Staging question

[bimo]

I have 2 way speaker system which powered by bi-amp. This speaker is cheap but imaging/staging was good, the vocal is forward.
I have 3 way speaker also. It used passive crossover. The staging is flat.
What are influenced the staging? The crossover design, amplifier, or the shape of box?
I'm sorry of my English.

 

[whgeiger]

False Premise

I have 2 way speaker system which powered by bi-amp. This speaker is cheap but imaging/staging was good, the vocal is forward.
I have 3 way speaker also. It used passive crossover. The staging is flat.
What are influenced the staging? The crossover design, amplifier, or the shape of box?
I'm sorry of my English.

Only if we presume that the two sets of loudspeaker units were:
a) connected to the same audio system
b) driven by the same program signal to
c) levels of equal intensity across the frequency spectrum
does the assertion of materially unequal and inferior response of the latter units become meritorious.
It may very well turn out, that if properly driven; the units currently considered inferior may in fact deliver a superior performance.
In any case, what then remains uncertain and undeterminable from the information given, is why.

Regards,

WHG

 

[bimo]

All pass filter

I connected all pass filter with variable time delay before amplifier of my 3 way speaker system. It seem the vocal is more forward and the staging was improved.

 

[cT equals piD]

Other people who have listened to a wide variety of speaker systems, unlike me, could probably answer better than me.. Also the quality of the answer you get depends on the detail that you provide about the speaker systems, amplification, and listening room. But I can think of two possible reasons.

(1) Properly designing a three-way system is more difficult than a two-way. So it could be that the three-way system has problems that weren't addressed, such as poor frequency response. I think that I correctly recall the opinion that imaging is improved by a flat frequency response characteristic.

(2) The width of the speaker system makes a difference. The claim is made that a narrow speaker cabinet produces better imaging than one that is wide. Narrow would be something like 20 cm.

What made you decide to try adding an all pass filter in the amplification chain to improve imaging?

-Pete

 

[bimo]

Other people who have listened to a wide variety of speaker systems, unlike me, could probably answer better than me.. Also the quality of the answer you get depends on the detail that you provide about the speaker systems, amplification, and listening room. But I can think of two possible reasons.

(1) Properly designing a three-way system is more difficult than a two-way. So it could be that the three-way system has problems that weren't addressed, such as poor frequency response. I think that I correctly recall the opinion that imaging is improved by a flat frequency response characteristic.

(2) The width of the speaker system makes a difference. The claim is made that a narrow speaker cabinet produces better imaging than one that is wide. Narrow would be something like 20 cm.

What made you decide to try adding an all pass filter in the amplification chain to improve imaging?

-Pete

Thank you, Pete for your opinion.
I read Douglas Self's book, the title is The Design of Active Crossovers. Then I try to build all pass filter. I think the problem of 3 way speaker is time alignment of the drivers, but I am not sure.

Anistardi

 

[cT equals piD]

Thank you, Pete for your opinion.
I read Douglas Self's book, the title is The Design of Active Crossovers. Then I try to build all pass filter. I think the problem of 3 way speaker is time alignment of the drivers, but I am not sure.

Anistardi

Imaging that you judge to be poor is a difficult problem to solve. Correct imaging can't be measured, the best that you can do is generally identify characteristics that seem to allow the subjective judgement of producing good imaging.

It seems that you are saying that you replaced the passive cross-over network of your 3 way system with an active cross-over, and got some improvement that way. But that could be the result of many different things.

If you were to describe your 3-way system in detail, there are members here who might be able to identify something that is flawed about it. All that you have to do is list the speakers in it, name what the enclosure is and the size, and post the cross-over network design if you can. Not having built a 3 way system myself, I probably wouldn't be much good at helping you with it.

Regards,
Pete

 

[Jay]

I have 2 way speaker system which powered by bi-amp. This speaker is cheap but imaging/staging was good, the vocal is forward.
I have 3 way speaker also. It used passive crossover. The staging is flat.
What are influenced the staging? The crossover design, amplifier, or the shape of box?

Mainly the crossover (including driver characteristics). A little from amplifier, box and recording.

Imaging needs speaker ability to produce low level detail at midrange and higher frequencies. Forward focal is the sign of too much midrange. Tho it may improve staging, it is not always favored.

Low level details can be killed by complex filter, especially notch filter, especially notch filter working at the mid frequency (1kHz-5kHz). Second order (electrical) is usually optimum (depends on driver difficulty).

High frequencies is easily localized by ears, so any breakup (which is common with tweeters) will ruin the image. Tweeter quality and crossover design to handle the issue with tweeter affects imaging. It is better to roll-off the top frequencies than produce them but wrongly. I guess many cheap paper tweeters don't even have the capability to produce 8kHz at sufficient SPL, so it may improve imaging. Tweeters (and associated design) with limited directivity will also improve imaging (such as Vifa XT25). I've seen (not heard) many rising response at top ends. This is not good. Notching is even riskier.

Any crossover is assumed to blend well at crossover frequency. Woofer and tweeter phase response should be overlapped at crossover frequency (and roughly overlapped, probably one or two octave above and below crossover frequency). Achieving this in a 3-way is harder because the midrange should blend with the tweeter and also with the woofer. The woofer roll-off at higher end is usually not steep so the out-of-phase signal from the woofer may still interfere or ruin a little portion of the midrange.

Bigger box (as in a 3-way) cannot disappear as easily as smaller ones because of diffraction, audible box resonance, etc. You don't want to hear any mechanical sound from the box and the driver (and any overlapped mid frequency must be in phase, that's all). Low frequency mechanical sound (such as box and port resonances) has less effect than higher frequency. Piramid shape or any method to absorb tweeter diffraction will help. Tweeter baffle must also free of vibration.

Crossover components waste power, and big woofer (as in 3-way) needs extra power to come alive (big woofers are rarely sensitive). Multi amping, active crossover and high power amplifiers will help here. And high frequency reproduction is also an issue with amplifiers. Many tube amps roll-off the treble early, which may mask the HF issues (with recording or with speaker). Current feedback amplifiers usually have better performance at high frequency.