8 ohm/4 ohm = rarely use amp's full potential

[agedhorse]

Do not use the serial loudspeakers connection for bass (only parallel), it is killing the loudspeaker LF damping factor. However - it sounds very good for lead guitar. Not so good for rhythm guitar, ac. guitar, keyboards, Hi-Fi, etc. "clean" sounding sources.

For identical speakers, this is not true.

 

[Snert]

You really have got those sufficiant equipment available to measure 10m ground plane?

Yes.

If I understand correctly you do measurements for different distances:
nearfield
1 Meter
2 Meter
10 Meter

For large LF capable enclosures, yes. For full range speakers, especially those with less LF capability, I use a combination of techniques depending upon what I'm measuring. For instance I don't really care about the polar response at LF, but I do above the frequency range where the speaker stops radiating omnidirectionally.

 

[ThisBass]

Yes.

For large LF capable enclosures, yes.

So the question is, what kind of difference do you measure for the LF roll off shape respectively for LF response when you measure:
nearfield
1 Meter
2 Meter
10 Meter

 

[seamonkey]

Subwoofers are often measure at 10M @ 28.3V
And there's plenty of venue simulation software for setting up bass arrays
Even for cardioid when you need it.

 

[ThisBass]

Subwoofers are often measure at 10M @ 28.3V
And there's plenty of venue simulation software for setting up bass arrays
Even for cardioid when you need it.

The question is:
does @Snert measure a difference for the roll off shape for his LF gear when he does measurements for:

nearfield
1 Meter
2 Meter
10 Meter

The measurement at 10 Meter could even be done with 1/2 the voltage to get just the same outcome for the roll off shape (normalized low response).
f3 points shoudn't be effected (too much) by the number of the input voltage.

 

[Snert]

The question is:
does @Snert measure a difference for the roll off shape for his LF gear when he does measurements for:

nearfield
1 Meter
2 Meter
10 Meter

Nearfield depends upon port location, and sometimes if it is at the rear like on some monitors or hifi speakers, 1m will not give the same result as it will at 2 or 10m. Then I'll measure the nearfield at the driver as well as the port and summate the responses. This depends though on the size of the enclosure. 10m as seamonkey stated is for higher SPL , which I have already said.

 

[ThisBass]

Nearfield depends upon port location, and sometimes if it is at the rear like on some monitors or hifi speakers, 1m will not give the same result as it will at 2 or 10m. Then I'll measure the nearfield at the driver as well as the port and summate the responses. This depends though on the size of the enclosure. 10m as seamonkey stated is for higher SPL , which I have already said.

It doesn't answer the question:
whats's the difference you do measure for the normalized response at:
nearfield
1 Meter
2 Meter
10 Meter

I agree that nearfield is problematic to be measured with LF gear.
If you wouldn't have mentioned that you are doing it even for LF gear, I wouldn't have asked for it.

Anothether question that I want to ask is:
you have mentioned that stacking of multiple cabs does not lower f3.
At which distance to the cabs was this measurement done?

 

[G-Point]

For identical speakers, this is not true.

What is so special with identical speakers ? Please let me know. There are several theories about serial speakers, but I can hear the difference in sound/tone in comparison with parallel connection. Try 2x 8ohm speakers in series connected to 16ohm output, and then parallel connected to 4ohm output. Checked many times using different speaker pairs and different amps. There is a little paradox because serial connection reduces the damping factor, but from another side - a higher load's impedance increases it. Itis even more complex in the case of tube amp's output transformer.

 

[agedhorse]

We have been discussing solid state amps in this regard. With dissimilar speakers/cabinets, the virtual ground point between the two speakers in a series connection moves around and each speakers reactance is in series with the other.

In a tube amp, different (additional) mechanisms come into play, specifically the lower damping factor of the amp and non-ideal parameters of the transformer from tap to tap (and sometimes where the feedback is taken from)