A really big thanks to all who replied to my question. Yes, the gain of 2 is on purpose, because in the stage before the Amp there's a CS3310 which can drive up to +32dB to the Signal. That should be sufficient to drive the amp. But if I encounter the prolem that it's too quiet it should'nt be a problem to modify the gain.
True. I've driven even 12 Ω headphones with the TPA6120A2. It's a very capable amp. BUF634A is nice too. And LME49600.
Tom
Well headphones's impedance variation is not really a big problem...they already have thin 2...4 meters of wires before the driver.
You could go with RNHP "near zero" output impedance, but there's a catch in that design with the series LC true load as tpa6120 would get into serious clipping with its 24V supply without that trick and I know becsuse I tried it.
On the other hand if you really want to prevent even negative impedance, there's a system disputed between Sandman and Technics that sounds as good as tpa6120 with njm4556 and I know because, of course....I tried them both!
Attachments
You get some talk over class AA...I was only curious about op amp implementations in Technics SL-P990 and they are touching all meaningful topologies there.I have it used in my DENON DCD 1560 cd player as I/V converter as well.
https://www.manualslib.com/manual/1001309/Technics-Se-A100.html?page=5#manual
https://www.manualslib.com/manual/1001309/Technics-Se-A100.html?page=5#manual
It looks like a Fontana Bridge: https://en.wikipedia.org/wiki/Fontana_bridge (so compensated current injection?)
When I make an expensive refurbishment to a cassette deck or a good cd player I also need to have the right headphones preamp to listen the results , so I always transform it into Yamaha's heasphones amp with a small difference, I use at least 5x gain so that I can use virtually any op amp. Then I do the ground mod so that no output or supply noise gets into the input...I usually use my headphone's output instead of line output based on capabilities and on the fact that ususlly it's also provided with a volume control which the line output doesn't necessarily have or when it does, its output impedance is raised significantly from the fixed one.
This time I'm trying some NTC resistors for the 150 ohms series resistor output, just curious to see the results...
If I haven't said that enough I found this particular headphones amp from yamaha kx990 to be the best sounding with njm4556 of all topologies except the Technics class AA buffer.The last photo will be the original headphones section in my kx 400 which is identical with the one in kx 990, but there's no schematic for the kx 400.You wouldn't believe it sounds really good just by the look of it.
This time I'm trying some NTC resistors for the 150 ohms series resistor output, just curious to see the results...
If I haven't said that enough I found this particular headphones amp from yamaha kx990 to be the best sounding with njm4556 of all topologies except the Technics class AA buffer.The last photo will be the original headphones section in my kx 400 which is identical with the one in kx 990, but there's no schematic for the kx 400.You wouldn't believe it sounds really good just by the look of it.
Attachments
Link in post #25 is infected with a virus. Don't click to first page in manual. To bad very interesting circuit.
What virus? What virus-checker?
manualslib.com is a well-known popular site. I've never heard of malware there. Trend Micro does not see a problem. Norton sitecheck says OK.
Maybe I'm using the wrong term but click on the link and then click on the first page of the manual and watch what happens. Nothing overt happens on the schematic page linked to.
I saw that and did that. Two different browsers. I got the first page of the manual. What do you get?
If it IS malware we should let the moderators know. But I don't see a problem??
Im glad no one else is experiencing this but just as an FYI here is an alternate source for the manual. Another great site in case you dont know it.
https://www.hifiengine.com/manual_library/technics/se-a1010.shtml
https://www.hifiengine.com/manual_library/technics/se-a1010.shtml
Link scanned with 91 antivirus engines, nothing found.
https://www.virustotal.com/gui/url/...f65f1bbf1777ecc17203bffb256bddd73c6?nocache=1
https://www.virustotal.com/gui/url/...011c4719298f9d496034be006326b47f11b?nocache=1
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Wow. Yes, I remember when all my friends were getting that every week. (Not even fake Microsoft-- they got porn.) I understand your concern.
Out of curiosity, what were the results of testing a NTC in series with the output?