So there's this turbo board, and it works with 2 x GI/AY chips and it works with 2 x YM but if you mix AY and YM... Well, one channel disappears. It seems to be that the YM always 'wins', in either chip socket. It's as if the AY is just not there.
If the addressing/enable of the brand of chips were opposite then I could see what was happening, viz: both chips are playing the same channels. It's not the case according to the data sheets though... I thought these things were supposed to be compatible
So the devices are both working, but when the YM is present the AY's output is suppressed as to be inaudible.
I bent channel B pins out of the socket on both chips. Listening directly to what was on this pin showed that both chips are being driven and outputting the right stuff.
Is it an incompatible difference in the output drivers in each type?
As you know Charlie it works for me with my turbo set up.
A 30 year old Zonx AY chip + a more modern yammadiddle chip into two separate amps.
No suppression of any kind.
I can only assume it's because you have both on the same board driving into the same stereo out-put as opposed to turbosounds usual mock quadraphonic setup, IE two separate amplifiers/speaker sets.
(Edited to remove excess gibberish. )
Last edited by Moggy on Wed Jun 07, 2017 5:17 pm, edited 5 times in total.
To put what Moggy said in fewer words... the outputs are competing with each other. I'm not surprised that the later YM type wins. Yamaha most likely improved the output stage.
Feed the outputs of each chip through some suitable resistors to the input of an amplifier chip (or op-amp). Although if the outputs are the same frequency, same voltage and are in-antiphase, they will still cancel each other out at the input of the amp. But it will be easier to see on a 'scope
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As for Yamaha "improving" the analogue outputs I can only assume,as you didn't go into any detail, that you mean bigger out-put voltages/currents. In practice I have always found my AY to be the better driver of an amplifier, when inserted separately into any stereo set-up my AY plays any common tune louder at a given set volume than the YM, but then again my resistor pattern on the AY's out-puts is different to the "golden ratio" setup Charlie uses for the YM so perhaps that's where the answer lies?
A quick glance at the pdf's for these two chips give a high out-put of over 2volts for the AY and 1.35v for the YM.
It's simplistic but it works. I think turbo should, like Mark suggested, have some additional signal conditioning on there. It's a naive job, but someone's got to do it
I also said conditioning was needed but my post was deemed long winded so will answer this problem from now on by email, anyway by what means are the channel out-puts connected to the stereo socket?
The schematic doesn't make it clear.
(I'm sure you've posted this schem' before then said whoops wrong one)
Moggy wrote: ↑Wed Jun 07, 2017 6:57 pm
I also said conditioning was needed but my post was deemed long winded so will answer this problem from now on by email, anyway by what means are the channel out-puts connected to the stereo socket?
The schematic doesn't make it clear.
(I'm sure you've posted this schem' before then said whoops wrong one)
@Moggy
No one said your post was long winded
We welcome your detailed posts
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There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Moggy wrote: ↑Wed Jun 07, 2017 3:41 pm
As for Yamaha "improving" the analogue outputs I can only assume,as you didn't go into any detail, that you mean bigger out-put voltages/currents. In practice I have always found my AY to be the better driver of an amplifier, when inserted separately into any stereo set-up my AY plays any common tune louder at a given set volume than the YM, but then again my resistor pattern on the AY's out-puts is different to the "golden ratio" setup Charlie uses for the YM so perhaps that's where the answer lies?
A quick glance at the pdf's for these two chips give a high out-put of over 2volts for the AY and 1.35v for the YM.
Sorry, my comments were pure speculation. I was travelling on a train when I posted it. Hence I did not read the datasheets
It sounds (sorry ) like you have practical experience, in which case I defer to your experience.
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
)
Standby alert 
) like you have practical experience, in which case I defer to your experience.