Prelude 1200 - heavy distortion (and crash) above 27420Hz

[paul1981]

Hi there.

 I have just acquired a Prelude 1200 (clockport) and, while the device seems to output fine now for the most part, I have some trouble getting it to play in full quality.
 
Im trying to get AmigaAmp and Digibooster to play but as soon as I go above 27420hz frequency, the sound is distorted (very high pitched garbage / hissing) and the machine crashes soon after.

 I am currently using:
 
- OS3.9 (bb2)
- AHI 4.18 (Aminet)
- Prelude Install 2.0 (ACT website)
- Prelude.library 5.3 (ACT website)
 
I've set up Unit 0 (which is used in AmigaAmp) in AHI as Prelude: HiFi 16 bit stereo++ realtime, and this is the same mode I have chosen to use in Digibooster. BTW I use the WarpUp engine in AmigaAmp.
 
Like I said, playback at 27420hz works fine. But this card can do better, right?
 
Things I've tried:
 
- disable MCP
- enable 56KHZAUDIO tooltype in CGX4
 
Anything else I should look into?

Sampling frequency if we're all gonna nit-pick!

Well I have a Prelude 1200 which I use with Workbench 3.1 and an Apollo 1260. Works fine at the 64k sampling rate, so no issues there.
What CPU do you have under the bonnet? You might be pushing your CPU well over the edge or something, if you're trying to play an mp3 especially...
And Digibooster... too many channels or something? Again, not sure, but you should go back to basics and play some 44.1KHz aiff's with the Prelude Tape Player (IIRC) and make sure that plays correctly to start with. Not sure whether you've tried that yet??

[paul1981]

But your ears can't.

Yes:
http://en.wikipedia.org/wiki/Audible_range

http://en.wikipedia.org/wiki/Sample_rate

To avoid misunderstandings, you may want to refer to "27420 Hz sample frequency (or sample rate)" instead of "27420hz frequency".

"27420hz frequency" denotes a tone with a frequency of 27420 Hz, which no human being is able to hear (in my best days I could hear frequencies up to 24.500 Hz...).

The maximum frequency a 27420Hz sampling rate can achieve is approx.  13.5KHz, half the sampling rate. And that would be one hell of a crappy  square looking 13.5KHz wave. This is why the higher the sampling  frequency is, the better more accurate representation, even way way  beyond double audiable range. 192KHz is nice, but sampling frequencies  in MHz ranges would be even better at correctly capturing the high end  audiable frequencies and harmonics which just aren't represented at all in todays digital world of crap sound.
Makes me glad I have my Tascam reel to reel mastering machine and a decent vinyl collection.

[paul1981]

Finally I meet someone with a prelude 1200!! I've been looking for a long time. Good to 'meet' you..
 
 Anyway. As my sig states, I have a 060/50 too, so that is not the issue. Too many channels? Nah, dont think so either. It happens with AmigaAmp too and the mp3 decoding is handled by the ppc processor, so..
 
 Could you perhaps do a version on the prelude.library and also on devs:ahi.device? curious to know how you have installed your device.

With Prelude Tape Player, do you mean Play16 by any chance? I havent tried that. The program PrlTest does play a very short sample, but that is too short to tell in what frequency it plays.

No I mean Prelude Tape Deck, sorry...which is part of the Prelude software so you should have it. It only plays AIFF's though which macs use a lot.
You can also use Play16 to use the Prelude directly by setting the tooltype PRELUDE. This is what I recommend instead of using AHI in Play16.

I can do version checks tomorrow for you, but not this evening.

[paul1981]

awesome, thanks so much for your help. I will try out what you said tomorrow. I really hope I can get this thing working. I believe this will be my Final Expansion. But, you never know.

Final expansion? :roflmao:

[paul1981]

I dont see why that is funny! But I dont care, because you have a Prelude 1200.

Every Amiga owner always thinks they've purchased their last upgrade... lol

prelude.library 5.3
ahi.device 6.6

[paul1981]

really? you have installed AHI 6? Well, perhaps that makes sense. I was always against AHI 6 because of the beta state and the fact that there was no normal Paula device included, I never figured out why.. but now that Im going to use AHI only for Prelude playback, perhaps I shouldnt even care. Do you remember if it was a lot of trouble installing it? It has to be done manually, right?

And, well.. I dont have much room for expansion left in my machine. And I'm not going to add zorro or pci either. So I guess Im 'done'

I can't remember whether I upgraded my AHI or whether that's the first one it had. Come to think of it I do seem to remember doing a manual upgrade I think, but I'm sure it was nothing difficult.
I got my Prelude in 2007 and purchased Audio Evolution, recorded one serious multitrack song with it and then haven't really recorded much else since. The song came out fantastic, and no one's ever heard it except for my family.

IIRC, don't people say to use the old AHI versions because they are faster? Doesn't really matter though on 040/060.

Have fun.

[paul1981]

AHI 6 didnt help..
 
 @Paul1981 what screenmode is your machine running?

It works in any mode/colour depth mate. My Workbench is Euro72Hz Productivity. My Audio Evolution screen mode is Multiscan Productivity. Can't you try your Prelude connected straight to the 1200 motherboard like it's supposed to be? At least that would let you know if it is a cable issue or not.

[paul1981]

I like your thinking, but Im afraid its not going to help. I have just tried with a 030 card and have encountered the same issue. Also, Im doing this on a fresh Workbench 3.1 installation with no CGX installed.

As soon as an accelerator card is in place, the timing is broken. Then again, it could be broken without an accel card too, since the basic 020 is not able to play mods in realtime in that case and it may not have to shift as much as data in that case. Just guessing.

Are you making sure you are using the correct ahi.device and paula.audio for your cpu? Do you get problems when using the paula audio driver?

So ahi.device is for 020 through to 040
ahi.device.060 is for 060

Remember to manually rename cpu specific files around when swapping between an 020/030 cards and your 060 card - either that or re-install AHI with its installer and make sure it re-installs for correct cpu. I'm guessing this is how it works, but like I said, haven't installed AHI in 7 years.

Remember that the PreludeTapeDeck program doesn't need AHI, nor does play16 if you set the PRELUDE tooltype... so what happens when you use either of these programs? Does it work?