ping BAD OT ????

[skeezics]

I read another post by you about speakers. While im not an audiophile I do like good sound. I have an older pair of cerwin vega vs120 speakers. They sound great to my ear BUT there is a problem. my space is a lot more limited than it was when i bought them. I've thought about building new boxes for them a little smaller. I only need to go

1/2 inch narower but i gotta shorten them by 4 inches. Then i would use the speakers and crossovers in the new boxes. In your oppinon will i lose a lot in quality by doing this? also what material would be good? I realy dispise mdf and I realy dont like particle board of any type. solid wood would look the best but I'm not sure how this would effect sound quality either. I have been to web sites about DIY speakers and am sorry to say they speak a language i don't understand. I'm just a dumb carpenter with a HS education. :-] We can take it to e-mail if need be. any suggestions? Again tech terms mean little to this old hillbilly so english please! thanx skeez

[Bay Area Dave]

skeez,

Being an audiophile (in the past), one of the things I learned quickly is that speaker technology is damned near a black art. The deepest I got into speaker construction was to remove my ADS's midrange and tweeters, shave down their metal mounting flanges a bit to fit, and re-arrange them in a vertical alignment for MUCH better sound staging (imaging). There is plenty of science available regarding the enclosure size (volume) to provide optimum damping for the lower frequencies. (I'm presuming, perhaps incorrectly, that your speakers are acoustically suspended. If they have a port, you will have a tough time getting the port to sound identical if you change the cabinet dimensions) You'd need to know the requirements of the drivers before you researched what volume to shoot for, however. If "close enough" is fine for you, than you could pretty much measure the interior volume of your current enclosures and match that. Since you want to go narrower and shorter, you will need to go deeper.

MDF is pretty darn good stuff for building speakers. Sorry it isn't your fave material! :) Whatever you do, be sure to brace them well, glued and screwed backs to sides, etc. Look inside your present speakers for the idea.

If your ears are as good as mine used to be ( I lost the hearing in one ear in '96 due to an operation), you'll also benefit from mounting the mid, tweeter, and bass in a vertical line. The sound stage depth and stability is an order of magnitude better than non-aligned speakers. Getting their voice coils all arranged at the same distance to the listener's ear is another trick for cohesive sound, but less likely to impress any but the most discerning ear. I'd not worry about that.

When you are all done, don't use "speaker wire" to hook them up! Use at LEAST 14 ga. lamp cord or better. Monster cable works but it's over priced. I've used Mark Levinson cables with my system, but only because I talked the salesman into providing them free with an amp purchase. Truth be told, heavy lamp cord for short runs sounds the same.

dave

[e-mail] wrote:

[Iraxl Enb]

okay, i know i am butting in, and am not BAD...

with speakers you want them to produce the sound that the driver is producing, not change it in any way. With solid wood, the wood would have a resonating frequency due to which it would amplify some sounds more than others. Plainspeak: if you tap a box made with the same thickness of MDF and solid wood, the box made with mdf would produce a duller thud. That is kind of what you need for a good speaker cabinet.

And changing the volume of the cabinet will change the perforfmance of the driver. If possible, you might want to increase the depth to keep the volume the same.

I suppose that this is a sealed cabinet, otherwise you get into other issues with the size and length of the port etc...

Oh wait. I checked. This is a bass reflex speaker - it has a hole in the back.

My opinion is you sell this on ebay and buy something that will fit better. Even if you just use the money from selling these to buy new speakers, I think you will get better sound quality than messing with these, YMMV...

irax.

[e-mail] wrote:

[Greg G.]

Solid wood colors the sound, due to resonance. Use THICK MDF, but veneer it or paint it with black lacquer if you don't like its looks. All joints must be airtight and solid. The dimensions (LxWxD) of better speakers are chosen to reduce mathematical multiples of standing waves present in the enclosure - changing these dimensions can increase the intensity and quantity of 'bumps' in the response curve due to these standing waves. Non-parallel walls help reduce internal standing waves. Most of the enclosure's volume is for tuning the woofer, the midrange and tweeters should be isolated from the main chamber volume to eliminate blowing the cones out of the midrange and tweeters, and to eliminate intermodulation distortion.

If you change the volume of the box, it WILL upset the tuning of the enclosure. Generally, making the box smaller will push the resonance point up, and you will loose deep bass, and end up with an annoying bass peak at 80-100Hz. The enclosure and driver match and resulting resonant frequency determines the beginning of the low end rolloff point. On a bass reflex, you can make minor adjustments with the port length and diameter, but without test equipment, you are guessing.

FWIW,

Greg G.

[Bay Area Dave]

I agree if it has a port, it's not a good idea to monkey with building a new enclosure, UNLESS your ears are not too critical...

dave

Iraxl Enb wrote:

[Bay Area Dave]

Bose must have done a lot of guessing!! I HATE the sound of Bose speakers! And JBL's, for that matter. Give me something with a flatter response and smooth, extended silky high end. and no thumpy, fakey bass either. Ever heard ADS 810's?

dave

Greg wrote:

[Swingman]

.. and most of what folks love to listen to over those things was mixed over some Auratone Cubes about 4" square, or worse yet, Yamaha NS10's. ;>)

[<pridday]

Remember too that your crossover can be used to get a flatter response out of your speaker, If you feel like tweaking it at all (Only if the crossover is not one of those mounted on a circuit board and then covered in epoxy) as well as the proper selection of drivers if you decide to use something other than your CV drivers. As has been noted before in this thread, MDF is quite good for cabinets, but is unfortunately not the best looking, (as SWMBO reminds me constantly) and is hell on blades. If you don't like the looks, you could also overlay the MDF with solids or veneer. Just my butting in 2 cents worth.

Paul

[Bay Area Dave]

oh man, I remember those POS Yamahas! They had the driest bass of any speaker that I'd auditioned! Drums sounded like blocks of wood being pounded upon. Nasty!

dave

Sw> .. and most of what folks love to listen to over those things was mixed over

[Bay Area Dave]

Judging from the OP's comments, he isn't going to be doing any tweaking of the x-over. You've reminded me of when I got ADS 320i's for my car and got to play around with an active/passive crossover for the subs. They were mounted on the rear package tray of my Delta 88 and the

320i's had the mids on the doors and the tweeters fit into the dash. A Nakamichi tape deck/radio was the source. Sounded nice to my ears! Now I have a POS Ford radio. sigh...gave the Delta to my son.

dave

[e-mail] wrote:

[B a r r y B u r k e J r .]

"No highs, no lows, must be Bose!"

Barry

[Swingman]

JBL - Junk But Loud

[skeezics]

makes sense

dave mentioned that also and thats not a problem. i can get more or less the volume thats there now realy easy. got plenty of room to make deeper.

yup 2 of em.

i have listened to many smaller bookshelf speakers and have not been impressed yet. these just sound sooooo goooood i hate to part with em. till you get into realy high priced its hard to find the sound quality im used to.i suppose i could use these in another room though.

thanks for the reply skeez

[Greg G.]

I can't remember the exact model number, but I used to have a pair of OLD AR speakers on my repair bench. Damn those things would rock! They were an irregular shape, and only two way, but they had a deep bottom end and amazing SPL levels for smallish bookshelf speakers. Would have made great small studio mix monitors.

Now everything sold caters to the moron crowd, with boomy bass response at 80Hz and no real bottom end. Ugghhh....

When I was younger, and had the time to spend the time on such things, I built enclosures in my old Peugeot that went almost flat to 40Hz. Listening to piano music in traffic was amazing! Now, like Dave, I have only the POS Ford radios and speakers - I can barely stand to turn them on...

Greg G.

[skeezics]

thanx for the reply dave. my ears a>

[skeezics]

that makes sense. hell i been guessing all my life!!!! lol. wish i could decifer all the technical jargon on those sites i visited. thanks skeez

[Greg G.]

And unless it's an active crossover with bi-amping, it isn't going to alter the shifts in bottom end response that the OP was considering.

Passive crossover components add their share of coloration, and on a high power woofer, are of such mass, that they are best left as simple as possible - you run the risks of altering dampening factors, severe phase shifts, and lessening SPL levels. All that is realistically possible messing with the crossover is altering the crossover point a few 100Hz up or down. You cannot change the bottom end rolloff point with a passive crossover of any design - this is a factor of the enclosure/driver design.

FWIW,

Greg G.

[Bay Area Dave]

Greg, speaking of AR's, I got my dad's AR3's as part of a wedding gift back in 70. Those were 3 way with level controls on the back. The bass was awesome! The controls weren't such a hot idea, as the pots would eventually get dead spots and the tweeter would shut down as you tried to adjust their level. Then I blew out one of the tweeters, but thank God it was under warranty. Probably due to clipping, as the Fischer

440T that was driving them was too puny to deliver the kind of levels that I liked without some distortion. So know I have an amp that puts out tons of juice -- a Mark Levinson. Best piece of ANY kind of equipment or toy I've ever owned.

dave

Greg wrote:

[Greg G.]

I don't know if ARs are of the same quality since Teledyne bought them up, but some of their old stuff was pretty good. Ditto on the level controls - they all suck, not just ARs. My current speakers have a

3db +/- switch that seems to hold up fine - plenty of range for moderate 'drapery' tuning. And yes, clipping in a low power amp creates a rich plethora of harmonic TIM that will fry a tweeter without you even hearing it.

I have a homebuilt 350 watt class AB dual channel amp from the 80s. Then I get a lot of recent 'consumer' stuff from the junk piles of various shops, and after fixing it, it never sounds right. No dynamic range, a crispiness in the high end that I find annoying. Then I hook up the old 350 and all is right again. I keep trying to find a modern (pre) amp, with all the remote features, fancy AC3 5.1 inputs, video switching and such that sounds good - but no such luck. They just don't make anything today that sounds like an analog 'wire with gain.' I have a pile of neglected Sony, Pioneer, etc. amps that just don't cut the mustard. 200 watts per channel x 5 @ .01% THD my ass!

I also have an old Yamaha P2250 rack mount amp, meant more for sound stage use than home stereo, but it sounds almost as good - if you can get over the unusual appearance of balanced XLR connectors on the back.

Big old amps, and romex speaker wiring - yea! ;-)

Monster cables are pure marketing hype! Went on a call last year, and the guy had gone whole-hog on the 'monster cables' and such on his new 'home-entertaiment center'. 16:9 projection TV, DVDs, S-VHS VCRs, laser disc, 5.1 amp, satellite, etc. The owner couldn't believe it when I found that his problem was one of these high dollar video cables. Pulled the defective one apart to find cheap chinese connectors CRIMPED onto the crap wire - but not very well. Soldered it back together and laughed on my way out the door at the prospect of what he paid for these cables, and what the salesman's commission must have been.

P.T. Barnum was right...

Greg G.

[B a r r y B u r k e J r .]

They used to make those right down the street from me. Madrigal Audio Labs was located in Middletown, CT, seemingly forever.

The parent company, which is now the same as JBL, Lexicon, and several other brands, closed the Middletown shop last year.

Barry