Nelson Pass ACP+

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poseidonsvoice

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Nelson Pass ACP+
« on: 5 Nov 2019, 05:53 pm »
http://www.firstwatt.com/pdf/art_acp.pdf

I'll get to hear this along with others at Burning Amp in SFO this weekend.

Best,
Anand.

kazsud

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Re: Nelson Pass ACP+
« Reply #1 on: 8 Nov 2019, 03:11 pm »
Typical Microsoft Word document that adds extra pages at the end for no reason  :)

adydula

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Re: Nelson Pass ACP+
« Reply #2 on: 11 Nov 2019, 02:14 pm »
Nelson's design of a preamp/headphone amp kit for DIYers. — at Fort Mason

Well here is a pix of the new Nelson Pass - possible DIY headphone amp kit!

All PPix courtesy diyaudio.com






Do these folks look like they are having fun....Imagine building your own headphone amp, a great design with
the designer in the same room helping you out, explaining the circuit etc...

I so wish I could have joined this group, but will patiently wait for the "kit" to appear over at diyaudio!





Alex

poseidonsvoice

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Re: Nelson Pass ACP+
« Reply #3 on: 11 Nov 2019, 05:29 pm »
Sadly, I didn't get a chance to listen to it, but folks seemed to be pleased with the build process and learning at the workshop.

I hope to listen to it someday. If there was anybody else who was at BAF who listened to the ACP+ extensively please let us know what you thought.

I did pick up a chassis for Tom Christiansen's/Neurochrome HP-2 headamp and have the PCB on order. I did listen to it for quite a while, and found it right up my alley, very transparent, detailed, with a tremendous soundstage on Sennheiser HD650's. The prototype that Tom had there sold within the first hour of BAF.

After I build it, I will be happy to forward it to you for a listen should you wish, since we both live in the same state. I hope to be able to compare it to the famed discontinued HP-1 which my colleague has in the RTP area. I have a feeling one can get 90% of the performance for less than 50% of the original price of the HP-1.

Kind regards,

Anand.

adydula

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Re: Nelson Pass ACP+
« Reply #4 on: 11 Nov 2019, 07:29 pm »
Thanks Anand!

I will keep that in mind.

I know another member is going to purchase on already built and will most likely send it to me for review.....so if that doesnt work out I
will let you know for sure.

Glad you like the amp.

I certainly look forward to "listening" with it.

The only way I can tell how good these things are ..is to get them in house and compare side by side for a few hours.

The recent experience with the Tuba amp was a great test for this method and worked well.

I will most likely just go ahead and build the new Pass amp. It doenst look very hard at all .....

...and his name and designs are legendary!

All the best from Raleigh!
Alex

hagtech

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Re: Nelson Pass ACP+
« Reply #5 on: 17 Nov 2019, 04:02 am »
Interesting application of an opto-isolator.  I wonder why they chose to go with a single supply.  Seems to me you could get rid of input and output caps.  Turn-on / turn-off issues?

jh

poseidonsvoice

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Re: Nelson Pass ACP+
« Reply #6 on: 17 Nov 2019, 04:16 am »
Interesting application of an opto-isolator.  I wonder why they chose to go with a single supply.  Seems to me you could get rid of input and output caps.  Turn-on / turn-off issues?

jh

Jim,

There is already an application of a headphone amp with a dual rail supply and opto isolator, it’s Wayne Colburn (of Pass Labs) WHAMMY design:

https://diyaudiostore.com/products/whammy



And this all originated from Pass’ M2 amplifier design and now the modern M2X. They’re interesting builds too.

The ACP+ is simpler and can be used with a laptop single rail supply geared for newbies. It’s complex enough to get their feet wet.

Best,
Anand.

adydula

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Re: Nelson Pass ACP+
« Reply #7 on: 17 Nov 2019, 02:40 pm »
I contacted the DIY AUdio store and asked when this might be a "kit" item at the store.

They replied they have no earthly clue at this time....so its a waiting game....

Alex