Car Audio Amps by Nelson Pass

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.
 
Member
Joined 2002
Paid Member
I found these online images of the ADCOM 4404, there is visual elegance to the design.

CIMG0543.jpg

CIMG0533.jpg

CIMG0542.jpg
 
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
 

Attachments

  • protovision nad306 .ckt.pdf
    44.8 KB · Views: 252
  • proto-42894.jpg
    proto-42894.jpg
    948.9 KB · Views: 1,038
  • Protoviosion 284 AMA.jpg
    Protoviosion 284 AMA.jpg
    70.3 KB · Views: 985
  • Protovision AMA actice crossover.jpg
    Protovision AMA actice crossover.jpg
    72 KB · Views: 310
  • Protovision AMA driver OP-Amp.jpg
    Protovision AMA driver OP-Amp.jpg
    81.8 KB · Views: 329
  • Protovision AMA SMPS.jpg
    Protovision AMA SMPS.jpg
    43.2 KB · Views: 329
  • Protovision-Alphasonic.jpg
    Protovision-Alphasonic.jpg
    88.5 KB · Views: 349
  • Protovision Reality 284.jpg
    Protovision Reality 284.jpg
    99.8 KB · Views: 241
  • Protovision David Alpha 265.jpg
    Protovision David Alpha 265.jpg
    36.1 KB · Views: 315
  • ProtovisionReality 284.jpg
    ProtovisionReality 284.jpg
    166.6 KB · Views: 292
Last edited:
The one and only
Joined 2001
Paid Member
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. :p

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.

:cool:
 
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?

IMG_20101104_161947.jpg


IMG_20101103_134823.jpg


IMG_20101104_162555.jpg
 
F5 in Car

F5 for car amplifier. Thanks Mr.Pass for making this possible :)
First step is to look for a suitable heatsink. Ordinary car amplifier heatsink won't hold the heat. An industial heatsink is more suitable
 

Attachments

  • IMG-20110308-00072.jpg
    IMG-20110308-00072.jpg
    194.6 KB · Views: 808
  • IMG-20110513-00495.jpg
    IMG-20110513-00495.jpg
    229.4 KB · Views: 790
  • IMG-20110513-00496.jpg
    IMG-20110513-00496.jpg
    235.4 KB · Views: 809
  • IMG-20110513-00498.jpg
    IMG-20110513-00498.jpg
    142.1 KB · Views: 798
  • IMG-20110513-00499.jpg
    IMG-20110513-00499.jpg
    269.9 KB · Views: 790
  • IMG-20110513-00500.jpg
    IMG-20110513-00500.jpg
    271.8 KB · Views: 385
F5 for car amplifier. Thanks Mr.Pass for making this possible :)
First step is to look for a suitable heatsink. Ordinary car amplifier heatsink won't hold the heat. An industial heatsink is more suitable

Could you post a build up of this amp. How do you like the sound in car? Did you design and build the SMPS yourself? I know that I would love a car version of the F5 as well as a few others. i have a pair of compression horn drivers that would work great with an amp like this in my car.