Newbie Q' - is this cheap speaker going to sound similar to the expensive one?

[Gary Lightfoot]

Hi,

I'm attempting to build my first speakers for surround duties in my home theater room, so before I knew anything about the subject, I built a box to mimic the style of some speakers I liked (but couldn't afford).

The internal volume is 11.9litres not including drivers or crossover (I've no idea what the speakers I'm copying are though volume wise, only the external dimensions. No internal info is known).

The originals use what looks like a can Speak 15W-8530K00, and plotting it in WinISD gives what looks like a reasonable result when tuned for 45hz.

I then stumbled across a cheapo car speaker that when put into the same box, plots a very similar curve when tuned to 49hz.

I was going to use some existing AE Aegis One drivers, but can't find any T&S data for them anywhere, hence the search for other alternatives that won't break the bank and can help with the learning curve.

Here's the WinISD plot - Any comments etc appreciated.

[5th element]

Just because the cheapo car speaker gives you a similar bass response it doesnt tell you anything about the sound quality.

The Scan driver is excellent the car driver is probably not.

[Gary Lightfoot]

Thanks for the reply 5th,

Is there any way of telling how good a speaker will actualy sound without hearing it? Do frequency response charts tell the whole story or is there more to it than a chart and T&S data?

Thanks.

Gary.

[BillFitzmaurice]

Frequency response doesn't tell you the half of it, but frankly for surround duties you don't need the fidelity of your mains, especially if this is for HT and not DVD music. The sonic demands of HT on the surrounds is minimal.

[Timn8ter]

Originally posted by BillFitzmaurice
Frequency response doesn't tell you the half of it, but frankly for surround duties you don't need the fidelity of your mains, especially if this is for HT and not DVD music. The sonic demands of HT on the surrounds is minimal.

I like your approach to learning speaker design. I agree the demands on HT surrounds are minimal. First off, bass response is not a big deal since HT receivers typically cut off at 80 Hz. The nice thing is that you get to try your ideas and then figure out how to make it better. Car drivers are typically not going to come anywhere near a quality home driver but you can learn a great deal for a minimal investment and they can still handle surround duties when you're finished and ready for your next design. There are plenty of single driver solutions that are inexpensive and provide a good learning experience. You may want to consider this one.
http://www.partsexpress.com/pe/showd...number=290-045

Keep going!

[Gary Lightfoot]

Thanks for the replies and encouragement.

That looks like a nice driver Tim, and it sems to work well for my box according to WinISD. Unfortunately it's a little too large for my box which is narrower at the point the speaker should go.

Any other programs that can help me with speaker selection other than WinISD?

I initialy was going to use the Aegis drivers crossover etc, but I think I'll try the complete DIY approach as I'll learn more in the process. I may first reduce the box volume down to match the Aegis and then see how it sounds. Curently it seems a little thin in bass compared to the other Aegis which I've not touched.

My next question, is to ask for a link to calculate the crossover components for my 8ohm woofer, and 4 or 6ohm tweeter - I've not yet decided which one to choose, but I'd like the final impedance of the speaker to be 6 to 8ohms which is what the manufacturer recommends for the receiver. I believe the impedance changes depending on frequency, but I don't know much about electronics so this is another learning curve for me.

Do I also have to pick a tweeter that is 3db or more, greater than the woofer db rating? I've read some threads mentioning this, along with baffle step, but this further complicates things for me at the moment. Any simple and concise links or threads come to mind?

I've used the search, but with so much info, I end up with more questions than answers..

Thanks again for your time.

Gary.