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Old 13th April 2011, 06:29 PM   #21
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Quote:
Originally Posted by a.wayne View Post
The original soundstream "Class-a" amps ( circa 1986) supposedly designed by NP
Supposedly? He says yes...

http://www.linearaudio.nl/JDpubs/Int...iew_MMM110.pdf

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Old 13th April 2011, 07:51 PM   #22
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Quote:
Originally Posted by Nikolas Ojala View Post
I don't need car amplifiers, and I don't think that a car is a good place for listening music. Usually radio programs are poor quality (compressed) and investing money to a car amp would be futile. That is my opinion only. I don't mean to suppress anyone's project. Anyway audiophilia is much better compared to many other philias you can do in a car.

I think that in the coming age of electric cars efficient speakers will be appreciated again. How about amplifiers... Class D?
Some days I have a six hour drive to work. Other days it is 15 minutes and I can listen to the FM station I built, almost no compression and they play music I like.

Where I am staying at the moment it had 55 dba background noise level. I mentioned the heating system was too noisy to the manager of the place. He checked it out while I was gone, but I did leave my Bruel and Kjaer second generation sound level meter kit where he saw it. Now it is down to 42 dba. So my car is not far off of some apartments.
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Old 15th April 2011, 03:18 AM   #23
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I found these online images of the ADCOM 4404, there is visual elegance to the design.

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Old 15th April 2011, 08:32 PM   #24
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I thought the Adcom stuff was particularly nice, but it wasn't very successful,
possibly because we chose a sound which was good in a listening room,
ignoring the popular car audio aesthetics of the time.

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Old 19th April 2011, 06:00 AM   #25
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Quote:
Where I am staying at the moment it had 55 dba background noise level.
In my experience that's pretty typical for the US and tropical countries where air conditioning is everywhere; in a premium limo background noise level may easily be much lower than that. Good point!

Hannes
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Old 11th May 2011, 04:24 PM   #26
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in the pdf attachement you will find a audio power amplifier topology, that I have only find in this German amplifier models for car audio:
1) AMA Stereo 50
2) Protovision 264/Protovision 284
3) Smart Devices Stereo MkII
4) Alphasonik David 265
All this amps sounds very fine if the temperature is approximately 50 degrees but it seems to be very sensitive against variuos unwanted parasitic effects, because a lot of damage devices there are, as to read in various German audio/hifi forums.
Is this topology a slightly modified version based on a certainly topology from Threshold/Nelson Pass?

What I miss is the requirement for bias adjust and bias stability or bias servo unit like
http://www.freepatentsonline.com/5055797.pdf
Attached Images
File Type: jpg proto-42894.jpg (948.9 KB, 469 views)
File Type: jpg Protoviosion 284 AMA.jpg (70.3 KB, 445 views)
File Type: jpg Protovision AMA actice crossover.jpg (72.0 KB, 127 views)
File Type: jpg Protovision AMA driver OP-Amp.jpg (81.8 KB, 124 views)
File Type: jpg Protovision AMA SMPS.jpg (43.2 KB, 126 views)
File Type: jpg Protovision David Alpha 265.jpg (36.1 KB, 111 views)
File Type: jpg Protovision Reality 284.jpg (99.8 KB, 89 views)
File Type: jpg Protovision-Alphasonic.jpg (88.5 KB, 132 views)
File Type: jpg ProtovisionReality 284.jpg (166.6 KB, 117 views)
Attached Files
File Type: pdf protovision nad306 .ckt.pdf (44.8 KB, 69 views)

Last edited by tiefbassuebertr; 11th May 2011 at 04:36 PM.
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Old 12th May 2011, 01:22 AM   #27
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That's interesting. I developed a minimum peak hold detection circuit
for biasing output stages right about the same time. It comes from the
observation that in a push-pull follower the bias figure will be the minimum
voltage value from emitter to emitter. I recall that a prototype went to
CES, but by then I was on my way out the door.

There are a couple of other very cute circuits for this sort of thing, but
modesty and greed prevent me from disclosure at this time.

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Old 12th May 2011, 01:26 AM   #28
49 - for the 18th time
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Quote:
Originally Posted by Nelson Pass View Post
There are a couple of other very cute circuits for this sort of thing, but
modesty and greed prevent me from disclosure at this time.

Ohhhhh That remark will get the hen's clucking all night long....

Maybe a good thing tho - it's been pretty quite around here lately....
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Old 12th May 2011, 12:58 PM   #29
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I had 4 adcoms I cannot remember the model numbers, but they were the best car amplifiers I have ever owned, I miss them lol one was three feet long they sounded amazing
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Old 12th May 2011, 01:13 PM   #30
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Today I run a Soundstream MC140x in my car, and I've been telling people it's design roots are of Nelson pass. I beleive the MC series of amps were similar to the Dxx series of the time - MC being the higher end. Its a Class-B design using TIP102/107 otuputs.

Am I correct in calling this amp a Nelson Pass?

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