Peerless 830657 for <$6a piece!

[AlexRivera]

You can definitely just use the sound card in your laptop. That's what I've done for 10+ years.
If you use LIMP for impedance, you don't really need DATS, but that application has some nice "bells and whistles".

Oh well Don this is great then, so basically you have to use RCA to 3.5mm adapters to connect to and from the laptops headphones and microphone jacks respectively?

[donradick]

Oh well Don this is great then, so basically you have to use RCA to 3.5mm adapters to connect to and from the laptops headphones and microphone jacks respectively?

Yep, I've got about 6-8 of those cables. Also seem to need a few more periodically.
Cheap ones are $1.50 - nice gold plated ones are $7.00

https://www.parts-express.com/cat/y-adapter-cables/2149

[AlexRivera]

Yep, I've got about 6-8 of those cables. Also seem to need a few more periodically.
Cheap ones are $1.50 - nice gold plated ones are $7.00

https://www.parts-express.com/cat/y-adapter-cables/2149

Awesome!!!

Ordering now to start playing with that case of woofers that received yesterday, Thanks again Don...

[donradick]

A few more details from my build that may help someone -

I made my window braces with a large "U" cutout next to the woofers so they could breath better.


The Unibox model said "heavy fill", so after I lined the walls with Dow 703, I shoved a bunch of
Ultratouch denim in each cavity, while taking care to leave the front open for the woofers.

Sorry, pictures somehow decided that they needed to be rotated...

[AlexRivera]

Don,

Can you comment on what made you chose the Tymphany BC25SC06-04 and where did you end up crossing it?

Thanks,
Alex

[donradick]

I thought that I needed the 96 dB efficiency of the Vifa BC25, but maybe that was not strictly necessary.
I had a couple of spares on hand, and didn't think this project was going to be in demand.
If I had to do a fresh design, I'd be interested in using a TB or SB tweeter - something mid-priced about $30 max.

Passive Crossover Designer sim shows that the listed crossover has about a 3.3Khz Fc third order.
I wanted to cross the tweeter a bit high for protection if someone wanted to explore high volume reproduction
I'll see if I can find a measurement.

[AlexRivera]

Hi All,

I measrued my lot of drivers today and here are the results, the averages are not too far appart from Don´s lot.

[donradick]

Hi All,

I measrued my lot of drivers today and here are the results, the averages are not too far appart from Don´s lot.

The inconsistencies are a drag, but in practice don't seem to impact performance.
Good work on the spreadsheet!

[AlexRivera]

The inconsistencies are a drag, but in practice don't seem to impact performance.
Good work on the spreadsheet!

My next learning would be how to obtain the FRD files of these, if I get them I'll post them here too.

Any advice is much appreciated.

[donradick]

While re-examining the crossover to support PassingInterest's tilt-back version, I'm taking a close look at my current crossover response, and
have no doubt that I will be able to modify and measure a superior crossover version. Stay tuned.

I never measured each individual frequency response, but I feel that they would be largely identical.
Good exercise though.
I like to "play" with Omnimic - the demanding, precise measurements are done at 1/24 octave resolution,
but I'll also take a look at 1/3 octave and 1/6 octave resolution for overall trends.

[AlexRivera]

Don,

Do you have like a best practices quick list for frequency response measuring with Omnimic that you would recommend me following?, as you may know the product doesn't have the best manual/guide...

Thanks,
Alex

[donradick]

Alex, I don't have a good guide, and I haven't seen one either.
You want to measure well away from walls and pretty much equidistant between floor and ceiling.
So for a smallish 2 way, you will need to lift it up with a chair or table.
Many of us measure at 1 meter, but some measure at 20 inches.
Leave the "button" set to "blended" unless you know what you are doing.
Setup your mike on the tweeter axis.
Typically use "Track 2" "Short sine sweep". Measure at 75-80 dB at minimum, or else ambient noise will affect the results.
If you are going to import the FRD files into PCD or another sim, be sure to turn on "phase"

hope this helps!

[AlexRivera]

Thanks Don, definitely good advice and way better than the instructions they provide. Sent from my iPhone using Tapatalk

[AlexRivera]

Hi All,

Today I measured the woofers again doing some things differen to see what happened, well, the results are definitely different and I think favorable, what I did was:

1. Put the woofer in a rubber pole 30 inches from the floor without anything under it (see picture).



2. Found a proper volume level in my computer where the result was a smooth response line, in this case anything from 20 to 40 percent worked very well (see picture, added mass).



3. Make sure I had the right weight centered and secured in the woofer, used 20 Grams with some blu tack to stick it.



So, do you think this would be more accurate?

Thanks,
Alex

[donradick]

I'd have to find my LIMP user guide, but I think you used too much weight for the T/S params.
I'm pretty sure that it's recommended to use enough weight to shift the Fs about 10-15%.
I used 10G when I measured T/S on my batch.

And I don't recommend that you repeat the tests!
What you might do is to break in 1 or 2 of the drivers, then measure the T/S with 10g weight.
That is textbook, since the params will shift a bit after breakin.