tri-amp/crossover?
Karen Olson
Is using 1st order passive crossovers (with only Solen air core
inductors from Madisound in the signal path), with tri-amped,
individual power amps driving mid and woofer (Dynaudio 17M75 and
30W100), a recommended setup?
If so, with all audio frequencies passing from pre amp to power amp,
then restricted by the inductor only crossover, does this "back
up/restriction" of unused/high frequencies degrade overall
loudspeaker performance?
With regard to the Dynaudio mid, 17M75, does this driver's "natural"
roll-off allow using a LOW PASS crossover when playing with the
Dynaudio 30W100... OR, should I use a BAND PASS crossover to filter
out the lowest frequencies?
Is there a best way to split the output from the preamp 3 ways to
drive 3 power amps? Is using RCA "Y" adapter cables OK to split the
signal 3 ways? Would you recommend a better method?
I originally tried a solid state active crossover (home made Walter
Jung design) with a band pass filter to the 17M75, and a low pass
filter to the 30W100, but believe I can do better.
Thanks!
Scott Maurer
John Michaelsen
The Passive units you are using are (all be they high quality)
degrading the sound quality of the system. ANYTHING between the amp
output section and the voice coil of the driver IS a bad thing. I use
and recomend a DB Systems crossovers. They can be built pretty much
any freq. and slope you desire.
Mail
any questions
John Michaelsen
uh OH!
On 25 Feb 1998 09:23:10 GMT, "John Michaelsen" <john...@erols.com>
wrote:
> The Passive units you are using are (all be they high quality)
>degrading the sound quality of the system. ANYTHING between the amp
>output section and the voice coil of the driver IS a bad thing.
Oh god. This sounds like a sales literature for an electronic
crossover. If the passive crossover is intelligently and
deliberately optimized to take into account the response of the
drivers used on a given baffle, chances are that the overall response
will be far flatter than using a generic active design.
And why is putting capacitors, inductors, and resistors between an
amp and a speaker worse than putting capacitors and buffer amps
between a preamp and an amplifier? Depending on the devices used, a
passive design might prove far superior.
There are benefits to active crossovers. It places less demands on
the quality of the amplifiers, although it requires more amplifiers.
If you don't know what you're doing, you can go in blind and get
higher order slopes to work moderately well, which is probably why
electronic x-overs are so popular in sound reinforcement where they
often get a bunch of drivers and have to hook them up with steeper
slopes to protect the drivers. And, if they set their limiters
improperly, the bass amplifier can distort without sending harmonic
content to the HF drivers, but if the amplifiers aren't distorting,
what's the gain? Unless you're using a digital crossover, which
would require as many D/A converters as you had dedicated driver
ranges, you've still got phase shift.
Much of the hubbub about active designs is the ability to get deeper
bass with the amplifier "optimized" to the bass driver, although it's
often just a case of equalization. That might make a good case for
using a seperate amplifier for subwoofers using an EQ circuit.
colin
Greg Graff
Depending on how sophisticated you wish to make your crossover, you
should look at other crossover parts. First, you should look at air
core inductors using either insulated foil copper or litz
configurations to reduce overall crossover resistance and phase
shifts. Second, since you are designing the crossover for line
levels, you will not need at large of value parts. Therefore, you
could use a cap and inductor combination using MultiCaps. This will
give you a much better sound than just using an inductor. I disagree
with the people who say active crossovers are preferable.
Theoretically, they are correct, but unless you use the highest
quality parts, active crossovers introduce significant noise,
especially microphonics and RF which can be designed around in a
passive curcuit. Also, an active curcuit substantailly reduces the
damping factor of an amp.
Whatever you do, do not use a Y connector for the preamp out, You will
just defeat the whole reason to bi or triamp. The signal degredation
will be horrendous. Hope this helps.
gjg :)
John Michaelsen
uh OH! wrote in message <6d2g1t$q...@news01.aud.alcatel.com>...
>> The Passive units you are using are (all be they high quality)
>>degrading the sound quality of the system. ANYTHING between the amp
>>output section and the voice coil of the driver IS a bad thing.
>Oh god. This sounds like a sales literature for an electronic
>crossover. If the passive crossover is intelligently and
>deliberately optimized to take into account the response of the
>drivers used on a given baffle, chances are that the overall response
>will be far flatter than using a generic active design.
Yes, I do sell electronic crossovers. And yes a "CAREFULY"
designed passive crossovers can be used to manipulate the response of
specific drivers. And "MAYBE" it could be flatter than with a
"GENERIC" active unit. And a "PROPERLY" trained race horse "MIGHT" be
able to beat a "GENERIC" internal combustion vehicle. SO? I don't see
any horses in the Indy 500? The reason I brought up the DB Systems by
name is because the are avalible at any frequency an almost any slope
and or alignment you desire. Besides, if you have a problem with the
response charcteristics of a specific driver "GET RID OF THE DRIVER
AND GET A REAL ONE", don't try to patch an open wound with a
band-aid?
>And why is putting capacitors, inductors, and resistors between an
>amp and a speaker worse than putting capacitors and buffer amps
>between a preamp and an amplifier? Depending on the devices used, a
>passive design might prove far superior.
Because the impedance between the amp and the drivers is a
function of frequency and gain. Where the impedance between the pre
amp and power amp is a constant. We "the collective audio consumer
market" spend outragous amounts of money on speaker cables to try and
reduce inductance, capacitance, and most of all resistance.
Then you want to hook good heavy gauge speaker wire to a coil that is
at MOST 1/4 the size of the wire and probably longer.
[quoted text deleted -- deb]
Leslie Williams
I would love to debate active vs passive, but instead one strange
statement mentioned in another response MUST be addressed: Putting an
active filter before the amplifier CANNOT deteriorate the damping
factor of the amplifiers output. Only a passive filter after the amp
can do this - and does so dramatically (one of the chief arguments FOR
an active crossover).