P1.7 / APOX completed

[ARAD]

Thanks for the nice comments. It helps building in a team - and no, I am not Peter Daniel's brother but admire his work and the numerous tips and hints he is providing (e.g. on tooling, metal work).

Paul, the sound (lack of) is very nice. Very detailed, good soundstage and firm control. It was a big improvement from my old Classé preamp to the P1.7 (almost as big as the step from the ZENs to the Aleph5s).

Thomas, please find attached two more pictures.

[ARAD]

the backplane :

[Audiofanatic]

Hi ARAD,

Which Classé pre did you use befor this Pass P1.7?
A friend of mine wanted to buy a Classé pre or make a DIY pass pre. His partner hates DIY audio gear due to the looks of it! so I hope you understand my qwestion.

Best regards,


Audiofanatic

[ARAD]

I had two Classé preamps. For a long time a very old DR5 that sounded very good and was build like a tank. I sold it eventually and got me a Classé 'Thirty'. Sound was similar but it had a remote volume control.
I think I liked the DR5 better - the 'Thirty' only lasted a couple of months before I started to build the P1.7.

Regards,
Andreas

[Klaus]

Hi Andreas,

My congratulation, one of the nicest works around!

One hint from my side – increase your PSU capacity to get best performance. I also celebrate an Aleph 1.7 for now some months. Pictures to follow, a lack of a digital camera blocks it… I extensively tested the sound performance versus the PSU potential and impulse bypass cap tweaking. The same result like with former tests: there is never too much PSU! The "stability and hardness" in the sound of the 1.7. – originally already excellent due to the consequent CCS´s use? – increases really dramatically. Now there seams to be no most complex signal available ever to disturb the breath of heights ore whatever – if you know what I mean… With the original 2 x 2.200uF or so it is given, somehow there is a last bit of influence or nervousity. The technical explanation for this is not easy to be found, I know!

So my PSU stranded up with 350VA transformer, soft recovery diodes, 4 x 10.000uF 100V BC cans (with cascade bypass caps 1uF Wima MKP10 + 0,1uF M-Cap Supreme + 10nF MKP ERO1837 (just 63V rated, but well undersized)). The original P1.7 regulator and 1.000uF Panasonic FC electrolytics everywhere follow. The Zener stack is supported by 0,1uF Wima MKP10, the gate electrolytic with 0,1uF M-Cap Zn, the buffer electrolytic behind the FET regulator with my best known cascade (0,1uF M-Cap Supreme ´+ 10nF MKP ERO 1837). The 1.000uF caps on the analog board ought to have no bypass at all – it disturbs harmony. The front cap needs to be less impulse capable than the can right behind the distanced regulator buffer. I found this effect often before. Tweaked this way the performance of the P1.7 circuit is really outstanding. The inner silence of the music is the best I have heard. And please believe me - I do not talk about small differences with and without tweaking! The tweaked 1.7 combines all purposes, extremely solid vs. fast, open and transparent vs. colorful painted. The original 1.7 is somewhat clearly less relaxed.

By the way, your WIMA coupling cap monsters also benefit from good bypasses. Do you use some? Without you loose much transparency and dynamic agility of the music.

Best regards

Klaus

[ARAD]

Klaus,

Thanks for sharing your thoughts. We discussed for some time whether we should try to 'improve' the original circuit. The four of us, all EEs, came to the conclusion that we wanted to be as close to the original as possible and therefor decided not to tweak the P1.7 as far as the analog portion is concerned. We realized over time (after building Aleph5s and Onos) how well designed the original Pass products are and that apparently everything was done for a reason.
I grant you, that even subtle changes might be audible - the question remains whether the changes result in a more correct reproduction of the music.
Before I would seriously try to improve the quality of my Ono/P1.7/Aleph5 as they are now, I would throw a lot of money towards my music sources and my speakers.
Maybe I could be convinced to try some tweaks, if a direct comparison of my P1.7 versus an improved version would reveal a significant better reproduction of music that is clearly closer to the original.

Best regards,
Andreas

[JOE DIRT®]

Arad..you have hit one point dead on....the source

DIRT®

[relder]

Looks great, do you have a remote to go with it yet? (let's see it!)

Rob

[tomchaoda]

Does APOX-1 or APOX-2 still available? None of their web link works?

Thanks

Thomas

[BobEllis]

the new apox site is http://www.apoxcontrols.com/apox.htm