Building cheap surrounds, what wide-range driver?

[St= Z]

Hi all, DIY newbie here.

I'm building a Home Theater chair and I want to put the surrounds into the headrest. As you can imagine the drivers will be pretty close to the ears.

I want to keep the cost of the speakers very low, like $35 for the pair. So I was thinking of a 1 way design to keep everything simple and cheaper. But I'm at a loss for what would be an acceptable wide range, I cant seem to find one that gets near 20 khz (at any price), while I know I dont need bass, I certainly need top-end aswell as midrange. There are tons of HT systems with 1-ways and a sub, why cant I find a wide range with acceptable specs?

Can somebody recomend a cheap wide range for surrounds?

Also If I do use the 1 - way does it mean I do not need any type of crossover?

Thanks for any help

 

[Super]

If its a smaller driver, you may want to filter out low frequencies to prevent the driver from being damaged, and distortion would be high anyways due to cone breakup.

 

[Nonlethal]

I think Fostex has some relatively cheap/small fullrange drivers (Like the FE87) ... you could check them out, and maybe add a dome tweet with off axis with a inline cap for filtering or something if there isnt enough high highs.

 

[St= Z]

Super, I figured that in HT, the surrounds arent usualy fed low signals?

Nonlethal, thanks for the link, that fostex looks pretty good. I'm really new at this so if you can entertain a dumb question... the in line filtering, that means I let the Fostex run full range signal while a tweeter gets a simple low freq filter? Is this cheaper than a full x-over?

 

[Nonlethal]

Yes, St, It could be as simple as a single cap. However by doing this you could end up with the opposite problem (too much high) which is why i suggested putting the tweets off axis. You should probably just try the full ranges first. Btw, Parts Express has some alternatives to the Fostex i mentioned above. So are you going to be putting some sort of LF Transducer in the chair (like bass shakers or something?) or just using subs?

 

[St= Z]

Yeah there will be a bass shaker TT in the seat (any advice on this?)

I'm a little mystified by these wide-ranges, they dont seem to go up as high as they should, do they run out of spec when they are so close to the ear? I mean all those crappy all in one 5.1 dvd systems have wide ranges and their spec'd up to 20khz. The Fostex you pointed out seems to be the widest, dynamicly, I've seen.

I will probably throw a pot in between for easy adjustment as they will likely be too loud.

 

[Nonlethal]

Some of the commercial offerings simply lie... the others (ala Bose) simply use large cone tweeters that play down into the upper mid, and then run the rest of the midrange through the 'sub', which ends up being more of a mono woofer...

As for the Bass Shakers: just dont cross them over too high, you get a 'voice-in-your-butt' effect... and a lot of people don't like them for use with music, so if this is a dual purpose system, you might want a switch on the chair or something.

Good luck.

 

[St= Z]

Thanks for the advice, I will keep my eye out for good wide-ranges, it doesnt seem many people have much experience with them.

As for the TT, I'm going to use a small sub-amp to drive them I think it has a crossover built in so I can dial in the cutoff probably about 140-40, its really mostly for HT aps, I'm aware bass shakers aent really a great musical thing (neither are surrounds for that matter)

 

[planet10]

So I was thinking of a 1 way design to keep everything simple and cheaper.

If you can find some the Radio Shack 40-1197 (aka FE103) is an astounding driver for the $5 clearance price. The Tag-Band 3" drivers are also getting very good reviews (available at MCM IIRC) and some select units at http://www.nuera-acoustic.ca/.

dave

 

[SteveG]

I would have to agree with planet10- tang band. They seem to have decent specs, and are like $4 US a piece at mcmelectronics.com (if you can find them on the site- it's really hard to navigate). Sounds like a cool project.
Steve

 

[SteveG]

Oops... forgot the website-
http://www.tb-speaker.com/
click on tweeters and scroll down to full range section. check this out:

 

[St= Z]

Thanks guys this is EXACTLY what I was looking for.

I see you pointed to the W3-319 would this be the model you would recommend? (Looks like any one of them will do).

Being that they are serving as near-field surrounds I'm thinking of running a little pot in-between (to dial down the volume), I know very little about EE, can I just slap a pot in the line of speaker wire? Is there certain specs of the pot I should look for?

And wilst I have your attention, any recommendations on a little sub amp (25-50W) I'm looking at the 25/25 Watt on apexjr.com .

 

[SteveG]

Well, not having heard any of them, I can't really recommend which one is better. The model I posted was the one I was looking into for a budget surround setup. As far as attenuation goes, you need an L-pad in line with the speaker. It's basically a high-powered potentiometer set up to keep the impedance (ohms) seen by the amp at the same level while attenuating the driver. You should be able to find them about anywhere. Don't know about the sub amp. I know that you can get 75 watters for pretty darn cheap these days. Look at www.partsexpress.com
Steve

 

[St= Z]

Okay an L-pad, any idea of what watt I should look for? The surrounds will probably be "doubled up" on the amps taps, so I have the headrest and outside surrounds going (for riends). Do you think a 50W L-pad would be apropriate? Are there special considerations on the "doubling up", I figure it will be negligable.

also any idea why the l'pads have a pair of three leads instead of two? (maybe a ground?)

Thanks again for the advice it is proving most usefull.

 

[SteveG]

check out this link for L-pad wiring:

http://colomar.com/Shavano/lpad.html

 

[St= Z]

you are the man.

 

[hifiZen]

why not use analog attenuation before your power amplifier? I don't know what kind of setup you have, but a stereo pot to attenuate your line level signals is probably a better way to go.

 

[St= Z]

Thanks for the suggestion

The chair is designed to be able to easily integrate into most HT setups, the headrest surrounds are in addition to existing ones so they require their own volume control, not the audiophile option, but I think an L-pad makes the most sense.

Hey SteveG, where are the TB's for $4? Under 3" drivers I see them for $7, I'm assuming that the MCM brand 3" wideranges are just OEM's of TB's right?

 

[SteveG]

Well, I thought that MCM was selling them for that. Maybe they raised the price back up when they realized that they would sell A LOT of them! Yes, the MCM brand are relabled TB's. If you look closely at the picture on their site, you can see the TB label. Sorry to give misinformation on the price! I thought they were down around $4.

 

[St= Z]

Thats pretty much what I figured, still cheap though at $6 quantity.