Curved SLA build with added jig

[LelandCrooks]

.. make a brace nub ...

WTF is a "brace nub"

There's got to be a good joke in here somewhere.

Just a nubbin of ply extending the length of the baffle to reinforce the break. Minimal in size so as to affect volume in the cab as little as possible. I do it all the time on other speakers.

[modernprimitive]

i'm assuming the answer will be "no", but i meant to ask if you have any issues the 818 running out of power with the sla??

Hell no! Never maxed it out. Maybe I should try but would need to wear ear plugs! I suppose it depends on your room.

good to know.

in 2.1 stereo, the most i've taken mine has been 75, and it's definitely quite loud. one of these days i'll aquire an spl meter, just to curb my curiosity. i should probably also get a mic that i can use with my computer to run rew. be nice if it could also be used with the 818 to run audyssey. any suggestions on a decent mic as well as a decent spl meter??

[Ian Westwood]

any suggestions on a decent mic as well as a decent spl meter??

I use the checkmate CM-140 SPL meter that also has audio out. I chose it because REW has the calibration files for download.

It seems to work well enough for me to get the results I want.

I use the mic that came with the 818 for calibrating the receiver.

[modernprimitive]

any suggestions on a decent mic as well as a decent spl meter??

I use the checkmate CM-140 SPL meter that also has audio out. I chose it because REW has the calibration files for download.

It seems to work well enough for me to get the results I want.

I use the mic that came with the 818 for calibrating the receiver.

ok. i'll check that out. thanks.

unfortunately i don't have the mic for the 818. it wasn't in the box. i just assumed it was an optional item, till i contacted onkyo about how to order one, and they told me it should have come with the 818. so i contacted the company i bought it from, but since enough time had passed, they said that they would not return mine for another unit, and nolonger carried the 818. so i need to find a mic that can do double duty, if possible. i've read somewhere that some people use a model from dayton. but i'd kinda like to purchase a model that someone on the forum has used, so i don't get something that's of poor quality, or won't work for what i need.

[Ian Westwood]

it wasn't in the box. i just assumed it was an optional item, till i contacted onkyo about how to order one, and they told me it should have come with the 818. so i contacted the company i bought it from, but since enough time had passed, they said that they would not return mine for another unit, and nolonger carried the 818. so i need to find a mic that can do double duty, if possible. i've read somewhere that some people use a model from dayton. but i'd kinda like to purchase a model that someone on the forum has used, so i don't get something that's of poor quality, or won't work for what i need.

That sucks. I think Onkyo uses the same mic for several other products including their car audio stuff. I'm on the road this week but if I remember I'll post a pic of it and any identification marks over the weekend.

Hopefully you'll track one down on ebay or something.

I presume Onkyo have their own calibration for their mic... so others might not give as good results.

[modernprimitive]

That sucks. I think Onkyo uses the same mic for several other products including their car audio stuff. I'm on the road this week but if I remember I'll post a pic of it and any identification marks over the weekend.

Hopefully you'll track one down on ebay or something.

I presume Onkyo have their own calibration for their mic... so others might not give as good results.

ok. thanks.

[Bill Fitzmaurice]

I had a Sherwood AVR, it died and I just got a Pioneer. Identical mic. There are far more identical parts in AVRs than different parts across brands.

[ecut1]

Has anyone ever used their receiver mic plugged into a laptop with the software to measure sound in the room? I didn't think about it until reading this thread. Would it work?

[miked]

As long as you can calibrate/set the software to the mic's characteristics (freq response, impedance, etc) I don't see why it wouldn't work.

BTW, go here and put in your receiver's model number. The "7000 mic" is $22. https://www.shoponkyo.com/products.cfm?group_id=11

A quick search on EBay turned up some 5000-series Onkyo mics, but no 7000. I'd just buy it from Onkyo and be done with it.

[Tom Smit]

http://www.parts-express.com/dayton-aud ... e--390-801

https://www.google.ca/search?q=ecm+8000 ... 2AXYjICIAQ

[modernprimitive]

i'll probably just get the onkyo mic and be done with it. if i plug it in to audyssey and then set it up so i get the same readings in rew, then i should be good to go.

thanks for all the help.

oh, by the way. a disk full of build plans showed up in the mail today.

[modernprimitive]

so if i'm looking at this correctly, the nominal impedance for the curved sla with 6 drivers and 6 tweeters should be 10.6 ohm??

three 8ohm drivers in parallel = 1/[(1/8) + (1/8) + (1/8)] = 2.666

then 2 banks of 3 parallel drivers run in series = 2.666 + 2.666 = 5.3ohm

then wiring the tweeters up the same way resulting in 5.3ohm

so taking the 5.3ohm nominal for the tweeters and combining that with the 5.3ohm nominal for the drivers wired in series, should net a nominal impedance of 10.6ohm.

or did i miss something??

[Bill Fitzmaurice]

so taking the 5.3ohm nominal for the tweeters and combining that with the 5.3ohm nominal for the drivers wired in series, should net a nominal impedance of 10.6ohm.
or did i miss something??

You don't add the impedance of the two lines, the crossover separates their loads.

[MissileCrisis]

+1 to what Bill said. Basically because we are dealing with an AC signal rather than a straight DC voltage and the impedance depends on frequency what he said follows.

[Ian Westwood]

or did i miss something??

We all struggle with this at the beginning so I made a page on my site that fleshes this topic out a bit.

Hope it helps.