Megalextoria
Retro computing and gaming, sci-fi books, tv and movies and other geeky stuff.

Home » Digital Archaeology » Computer Arcana » Apple » Apple II » Mockingboard Sound Quality
Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend 
Switch to threaded view of this topic Create a new topic Submit Reply
Mockingboard Sound Quality [message #388690] Tue, 12 November 2019 11:02 Go to next message
Vince Weaver is currently offline  Vince Weaver
Messages: 136
Registered: April 2013
Karma: 0
Senior Member
Hello

so I was at Demosplash showing off a new Apple II demo (I'll post it
eventually, there are a few bugs I need to sort out first).

Anyway though, I was once again disappointed by the sound quality of
the Mockingboard compared to other AY-3-8910 based hardware. Especially
the bass notes.

I think this is a hardware issue, as things sound fine in emulators.
And it's not on the actual AY chip as my Raspberry Pi AY player (with
actual AY chips) sounds fine too.

So the output amplifier on the Mockingboard, does anyone know how
high quality it is? I know 386 amplifiers are pretty low-end. Is there
a high-pass filter on the output that might be cutting out the bass notes?

I'm just wondering if I can pop out the 386 chips and hook up some
circuitry to get either a line out, or else maybe pass in to a better
amplifier (my pi based player uses some cheap class-D amps which seem to
work OK).

Vince
Re: Mockingboard Sound Quality [message #388733 is a reply to message #388690] Tue, 12 November 2019 19:53 Go to previous messageGo to next message
Anonymous
Karma:
Originally posted by: Frank M.

Probably not the LM386. They are common in guitar amps and pedals as a preamp and have a flat frequency response.

There are some 10 or 15uf capacitors in series after the AY, before the amps, that are (probably?) acting as a filter. I'm no expert though. Michael Mahon?

You can also take audio directly from pins 3 and 4 of the AY and feed your own EQ and amp.

f
Re: Mockingboard Sound Quality [message #388761 is a reply to message #388733] Wed, 13 November 2019 18:20 Go to previous message
Michael J. Mahon is currently offline  Michael J. Mahon
Messages: 1767
Registered: October 2012
Karma: 0
Senior Member
Frank M. <frank_o_rama@hotmail.com> wrote:
> Probably not the LM386. They are common in guitar amps and pedals as a
> preamp and have a flat frequency response.
>
> There are some 10 or 15uf capacitors in series after the AY, before the
> amps, that are (probably?) acting as a filter. I'm no expert though. Michael Mahon?
>
> You can also take audio directly from pins 3 and 4 of the AY and feed your own EQ and amp.
>
> f
>

I agree with you, Frank—it’s not the 386, it’s the coupling capacitors.

Get it generating a, say, 60Hz squarewave and take a look at the output
with an oscilloscope. For good low frequency response, you shouldn’t see
much “sag” in the squarewave. This test should be done with the output
loaded (as you’re using it) and unloaded, to see what effect the load is
having.

Poor low frequency response can result from using the card to drive a low
impedance load, like a speaker or even headphones. Try using the card to
drive a line-level input to an external amplifier (line input impedances
are typically 10k Ohms or greater).

--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
  Switch to threaded view of this topic Create a new topic Submit Reply
Previous Topic: Merlin 32 bugs & quirks
Next Topic: SCSI Card Fixed Versions of Pitch Dark/Darker?
Goto Forum:
  

-=] Back to Top [=-
[ Syndicate this forum (XML) ] [ RSS ] [ PDF ]

Current Time: Thu Mar 28 11:36:23 EDT 2024

Total time taken to generate the page: 0.03820 seconds