klb3088@ultb.UUCP (K.L. Bell) (11/08/89)
I would like information regarding the sound fix for the Amiga 1000 to have a software switchable audio filter. I remember somebody mentioning an issue of AmigaMail, but I do not remember which issue. Could someone point me to the source of said beast? Thank you, Kristen Bell .sig goes here.
nix@tolsun.oulu.fi (Tero Manninen) (11/09/89)
In article <1574@ultb.UUCP> klb3088@ultb.UUCP (K.L. Bell) writes: >I would like information regarding the sound fix for the Amiga 1000 >to have a software switchable audio filter. Is it possible to do ? I have an old A500 which doesn't have any efect in audio when power led is blinking.. (that is the filter switch ?). Please mail, post or do whatever you like. I'm not afraid of *small* hardware fixes, the warranty has gone ages ago :-) ++Tero
so-tsa@stekt.oulu.fi (Tommi Saarinen) (11/09/89)
In article <1574@ultb.UUCP> klb3088@ultb.UUCP (K.L. Bell) writes: > I would like information regarding the sound fix for the Amiga 1000 > to have a software switchable audio filter. I remember somebody > mentioning an issue of AmigaMail, but I do not remember which issue. > Could someone point me to the source of said beast? Yes, there is a switchable audio filter - BUT - *only* in A500s, A2000s and newer Amigas. Thus, the filter cannot be turned off in Your Amiga 1000 (nor in mine, snyf...). So we must only suffer from the lack of the switchability of the audio filter. > Thank you, You are welcome... > Kristen Bell > .sig goes here. Where???? (Mine goes here:) --------------------------------------------------------------------------- // ***AMIGA IS THE BEST*** // E-mail: so-tsa@stekt.oulu.fi \\ // Oulubox: SuperBrain \\/ --------------------------------------------------------------------------
hamilton@intersil.uucp (Fred Hamilton) (11/09/89)
In article <SO-TSA.89Nov8225049@stekt.oulu.fi>, so-tsa@stekt.oulu.fi (Tommi Saarinen) writes: > In article <1574@ultb.UUCP> klb3088@ultb.UUCP (K.L. Bell) writes: > >> I would like information regarding the sound fix for the Amiga 1000 >> to have a software switchable audio filter. I remember somebody >> mentioning an issue of AmigaMail, but I do not remember which issue. >> Could someone point me to the source of said beast? > > Yes, there is a switchable audio filter - BUT - *only* in A500s, A2000s > and newer Amigas. Thus, the filter cannot be turned off in Your Amiga > 1000 (nor in mine, snyf...). So we must only suffer from the lack of > the switchability of the audio filter. Actually, Amazing Computing ran an article on how to bypass the low pass filter in the A1000 just as the 500s and 2000s do. I did it and it works well. I can't remember what issue it was, it was about two years ago however. A quick and dirty solution is to just bypass the filters with two jumpers (then they will be off ALL the time) or a DPST switch (you can switch it on and off manually with an external switch). The Amazing Computing hack works off of the Power LED. -- Fred Hamilton Any views, comments, or ideas expressed here Harris Semiconductor are entirely my own. Even good ones. Santa Clara, CA
mikey@NRC.COM (Mikey Goodglick) (11/10/89)
In article <1574@ultb.UUCP> klb3088@ultb.UUCP (K.L. Bell) writes: > > >I would like information regarding the sound fix for the Amiga 1000 >to have a software switchable audio filter. I remember somebody >mentioning an issue of AmigaMail, but I do not remember which issue. >Could someone point me to the source of said beast? > Here is a fix for ya... This is a modification I did of a fix that was in an Amazing Computing Issue. My changes & additions will allow hardware switching capabilities...Do the physical switch mode...it is REALLY worth dilling a hole in your Amy case. I have done 4 of these mods to date & never had a disappointed "customer". Of course if you don't wish to have the added physical switch capability, just follow the instructions in the magazine, for the software toggle only. (Here's how....) Due to an overwhelmingly high response regarding my posting about the audio fix for the Amiga 1000...I have decided to make this easy on everyone... What I have done is taken the audio filter hack from Amazing Computing issue Vol3 number 3. On page 64, the diagram of the IC I have changed a few things. The 10k resistor no longer attaches to the base of the transistor, it now goes to the center of a SPST switch (on/on switch). One of the other ends of the switch goes to the 1k, the end that connects to the base of the transistor. Do not disconnect the 1k from the base. The other end of the switch goes to pin 5. That is it...everything else hooks up as instructed. Remember: I cannot take responsibility for any problems that you may encounter during this modification. Let me know how you like your new HI-FI Amiga! By-The-Way.. If you attempt the PAL fix on pages 58 & 59 of that same issue of AC. DO NOT build it by the diagram, it is incorrect. The text is correct. -- **** Mikey ****, "Changed my hair-style so many times In 3D, Part II, The Final Chapter now, don't know what I look like." A New Beginning...But this time, -Talking Heads Someone is waiting. ---------------------------------- (Amiga, a REAL Chameleon) | mikey@nrc.com mikey@nrcvax.UUCP
GORRIEDE@UREGINA1.BITNET (Dennis Robert Gorrie) (11/11/89)
What you said was not completely true. A stock A1000 does not have a software switchable filter. HOWEVER it is very easy to make the filter software switchable. A complete article of how to do it was in a 1987 Amazing Computing mag. I will mail the person who posted the question the volume number as soon as I find it. The switch even works with the software pro gram LED, same as a500s and A2000s do. Personaly, I could find no instances where I ever wanted the filter on, so I just put two jumpers across the audio buffer chip pins that cut out the filters there. I still have not found a any music samples that needed filtering. Even so, if a person was concerned about aliasing noise, they would get better results if they used a good equalizer instead of the built in Amiga filter. +-----------------------------------------------------------------------+ |Dennis Gorrie 'Chain-Saw Tag... | |GORRIEDE AT UREGINA1.BITNET Try It, You'll Like It!'| +-----------------------------------------------------------------------+
GORRIEDE@UREGINA1.BITNET (Dennis Robert Gorrie) (11/11/89)
Amazing COmputing Vol 3, num 3, has the plans for the software switchable filter for the A1000. Vol 3, num 4 has the much easier quick and dirty filter jumper mod. +-----------------------------------------------------------------------+ |Dennis Gorrie 'Chain-Saw Tag... | |GORRIEDE AT UREGINA1.BITNET Try It, You'll Like It!'| +-----------------------------------------------------------------------+
kent@swrinde.nde.swri.edu (Kent D. Polk) (11/11/89)
In article <8911101921.AA06411@jade.berkeley.edu> GORRIEDE@UREGINA1.BITNET (Dennis Robert Gorrie) writes: > > What you said was not completely true. A stock A1000 does not have >a software switchable filter. HOWEVER it is very easy to make the filter [...] While we are on this subject & I have never seen the A1000 schematics, please answer the following question: Q: Are the stereo outputs that come out the 8 pin connector on the back of the A1000 filtered? I ask this because I don't think they are. They don't sound like it, and their outputs are apparently not directly connected to the RCA jack stereo outputs. I say this because I can have the y-cable hooked to my monitor (which obviously ties both channels together), but still get stereo out the 8 pin connector hooked to my stereo amplifier at the same time. Anyone want to comment who has the schematics for the 8 pin plug? Thanks ==================================================================== Kent Polk - Southwest Research Institute - kent@swrinde.nde.swri.edu Motto : "Anything worth doing is worth overdoing" ====================================================================
GORRIEDE@UREGINA1.BITNET (Dennis Robert Gorrie) (11/13/89)
>While we are on this subject & I have never seen the A1000 schematics, >please answer the following question: > >Q: Are the stereo outputs that come out the 8 pin connector on the back of >the A1000 filtered? > >They don't sound like it, and their outputs are apparently not directly > >Anyone want to comment who has the schematics for the 8 pin plug? > >Thanks >Kent Polk - Southwest Research Institute - kent@swrinde.nde.swri.edu > Motto : "Anything worth doing is worth overdoing" I only have the schematics from the Amazing Computing mag. The don't show anything about the audio lines to the modulator connector. I don't have the a1000 schematics. But from looking at the motherboard, it appears that there the audio signals from Paula go strait go the U5G, the buffer/filter chip. It would appear external audio signals must go through this chip. All the variety of filter mods are basicaly done to this chip, including the A500 and A2000 versions. So, what ever sound difference you are hearing, it must be bypassing filters somwhere else. The article in Amazing Computing Vol3, Issue 3, mentions more filters. In particular, 2 of them right beside the audio rca jacks. Perhaps the modulator connection does not have these filters, and that is why it sounds different. (they are labeled c5 and c6 I think.) Than you for mentioning the second source of stereo output. I am sure most people forget about the modulator connection on their A1000's.
stevep@galadriel.bt.co.uk (Steve Paine) (11/13/89)
From article <910@tolsun.oulu.fi>, by nix@tolsun.oulu.fi (Tero Manninen): > Is it possible to do ? I have an old A500 which doesn't have any > efect in audio when power led is blinking.. (that is the filter switch ?). How do you turn the audio filter on/off on newer A500's? Steve Paine.