Hi Peter,
Did you try clipping it at 10khz? My clipping profile looked perfect at 1khz but at 10khz it gets a little funny looking. Just wonder if yours does the same thing.
Blessings, Terry
bimo
Listening test needs some time, but first impression is really OK. Bass is very good, the top octave at some songs is a tiny bit too harsh but IMHO a small adjustment will do the job. Generally it is very good amp, highly recommended. I allways liked the hitachi VAS (like symasym) but this one seems to be a better one.
OS
I am doing measurements in ''home made'' way so the may be not accurate but it is good enough just to confirm that amp is working without some hidden bugs, card is EMU 204 at 24bit/192k.
Terry
The clipp is OK at 20kHz. Bellow 1k 10k and 20k clipp.
Regards
Listening test needs some time, but first impression is really OK. Bass is very good, the top octave at some songs is a tiny bit too harsh but IMHO a small adjustment will do the job. Generally it is very good amp, highly recommended. I allways liked the hitachi VAS (like symasym) but this one seems to be a better one.
OS
I am doing measurements in ''home made'' way so the may be not accurate but it is good enough just to confirm that amp is working without some hidden bugs, card is EMU 204 at 24bit/192k.
Terry
The clipp is OK at 20kHz. Bellow 1k 10k and 20k clipp.
Regards
Attachments
I see the 20k negative "sticking". Not as bad as a blameless , not as
good as a ND.
Symetri clamps saturation down to a mA at the VAS bases. ND VAS
fully shuts off at this point (nA at bases).
So the current you run the input differentials at would determine
how much an effect this has on the resulting "clipp" (sticking).
I actually can see this behavior on my simulator.😀
PS - this is the compromise for having only 10 devices.
OS
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OS
How about clamping the two front LTP's with diodes ? It should reduce a bit bad clipp ?
It is not so bad for the simple circuit like this.
I think some of the ''voice'' for this amp can be added by replacing two front CCs with zener reference voltage + resistor, I have made some tests in the past and it was adding a bit more H2 (like old amps have).
regards
How about clamping the two front LTP's with diodes ? It should reduce a bit bad clipp ?
It is not so bad for the simple circuit like this.
I think some of the ''voice'' for this amp can be added by replacing two front CCs with zener reference voltage + resistor, I have made some tests in the past and it was adding a bit more H2 (like old amps have).
regards
Try the zener , should work. zener might add noise.
(love LED's , hate zeners - biased)
OS
Look at the Mezmerize B1 Buffer Preamp. They did the same with strings of seven yellow leds. Mezmerize B1 Buffer Preamp (Makes 2 channels; Rev 1.0) - Circuit Boards
Led = diagnosis.
Spooky amp - one blue would go out , then the other would If I
touched or tapped the board. CCS reds stayed on.
What did this tell me ?
- Input stages and servos were good (reds).
- blues go out when the cascode saturates (hits the rail).
Nothing smokes .... must be feedback related (open NFB wire).
LED's led me to the problem in 10 seconds.
Spook pretty much has a 4 led error code readout !!
OS
Borys , I'm now satisfied that the new OPS is ready for the test of time.
(below)
I really don't think a V4 is really needed.
I've just abused this OPS more than a normal user would in a year.
20-35C ambient and 20-57C extrusion , it keeps on tickin' ...
I left the worst unmatched "hogs" on the PNP side to see what hot
would do .... NOT an issue.
PS - your Yamaha e-waste makes a good shop amp !!
OS
(below)
I really don't think a V4 is really needed.
I've just abused this OPS more than a normal user would in a year.
20-35C ambient and 20-57C extrusion , it keeps on tickin' ...
I left the worst unmatched "hogs" on the PNP side to see what hot
would do .... NOT an issue.
PS - your Yamaha e-waste makes a good shop amp !!
OS
Attachments
OS
The DIY OPS is really bullet-proof. Temperature transfer with V3 is really good and it saves a lot of room in enclosure. Maximum performance in small box. The output transistors can be really abused a good bit, in real life they can survive a bit more than is written in the datasheet.
You can solder Symetri IPS in free time, sounds really good.
Regards
The DIY OPS is really bullet-proof. Temperature transfer with V3 is really good and it saves a lot of room in enclosure. Maximum performance in small box. The output transistors can be really abused a good bit, in real life they can survive a bit more than is written in the datasheet.
You can solder Symetri IPS in free time, sounds really good.
Regards
With the 55C and 57C end to end , I don't see how any more heat could
be transmitted to the room. Bottoms are >50C , but this difference is
either P or N. feedback will even that out.
Even running my 4R sub on one channel , still <60C.
You have a V3 , too ??
Edit - I want the "ND" , not the symetri. ND should have the killer bass + highs.
The way it works/simulates ... It should be a spooky/cfa-x mix !
OS
I do not have V3 yet but I am going to build this year a new OPS - for 7cm high radiator, all transistors in line and IPS connected on ribbon HDD cable.
Post the ND schematic please, in free time I will try to solder it.
THX
Peter
Post the ND schematic please, in free time I will try to solder it.
THX
Peter
No , brother Jeff (Jwilhelm) did. After I try them ... maybe a "preferred"
IPS to go along with this "sweet" OPS.
Maybe jeff has some more ??
OS
Is C2 supposed to be left empty?
I'm building up a Pitchfork DAC right now, but hopefully I can have the Kypton-ND up and running by the end of the weekend. If it's all good maybe that could be Evan's next group buy.
Sorry I forgot C2 (testing 350V/us slew 😀).
The amp would actually work without it , but might amplify AM broadcasts !
C2 can be 100-220pF.
My new OPS is "craving" ND performance..... 😀
OS