"Sonnova" <sonnova@[EMAIL PROTECTED]
> wrote in message
news:fqkrvc0v05@[EMAIL PROTECTED]
> On Mon, 3 Mar 2008 15:21:55 -0800, jamesgangnc wrote
> (in article <fqi16j0aie@[EMAIL PROTECTED]
>):
>
>> "Sonnova" <sonnova@[EMAIL PROTECTED]
> wrote in message
>> news:fqegm601de9@[EMAIL PROTECTED]
>>> On Sat, 1 Mar 2008 13:56:58 -0800, jamesgangnc wrote
>>> (in article <fqcjfa02enj@[EMAIL PROTECTED]
>):
>>>
>>>> "bear" <bearlabs@[EMAIL PROTECTED]
> wrote in message
>>>> news:fqc0ig01jv6@[EMAIL PROTECTED]
>>>>> jamesgangnc wrote:
>>>>>> I updated my setup to bi-amp last year. I was wondering if any
>>>>>> others
>>>>>> in the group is doing this now and what your set up and experiences
>>>>>> were?
>>>>>>
>>>>>> I'm using a dbx 223 crossover usually at 700hz. I play around with
>>>>>> it
>>>>>> a bit but keep it between 500 and 1k. The lower end I'm running to
>>>>>> an
>>>>>> adcom 555 connected to 4 ten inch moderately priced woofers in
closed
>>>>>> cabinets, two woofers to a side wired in parallel. The high side I
>>>>>> have going to an adcom 535 with a pair of 5 1/4 midwoofers and one
>>>>>> ribbon tweeter on each side also in closed cabinets. The passive
>>>>>> crossover on the high side is just a simple 6db centered at 5k. Of
>>>>>> course it is subjective, but I feel like moving the bass out of the
>>>>>> rest of the signal improved overall clarity. The two adcoms, when
I
>>>>>> experimented with them independently also seemed better suited to
the
>>>>>> separate tasks. Besides the obvious power difference the 535
seemed
>>>>>> to have a better sound at mid and highs than the 555 when listening
>>>>>> to
>>>>>> them with a full signal range at about the same sound levels. Of
>>>>>> course the 555 is obviously the choice for the low end anyway due
to
>>>>>> the power difference.
>>>>>>
>>>>>> For a signal source I'm using a technics sh-ac500d as a preamp and
>>>>>> either xm radio or itunes acc ripped at 256k via a squeezebox. The
>>>>>> setup doubles as part of my surround sound as well hence the
ac500d.
>>>>>> I mostly listen to old and new rock but occasionally anything else
as
>>>>>> well, except country. I'd like to take some measurements as well.
>>>>>> I've got a signal generator and a scope but don't have a good high
>>>>>> quality mic.
>>>>>>
>>>>>> As I suspect most of us are, I'm trying to decide what to change
next
>>>>>> as well :-)
>>>>>
>>>>> I'd get a higher order filter on your ribbons first.
>>>>>
>>>>> The distortion increases in typical ribbons when the excursion below
>>>>> the
>>>>> useful rolloff does not decrease substantially. A first order filter
>>>>> in
>>>>> practical terms tends to make the excursion *remain the same* below
>>>>> the
>>>>> inflection point of the "rolloff". That means that you've got excess
>>>>> deflection/excursion. I'd consider a 24db/oct filter there... most
>>>>> ribbons
>>>>> can not handle a first order filter.
>>>>>
>>>>> Then use one of the various freeware FFT programs and a halfway
decent
>>>>> mic to measure the freq response of the mid/HF combo. Take note of
the
>>>>> off axis response and the waterfall as well. Look at the impulse
>>>>> response of the two drivers together.
>>>>>
>>>>> You may need to adjust the xovers and do other things to arrive at a
>>>>> best compromise response for the mid/tweeter combo.
>>>>>
>>>>> Then you can look at the relation****p between the woofs and the
upper
>>>>> range.
>>>>>
>>>>> After that I'd say that with the "average" sort of ripped music, it
>>>>> probably won't make much difference what else you do. BUT, once you
>>>>> get
>>>>> the speakers optimized you may start to hear larger differences in
>>>>> terms
>>>>> of source material - then it may make sense to think about upgrading
>>>>> other
>>>>> parts of your system.
>>>>>
>>>>> Btw, the difference you are now hearing is likely due to two things:
>>>>> - different amplifier & load to the amp
>>>>> - different crossover slope & Q
>>>>>
>>>>> Until then, enjoy the experimenting! :_)
>>>>>
>>>>> _-_-bear
>>>>
>>>> Thanks. Interesting. The low end on the ribbons is around 2k so I
was
>>>> thinking that I would get way with the 6db crossover because I was so
>>>> far
>>>> above it. Given that would you still recomend the 24db crossover or
>>>> maybe a
>>>> 12? Some of what I have read on the topic suggested keeping the
>>>> mid/high
>>>> crossover simpler. In all honesty I'd probably think a little bit
>>>> about
>>>> switching to a three way active to get a 24db crossover rather than
>>>> using
>>>> passive.
>>>>
>>>> I'm clueless in the mic world. But I would like to be able to really
>>>> test
>>>> rather than rely on subjective listening. Can I hook the mic directly
>>>> to
>>>> my
>>>> scope or should I have a preamp on it? I realize I will have to
power
>>>> the
>>>> mic if I do not have a pre-amp involved. What mic brands tend to be
>>>> decent
>>>> and what kind of dollar level should I be shopping at? tia
>>>
>>> You can get a very nice condenser mike with a big 1-inch capsule and
>>> very
>>> flat frequency response that outputs directly to USB for less than
$100.
>>> The
>>> Samson C01U, for instance, is $89 from Zsounds and has 20-18KHz +/-
3db
>>> frequency response. All you need with it is a USB cable, your computer
>>> and
>>> the freeware sound capture and editing program "Audacity" (available
for
>>> Windows, MacOSX, Linux). Connect the Microphone to your computer via
>>> USB,
>>> start Audacity, set the preferences to the USB input, and start
>>> capturing
>>> audio, select a section and then then go into the "Analyze" menu and
>>> select
>>> "Plot Spectrum" It will even give you a cursor to look at any point on
>>> the
>>> plot.
>>
>> Does have a lot of sound editing capability. But what about measuring
>> level
>> and frequency? How sensitive can it measure level? I see it does have
>> multiple channels.
>>
>> It is different from what I was thinking, which was to hook one scope
>> channel and the function generator to an rca input and the other scope
>> channel plus an rms meter to the mic on a stand in front of one of the
>> speakers and take readings voltage at points between 20 and 20k while
>> observing the signals for distortion or phase ****ft on the scope. Not
>> that
>> I'm against your suggestion, just didn't consider this path.
>>
>
> There are also real-time spectrum analysis tools available for most
> computer
> platforms, I merely used Audacity as an example of a free program. One
can
> also get oscilloscope programs and fast -fourier analysis programs. They
> all
> should work with a USB microphone, thank you.
Yes I know about the use of pcs as scopes. All the more serious stuff
also
has a hardware component as well. But I already own a dual trace
tektronix
scope with a built in rms meter. Admittedly older but it suits my other
purposes fine. I don't do this for a living. So I'm looking for the
route
that requires me to get the least amount of new things. Particularly new
things that cost money. They used to do this with scopes and rms meters.
Is doing it with a pc really going to give me appreciably better results?
I
don't care about faster because my time is not a factor in my hobbies.
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