I think that the logic on the IcePower 1200AS uses inverted pull down logic gate. That is, when in standby, Dvdd (5v) provided by 1200AS on pin 1 of J401 is applied to pin 2 via the 10k pull-up resistor R431. When enable logic is applied to Q408, that conducts and lights up the LED inside the optoisolator U409 and this shunts current thereby dropping the voltage of the pull-up resistor at pin 2. This enables the 1200AS amp. I believe this can be paralled to both amps - although I am not sure if it would be happy of DVDD from one amp was connected to DVDD of another amp. I think only use pin 1 on one amp. So parallel pins 2 and 3 from HyperSET to both amps. But connect pin 1 to only 1 amp.
Give this a try and if it doesn’t work, you can use the auxiliary optoisolator U408 to replicate the same circuit block (add 10k resistor and third pin connection to amp’s Dvdd.
Hope that helps. I assume you know which pins on the 1200AS need to be connected to the three pins on J401.
Give this a try and if it doesn’t work, you can use the auxiliary optoisolator U408 to replicate the same circuit block (add 10k resistor and third pin connection to amp’s Dvdd.
Hope that helps. I assume you know which pins on the 1200AS need to be connected to the three pins on J401.
Hi X,
many thanks for the recommendation.
I thought I would use pin 10 on P101 of the 1200AS, which disables the amp when pulled high and enables it at low. In this case there is no DVDD mismatch, both modules would see the logics high or low state. If the HyperSET logic is at high after hard turn on (so 1200AS is disabled) and switches to low (AS1200 enabled) after the few seconds when HyperSET is ready, than it's fine. Does it work this way?
Sorry if I'm slow-witted, I'm only 4 hours after a surgery under anesthesia 🙈
many thanks for the recommendation.
I thought I would use pin 10 on P101 of the 1200AS, which disables the amp when pulled high and enables it at low. In this case there is no DVDD mismatch, both modules would see the logics high or low state. If the HyperSET logic is at high after hard turn on (so 1200AS is disabled) and switches to low (AS1200 enabled) after the few seconds when HyperSET is ready, than it's fine. Does it work this way?
Sorry if I'm slow-witted, I'm only 4 hours after a surgery under anesthesia 🙈
Hope your surgery went well.
You have it right mostly. It is open collector logic which means that you need to provide the reference voltage that needs to be pulled down when enabled. That’s provided by 1200AS P101 pin 1. Pin 10 is indeed the Enable and needs to be pulled low to enable. That means low relative to the AuxGND on pin 2 P101.
So I normally connect
P101 pin 1 to J401 pin 1
P101 pin 2 to J401 pin 3
P101 pin 10 to J401 pin 2
If you don’t connect P101 pin 1, you won’t have any source of voltage to “pull down” when the optoisolator is active.
It might work your way if we had used a logic gate with internal open collector topology - then it can pull down parallel circuits to internal ground.
Here the pull down is the external (on 1200As GND defined at pin 2 or pin 10 of P101).
Anyhow, you might try your way and see what happens. You would still need to connect P101 pin 2 to J401 pin 3 in addition, to have a place to GND pin 10 P101.
You have it right mostly. It is open collector logic which means that you need to provide the reference voltage that needs to be pulled down when enabled. That’s provided by 1200AS P101 pin 1. Pin 10 is indeed the Enable and needs to be pulled low to enable. That means low relative to the AuxGND on pin 2 P101.
So I normally connect
P101 pin 1 to J401 pin 1
P101 pin 2 to J401 pin 3
P101 pin 10 to J401 pin 2
If you don’t connect P101 pin 1, you won’t have any source of voltage to “pull down” when the optoisolator is active.
It might work your way if we had used a logic gate with internal open collector topology - then it can pull down parallel circuits to internal ground.
Here the pull down is the external (on 1200As GND defined at pin 2 or pin 10 of P101).
Anyhow, you might try your way and see what happens. You would still need to connect P101 pin 2 to J401 pin 3 in addition, to have a place to GND pin 10 P101.
On the bench tonight are the production Vanguard Archer crossovers which just arrived. 3lbs 6oz of pure 16ga copper air core joy. This is really a special speaker. All components including film capacitors are custom made for Vera-Fi Audio. I don’t think have ever seen air core coils this big or this heavy. Wound on bobbins makes them really robust and accurate.
Time to install them inside the test cabinet and have a listen.
Time to install them inside the test cabinet and have a listen.
Many thanks X, now I understand your first post clearly - I will use pin 1 from one module for both enable inputs and hope it works. If not, I could use a turn on delay with about 15 seconds or so on the enable inputs.
Oh... you wrote a much better recommendation, I will use the auxiliary optoisolator.
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