Hello All,
I am currently in the process of building my own speakers. I am using parts from an existing set of speakers:
5" driver - 4 ohms
Dome tweeter - 6 ohms
Passive crossover
In my new speakers I would like to introduce an 8" woofer (which is 4 ohms). If I keep the wiring of the existing speakers/crossover as it is and wire the 8" woofer in series with the 5" driver, would this work??
Thanks in advance,
Dave
I am currently in the process of building my own speakers. I am using parts from an existing set of speakers:
5" driver - 4 ohms
Dome tweeter - 6 ohms
Passive crossover
In my new speakers I would like to introduce an 8" woofer (which is 4 ohms). If I keep the wiring of the existing speakers/crossover as it is and wire the 8" woofer in series with the 5" driver, would this work??
Thanks in advance,
Dave
Nope!
Every speaker deserves its filter ( even if it's a first order one or a mechanical one )
So: lowpass for the woofer and highpass for the midrange - in the case of the midrange you can raise the frequency of crossover to the tweeter.
Or: you can rely on mechanical highpass of the midrange but it will be severely limited in maximum output level ( MOL ) and also MIL ( input )...well, reversed! first MIL, then MOL.
Crossover takes into account the impedance Z of the speaker so what you proposed is also worthless in a theoretical way, as 2 speaker in series ( wait ! a speaker is a complex load, and two different speakers in series is a more complex load ! ) being each 4 Ω would represent a 8 Ω load to the crossover, which was intended to work with 4 Ω speakers.
Every speaker deserves its filter ( even if it's a first order one or a mechanical one )
So: lowpass for the woofer and highpass for the midrange - in the case of the midrange you can raise the frequency of crossover to the tweeter.
Or: you can rely on mechanical highpass of the midrange but it will be severely limited in maximum output level ( MOL ) and also MIL ( input )...well, reversed! first MIL, then MOL.
Crossover takes into account the impedance Z of the speaker so what you proposed is also worthless in a theoretical way, as 2 speaker in series ( wait ! a speaker is a complex load, and two different speakers in series is a more complex load ! ) being each 4 Ω would represent a 8 Ω load to the crossover, which was intended to work with 4 Ω speakers.
Sorry. This is correct. You would need a new crossover for a three-way speaker.
You could go semi active, by using a pair of subwoofer plate amps to power the 8" drivers. Choose a subwoofer amp that has high level inputs, and high level outputs, so that you can use your existing amplifier. Amp > High level input. High level output > your existing crossover > 5" driver and tweeter.
Your subwoofer plate amp should have a variable crossover (high pass/low pass) some go up to 250hz. This will cut the low frequencies going to your existing crossover, thus allowing them to do midrange duties better.
An expensive, but useful solution.
You could go semi active, by using a pair of subwoofer plate amps to power the 8" drivers. Choose a subwoofer amp that has high level inputs, and high level outputs, so that you can use your existing amplifier. Amp > High level input. High level output > your existing crossover > 5" driver and tweeter.
Your subwoofer plate amp should have a variable crossover (high pass/low pass) some go up to 250hz. This will cut the low frequencies going to your existing crossover, thus allowing them to do midrange duties better.
An expensive, but useful solution.
Without knowing all of the specifics regarding your individual drivers, box size etc I cannot say with certainty the best way for you to proceed as for end results sonically speaking
What I can say however, is that it is PERFECTLY FINE to run the LF driver (i.e. the "woofer) full range with no harm done, physically, to the driver itself (assuming it is indeed a true "woofer")
There have been dozens of EXTREMELY successful speaker systems/designs employing this technique for years, notably the late generation JBL L100 as well as more than a few others
One driver that comes to mind employed in such a fashion, quite frequently and to an astonishing degree of realism and high performance (ALMOST good enough to be a single point full range) is the JBL LE14A as well as (but to a lesser degree due to it's natural roll off) the JBL 123A-3 - but the 123 does have significant roll off and is better suited as just a driver to use to keep the quality high and the parts count low (the keep it simple principle) in a multi driver array - but is still quite capable on it's own
Both of these drivers actually shine their best when run wide open - in almost ANY circuit
The sonic results will of course be determined by the natural roll off of your woofer(s)
But in brief, there is NOTHING "wrong" or negative about running a LF "branded" driver full signal
And not to be redundant, the only "negative" could conceivably be the system as a whole's frequency reponse (again, requiring more data on what you have in mind)
Just make sure the mids and HF drivers are appropriately protected with adequate capacitance
There are plenty of other excellent drivers that could be employed in this minimalist fashion - I only reference the two JBL models as I happen to be intimately familiar with the both of them (and have owned and loved them both for years)
Keep in mind too, there is NOTHING wrong with experimentation (within the confines of common sense and good practice to protect your mids and tweets AND your amp(s)) despite what the "tech" sheets and the "experts" may have to say about it
Speaker design (getting good Musical, pleasing and euphoric results) is a much an art as it is a "science"
Marshall
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