The Aleph-X

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#1,645
I am gearing up to load my pcbs for the Aleph X.

Has any one done any conclusive test or objective evaluation of the various CCs schemes in the Aleph X aside from dc stability?

I note from my sweep of this thread earlier today the photos by Mr Pass of the AX200 show what appears to be a simple bias arrangement for the diff pair not unlike Greys original circuit (and the original Aleph with the added 4.7K return resisters an R100 resisters).

One can only assume this is sufficient once the amp has been correctly designed and implemented to matched parts.

Ian
 
#1,646
Ian,

Here are 4 links that discuss various aspects the HHCCS. The last 3 are implementations by Fred and Peter. If it works the way they say, it should make a difference with the high efficiency speakers like your horns.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=4295&highlight=Noise+Lm329

http://www.diyaudio.com/forums/show...perpage=15&highlight=Noise Lm329&pagenumber=6

http://www.diyaudio.com/forums/showthread.php?s=&threadid=5392&perpage=15&pagenumber=3

http://www.diyaudio.com/forums/showthread.php?s=&threadid=3748&perpage=15&pagenumber=15

Rodd Yamashita
 
#1,647
Macka,
I have the LM329 biased at 1mA with just a resistor to -15V, no current diode and a 0.039 uF cap in parallel, I can't remember if it's a 10k or 5k that I used for biasing. I know I measured the current and it's about 1mA. I am using an irfp9610 instead of the zvp3306 with a 221 ohm on the gate.
I am working on prototypes, I didn't want to deal with heating control with the zvp, yet. I have only 2 current diodes generously donated by Shawn Wessol that I want to use when the ver 1.0 boards arrives. Fred CCS is set up to be the better CS. Everything else works but "working" is not all there is to it.

Somebody please set up a wiki page for the lottery, NO cheating! 😉
 
#1,649
roddyama said:
Here are 4 links that discuss various aspects the HHCCS. The last 3 are implementations by Fred and Peter. If it works the way they say, it should make a difference with the high efficiency speakers like your horns.
Click to expand...
Actually, it will only make a small difference. The Zener noise
is one factor, but you still have the noise of the P channel
Mosfets.

If you have an efficient horn mid/top driver, think about
using a well regulated supply, lower the gain of the amp
from 20 dB to 10 dB, use a JFET CCS instead of a
resistor off the Source of the diff pair's current source,
and use low noise P channel JFETs in parallel on the input.

Oh, and get the power supply AC line/transformer/bridge/
first set of cap a couple of feet away from the circuit and
only use one supply per channel, isolating the ground through
bridges to kill loops.
 
#1,650
Hmm,

I suppose the extra current via the supply rail is an issue for ripple on the rails.

In intend to run CRC and dual bridge to help and will build up on the bench to spread out the parts so as not to induce hum.

Thankyou all for your input.

Ian
 
#1,651
The speakers are run in passive mode at the moment so the mid and horn are cranked back to @ 95-96 dba to match the woofer, but that is still well above the av sensitivity for hifi.

Its the bandwidth from -3db from 32 up that makes it sound loud via the 18" 2245 JBL woofer.

I watched Stark Trek 6 Undiscovered Country last night, my neighbours must of thought there was on earth quake when the Kingons got blown up! MUhhhhhhhhhh.

There is little if any hum and noise from the Aleph 2 so it will be a good becnh mark to develop the X.

I look forward to the X project

Thanks for your help


Ian
 

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#1,652
taking it to the limit.....

I think Nelson did an excellent job of explaining what lengths one can go to in order to achieve optimum results. But really...... my high frequency horn is 110 db 1 watt at 1 meter and I hear only the very faintest of hum with my head buried halfway down the darned thing. Stand back a bit and you find that the ambient room noise is louder than the hum. I'm referring to the furnace grills blowing, the freeway traffic 3/4 of a mile away, the wind whistling down the gorge, the squirrels farting outside my door.......
 
#1,657
'Cuz I turned it off last fall when I...uh, took a vacation from the site. I've left it off so as not to get bogged down with e-mail. I know it sounds stupid, but it takes me forever to write these posts, then I check them about fifty times, change things around, try to remember to go over the spelling so as not to look ignorant, etc. I do the same thing with e-mail. Takes forever. At the moment, I can't afford the time. I hope to be able to turn it back on this spring sometime after I get over a few more humps.
I'll get with you directly.
<i>One moment, please...your call is being connected...</i>

Grey
 
#1,658
Hi Grey,

On a more meaning note than my previous posts, I really appreciate the detail of your posts regards matching of the diff pair and balancing of the X circuit for optimum results.

Aside from the excellent enhacement with the CCS, I expect that the final tweeking for lowest noise will be the balancing of the differential pair as you discussed and as Peter has referred to in an earlier post.

I also appeciate Mr Pass's recomendations regards the power supply and variation of the input pair, I will include these ideas as the project progresses.

Noce to be involved in this project.

regards

Ian
 
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