Toshiba 2SC2238/2SA968 as driver transistors.
Click to expand...
Interesting...

So there appears to be a dividing line emerging for some transistors in some models, where previous advice, dare I say 'rules', given by some about the use of certain transistors in certain locations is being revised on-the-fly. Soon we'll be hearing that it's fine to use MJ2119x in G-33000's and the like. :biggrin: :rolleyes:
 
Hyperion said:
Interesting...

So there appears to be a dividing line emerging for some transistors in some models, where previous advice, dare I say 'rules', given by some about the use of certain transistors in certain locations is being revised on-the-fly. Soon we'll be hearing that it's fine to use MJ2119x in G-33000's and the like. :biggrin: :rolleyes:
Click to expand...
I take it that is directed at me, again, the drivers in the 919 are 30mhz, the drivers in the X1 are 100mhz, the two amplifiers are different designs, the output transistors are not the same.
In my experience, swapping the drivers in an amplifier which is designed with 100mhz devices for devices which are 30mhz is clearly audible.
Also, in my experience, swapping the drivers in an amplifier which is designed with 30mhz devices with 100mhz devices made no audible difference, personally I would not expect it to.
This changes nothing about any previous advice I have given.
 
So, all joking aside, if the latest advice is that MJE1503x are ok as AU-919 drivers that's fine however, personally I still think they are significant overkill, at 8A Ic for a driver transistor, so not an ideal device, but maybe that's the World we live in repairing Vintage HiFi. For the time being I'll continue using devices closer to the spec of the originals for these positions whenever I can but I'll keep that as a personal SOP rather than advice to pass on.
 
Hyperion said:
personally I still think they are significant overkill, at 8A Ic for a driver transistor, so not an ideal device,
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This I agree on, and there normally should be a downside to this current capability that the original NEC's and more similar substitutes don't have. Maybe the non linearity and low hfe at smaller collector current (below 100 mA) as JoseHH quoted from ilimzn is something that plays its role here.
On the other hand the MJE150.. are advice an used in the slower amplifiers as substitutes with good results.
For me, I will keep trying to substitute with as similar as I can, for that I bought enough driver transistors from the Sanyo's because also like to use the metal tab.
As long as that will last . .
 
:lurk: I would just like to add to this by saying that when I changed them to the onsemi the sound seemed to improve. Keep in mind though that I also changed the outputs to the ST at the same time.
PS...I just talked to mouser on the phone and they suggest that I keep the onsemi in there.:smoke:
 
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kevzep said:
I take it that is directed at me, again, the drivers in the 919 are 30mhz, the drivers in the X1 are 100mhz, the two amplifiers are different designs, the output transistors are not the same.
In my experience, swapping the drivers in an amplifier which is designed with 100mhz devices for devices which are 30mhz is clearly audible.
Also, in my experience, swapping the drivers in an amplifier which is designed with 30mhz devices with 100mhz devices made no audible difference, personally I would not expect it to.
This changes nothing about any previous advice I have given.
Click to expand...
I have to disagree with the last part but before I do ,you need to know that a non tech nor educated in sound is writing . Just a hobbyist and if I had to describe my self towards a restoration with two word it will be
“An Indian with a screwdriver “
That been said and that I have no idea how a fast amp it sounds and I don’t know if this will work in the amps mention above or with different speakers in a different listening room , I have to tell you ,with certainty, that when I replace the Onsemis to TO-3Ps and the drivers to 100mhz devices on my AU717 the sound transformed equally before-after Leestereo restoration/upgrade . In the beginning I thought it was the TO-3Ps at the OPs that did that but I couldn’t say with certainty cause I did the replacement in both positions at the same time.
Now I’m finishing an AU517 ,the 517 after the restoration following Leestereo’s proposals it sounds awesome but far less good as the 717 . So now I replace the OPs from Onsemis to Sanken’s TO-3Ps and left the original drivers in for the sake of the experiment …. Nothing auditable happen and if there is something auditable there it’s very mild. Today I replace the drivers too with a 100mhz device from UTC until the appropriate Sanyos arrive ( if ever ) …. And there it is , like I tern a switch on (or off) the 517 is sounding unbelievably good equal to 717 and it didn’t took more than 10sec. to audibly recognise that .
My hearing according my last P.M.E (periodical medical examination ) is exceptional , this is what is stated in the document at least .
With all due respect , this is not an argument, we can not argue , I have only my hearing .
More likely is for a tech with your latitude , if you get the chance to check it out and let us know too about what happened,if something happens at your end !
Cheers
Kostis
 
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Hyperion said:
So, all joking aside, if the latest advice is that MJE1503x are ok as AU-919 drivers that's fine however, personally I still think they are significant overkill, at 8A Ic for a driver transistor, so not an ideal device, but maybe that's the World we live in repairing Vintage HiFi. For the time being I'll continue using devices closer to the spec of the originals for these positions whenever I can but I'll keep that as a personal SOP rather than advice to pass on.
Click to expand...
This is most certainly true and no disputing this, however, we were in a deep discussion about transition frequency, you weren't clear about the particular parameter/s you were referring to, so I assumed it was the transition frequency to which to which you were referring.
Now that we know this, I absolutely agree, but at the same time I don't think its worth changing them out if they are already in the amp.
 
ARGOU said:
I have to disagree with the last part but before I do ,you need to know that a non tech nor educated in sound is writing . Just a hobbyist and if I had to describe my self towards a restoration with two word it will be
“An Indian with a screwdriver “
That been said and that I have no idea how a fast amp it sounds and I don’t know if this will work in the amps mention above or with different speakers in a different listening room , I have to tell you ,with certainty, that when I replace the Onsemis to TO-3Ps and the drivers to 100mhz devices on my AU717 the sound transformed equally before-after Leestereo restoration/upgrade . In the beginning I thought it was the TO-3Ps at the OPs that did that but I couldn’t say with certainty cause I did the replacement in both positions at the same time.
Now I’m finishing an AU517 ,the 517 after the restoration following Leestereo’s proposals it sounds awesome but far less good as the 717 . So now I replace the OPs from Onsemis to Sanken’s TO-3Ps and left the original drivers in for the sake of the experiment …. Nothing auditable happen and if there is something auditable there it’s very mild. Today I replace the drivers too with a 100mhz device from UTC until the appropriate Sanyos arrive ( if ever ) …. And there it is , like I tern a switch on (or off) the 517 is sounding unbelievably good equal to 717 and it didn’t took more than 10sec. to audibly recognise that .
My hearing according my last P.M.E (periodical medical examination ) is exceptional , this is what is stated in the document at least .
With all due respect , this is not an argument, we can not argue , I have only my hearing .
More likely is for a tech with your latitude , if you get the chance to check it out and let us know too about what happened,if something happens at your end !
Cheers
Kostis
Click to expand...
If you were talking about a AU919 you were experimenting with, then that would be different.
The 517/717 is a different amplifier and may respond differently to these changes.
It is interesting you have found some audible improvement increasing the FT on the 517. When I did it to the last 919 I had here, it may have made some difference, but not enough to go to the trouble of changing the drivers, in general, it would be fair to say "little to no difference".
There will be some reason for this, what it is I am not sure.
 
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