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Attenuators with naim preamplifier

Hottuna

Hottuna

pfm Member
Hi, Haven't been here for a while, recently got some naim amplification and found that the CD player output limits the volume control knob range.

I am trying some attenuators, fitting them at the amp end seemed to soften the sound to an unacceptable degree yet fitting them to the CD player much better without the softening of sound.
I'm no electronics expert, so perhaps some experts here can help!

Looking at rothwells website they do two versions of an attenuator, one for the source (CD player) and the other version for the amplifier input.

Why would an attenuator be different for source Vs amplifier end, it's a resistor isn't it?

Does it really matter which end the the attenuators go?
 
Hottuna said:
Hi, Haven't been here for a while, recently got some naim amplification and found that the CD player output limits the volume control knob range.

I am trying some attenuators, fitting them at the amp end seemed to soften the sound to an unacceptable degree yet fitting them to the CD player much better without the softening of sound.
I'm no electronics expert, so perhaps some experts here can help!

Looking at rothwells website they do two versions of an attenuator, one for the source (CD player) and the other version for the amplifier input.

Why would an attenuator be different for source Vs amplifier end, it's a resistor isn't it?

Does it really matter which end the the attenuators go?
Click to expand...

It does matter which way round the attenuator goes as it is more than just a resistor... it's two! The in-line resistor must go towards the source (CD) and the resistor to ground to load (amp) or it won't act as an attenuator. The differing one's available from Rothwell will no doubt just have male and female phonos at opposite ends.
 
Short answer - attenuators are polar.

(Which I certainly had not appreciated until I looked at what they are on Wiki - easily asumed that they are just R - they are not.)
 
Vinny said:
Short answer - attenuators are polar.

(Which I certainly had not appreciated until I looked at what they are on Wiki - easily asumed that they are just R - they are not.)
Click to expand...

It depends.... constant impedance "pi" and "T" one's are not "polar"... but are usually used at RF and/or in measuring environments.
 
Arkless Electronics said:
It does matter which way round the attenuator goes as it is more than just a resistor... it's two! The in-line resistor must go towards the source (CD) and the resistor to ground to load (amp) or it won't act as an attenuator. The differing one's available from Rothwell will no doubt just have male and female phonos at opposite ends.
Click to expand...
Thanks this helps alot
 
Hi

Depending on the pre amp buying plug in replacement boards from Avondale or Neil Jadman is a better option, in my opinion, as they give an upgrade to the pre amp and allow longer travel of the volume pot.

Check the Avondale Audio 821 Standard Audiophile Preamplifier Modules (Pair) and eBay for the Neil Jadman boards.

I understand there are other options along the same line, these are the only two I have tried.

Cheers

John
 
Eyebroughty said:
Hi

Depending on the pre amp buying plug in replacement boards from Avondale or Neil Jadman is a better option, in my opinion, as they give an upgrade to the pre amp and allow longer travel of the volume pot.

Check the Avondale Audio 821 Standard Audiophile Preamplifier Modules (Pair) and eBay for the Neil Jadman boards.

I understand there are other options along the same line, these are the only two I have tried.

Cheers

John
Click to expand...
Hi John, Thank for the suggestion, I have a NAC42 so that isn't an option for me unfortunately.
 
The 42s internal wiring would easily accommodate a simple L pad attenuator on one of its inputs if you can find someone to do the simple soldering involved.
 
Wright said:
Timely topic.

I've purchased a used pair of Rothwells. Is there a simple way to tell which I have; source or amp?
Click to expand...
I use Rothwell's XLR attenuators, and they can only go one way round. However, I suspect the vast majority of Rothwell's RCA attenuators will have input on the female end and output on the male end (but as you write they do supply "source" versions the other way round - in smaller numbers I suspect).

Insert yours at the input end of a connection and if the volume control needs to be significantly adjusted up for the same audio level, then they are the right way round.

The wrong way round, up to about 20 dB attenuators, should be safe enough (they will probably present a lowish 2k Ohm load on the output but normally that's fine) but will not attenuate much unless the source output impedance is high. If the source is a valve amplifier it might be high enough for the difference to be less clear, so be aware of that possibility.

If you have a multi-meter with a resistance setting the resistance from output end to case will be noticeably lower than from input end to case. The output side will probably be between about 2k Ohm (20 dB) to about 8k Ohm (10 dB) if Rothwell design for 20k Ohm input side impedance.
 
Hottuna said:
Wanted an adaptor like the Russ Andrews one, can use existing interconnects to try and or add attenuators. Might even end up having to make one, but hopefully there is a reasonably priced version available somewhere.
Click to expand...
Get a set of Rothwell source ones then, they plug into the source and you can use your existing interconnects
 
Can you not control cd player output. Some older players have. Mind you it ways always said this reduced sq.
 
I've never thought of trying my -6dB Goldenjacks at the (valve) CD end as it seemed logical to attenuate at the (valve) pre-amp end. As it's simply female in and male out, I s'pose I could easily reverse it; hmmmmm! Works well at the mo', so little incentive to bugger about, which would be reversing the resister or whatever, I guess.

I did find, though, when trying to tame the very high output lever (3.4+V), that -10 and -15 dB really flattened the s,q, -6 dB doesn't.
 
Naim alp volume pots only seemed to have a usable range with vinyl in my set-up…..phono-stages have a lower input voltage than CD.
I actually found with all digital sources that my Naim kit would be really loud at 9 volume position and ear-splitting at 10! Adding some very low sensitivity speakers helped to bring some volume range in, mind. However, it wasn’t until vinyl became my go to source did the Naim attenuation work sublimely for me….i didn’t like the idea of additional attenuators plugged in at the back, perhaps it’s fine?
 
You could buy a simple one in one out passive pre and insert that between cdp and amp and that will give you variable attenuation to set to whatever level you want.
 
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