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Pokeymax version 3 preorder

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20 hours ago, Pmetzen said:

Will there ever be games where you can enjoy the Sid sound?

It is rather a question to game developers..... We provide the hardware, now it's their turn....

I hope to release Gravity Worms with SID music, but date is not known yet.

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19 hours ago, Pmetzen said:

Can the audio input of the PokeyMax V3 be used to load WAV files from CAS images into the computer?

No, it has no sound sampler. The sio audio mixing is analogue, using an op-amp mixing circuit.

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1 hour ago, Mr Robot said:

Mail Call: It finally arrived! 

 

IMG_4667.jpeg

So pretty.  I one day hope to have one of these in my 800xl that already has an U1MB and a Sophia 2.

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21 hours ago, Mr Robot said:

Mail Call: It finally arrived! 

Cool. Does it fit in the 576NUC+ ?

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4 hours ago, Dinadan67 said:

Cool. Does it fit in the 576NUC+ ?

Also, from what I understand it may not be 100% with the keyboard setup of the 576NUC+

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43 minutes ago, scorpio_ny said:

Also, from what I understand it may not be 100% with the keyboard setup of the 576NUC+

This is the main reason. There is an issue with the POKEY timing in relation to the keyboard TKII that needs to be resolved to be able to use this as a POKEY in the NUC. Pokeymax can be used as a second POKEY in a 1088 

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I have two Pokey Max 3 installed in both my 600XL and 800XL. They sound so impressive and it is a lot of fun to program them.

 

The only disadvantage (or advantage?) is that silent SIO sound is now completely silent 😎

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2 hours ago, patjomki said:

I have two Pokey Max 3 installed in both my 600XL and 800XL. They sound so impressive and it is a lot of fun to program them.

 

The only disadvantage (or advantage?) is that silent SIO sound is now completely silent 😎

I do not know if you are looking for a “fix” for the SIO sounds, @foft gave some insight on how to get it back in an earlier post on this thread.

 

I am also eagerly waiting for mine to eventually ship to put it into my Sophia 2 and U1MB upgraded 800XL 😀.

 

 

 

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On 8/25/2021 at 10:35 PM, scorpio_ny said:

I do not know if you are looking for a “fix” for the SIO sounds, @foft gave some insight on how to get it back in an earlier post on this thread.

 

I am also eagerly waiting for mine to eventually ship to put it into my Sophia 2 and U1MB upgraded 800XL 😀.

 

 

 

 

Yes, I am looking for a "fix". I want to hear SIO beeps even when they are switched off (like on an original POKEY). According to @tf_hh this is impossible with PokeyMax3 although @foft wrote that:

 

"

AUDIN:

  What it is: In the pokeymax there is a mixer which mixes the digital audio output and two analog inputs. The two analog inputs are mixed to both left and right outputs.

  What it is for: Allowing hearing SIO 'interference' noise on the external audio outputs ('tch tch tch' when sio beeping is turned off)"

 

Perhaps @foft can tell more. I want PokeyMax3 to behave as original to a pokey as possible (except those additional features like sid, quad etc.).

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On 8/27/2021 at 4:35 PM, patjomki said:

 

Yes, I am looking for a "fix". I want to hear SIO beeps even when they are switched off (like on an original POKEY). According to @tf_hh this is impossible with PokeyMax3 although @foft wrote that:

 

"

AUDIN:

  What it is: In the pokeymax there is a mixer which mixes the digital audio output and two analog inputs. The two analog inputs are mixed to both left and right outputs.

  What it is for: Allowing hearing SIO 'interference' noise on the external audio outputs ('tch tch tch' when sio beeping is turned off)"

 

Perhaps @foft can tell more. I want PokeyMax3 to behave as original to a pokey as possible (except those additional features like sid, quad etc.).

Patjomki,

 

I see what you are saying now. Hopefully there will be a solution to enable SIO sounds. I am happy there is modern replacement for the Pokey chip since it seems be more difficult (and more expensive) to get one these days if one needs to replace a defective one.

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I did some research into this a few months ago.

 

The SIO interference is present in the tv output, since the mixing circuit in the Atari is the original.

 

The SIO sound is also present in the Pokeymax line outputs, however at a lower level. 
 

This is due to a difference in the mixing circuits.

 

Pokeymax has a real mixing circuit which equally mixes pokey output and the audio in. Pokeymax has a better quality mixer, so with higher level input on the sio pin it will work better.

 

Atari has a bizarre mixing circuit! Essentially they do:

Pokey pin 37->25x attenuate -> direct connection -> 34x gain -> 6x attenuate!

 

So this means that the sio audio in has a gain on 5.6x, and accepts a pk-pk of 150mV before clipping.

 

Anyway to get similar ‘silent sio’ interference on pokeymax we’ll need to change the gain on the op-amp. To do this we’ll need to change/add a few resistors.

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From the 600XL schematic:

1903159525_600xl_schematic_withnotes.thumb.jpg.ef2ce9c6ebed398a668ed198939c0b50.jpg

I added/simulated it in microcap to confirm:

atari_schematic_microcapv2.thumb.jpg.606205ab83d8967175cc3ae9b93b40c2.jpg

Here is the microcap file if anyone wants to experiment:

atari_opamp.cir

Edited by foft

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To get a similar disproportionate mix on pokeymax v3 I think we need to decrease the resistance of RN4 (on the bottom) from 1Mohm to about 200Kohm. i.e. solder a 250Kohm resistor in parallel between pin 1-8 and between pin 2-7.

 

Ideally then the gain should be increased on the op-amp too, the simpler alternative to that is to turn up your speakers.

 

Of course modifications of this nature should only be undertaken if you know what you are doing.

 

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Loss of the SIO noise...NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

 

I'd want my bleeps.... Or bleeping bleeps..

Edited by Mclaneinc
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6 hours ago, foft said:

To get a similar disproportionate mix on pokeymax v3 I think we need to decrease the resistance of RN4 (on the bottom) from 1Mohm to about 200Kohm. i.e. solder a 250Kohm resistor in parallel between pin 1-8 and between pin 2-7.

 

Ideally then the gain should be increased on the op-amp too, the simpler alternative to that is to turn up your speakers.

 

Of course modifications of this nature should only be undertaken if you know what you are doing.

 

 

So, if I understand correctly you suggest a modification on PokexMAX3: 2 additional resistors (250kOhm) one between pin 1 and 8 and the other between pin 2 and 7?

 

Alternative doesn't work because even if I put volume to maximum on my TV SIO sound is not noticeable (perhaps for cats but not for my old ears).

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Before you try anything. Give me another day or two to check the schematic, calculate some values and try it here.

 

The volume wasn’t an alternative suggestion btw. I meant that by changing the resistor to adjust the mix this will also make pokey quieter. So we might need to change another resistor to increase the gain on the op-amp too.

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21 hours ago, foft said:

Before you try anything. Give me another day or two to check the schematic, calculate some values and try it here.

 

The volume wasn’t an alternative suggestion btw. I meant that by changing the resistor to adjust the mix this will also make pokey quieter. So we might need to change another resistor to increase the gain on the op-amp too.

 

O.k. I'll wait. Just take your time.

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On 8/25/2021 at 12:19 PM, KlasO said:

Is there an updated user guide for the v3?

Asking for a friend :)

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I've done some analysis on this tonight. It is not going to be a trivial modification. In fact I think it may be best done either in a v4 board or in an external adaptor, which scale and bias the input first.

 

The circuit on pokeymax v3 for the second two channels is a non-inverting summing amp.

https://microchipdeveloper.com/asp0107:non-inverting-summing-amp 

Essentially this is a passive averager + an op-amp with a fixed gain.

The gain is set to 3x. The averager scales the fpga output by 2/4 and the sio and pbi inputs by 1/4. Then it sums them. Giving overall fpga output * 1.5 (i.e. 3.3v->5.0v) and sio in * 0.75 (or connect to both inputs for *1.5).

 

We need instead a gain of ~6x for the sio input and need to maintain 1.5x for the fpga output. Also we need to decouple and bias the channel input since its not realistic to digitally bias at this scale.

 

Ratios between channels are set with RN4 (ext audio in), R8 and R9 (the two channels). Currently RN4 is 1M and the other two 500K.

Gain on channel 3/4 is set with half of RN6 and RN7. Gain = 1+RN7/RN6. The half of RN7 used is 1-8 and 2-7. The half of RN6 used is 3-6 and 4-5. 

RN6 is currently 10K and RN7 is currently 20K.

 

So, this is one potential solution:

RN4: 120ohm       -> ~10% fpga, ~45% per channel

RN6 (half): 1.5K   ->gain ~14x

Then the audio input should be decoupled then biased to 2.5v.

The other audio input should be disconnected.

 

 

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