Hi all.,
Adam Audio rates these speakers as 70W bass, 20W treble.
Some internal details here - ADAM T8V - Active Nearfield Monitors - Age of Audio
Looks to me like a 40W stereo burr-brown chip. What I don't understand though is why there's an ADC in there as the speakers don't have digital in.
The Burr Brown can accept I2S. I'm thinking now they are converting the signal to PCM, feeding it into a digital converter to do the low/high roll-off then sending into the amp.
Which begs the question whether these speakers have been made for a digital upgrade. I see a header on the picture. At the moment when I look at my flow I have
SPDIF -> DIR9001 -> PCM1794 -> NE5534 -> XLR -> ADC -> DIG FREQ -> AMP
Seems a natural progression to try and get the DIR9001 signal directly into the DIG FREQ. I'm thinking a SPDIF & DIR9001 in each speaker.
Adam Audio rates these speakers as 70W bass, 20W treble.
Some internal details here - ADAM T8V - Active Nearfield Monitors - Age of Audio
Looks to me like a 40W stereo burr-brown chip. What I don't understand though is why there's an ADC in there as the speakers don't have digital in.
The Burr Brown can accept I2S. I'm thinking now they are converting the signal to PCM, feeding it into a digital converter to do the low/high roll-off then sending into the amp.
Which begs the question whether these speakers have been made for a digital upgrade. I see a header on the picture. At the moment when I look at my flow I have
SPDIF -> DIR9001 -> PCM1794 -> NE5534 -> XLR -> ADC -> DIG FREQ -> AMP
Seems a natural progression to try and get the DIR9001 signal directly into the DIG FREQ. I'm thinking a SPDIF & DIR9001 in each speaker.
Attachments
I've got it wrong, I think the bottom left is a MCU, and is sending control to the PCM1862 (ADC) which is responsible for gain and bass/treble filtering. P2 looks like programming pins for the MCU and possibly those are I2S pins above it.
Hard to read the part numbers, but it looks pretty straightforward: Analog in -> ADC -> Dig Input to the TAS power amp/DSP and then a uC for controlling the lot. If you don't know how the DSP functionality of the power amp chip is programmed and the detailed architecture of the board I'm honestly not sure you can improve much by going direct. Also, a couple of problems that you may not have thought about:
- There is no guarantee that the ADC spits out I2S. It's likely, but both chips support multiple formats as far as I can see.
- SPDIF/I2S doesn't understand right/left channels directly, so you'll have to find a solution to that.
- If you want another board in the monitor (SPDIF-receiver) you'll need to find the right voltages on this board - no guarantee that you can find what you need and get it out.
Last but not least: YMMV but to me you're overthinking this (and overestimating the benefit). If you want to avoid the ADC step, either get monitors with a fully-analogue amplifier stage and filter, monitors with a digital input to skip part of your analogue chain or simply passive monitors where you can influence the whole thing incl. the amplification. With all due respect these Adams are probably good, but they are fairly cheap (= "built down to a price") and so the all-in-one-solution with DSP on board is probably the best all things considered.
- There is no guarantee that the ADC spits out I2S. It's likely, but both chips support multiple formats as far as I can see.
- SPDIF/I2S doesn't understand right/left channels directly, so you'll have to find a solution to that.
- If you want another board in the monitor (SPDIF-receiver) you'll need to find the right voltages on this board - no guarantee that you can find what you need and get it out.
Last but not least: YMMV but to me you're overthinking this (and overestimating the benefit). If you want to avoid the ADC step, either get monitors with a fully-analogue amplifier stage and filter, monitors with a digital input to skip part of your analogue chain or simply passive monitors where you can influence the whole thing incl. the amplification. With all due respect these Adams are probably good, but they are fairly cheap (= "built down to a price") and so the all-in-one-solution with DSP on board is probably the best all things considered.
I think the ADC is the DSP as the datasheet says it has one, it's controlled by the MCU which has had it's print scrubbed, perhaps a chinese clone. It's also the active crossover so yeah, I can't ditch it. Board isn't well designed (I'm a part time electronic engineer) but it does work and sounds fantastic.
The PCM1862 datasheet mentions something like "features that partially replace a DSP", but the section "audio processing" on p.53 it also says that not of the filters are user programmable, so what you can do is mostly gain matching etc. It is however SW-controlled, so you need a connection to the uC to select formats etc.
The TAS-datasheet specifically mentions that it has an integrated audio processor and although I can't be bothered to read the whole thing, it says you can create a subwoofer signal for a 2.1 configuration, so pretty sure this is where the filter is implemented.
Oh, and I have an old pair of Adam A5s on my desk, so I am not doubting that these sound great as well 😉
You're right, I missed that about the TAS5754M. Reading up it requires an upload on boot to define it's operation which is coming from the MCU. The MCU is also setting the gain on the ADC as you said.
According to the datasheet the TAS5754M doesn't have the processing power to do 1.1 digital processing above 48KHz, so this will be what the ADC outputs and any input signal above this, or above 103db/A is a waste of time.
There I was building a custom PCM1794A to feed them and there's no point.
According to the datasheet the TAS5754M doesn't have the processing power to do 1.1 digital processing above 48KHz, so this will be what the ADC outputs and any input signal above this, or above 103db/A is a waste of time.
There I was building a custom PCM1794A to feed them and there's no point.