To remove or not to remove R141 resistor

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karmakuma

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To remove or not to remove R141 resistor
« on: 5 Jan 2014, 11:50 am »
Hi everyone

maybe some of you folks can help me on deciding wether to remove or not the R141 resistor to lower my NCores gain.

My system consists of a Nad M51 and 4 NCore modules bi-amping my Quadral Aurum Titan VII speakers (ca. 90db).

The NCores have a sensitivity of 2V and - at least on paper - the Nad M51 has an output rating of 4V on XLR if I am not wrong.

Without removing the resistor my lusual istening levels move between -50 and -25 db for low to pretty much appartment shaking output levels.

As I understand it, removing the resistor would lower the NCores gain from 26 to 13 db. What i am unsure of is, if the NCores gain correlates directly to the Nad M51 attenuation. Meaning, if I remove the resistor the Nads attenuation would be lowered by the exact same 13 db the resistor removal would lower the NCores gain. In my situation resulting in a future attenuation on the Nad M51 to approximately -37 to -12 db instead of the current -50 to -25 db (13 db difference equalling the R141 resistors 13 db gain). Which shoud be enough headroom for loud playing levels.

Also comparing the NCores input sensitivity to the Nads output rating (2V vs 4V), removing the resistor should, at least in theory, put the two into a perfect match, halving the NCores input sensitivity from 2V to 4V. Or am I mixing things up in relation to gain and logarithmics also being relevant in this place???

What I am afraid of is, that removing the resistor would not leave me with enough gain to still play my music on pretty loud levels...

Any first hand experience anyone? Or some help otherwise...
Thanks in advance!

Bubbleboy76

  • Jr. Member
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Re: To remove or not to remove R141 resistor
« Reply #1 on: 5 Jan 2014, 07:17 pm »
you can always put the resistor back, if you get too low gain...

I have removed r141, and it is perfect in my setup.

karmakuma

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Re: To remove or not to remove R141 resistor
« Reply #2 on: 5 Jan 2014, 09:46 pm »
May I ask what your setup consists of?

Julf

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  • Grumpy second cousin of Mark V Shaney
Re: To remove or not to remove R141 resistor
« Reply #3 on: 6 Jan 2014, 11:12 am »
you can always put the resistor back, if you get too low gain...

It does require good eyesight/magnification and stable hands. Removal is easier than replacement.

Julf

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  • Grumpy second cousin of Mark V Shaney
Re: To remove or not to remove R141 resistor
« Reply #4 on: 6 Jan 2014, 11:17 am »
Also comparing the NCores input sensitivity to the Nads output rating (2V vs 4V), removing the resistor should, at least in theory, put the two into a perfect match, halving the NCores input sensitivity from 2V to 4V. Or am I mixing things up in relation to gain and logarithmics also being relevant in this place???

Unfortunately yes. 13 dB is a voltage factor of 4.5, so the input sensitivity becomes 9V.

I wouldn't worry about the small mismatch (2V vs 4V), but if you really feel you want to address it, you could replace R141 with a larger value.

Bubbleboy76

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Re: To remove or not to remove R141 resistor
« Reply #5 on: 6 Jan 2014, 10:46 pm »
May I ask what your setup consists of?

Oppo BDP-105 - bridged nCore monoblocks - JBL 4365 studio monitors.

hopkins

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Re: To remove or not to remove R141 resistor
« Reply #6 on: 7 Jan 2014, 09:59 am »
I added 20db in-line attenuators to the XLR outputs. Work fine, and I did not notice any degradation in the sound quality, but I assume it is probably best to remove the resistor.

http://www.canford.co.uk/Products/20-923_CANFORD-IN-LINE-ATTENUATOR-With-phantom-pass-through-20dB-600-ohms

karmakuma

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  • Posts: 3
Re: To remove or not to remove R141 resistor
« Reply #7 on: 7 Jan 2014, 11:22 am »
Well, many thanks for all the information! It does not seem to make a lot of sense removing the risistor with an audio source / preamp being this close to the original input snsitivity....

BR
KarmaKuma