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-   -   Help in choosing a potentiometer as a "Passive preamplifier" (https://www.diyaudio.com/forums/analog-line-level/219342-help-choosing-potentiometer-passive-preamplifier.html)

diyralf 27th September 2018 08:58 AM

Quote:

Originally Posted by Chris Daly (https://www.diyaudio.com/forums/analog-line-level/219342-help-choosing-potentiometer-passive-preamplifier-post5557901.html#post5557901)


The man must be a bat or Count Dracula. I always find it funny when older people talk about 96 kHz or even 192 kHz sampling and even hear up to 10-12 kHz!

Chris Daly 27th September 2018 09:18 AM

Quote:

Originally Posted by diyralf (https://www.diyaudio.com/forums/analog-line-level/219342-help-choosing-potentiometer-passive-preamplifier-post5557932.html#post5557932)
The man must be a bat or Count Dracula. I always find it funny when older people talk about 96 kHz or even 192 kHz sampling and even hear up to 10-12 kHz!

That is just disrespectful. David is not so small minded to be just thinking of himself.
You should have noticed he garners opinion from many groups to inform of what is
perceived, and expresses findings in terms of the plural ( we) rather than the singular.

If you listen to what he says, where wide bandwidth is catered for, it seemingly improves
lower audible frequencies. He also talks in terms of perception rather than directly hearing
frequencies beyond what is our upper threshold.

DF96 27th September 2018 10:04 AM

Quote:

Originally Posted by Chris Daly
Indeed, but that does not have to confine the pot, to its traditional fairly mundane use.

It does in this thread, which is clearly about choosing a suitable pot for a conventional passive preamp which uses the pot as a signal voltage diviver. Choosing a pot for some other circuit use belongs in another thread.

Quote:

Originally Posted by diyralf
A good friend of mine (making audio devices for 40 years) once told me, that it is not the job of good audio devices to roll-off the signal and limit the bandwidth. If a signal is bothersome or dangerous, it has to be eliminated at the front of the source.

It is the amplifier which drives the speakers, so the amplifier is exactly the right place to put in any protection the speakers need, such as bandwidth limitation. The source is the wrong place to do this.

Chris Daly 27th September 2018 10:18 AM

Quote:

Originally Posted by DF96 (https://www.diyaudio.com/forums/analog-line-level/219342-help-choosing-potentiometer-passive-preamplifier-post5557981.html#post5557981)
It does in this thread, which is clearly about choosing a suitable pot for a conventional passive preamp which uses the pot as a signal voltage diviver. Choosing a pot for some other circuit use belongs in another thread.

That is then given equal prominence as a sticky type thread ? There are many exciting ways of using potentiometers in passive preamps which require discussion. ..

DF96 28th September 2018 09:54 AM

You could start a thread about the exciting issue of choosing a control pot for an LDR volume control, then ask the Mods to make it a sticky. I am going to guess that they might decline, on the grounds that part of the justification for LDR volume controls is that the pot is not really in the signal path so doesn't really matter too much.

On the other hand, people are always popping up asking about how to choose a passive volume pot value to use between X source impedance and Y load impedance so it makes sense to put the answer in a sticky.

jfetter 26th October 2018 03:03 PM

What is a "sticky" anyway?

.

DF96 26th October 2018 03:52 PM

This thread is a sticky. It is a thread which remains at the top of the forum area, not being displaced by more recent non-sticky threads.

Rockaway 25th May 2019 04:25 AM

1 Attachment(s)
Not sure if this is the correct location for this question but here it goes.
Iím building a dual mono passive preamp using Dact SMD pots. The chassis for each is
a repurposed Leads and Northrop Aryton Shunt Galvonometer. There are heavy duty binding post terminals with large brass posts. For aesthetics and simplicityís sake I would like to keep these. What sonic degradation might I experience forgoing the RCA jacks here? I have
Read that RCAs are a flawed design sighting skin effect and phase issues. I donít have an issue with them though Iíve always thought that a solder joint is the weakest link in the signal path.

DF96 25th May 2019 10:22 AM

Quote:

Originally Posted by Rockaway
I have
Read that RCAs are a flawed design sighting skin effect and phase issues.

No. You can safely ignore anyone who told you that. RCAs are flawed, but nothing to do with skin effect or phase. RCA is often flimsy, can have poor contact resistance, and makes the signal contact before ground. However, it is successfully used in most domestic audio systems.

The weakest link in a signal path is the transducers: microphones, speakers.

Using binding posts for inputs may mean a bit more hum because you unavoidably introduce some loop area.

Rockaway 25th May 2019 06:01 PM

I know that capacitance is a factor with passive pre’s.
The shielding on an RCA jacket must contribute to this. If I keep
Exposed area of the cable short on the top where it attaches to the binding posts seems like little RF could “get in”.

The brass posts inside are within the thick walled aluminum chassis and theoretically
Immune to RF magnetic fields ground loops etc.


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