VOGONS


Reply 480 of 487, by mkarcher

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Tiido wrote on 2022-01-08, 05:38:

SB has quite strong LPF at its output so it'll definitely round out those squarewaves.

Considering that many games of that time used 11kHz samples, so every signal above 5.5kHz is unwanted aliasing (i.e. noise), the quite strong LPF on the classic sound blasters actually is a quite good idea. OTOH, for that purpose, it would have been enough to filter the DAC output, and mix in the music output (which should be free of audible aliasing) after the filter. Taking the harshness from the square wave CMS output might be a good reason to have that one filtered, too, though.

Reply 481 of 487, by Jackal1983

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OK, so I'm looking at building one of these things but I'd like to know about some parts substitutions:
1.Substitution of most of the 74LS logic to 74F because they're actually available at Mouser and Digikey.
-The U7, U8 (74LS138) and U17 (74LS139) appear to be available, so they'll stay as they are on the BOM
-Additionally, I may swap out U29 (74LS14) for a 74ACT14 depending on availability when I order my board
2. I plan to use the PLCC-44 equivalent of the recommended microcontroller with a soldered in DIP-40 to PLCC-44 adaptor because of availability and the possibility of using an original Creative DAC if I ever come across one.
3.Also, I plan to use TDK FG and FA (for the .1 UF caps) series MLCCs throughout for all of the ceramics except for the 2 30 pfs attached to the crystal: I'll use either Kemet Goldmax MLCCs or Kyocera AVX SR Series caps. Any suggestion where I should try putting Film caps in to maximize the sound quality. I should have audio grade Nichicons on hand for the electrolytics.

Thanks!

Reply 482 of 487, by Klench

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Everyone, I hope this thread isn't too cold. I built a snark barker ISA and having problems (no sound from SB, Adlib etc....just a hum).
1. Does the snark barker require a volume knob/wheel installed on the potentiometer for me to hear anything from either the SB or Adlib on the board?
2. Will the potentiometer work without installing wires? I saw some blue wires soldered to the unit on one of the first postings in this thread and don't know what that's all about.
Thanks in advance for your advice. Can't wait to solve the problem.

Reply 483 of 487, by dionb

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As for the knob: no, it's just a mechanical part to make it easier to turn the pot.

Not too sure about the wire, but it is on the schematic, so probably a good idea. Mine is buried deep in a case I can't reach right now, and my pics aren't clear on that part, so can't check what I did exactly.

Reply 485 of 487, by Klench

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thanks for checking about patch wires around the pot. I'm going to start fresh again(sigh) and socket every IC. I'm hoping it was a bad IC off ebay (TEA, DAC, etc. )
last question on the pot for now...so without the wheel how do I turn the pot to increase the volume? Thanks again.

Reply 486 of 487, by appiah4

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Klench wrote on Yesterday, 01:14:

thanks for checking about patch wires around the pot. I'm going to start fresh again(sigh) and socket every IC. I'm hoping it was a bad IC off ebay (TEA, DAC, etc. )
last question on the pot for now...so without the wheel how do I turn the pot to increase the volume? Thanks again.

Please check backwards on this thread, I have inquired about this and gotten some feedback.

Start reading here: Re: Tube Time: Announcing The Snark Barker, a 100% Compatible SB 1.0 Replica!

You will need to solder a few resistors to set volume at a fixed level without the potentiometer. Reading back on the discussion leads me to believe no potentiometer would result in no sound.

Last edited by appiah4 on 2023-02-06, 09:24. Edited 1 time in total.

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Reply 487 of 487, by MJay99

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That's also correct: no potentiometer is going to be no sound. If the pot is placed (and not broken, wrong type, or turned all the way down), there should be some sound, even without any patch wire (in fact, I also didn't see one in the schematic -there's a dotted line between the two pots shown there, but that just suggests to me that the two pots shown there are driven together as one - that line also doesn't run to any pin of the pot, unless I'm totally cross-eyed now 😁).

As I understood Klench, he does have the pot installed, but is missing the knob and was wondering about the patch-wire that can be seen it the picture in the first post.

As for the latest question: Without the knob, the alps pot I got for this is indeed a bit difficult to adjust as it's threaded for a screw. Even just using some washers under the screw might simply block it. It might work just tightening the screw and trying to carefully turn it afterwards by the screw (which is what I did, before I printed the knob) - after all, when it's set once and with using external speakers, there's usually not much need to touch it again.

The better way would probably be to find someone with a 3D printer and having them print the part for you - it's a small thing with no big associated costs.

Maybe, if you'd want to hint where you're from, someone could also help you out with it. As long as it's not international shipping, I wouldn't mind sending you one.

Otherwise, you could let e.g. JLCPCB print one for you - the part itself is going to be 1 USD and with shipping, etc. it might come up to about 5 or 6 USD (unless you have more things to order).