HELP!!! How to drop 2 dB in volume with 8 ohm speaker - amp level or line level?

**Jim Smith** · December 9, 2018, 05:32 PM

Which would offer greatest transparency, assuming highest quality resistors?

Line level or speaker level?

My Tannoys are 8 ohm, and I need to drop their output 2 dB with minimal/no loss.

What value resistor(s) per application?

Thanks!

**jadedavid** · December 9, 2018, 06:37 PM

It is my understanding that it is more difficult to do and has more sonic penalties to do this speaker level than it does line level.
Rothwell makes some nice inline rca attenuators or
A search online for "Homemade RCA attenuator" on the Instructables web page provides all the details necessary to roll your own using your favorite resistors.

**W9TR** · December 9, 2018, 08:59 PM

Jim - low level would be my choice. Why? Constant impedance vs frequency as compared to a speaker load which can have large magnitude variations. I can do the calculations for you if I know the output impedance of your preamp and the input impedance of your power amp.
Tom

**Jim Smith** · December 10, 2018, 10:24 AM

Tom,

Thanks!

I also thought low-level, but since the Tannoys are such a simple load, thought I might be wrong.

It's actually my DAC driving my integrated.

DAC output impedance - 75 ohms

Integrated input impedance - 10k ohms.

Do you have a preferred brand/type of resistor for maximum transparency?

I thought I would insert it into the positive lead on my interconnect from the DAC to the amp.

Or is there a better way without going into the units?

Best,

Jim

**Jim Smith** · December 10, 2018, 10:25 AM

Originally Posted by jadedavid

It is my understanding that it is more difficult to do and has more sonic penalties to do this speaker level than it does line level.
Rothwell makes some nice inline rca attenuators or
A search online for "Homemade RCA attenuator" on the Instructables web page provides all the details necessary to roll your own using your favorite resistors.

Thanks!

I'll check it out.

**AJ Soundfield** · December 10, 2018, 12:55 PM

Line level is the better way to go than a ladder network at the speaker, which is 8ohms nominal, not constant. That said, why do you need to reduce the level by a constant 2db?
Harrison Labs makes in line attenuators (3db), but they may violate audiophile pricing laws at around $30/pr

**Jim Smith** · December 10, 2018, 01:46 PM

Hi AJ,

I had already ordered the -3dB Harrison units from Part Express.

My ASR Emitter 2 has an optimum volume setting where no relays, attenuators, gain circuits, etc. are employed.

Unfortunately that is about 2dB too loud for the majority of my playlists, especially for RoomPlay Reference sessions.

Probably due to my OCD

, I wanted to see which was the least degradation - an inline attenuator, or simply choosing the best volume setting overall.

**Nikhil** · December 10, 2018, 03:26 PM

Jim,

Is there any reason why this can't be done in software?
I'm sure this is going to be a learning moment for me but just had to ask.

Regards.

**Jim Smith** · December 10, 2018, 03:56 PM

Originally Posted by Nikhil

Jim,

Is there any reason why this can't be done in software?
I'm sure this is going to be a learning moment for me but just had to ask.

Regards.

I don't know.

Neither ASR nor Schiit have any thing to offer in the software area.

Not sure if Damien at Audirvana could help. I should probably ask him, but I doubt it will produce any results.

**Jim Smith** · December 10, 2018, 05:42 PM

DUHH!!!

I researched the level adjustment of Audirvana from my computer, and it was stupidly easy to do!

Thanks Nikhil!!!

**W9TR** · December 11, 2018, 10:33 PM

So this is probably late but here are the calculations:

-2dB is a voltage ratio of 0.7943 x=10^(-2/20)

This is a simple resistive series divider. Rx=(1-.7943)*10000/.7943

rx= 2589 ohms. Subract the 75 output impedance of your DAC and you get 2514 ohms.

Closest 1% value is 2.49kOhms
Closest 0.1% value is 2.52kOhms

I like Vishay metal film resistors.

Calculating back, the 1% 2.49k resistor will result in an attenuation of 1.98 dB.

You would put this resistor in series with the center conductor of your single ended interconnect, preferably at the preamp input end so the cable capacitance would not have a deleterious effect on frequency response.

There is a caveat to this method. It assumes that the input impedance of your preamp is constant vs. frequency, and this is not always the case.

Enjoy!

Tom

**Kingrex** · December 12, 2018, 02:51 AM

I asked this exact question of Emmanuel Go with First Sound as my speaker change went from 89dB to 96db. The lowest volume setting is to loud. He wants to put the resistor on one of the input of my preamp.

**Jack** · December 12, 2018, 02:56 AM

Why don't you just lower the level somewhere in the steps of your streaming chain?

**Jim Smith** · December 12, 2018, 07:03 AM

Originally Posted by W9TR

So this is probably late but here are the calculations:

-2dB is a voltage ratio of 0.7943 x=10^(-2/20)

This is a simple resistive series divider. Rx=(1-.7943)*10000/.7943

rx= 2589 ohms. Subract the 75 output impedance of your DAC and you get 2514 ohms.

Closest 1% value is 2.49kOhms
Closest 0.1% value is 2.52kOhms

I like Vishay metal film resistors.

Calculating back, the 1% 2.49k resistor will result in an attenuation of 1.98 dB.

You would put this resistor in series with the center conductor of your single ended interconnect, preferably at the preamp input end so the cable capacitance would not have a deleterious effect on frequency response.

There is a caveat to this method. It assumes that the input impedance of your preamp is constant vs. frequency, and this is not always the case.

Enjoy!

Tom

AWESOME!

Thanks!!!

Thread: HELP!!! How to drop 2 dB in volume with 8 ohm speaker - amp level or line level?

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