I want to have IR volume control. The amp I'm looking at getting (used fwiw) has a 20kΩ pot directly on the input. I was going to bypass that pot and put one in an external box, along with an arduino and stepper to control the pot for the IR control. I'm not changing anything schematically speaking wrt the amp but I'm wondering if there is anything I need to be worried about like RF? The DAC has an output impedance of 47Ω and interconnects will be short, likely 0.5m or less. Thanks!
Passive Preamp are you sure?
If it is not active, it does not amplify and therefore, by definition, is not a Preamp.
All you can do in step up the impedance and that causes a mismatch.
If it is not active, it does not amplify and therefore, by definition, is not a Preamp.
All you can do in step up the impedance and that causes a mismatch.
Seeing the actual amp circuit is certainly better than not seeing it, but you are likely on the right way. What does "going to bypass that pot" actually mean? I would physically disconnect the pot, not just link input and wiper and solder a fixed resistor of a much larger than the pot value in place.
This has been discussed ad nauseam. Preamp can mean pre amp, that is the thing before the amp. Whatever that is. Who said that thing has to be active? You? By what authority?
Passive preamp can amplify, if it contains step up trafo, but by increasing the voltage, current goes down, so next stage has to be high impedance.
Ryco, you are on the right track. You are simply replacing internal volume pot on the input with external volume pot (ir controlled). As mentioned, completely bypass the internal pot with shielded wire, there should be no danger to pickup rf if done right. Many power amps do not have volume control on input, yet are free from rf and silent.
Other option would be to put simple buffer after the ir controlled volume pot. Extrenal volume pot with buffer in the same box. That way you do not have to modify the amp. Just to be on safe side. Plus no change in amps resale value.
With the help of Google you will find any opinion that suits you.
And, btw, I consider John Snell as a well respected authority in the audio field.
A pre-amplifier is since decades a small signal amplifier.
There are no passive amplifiers.
Period.
And, btw, I consider John Snell as a well respected authority in the audio field.
A pre-amplifier is since decades a small signal amplifier.
There are no passive amplifiers.
Period.
You can just turn up the amplifier level control to maximum, there's no need to remove or bypass it unless you want to.
It's a matter of semantics. Preamp has the syllable 'amp' in the word, which implies an amplifier or signal enlarger, which a passive 'preamp' does not have. I'd simply call it an attenuator rather than a preamp. Ov course, since it does a function and is in an electrical position similar that of the active preamplifier, I would just colloquially call it that and get it over with.
There are also numerous remote volume control boards/modules available from eBay, etc., complete with motorized pot, IR detector, and remote control. Some are built with an Alps pot. This might be simpler than the arduino approach, but that’s for you to decide. I have tried several and they have been satisfactory. I was also able to teach the remote control for my Apple TV to operate the volume module, which reduces the number of remotes needed for the system. Good luck.
Preamplifier is designated to denote device preceeding the amplifier. It does not mean it has to be active. It does not mean it has to have gain.
Even passive transformer based attenuator can be configured with the gain.
Even active preamp can be just an attenuator. Especially if dac with 2Vrms is fed to it and 400mVrms is all it takes for power amp to blast to full power and clip. If less than one watt is needed from power amp in normal listening, than preamp will actually work only as attenuator, no gain. Calling it preamp by your definition would be wrong, since all it does is attenuate.
Agree. It's just a choice of nomenclature, really. When I listen to my setup, my active (vacuum tube in this case) preamp is usually always attenuating the input signal, since the volume is lower with the preamp in circuit than it would be if the source instead were directly plugged into the power amp sans preamp.
My personal experience with passive preamp is that it sounds best if buffered.
Something to do with damping factor.
If you do it as you suggest knutn, you may observe lower dynamics and generally more boring sound. Trust me, i tried it many times. Yes, you can turn amps pot to max, and use passive pre, essentially have two volume pots in series. Hopefully input stage is jfets, otherwise you may notice signal degradation.
Semantics:
Preneolytics denotes era before the neolytic started.
Prepubescent means age before onset of puberty.
Preamplifier is device before an amplifier.
Santa Claus is female...bacause, just like Santa Maria, Santa Monica, Santa Marta, Santa in spanish or italian denotes feminine form.
Semantics my friends.
You might want to think about de-powering the stepper when not moving, stepper motor driver chips are current-choppers and generate switching noise at substantial current levels, which could create noise injection issues.
I agree. additional you will have the benefit to pre-adjust the highest wanted level on the still present pot.
After find out the ideal position you can measure the value for resistance and replace the pot by two resistors (in a second step)
For the main volume control for RC a relay controlled approach I would prefer - go to
Passive Preamp: Arduino based, remote control, Relay R2R, input selection
Remote Controlled (RC) Volume Control Kits - Overview wanted
Infrared Remote Contr. Stepped Attenuator for Replacing RC Motor Volume Contr.Alps