Single sheet TH challenge

[Brian Steele]

Originally Posted by tb46

Hi 4pyros,

I'm with djk, but a 1000 Ohm resistor is large enough. Then you can use the precision 10 Ohm resistor in place of the speaker for an initial calibration. If any of this is unclear, get a WT3 :-).

Regards,

I actually prefer using a much smaller high-power resistor (e.g. 4 ohms) and using the method I suggested. It's a longer approach, but it also allows me to generate much higher voltages across the speaker and therefore track how t/s params might shift under higher drive levels.

[Djim]

Djk and Oliver, the first method I presented was based on

[Djim]

Yes you are right Brian, for accurate measurements your should change the 10 Ohm resistor in at least half the Re of the loudspeaker. You also need to measure the resistance of the cables.

[djk]

"I'm with djk, but a 1000 Ohm resistor is large enough."

No, it's not.

Some low Qes drivers can have impedance peaks in excess of 200Ω. A 1000Ω resistor in series with that kind of driver is hardly constant current, and will result in inaccurate parameters.

I generally use a Crest amplifier that will drive 92V RMS.

[tb46]

Post #864

Hi djk,

It's probably mostly irrelevant to the discussion of the SS15, but 1000 Ohm is quite a normal value for this measurement. I have never heared of anybody that applies 92Vac to the constant current circuit for measuring loudspeaker impedance, but that just proves, that I have to get out more. :-)

Regards.

[djk]

I realize that that is the value that most people use, and I explained why it is an incorrect choice.

BTW, my HP 200 generator (tubes) can put out 40V into 600Ω.

[m R g S r]

back to ss15 projects

here i just started today, didn't order the 3015 yet, will do that this week. going to dinner now will continue construction later on tonight!

good ol made in USA ply

got everything cut, started tracing out on the side piece. i also added some angled cuts to the pieces that don't meet at 90 deg to make it go together a little better.


should i add corner reflectors in every corner? i don't mind the small amount of extra added weight if they'll help and i have the wood sitting here....

[MRalx]

Originally Posted by m R g S r

I have a Mac so I can't as far as I know unless hornsresp works on a Mac now ? (not running windows on a Mac)

And woopss I meant 4pi Aka Into free space (that's how I'll be using my ss15)

Hi, FYI hornresp works fine on Intel Macs under "WineBottler" (windows emulator)
Give it a search, just my 2 pence.

Al

[4pyros]

should i add corner reflectors in every corner? i don't mind the small amount of extra added weight if they'll help and i have the wood sitting here....

I only used corner reflectors to rid the box of parallel sides in the wave path. Look at pic in post #827. I only needed 3 at 15 degrees each. Andy

[4pyros]

Here are the unofficial results. I wish it was better down lower but I got a good peak at 180Hz. I am calling it good to make more. Any other thoughts? Andy