Balancing monitors

Archived from groups: rec.audio.pro (More info?)

In article <faKdndfeDaCNchXfRVn-rg@comcast.com>,
Jonny Durango <jonnydurango1BUSH_FROM_OFFICE@comcast.net> wrote:
>I've just finished building a pair of LS3/5A monitors. I'd like to
>balance their frequency response by changing the capacitor values on the
>HF circuit and utilizing the built-in tapped inductors on the crossover.
>I've got them tuned to my own ears right now but I'd like a more precise
>method.

Ummm... if they are LS 3/5a monitors, you don't NEED to do any voicing.
The drivers meet the spec, the box meets the spec, the crossover meets
the spec, so the final device meets the BBC spec.

Stop fiddling around with crossover values and use the ones in the spec.
If the box and drivers meet the spec, they'll sound like LS 3/5a speakers.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

Listen to Mr. Dorsey, He's probably righter than I am...

Archived from groups: rec.audio.pro (More info?)

Jonny Durango <jonnydurango1BUSH_FROM_OFFICE@comcast.net> wrote:
>Actually he's not...B110's and T27's are more tightly controlled now due
>to computerized matching, but they used to be provided to licensees with
>tolerances centered around the specified level which was appropriately
>called 0dB. Usually both units would between -1dB and +1dB relative to
>"0dB" and therefor the original crossovers had a stepped inductor with 5
>taps that could be used to tune the HF output in .5dB incriments, so
>that you could match for example a -.5dB B110 with a +1dB T27.

This is true. The drivers, though, used to be marked on them what the
error was. If you can get drivers that are more tightly controlled,
it's even easier because you can dispense with the stepped inductor and
just wind a fixed one.

>The crossover I am using (supplied by Falcon Acoustics) is similar to
>this design, but instead uses 3 taps with 1dB incriments and
>interchangeable capacitors with values of .22, 1.5 and 2.2 to achieve
>many different combinations of HF output....3 taps x 3 capacitors = 9
>output levels, not including using two capacitors which falcon
>recommends for some tap values....for example, use a .22 + 1.5 cap to
>get a 1.72uF value, or a 1.5 and a 2.2 for super-high output.

Okay, so how close can you match the values of the original crossover with
these combinations?

>Anyway, I'm perfectly aware of the tight tolerances and exacting specs
>that these speakers were built to, because I built them myself....they
>took me about a year to complete, and most of that time was spent
>researching the design, materials, type of joinery, type of
>glues/sealants, different "models" and brands of LS3/5A (ie. 11ohm, 15
>ohm, Rogers, Chartwell, Goodman...even the JR149 take-off)...I would
>just like to make sure they are properly balanced. Hopefully someone can
>recommend a good method...and a cheap one too, unfortunately I've blown
>all my money on drivers, components, parts, cables, amps, etc. Thanks!

You can ship them off to an acoustics company like Wyle, spend a few
hundred bucks, and have them make a plot for you.

You could get a small chamber at home and a real reference microphone
and a computer system running MLSSA. You could get a cheaper reference
microphone and do swept sine measurements, but then you'd need a better
chamber. All of these options cost a lot more than sending it out.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

Jonny Durango wrote:
> I've just finished building a pair of LS3/5A monitors. I'd
like to
> balance their frequency response by changing the capacitor
values on
> the HF circuit and utilizing the built-in tapped inductors
on the
> crossover. I've got them tuned to my own ears right now
but I'd like
> a more precise method.
>
> Can someone recommend a cheap way to do this? Or maybe a
decent flat
> mic, perhaps one that could be useful in other
applications as well? I
> have a signal gen that will do sweepable sines and
white/pink noise.
> The flattest mics I have are Oktava MK012's, which I'm
afraid will
> over-emphasize HF's. What do you think of this "kit"?
>
>
http://cgi.ebay.com/ws/eBayISAPI.d [...] eName=WDVW

If you are measuring frequency response on the cheap, its
hard to beat a Behringer ECM 8000 measurements mic, and the
acoustics module of this software:

http://audio.rightmark.org/index_new.shtml

I've used an ECM 8000 and a DPA 4007 side-by-side. Above 20
KHz and below 40 Hz the DPA walks away from the ECM 8000
like nobody's business. Of course for balancing LS35a
crossovers, that's pretty meaningless.