Pass DIY Addict
Joined 2000
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Pass DIY Addict
Joined 2000
Paid Member
Thanks for the graph, JBL4435. I appreciate you taking the time to do this. Curious the dip and then the quick rise again as power increases... I've heard a number of people comment about lower distortion after changing the IRFP9610 front end to JFETs. I wonder if this makes a dramatic a visual difference...
I'll change the graph to logarithmic X-Axis. Then it will look more familar with distortion plots from let's say stereophile.
I'll do this later
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Dream Amps
While we have this discussion about distortion I want to point out that I LOVE my AX amps. They do sound wonderful and better than everything I heard before!!
I don't think that the AX amps have that high distortion for it's design. The Aleph design was made for SOUND and not for measuring.
I started this measurements only out of curiousity when I got an HP Audio Analyzer.
While we have this discussion about distortion I want to point out that I LOVE my AX amps. They do sound wonderful and better than everything I heard before!!
I don't think that the AX amps have that high distortion for it's design. The Aleph design was made for SOUND and not for measuring.
I started this measurements only out of curiousity when I got an HP Audio Analyzer.
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It was merely an observation based on comparisons with other high end amp distortion measurements. It was not a judgement on the quality of these amps
Yes, normally they are very quiet. I tested it with a normal load outside of the case and their was no noise. Absolut quiet.
But with the Aleph-X the current is in the first 15 minutes much higher than if it is becomes warm.You must know i have in my aplication very high charging current peaks about 50A.
If it is cold i hear the toroids a little bit. 15 minutes or 20 minutes later they are silent.
You only can hear it if you go with your ear in the case.
Distortion Balanced in
So, these will be the last THD Plots.
I finally finished my BNC-XLR input cable
THD seems not to change much with balanced or unbalanced in
1st: DIY XA160 8 Ohms load, Balanced in
2nd: DIY XA160 4 Ohms load, Balanced in
3rd: DIY XA160 4 Ohms load, Un-Balanced in
So, these will be the last THD Plots.
I finally finished my BNC-XLR input cable
THD seems not to change much with balanced or unbalanced in
1st: DIY XA160 8 Ohms load, Balanced in
2nd: DIY XA160 4 Ohms load, Balanced in
3rd: DIY XA160 4 Ohms load, Un-Balanced in
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I am surprised there is any difference if your BNC-XLR cable doesn't include a transformer or other single ended to balanced converter. Sounds like you're still feeding your amp a single ended signal, the only difference is where the negative input gets grounded. Try feeding your amp from a balanced preamp. You should see some difference.
I know how to make an 2xBNC to XLR adapter. Would I be able to build an AX amp if not?
I feed my amp from the balanced output of a HP8903B audio analyzer.
Pass DIY Addict
Joined 2000
Paid Member
I have been trying to increase the input sensitivity of my Aleph-X amps. I discovered that it takes nearly 2.5v RMS input signal in order to drive my amps to full output. All of my other amps (Marantz, Adcom, Behringer) all hit full volume output with input more on the order of 1.0 to 1.2v RMS. So I would like to increase the input sensitivity of my Aleph-X amp. I'm driving it with the RCA input and the appropriate pins on the XLR input are jumpered.
I following the advice that I found here: http://www.diyaudio.com/forums/pass-labs/98327-anyone-tried-up-aleph-x-input-impedance.html
Using the schematic linked here: http://www.facstaff.bucknell.edu/esantane/movies/axschem.jpg
I made the following changes:
Change R18 from 10k to 20k ohms
Change R19 from 10k to 20k ohms
Change R16 from 100k to 200k ohms
I didn't have any smaller values in my box of spare parts, so I left C2 unchanged at 3pF. I changed each of the complimentary resistors on the other side of the circuit board as well.
These changes seem to have made no difference.
Why didn't this increase the input sensitivity of my amp? Any insights?
Thanks,
Eric
I following the advice that I found here: http://www.diyaudio.com/forums/pass-labs/98327-anyone-tried-up-aleph-x-input-impedance.html
Using the schematic linked here: http://www.facstaff.bucknell.edu/esantane/movies/axschem.jpg
I made the following changes:
Change R18 from 10k to 20k ohms
Change R19 from 10k to 20k ohms
Change R16 from 100k to 200k ohms
I didn't have any smaller values in my box of spare parts, so I left C2 unchanged at 3pF. I changed each of the complimentary resistors on the other side of the circuit board as well.
These changes seem to have made no difference.
Why didn't this increase the input sensitivity of my amp? Any insights?
Thanks,
Eric
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