Attenuators v passive pre to reduce gain

[philv]

Hi,

possibly have a little too much gain with itargeted amp.

Now, i am only using it via amazon echo dot analogue out at present.
But i assume cd and streamer (airport express) will be similar.

What is best, rothwell attenuators or tilbury passive pre to reduce gain before integrated?

When just using the echo dot output, this can obviously be reduced by turning down the volume on the echo.
Is this better than setting at high volume and using attenuators/passive pre?

Thanks

[philv]

Amplifier -
Input impedence is 60k
100mv - input level at 1kHz for rated power output.
13mv - input level for 0dbw output both channels, with volume control at max.
8v - maximum input before input overload at 1khz.

Tilbury -
input impedance 10k.

Whatever that means!

[Mike Reed]

Afraid I've no idea of your situation, but when trying to reduce the gain from the 3.4V output of my CDP into my pre. (with VU meters), I tried 15 dB, 10dB and eventually settled on a 6dB in-line Goldenjacks attenuators. The first two showed s.q. loss but not the last, which I have now been living with for nearly a year.

Attenuators CAN affect dynamics, but seemingly not in small doses. No idea about a passive pre., which is essentially a pot, I guess. 'Orses for courses, I guess, but at least you have control with a pot.

[philv]

Afraid I've no idea of your situation, but when trying to reduce the gain from the 3.4V output of my CDP into my pre. (with VU meters), I tried 15 dB, 10dB and eventually settled on a 6dB in-line Goldenjacks attenuators. The first two showed s.q. loss but not the last, which I have now been living with for nearly a year.

Attenuators CAN affect dynamics, but seemingly not in small doses. No idea about a passive pre., which is essentially a pot, I guess. 'Orses for courses, I guess, but at least you have control with a pot.

The latest tilbury has a pot plus selectable fixed attenuation, so i guess everything to try in one box.
but min is 10db.

[philv]

Is the inout sensitive usually arrow d 200mv?
So 100mv for my amp would benefit from 3db attenuation?

[Stryder5]

It's Tisbury unless your talking about the docks.....:ner:

[philv]

It's Tisbury unless your talking about the docks.....:ner:

I hate my malfunctioning iPad that ignores half my key presses and then guesses at what i wanted to type.

[walpurgis]

I hate my malfunctioning iPad that ignores half my key presses and then guesses at what i wanted to type.

For some people, touch screens just don't work properly.

[Made in 1968]

I hate my malfunctioning iPad that ignores half my key presses and then guesses at what i wanted to type.

Predictive Text.. Turn it off its a pain in the harris.. Go to setting > Keyboard > Predictive text OFF

[Mike Reed]

The man who invented predictive text died last week. His funfair will be hello on sundial ! (Think about it !):lol:

I guess it's the fixed attenuation which is -10dB at its lowest. I had a lot a trouble asking the pre. manufacturer (E.A.R.) and the technical people of pfm what I should be looking for. They were all wrong, suggesting -20 dB and above. Assuming the Tilsbury is a fair bit pricier than a used attenuator (around £15 to £20), it might be worth experimenting. Or borrow one, of course. The output and input sensitivity figures might be a guide but they weren't in my case.

[Pharos]

Amplifier -
Input impedence is 60k
100mv - input level at 1kHz for rated power output.
13mv - input level for 0dbw output both channels, with volume control at max.
8v - maximum input before input overload at 1khz.

Tilbury -
input impedance 10k.

Whatever that means!

Your results can be achieved with a simple resistor in series with the O/Ps of your source device.
All O/Ps like to be loaded as little as possible, this reducing the current demands on the O/P cct, and placing a resistor in series with the O/P of your source will raise the effective I/P impedance (Z), that it 'sees', this is a benefit to the source circuitry.

You can just get a pot and use it as a rheostat, (adjustable series resistor) and approximate the condition you wish to achieve, and when you have done that replace it with a resistor. I would suggest a pot of 100k because it will give you quite a range of attenuation.

I'm sorry, but I've taken great care in using the qwerty to draw a cct diagram, but it becomes changed and unintelligible when I save it.

[Barry]

Adding a simple series resistor will increase the output impedance of the source; whereas a pot used as a voltage divider will maintain the low output impedance as well as providing suitable attenuation.

[Pharos]

Yes, but that is of no significance, what the I/P of the amp 'sees' is of no consequence, unlike a speaker O/P where a damping factor would be wrecked. A simple series R is a standard solution in AC signal ccts. (Thevenin and Norton).

A pot used as a potential divider would have the advantage of great control provided that its value is great enough to ensure that the Z presented to the O/P of the source is high enough, but that would also contravene your implied criticism that the load would perhaps see a high source Z.

[Barry]

In audio circuitry the source is treated as a voltage source, so has a low output impedance (< 1000 Ohm) feeding into a large load impedance (> 10,000 Ohm). Otherwise the transfer loss is high: for example, if the source impedance equals the load impedance the transfer loss is 6dB.

Using a pot as a voltage divider, the load 'sees' that part of the divider to which it is directly connected as being in parallel with the remaining part, which in turn appears in series with the source impedance. So overall, the source impedance is kept low, more or less, regardless of the voltage division ratio of the potentiometer.

[Light Dependant Resistor]

Hi,

possibly have a little too much gain with itargeted amp.

Now, i am only using it via amazon echo dot analogue out at present.
But i assume cd and streamer (airport express) will be similar.

What is best, rothwell attenuators or tilbury passive pre to reduce gain before integrated?

When just using the echo dot output, this can obviously be reduced by turning down the volume on the echo.
Is this better than setting at high volume and using attenuators/passive pre?

Thanks

Of those two the attenuators is the better choice , as you are avoiding losses associated with contacts, other than RCA plugs and sockets- but they can be removed as well.
https://pinkfishmedia.net/forum/threads/alps-potentiometers-gain-and-distortion.68076/

However if you require variable resistance and no contacts in the signal path at the same time including signal paths associated with input switching, then using NSL32SR3 LDR's
will give you what you need. There are poor ways of powering LDR's and much better ways, discussed here: https://www.stereo.net.au/forums/topic/293104-audio-purpose-ldr-discoveries/

[philv]

Maybe it is better long term to have the amp sensitivity reduced.

[Pharos]

In audio circuitry the source is treated as a voltage source, so has a low output impedance (< 1000 Ohm) feeding into a large load impedance (> 10,000 Ohm). Otherwise the transfer loss is high: for example, if the source impedance equals the load impedance the transfer loss is 6dB.

Using a pot as a voltage divider, the load 'sees' that part of the divider to which it is directly connected as being in parallel with the remaining part, which in turn appears in series with the source impedance. So overall, the source impedance is kept low, more or less, regardless of the voltage division ratio of the potentiometer.

Yes, but the tedium when tired of putting it into words.

[PaulBarnett]

Some years ago, while experimenting with attenuators, I got these:

https://www.amazon.co.uk/gp/product/B0057G44WM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

in-line attenuators with variable 10/15/20db attenuation. ok for experementing, but eventually I used fixed rothwell attenuators.

[Barry]

Amplifier -
Input impedence is 60k
100mv - input level at 1kHz for rated power output.
13mv - input level for 0dbw output both channels, with volume control at max.
8v - maximum input before input overload at 1khz.

Tilbury -
input impedance 10k.

Whatever that means!

Assuming the CD player has a typical output of 2V, this is some 13dB above what is required for full output from your amplifier.

I would suggest you fit a 50K Ohm potentiometer between the source (whatever you use: CDP, Echo Dot etc.) and the power/amplifier. This will give you some control of the volume level.

The Tilsbury is I believe a stepped potentiometer in conjunction with a switch to select the input source. As such it would be a neat solution to your problem.

[Stryder5]

Assuming the CD player has a typical output of 2V, this is some 13dB above what is required for full output from your amplifier.

I would suggest you fit a 50K Ohm potentiometer between the source (whatever you use: CDP, Echo Dot etc.) and the power/amplifier. This will give you some control of the volume level.

The Tilsbury is I believe a stepped potentiometer in conjunction with a switch to select the input source. As such it would be a neat solution to your problem.

Wasn't he the ""Dough Boy" :)

Gary

[Barry]

Oops - I meant Tisbury: https://www.tisburyaudio.co.uk/mini-passive-preamplifier