I am looking for multi channel volume contol, to be specific a 6 channel volume contol for ht projects. I know PT 2258 can do it, bit its i2c interface. And this ic is so hard to find.
What i need is analog interface using trim pots/ volume control. Like single volume control for all six channels..?? Does anything like that exist??
Or my another thought is.. If some ic exist which can contol gain by using the voltage values in some refernce pin.. Eg changes gain from 0db to 70/100db when voltage at some pin chnages from 0- 5/10 volts, i can use it too.. No problem even if the ic is single channel or multiple channel, we can still loop the voltage lines from single source .
Does anybody have any idea?? This is like real headache while making analog chips based ht. Please dont say you can do it with cd series analoge switches and resistors. I am looking for 1 or 2 chip solutions.
What i need is analog interface using trim pots/ volume control. Like single volume control for all six channels..?? Does anything like that exist??
Or my another thought is.. If some ic exist which can contol gain by using the voltage values in some refernce pin.. Eg changes gain from 0db to 70/100db when voltage at some pin chnages from 0- 5/10 volts, i can use it too.. No problem even if the ic is single channel or multiple channel, we can still loop the voltage lines from single source .
Does anybody have any idea?? This is like real headache while making analog chips based ht. Please dont say you can do it with cd series analoge switches and resistors. I am looking for 1 or 2 chip solutions.
MC3340P is a single channel voltage controlled attenuator. I use them for multiple volume control and auto level control.
MC3340P Datasheet
Still in production by OnSemi
MC3340P Datasheet
Still in production by OnSemi
This is another possibility and it's variants.
https://www.cirrus.com/en/products/pro/detail/P2.html
https://www.cirrus.com/en/products/pro/detail/P2.html
Mc3340 seems ok. I am looking for something like this.. Its perfect for handsoldering too. But those from cirrus seems not ok, as it needs serial bus. ( lol no serial or i2c because it needs programming and microcontroller. )
Any more suggestions??
Any more suggestions??
AD603 and AD605 are DC controlled gain elements but have only around 40dB gain range. If you need 80dB its possible to cascade them. List price is fairly expensive but they're cheap on Taobao.
http://i0.wp.com/hackmeopen.com/wp-content/uploads/2011/04/Voltage_gain_amp_1.png?resize=300,225
and there's your dinner.
and there's your dinner.
THAT corp have some blackmer style VCAs that are easy to use, note the minor temperature drift, and you want to drive the gain control pin from a low Z source for best effect.
The app notes are worthy.
Regards, Dan.
The app notes are worthy.
Regards, Dan.
I've used National Semi, Dallas and ADI digital pots for various applications (including filters). Most of the time "bit-banging" with a PIC or Stamp, but also with Arduino.
A little bit strayed from the topic -- I just happened to see this datasheet on a newish device from TI: http://www.ti.com/lit/ug/tidu034/tidu034.pdf This is a physically controlled pot.
A little bit strayed from the topic -- I just happened to see this datasheet on a newish device from TI: http://www.ti.com/lit/ug/tidu034/tidu034.pdf This is a physically controlled pot.
Yep- they make excellent post-amplifiers on my DACs, after passive I/V and passive filtering. Not the absolute best subjective dynamics mind (classA biassing helps) but very decent, especially at the prices on Taobao.
The AD605 being only 5V supplied and having 36dB or so of gain only just meets the noise requirements for RBCD in balanced mode.
OK, I know the noise is barely right for audio if you can get them to work good.
The price here is about $0.50 a piece for the AD605 - for a DC controlled volume element that's jolly hard to beat.
Wheww thats ti design is absolutely out of our scope of requirements.. Unless we have some alien ears. Also we cant use that design for our multi channel requirements.. Take a look at the pot lines. We cant make it work for multichannel ( anything above 2 channels) design. Unless we have a pot with 6 seperate variable resistor links. Besides in my opinion, this one is absolutely no use for audio purposes, because it just add extra components and chips for just replacing a pot that can be directly connected to input of an amp.
has its quircks but managable.
DIY Voltage-Controlled Amplifier | HackMe
you can read more about it here, and solutions for overcomming its "interesting" charactereistics. in real life its okay for most stuff.
an alternative can be some light sensitive resistor and a led pointed at it in an enclosed tube to form a part of a voltage divider, it sortha reacts slower, but if you don't need to rapidly change the volume it works nicely.
the bonus is with the led+photoresistor setup is, that you can use whatever crapy pot you can get your hands on. literally.
as it can't "crackle" even if the pot is an utterly junk quality.
and its not in the signal path in any ways.
There are certainly some cheap options out there - certainly can get a Chinese kit for under $40.
Size wise, it could be very tiny (on perf board or ideally a PCB) but the Chinese kits are a little large if space is a major constraint.
I have very good experiences with the CS3318. It's 8 channel and the specs run circles around anything else that has been mentioned here. It's only one chip so once you have the serial interface running you can do anything.
The 3318 runs on +/-9V analog but there is also a +/-5V version with reduced analog output of course, but the same stratospheric performance.
It's not VCA or such but a resistor ladder network, actually, like a stepped attenuator with 0.5dB or 0.25dB steps.
Jeff Rowland used it in some of his top amplifiers.
The VCA's may look nice but check the tracking - that may not be as good as you want!
Check it out!
Jan
The 3318 runs on +/-9V analog but there is also a +/-5V version with reduced analog output of course, but the same stratospheric performance.
It's not VCA or such but a resistor ladder network, actually, like a stepped attenuator with 0.5dB or 0.25dB steps.
Jeff Rowland used it in some of his top amplifiers.
The VCA's may look nice but check the tracking - that may not be as good as you want!
Check it out!
Jan
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Have you thought about using a 4-channel VCA? The gain/attenuation of channel can be separately controlled via a control voltage (CV). The CV can simply be a given via a potentiometer that is connected between two voltages (e.g. 3V and ground, or 2V and -1V, etc.) depending on the range of gain adjustment you want to achieve. Also, you can trim each channel by using a summing amplifier and combining a trim control voltage offset for each channel with a main voltage that will be used on all channels. This gives you a trimmable 4-channel volume control with an analog control interface. Channel-to-channel tracking is very good, likely much better than you could achieve with multiple single gain control units. The ICs only costs a few dollars each, not $25 like some multichannel digital volume control chips. I designed and built a 4-channel volume control (not with trimmable channels, however) and it works pretty well. Distortion and noise are not as low as a digital volume control, but on the other hand the analog volume control runs off of dual 15V rails and can output high analog voltages. This is something that many digital gain stages can not do by themselves.
This part used to be available as SSM2164. Cool Audio bought the rights to MFG it (it seems) and is making it as V2164. Info below:
Purchase here or through the MFG:
Coolaudio V2164D Quad Voltage-Controlled Amplifier
Cool Audio (MFG) product page:
:: Official website of Coolaudio Semiconductors (COOLAUDIO International Limited) - www.coolaudio.com
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