Line Attenuators

[eldarvanyar]

Hi,
I have a Rotel RC 1080 preamp going into a Quad 606 preamp

Here is the Rotel RC-1090









Quad 606 power amp



Quad 606 Power Amplifier Specification
Power Output: 140 watts per channel (8 ohms)
Distortion: < 0.01%
Input Sensitivity: 500mV
Input Impedence: 20Kohm
Crosstalk: -100db (100hz), -85db (1 khz) and -65db (10khz)
Hum and Noise: 105db
Voltage Rating : 220-200V AC (110-120V via simple power board modification)
Dimensions (WxHxD): 321 x 140 x238 (mm)
Weight: 12kg

The preamp out is 1v and the power amp input is 500mv

What level attenuator would I need to buy to match the preamp to the power amp
-10db or -20db or some other figure?

Thanks

Lee

[walpurgis]

Why, is it causing you problems? It's only a 3db difference, I'd have thought that would be OK.

I don't like line attenuators. They've compromised the sound every time I've tried them.

[eldarvanyar]

I thought that because the output voltage from the preamp being 1v is twice that of the input voltage 500v of the power amp, that it would distort or clip.

I also thought a better matched level would enable greater use of the volume control.

I don’t know too much about pre and power amp matching.

I have a Quad 44 preamp which has a 500mv output and am hoping that the Rotel RC -1090 would be an upgrade.

Thanks for all or any advice

[walpurgis]

I have a Quad 44 preamp which has a 500mv output and am hoping that the Rotel RC -1090 would be an upgrade.

It may well be. The 44 is not one of my favourite pre-amps.

If you're using the Rotel into the 606 and there are no audible issues, I'd not worry.

[Pharos]

Why, is it causing you problems? It's only a 3db difference, I'd have thought that would be OK.

I don't like line attenuators. They've compromised the sound every time I've tried them.

Times 2 is 6dB.

6dB is not that greater difference to the volume pot which probably has a range of 50dB+.

[Barry]

Agreed. For normal listening levels, ideally the volume control should be about half way round its range (say at 12 o' clock, if the range is 7 o' clock to 5 o' clock). With a doubling of input voltage this will move the position of the volume control back to, say, 10 - 11 o' clock)

[eldarvanyar]

I am finding I can only listen up to 11 o’clock maximum otherwise it is too loud. The 606 has a lot of power.

[walpurgis]

I am finding I can only listen up to 11 o’clock maximum otherwise it is too loud.

Probably about right then.

(3db increase is what you get with a doubling of power by the way, 6db increase is a doubling of loudness, not the same thing)

[Pharos]

I am finding I can only listen up to 11 o’clock maximum otherwise it is too loud. The 606 has a lot of power.

My normal listening level is about 60 dB - as a background, and the vol pot is at 9 O'clock for that.

When listening seriously I only raise the levels to 70 to 75, which is a rotation to about 11 O' clock.

The position of the vol pot has nothing to do with the capabilities of the 606, it is an indication of how much voltage is being delivered by your pre to the 606.

It is generally thought that 10dB represents a doubling of loudness.

[Barry]

It is generally thought that 10dB represents a doubling of loudness.

Correct.

Using a sound level meter, I found for normal listening the level was 55dBA. For serious listening the level would be increased to 60dBA. And at 75dBA, I was shaking the floorboards.