Yes, I have to check their datasheet, for voltage mostly.
Ehh like i guessed... 40V, i can use them only cascoded.
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ultra low noise transistors
I would like to ask You guys if there are any suitable low noise transistors ,
better than the originals sitting in my Roland RE-201 tapeecho ? Ten transistors
are : 2SC1000-GR (NPN) and two are 2SA493 GR (PNP) . Can 2SC2240
and 2SA970 be a good choice or what would You suggest . Stewen
I would like to ask You guys if there are any suitable low noise transistors ,
better than the originals sitting in my Roland RE-201 tapeecho ? Ten transistors
are : 2SC1000-GR (NPN) and two are 2SA493 GR (PNP) . Can 2SC2240
and 2SA970 be a good choice or what would You suggest . Stewen
Sony MC Head Amp Upgrade?
Hi
This is a very interesting thread, because at present I am thinking of trying to upgrade the head amp in my Sony amplifier which is 40 odd years old.
What I was thinking was replace the resistors with low noise types and changing the transistors for low noise types does anyone reading this think it would be possible.
Thanks Gary
I have attached a copy of the step up circuit, this runs on +/- 20v dc I intend replacing the input and output caps with Elna Silmic 11 types
Hi
This is a very interesting thread, because at present I am thinking of trying to upgrade the head amp in my Sony amplifier which is 40 odd years old.
What I was thinking was replace the resistors with low noise types and changing the transistors for low noise types does anyone reading this think it would be possible.
Thanks Gary
I have attached a copy of the step up circuit, this runs on +/- 20v dc I intend replacing the input and output caps with Elna Silmic 11 types
Attachments
Replacing the electros, yes. I doubt you would gain much replacing resistors tbh. Sony stuff of that vintage used decent parts, and they are low value anyway so noise contribution is minimal. The transistors... maybe... but Q101 and Q102 could be more specific than you might think. You would have to try it. Q102 might be worth looking at replacing with a larger device (bigger die) such as a BD132 as an experiment.
-/+20 volts ? It looks single rail to me apart from possible negative bias for the FET muting.
-/+20 volts ? It looks single rail to me apart from possible negative bias for the FET muting.
Hi guys,
Gary do you use the MC input? What cartridge?
If you only use MM phono then your sig path is through IC101 (BX269), which is an unknown to me. But knowing the age of the part, 1980's, the quality maybe?
I'd leave it, unless it is very noisy.
So best way to upgrade is change all ecaps on supplies, Nich UPW. Then look into Panasonic ECQ-V stacked films 1-2.2uF, for sig paths and if they do not fit, then Elna RFS or Nichicon UKL low leakage.
Now trace the signals through the schematic and come up with a parts list.
Mouser and Digi-key are good sources.
If you want to play more, get some fairchild ksa992 and ksc1845 bjts
Good luck
Rick
Gary do you use the MC input? What cartridge?
If you only use MM phono then your sig path is through IC101 (BX269), which is an unknown to me. But knowing the age of the part, 1980's, the quality maybe?
I'd leave it, unless it is very noisy.
So best way to upgrade is change all ecaps on supplies, Nich UPW. Then look into Panasonic ECQ-V stacked films 1-2.2uF, for sig paths and if they do not fit, then Elna RFS or Nichicon UKL low leakage.
Now trace the signals through the schematic and come up with a parts list.
Mouser and Digi-key are good sources.
If you want to play more, get some fairchild ksa992 and ksc1845 bjts
Good luck
Rick
The op-amps are definitely do-able even though they are non standard.
There was a thread on here (within the last 12 months I think) where we did just that.... or was that actually you, where the BX269 or 270 had gone duff
It was on the Vintage Radio forum as well... can't just find it though.
There was a thread on here (within the last 12 months I think) where we did just that.... or was that actually you, where the BX269 or 270 had gone duff
It was on the Vintage Radio forum as well... can't just find it though.Not me on any mods to this unit.
What I wrote is general advise that could be put into a vintage audio guide. Is there such a place in this web site?
I also have a large collection of vintage/obsolete device data sheets that I found on the net. Would be nice to have a place to upload them too, so i can share them.
What I wrote is general advise that could be put into a vintage audio guide. Is there such a place in this web site?
I also have a large collection of vintage/obsolete device data sheets that I found on the net. Would be nice to have a place to upload them too, so i can share them.
BD132
Mooly
Thanks for that, I have a simple view on this and lack knowledge and experience, plus the pre-amp section is very well packed in not too hard to dismantle as the boards all plug in.
Also Yes I am sure it was this site that helped sort out the replacements for the Sony IC that had gone, as I replaced all of them bar one but that is going to be done when I do a few other jobs on this amp. and too date they are all working perfectly.
Here is a picture of the pre-amp section you can see my home made PCBs in place
Gary
Mooly
Thanks for that, I have a simple view on this and lack knowledge and experience, plus the pre-amp section is very well packed in not too hard to dismantle as the boards all plug in.
Also Yes I am sure it was this site that helped sort out the replacements for the Sony IC that had gone, as I replaced all of them bar one but that is going to be done when I do a few other jobs on this amp. and too date they are all working perfectly.
Here is a picture of the pre-amp section you can see my home made PCBs in place
Gary
Attachments
rsavas
Yes I do use an MC cartridge (AT OC-5) I have worked out the signal path for the MC and MM cartridges.
The Sony BX IC's are Sony special ones, the amp dates from 1975.
I do not find it excessively noisy at all but was thinking could I improve it a little with low noise components, I have Elna silmic11 caps in the audio paths already now.
I see 2SA970BL and 2SC2240BL transistors are rated good for noise on here so I was thinking of replacing the old ones with these and using low noise resistors.
Gary
Yes I do use an MC cartridge (AT OC-5) I have worked out the signal path for the MC and MM cartridges.
The Sony BX IC's are Sony special ones, the amp dates from 1975.
I do not find it excessively noisy at all but was thinking could I improve it a little with low noise components, I have Elna silmic11 caps in the audio paths already now.
I see 2SA970BL and 2SC2240BL transistors are rated good for noise on here so I was thinking of replacing the old ones with these and using low noise resistors.
Gary
There isn't a special forum for that kind of thing but its possibly something that could be considered when the forum moves over to a new platform though.
AH SO! it was you that helped me do this!.........Excellent
Thanks so much for doing all that, I was cra***ng myself doing this job incase I blew it up (which I did later on but that's another story).............I was so relieved to know that I could repair it, infact one the bigger BX-269A IC's went and again after scraping the green off I checked all the components and they all measured and all that left was an IC mounted on the same board, much scraping later I got it off (early surface mount) and the imprint of the number told me it was.
It another Sony CX 0461 IC which was used in the mic pre-amp, out that came and in it went, result one working BX-269A and then I got another CX0461 IC off ebay and put back in the mic-pre-amp for safe keeping.
So here I am again wanting to having a fiddle as you can see
Thanks Nick
Gary
Thanks so much for doing all that, I was cra***ng myself doing this job incase I blew it up (which I did later on but that's another story).............I was so relieved to know that I could repair it, infact one the bigger BX-269A IC's went and again after scraping the green off I checked all the components and they all measured and all that left was an IC mounted on the same board, much scraping later I got it off (early surface mount) and the imprint of the number told me it was.
It another Sony CX 0461 IC which was used in the mic pre-amp, out that came and in it went, result one working BX-269A and then I got another CX0461 IC off ebay and put back in the mic-pre-amp for safe keeping.
So here I am again wanting to having a fiddle as you can see
Thanks Nick
Gary
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