KEL84 - Slight channel imbalance

[Sid and Coke]

Originally Posted by hooger

Sorry, just trying to help.

And you was mate, Thanks. Don't take any offence, it was a friendly reply from me .

[Sid and Coke]

Originally Posted by andrew ivimey

You gave five conditions you didn't change the interconnects right to left, left to right. That might give you piece of mind ... or drive you nuts.

I repeated the test using both Phono stages with essentially identical interconnects. ( DIY ones from same reel of cable , same plugs, etc ). Rotel was plugged into Phono input, CA640P was plugged into CD input , CD was plugged into, err.. Tuner input .

SPL meter was placed on a Camera tripod about 1.6m equi-distant from each speaker, i was sitting ( very still) about 1.5m behind the meter watching the needle.

I used the 1KHz tone from the Shure Audio Obstacle course LP, The 300Hz tone from HFN&RR Test LP, and the 1KHz tone from the HFN&RR Test Disc III CD. Basically i ensured that everything was equal for each test.

I need to get ready for work right now, so will look forward to investigating further tomorrow. Everything still sounds mighty fine from my favorite armchair .

[Sid and Coke]

Couldn't resist having a fiddle before I go to work:

CD Player set to repeat a 1KHz, tone recorded at 0dB. ( The recording level meters on my CD Player work ! )

Fitted a 10Ω 3watt resistor over each speaker output, (resistors well matched)

Set my DMM to 2 volts reading.

Adjusted volume control until i got a reading of 1.900 Vac on LH channel.

Cross checked RH channel, reading was 1.880 Vac.

Doesn't seem that much difference to me

Expert opinion please...

[Ianm2]

valves going duff?

try some measuring around the input valve/splitter, too, voltages, a.c, too, feedback as well, then I give up

[JerryT]

Originally Posted by Sid and Coke

Set my DMM to 2 volts reading.

Adjusted volume control until i got a reading of 1.900 Vac on LH channel.

Cross checked RH channel, reading was 1.880 Vac.

Doesn't seem that much difference to me

Expert opinion please...

In my view this demonstrates that any difference lies either with the loudspeakers or the room. If you are feeling strong swap the speakers left to right and repeat your measurements - no change means that you are measuring a room effect, lower level following the speaker means that your speakers have slightly different sensitivities.

If it all sounds good from your preferred seat though I do I wonder why you are bothering???

There is a separate thread from Jake and John (well probably just from one of them in reality) that illustrates the effect that rooms can have on measured responses.

All the best.

Jerry

[Sid and Coke]

Is this difference of 0.020 Volts at circa 1.9 volts playing a 1 kHz tone into a resistor load significant ?

I don't know enough about signal level voltages to know, it seems very small to me.

Originally Posted by JerryT

If it all sounds good from your preferred seat though I do I wonder why you are bothering???
Jerry

I wouldn't have noticed if i hadn't taken the time to be a bit more precise with my Phono stage home demo. It isn't spoiling y listening pleasure thats for sure. I'm just testing it because i had some spare time and i can. I didn't know how to check speaker output levels at the binding posts until last night, or what to expect so it all adds to the experience list.

[Sid and Coke]

Just repeated the test using my Mission 782 speakers instead of a resistor. Bi-wiring terminals do have their uses after all .
I got the same response as using the resistor; 1.900 vac at the LH speaker, 1.870vac at the RH speaker playing back a 1KHz tone.

Negligable difference, or not ?

[david counter]

just my opinion,

when you think of the differences in the values of individual components I don't think you stand a chance of both sides being identical, perhaps if you matched components side to side you might stand a chance,

I think any figure within 10% is acceptable

[Sid and Coke]

The Hi-fi actually sounds fine to my ears and i can't detect a channel imbalance at my listening position.

I'm just asking out of interest really.

I no longer bother with Bi-Wiring my speaker terminals, My speaker wires are of differing lengths (within 10%), one of my valves occasionally transmits morse code through the speakers, etc, etc, .
I'm quite easily pleased really