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DIY Stompboxes => Building your own stompbox => Topic started by: smoguzbenjamin on February 16, 2004, 08:54:44 AM

Title: Check this speaker out!
Post by: smoguzbenjamin on February 16, 2004, 08:54:44 AM
Check these spec's out:
(http://image01.conrad.com/m/3000_3999/3600/3680/3688/368881_LB_02_FB.EPS.jpg)
These are dirt-cheap (only about $40) and I get a set of two "disco speakers" with a 200mm bass speaker and a seperate midranger and tweeter. That's 6 individual speakers! They're rated at 100W and have a 3-way Xover inside them to send the right frequencies to the right speaker. I was thinking of buying a set and using them for building a bad-ass cabinet I don't desperatly need excellent clarity as long as the tone is OK I'm hapyy :D I think a 4 foot tall amp would look a lot more impressive than a 10W practice amp :twisted: I'll watch my buddies jaws drop as they enter my room :twisted:

Would it be worth it?
Title: Check this speaker out!
Post by: smoguzbenjamin on February 16, 2004, 09:29:33 AM
bump ;)
Title: Check this speaker out!
Post by: Mark Hammer on February 16, 2004, 09:53:33 AM
We get these here too, for something like $50/pair.

The standard configuration is a piezo mid/tweeter and a second rate subwoofer.

A word of caution about such subwoofers.  It takes great care to produce a speaker that moves over a wide frequency range without much prejudice (i.e., with a flat frequency response).  It takes very little care to produce a speaker that moves sluggishly over a very restricted frequency range.  In the same way that you can have poorly coded software that shrugs off the hard work and leaves it to faster CPUs to make up for sloppy coding, a great many of the inexpensive subwoofers out there (and there are PLENTY) aimed at automotive sound leave the hard work to the amplifier and EQ-ing.  In truth, for me "car hifi" is an oxymoron.  

These speakers come in solid cabinets, to be sure (easy to build solid things with MDF), and having them all finished with the carpeting, etc., is very convenient, especially for the price.  At the same time, don't expect them to sound great on their own, especially given that many of the sounds critical to guitars sounding the way they do are coming from the piezo tweeter, not the cone-based woofer.

Caveat emptor!
Title: Check this speaker out!
Post by: smoguzbenjamin on February 16, 2004, 10:05:51 AM
I think building the EQ to compensate for the lack of performance of the speaker shouldn't be too much of a problem. However, I'm not going to kill myself or blow anything up because I put those speakers in a cabinet together, right? In any case they are going to sound better than the speaker in my 10W practice amp which is apallingly bassy... :?

Thanks for the 2nd opinion Mark! :)
Title: Check this speaker out!
Post by: Nasse on February 16, 2004, 03:15:00 PM
:oops: I have almost same lookin type speakers, bought because they were at almost half price when local market selling this kind of junk were closin doors forever. But mine are two way, just a 8" with a piezo tweeter. I have used them on three "DJ" gigs, one with my bigger speakers I had some surround signal across these cheapos, and two small gigs in quite very small rooms when I did not want to take my bigger speakers with (well I had so much other stuff in my car). I just hooked those el cheapos to my stereo amp, and beefed it with 15" active subwoofer. Someone asked me if I could turn down the volume... But the impression of loudness was because of my subwoofer, and I intentionally cutted lows with EQ at main left and right channels so I could put more power through these cheap car stereo speakers. The audience was mostly drunk people, so they did not notice sound q so much anyway... The tweeters were piezos so I knew they would not blow... and speakers were up enough over audiences heads

But I would be aware of three-way speakers, the mid unit might be the first one to blow just my quess. And playing guitar trough hi-fi multiple element speaker might sound odd, especially if the x-over is bad. If there is a two way version (at cheaper price) I would take it instead. But if the 8" woofers are same elements as used in two way version dont´t know really. The box of my speakers is made of too thin chipboard, 11-12 mm so it is very low quality and resonates and ruins the sound. Using the elements in another design is difficult if you dont know their thiele-small parameters, so putting them in different size enclosure is not givin a satisfactory result. But maybe with speaker simulator and with low volumes, who knows... but you could not buy two piezos, woofers, grilles and handles and speaker terminals at such low price, but if you buy you know what you have :oops:
Title: I got to likin good speakers
Post by: petemoore on February 16, 2004, 03:29:04 PM
But I tend to like 'better' speakers even more.
 I've settled on 12'' or less cone size for guitar...for the most part.
 After A/bing the types described [ie, cheep, relatively  EZ to make against higher spec] and there's quite a difference.
 Mark pretty much laid it out...all of it matters...magnet and coil structure, cone suspension, tolerance between the magnet and the coil is a big one...too close is touching...the closer you get the 'better' tho...tricky], cone suspension...I would take the 40 and use that [and maybe something else] to get a high quality drive [something full range] that would be suited for guitar use.
 Guitars, even at the 'same' wattage rating can destroy 'regular' stereo or car speakers.
Title: Check this speaker out!
Post by: Nasse on February 16, 2004, 03:34:14 PM
Yes, agree. You can buy ceramic Jensen guitar speaker at 40 euros/dollars.
Title: Check this speaker out!
Post by: Jered on February 17, 2004, 12:46:08 AM
Think about all the testing amp Mfgs do to find speakers that make thier product sound the best. Celestion, EV, Jensen, etc...are used in guitar amps because they sound good with guitar. Sure your friends will be wowed with a 4 ft wall of speakers, until you start playing and it sounds like your playing through your home stereo. One good speaker sounds better than ten chinese paper funnels, or in this case four, and two buzzers, which is what those tweeters will sound like after they are pushed a couple of times.  IMHO   Jered
Title: Check this speaker out!
Post by: Boofhead on February 17, 2004, 04:04:45 AM
Not sure what to make of ithings like this.

My PC speakers are rated at 80W.  Inside boxes the speaker drivers are 4 or 5W max and the amplifier is a 2W rms IC.
Title: Check this speaker out!
Post by: aron on February 17, 2004, 04:35:41 AM
These speakers might work for something like a POD or any type of "system emulating" box. Just get a stereo amp and plug your digitial emulator right into the RCA inputs of the stereo amp and use that to drive those speakers.
Title: Check this speaker out!
Post by: Doug H on February 17, 2004, 09:16:39 AM
For $42 you can get a G12H80 from avatar speakers right now (http://avatarspeakers.com/). With $10-$20 of plywood you could build a cabinet for it and have a real guitar cabinet. I just got a G12H30 a few months ago and believe me, the Celestions are worth every penny. Big difference- even compared with the gtr spkr in my yamaha SS amp cab (which isn't shabby, by SS amp standards).

The point being, for roughly the same amt of $$ and a little sweat, you could have a real guitar cab that would definitely sound good, vs. a full-range cheap hi-fi cabinet that probably won't...

Doug
Title: Check this speaker out!
Post by: smoguzbenjamin on February 17, 2004, 10:43:58 AM
Cool. I'll check out the local tube amp man maybe he can sell me a good 2nd hand speaker for cheap too :D

Maybe I'll get these anyway, and ask for a guitar speaker set for my birthday, and I'll scanvenge around some 2nd hand stores for something that sounds good. I'd just test these cheap ones first before making them into a cab. If they sound OK then I'll make a cab out of them and use that. If not I'll just use 'em for my HIFI's 2nd speaker set :D
Title: Check this speaker out!
Post by: DaKurt on February 17, 2004, 10:52:40 AM
What about these speakers, for PA?
(http://www.pollin.de/productgfx/01/02/01/G640270.jpg)

German:
preisgünstige, leistungsfähige 2-Wege-Kombination mit 200er-Bass und Hochtonhorn für professionellen Sound. Monitorgehäuse mit Filzbezug.
Technische Daten: - Impedanz 4  - Belastbarkeit 250 Watt - Frequenzbereich 45-20000 Hz - Schalldruck 92 dB - Klemmanschlüsse Maße (BxHxT): 250x350x190/130 mm


250W
Frequency from 54-20000Hz, 92dB...


would they blow up immediately, too?


They cost 30â,¬ ;)
Title: Check this speaker out!
Post by: humbuck on February 17, 2004, 10:53:20 AM
The PC speakers are rated in PPMO - everything else, like guitar amps are rated in Root Mean Square (RMS). PPMO is the output at the very top of the wave - technically mains voltage PPMO is 340V but it is mesured in RMS, which is the "average" voltage/power.

Hope this helps,

H.
Title: Check this speaker out!
Post by: smoguzbenjamin on February 17, 2004, 10:59:17 AM
Hmmm. I'm in dubio. What should I do? :|
Title: Check yer thrift stores...
Post by: petemoore on February 17, 2004, 11:08:00 AM
Even the transistor stereo console stuff from the 60's and 50's and 70's sometimes have nice usable speakers in them that would handle the FF No Problem...
 Find an old tube job, and not only do you get that, the speakers are kwite likely to be bery good sounding units...
 Time scouting and thrifty shopping can get into nice usable speakers, and then you'll have more left over for actives etc.
 I had the 12'' SPks from the old RCA Victor that sounded superb till 30watts ate the coils. I wouuld try for 10'' or less size cone.
Title: Check this speaker out!
Post by: smoguzbenjamin on February 17, 2004, 11:11:29 AM
I'll have to go shopping then :D I still have to check out the amp store and the second hand stores around here. Hell maybe I can even find some good speakers from my parent's place. If I manage to steal them :twisted:
Title: Check this speaker out!
Post by: smoguzbenjamin on February 17, 2004, 11:46:51 AM
By the way, if the X-over is bad, can't I just build my own?
Title: LONG!
Post by: idlefaction on February 17, 2004, 07:38:46 PM
you can do anything if you put your mind to it!  :P

but yeah realistically you're really really unlikely to find something mega cheap that can be made into something that sounds really good, for reasons that have all been explained thoroughly in this thread.  speakers ain't speakers; crap ones sound like poo, playing a great set through a set of bollocks speakers with huge peaks at 400Hz will just make everyone's ears hurt and they will remember you for being in that band that sounded like crap.

sorry, but it's true.

if you really want to get a bad speaker and give it a good frequency response, you can:

take the driver out of the box, use some maths, a mic, a signal generator, and precision weights (aka coins ;)) to find the thiele-small figures for each driver - you can prolly do this using some expensive software too i think.
measure up the box and figure out what size/length the ports should be. uses some more maths.  if there is more than one port, it will be really hard to do by hand, you'd need some software, or block up all but one port.
do the above with the mid.  the mid won't have a port tho so it will be easier.  it will be in a seperate box.  If it's not in a seperate box, find a good size for a box for the mid using some more maths and build one around it :)
put it all back in the box, take out the crossover, and make some sensitivity readings of the seperate drivers using either a spectrum analyser and noise source, or a frequency generator and a db meter or similar.
Using some more maths, design a crossover for the drivers taking into account the relative sensitivities of the drivers.
put it back in the box, find the frequency and height of any peaks using whatever you used to do the sensitivity readings.
buy some bobbins, cores, enamelled wire, some bipolar capacitors, do a crapload of maths and build notch filters for all of the notches above.

This will (hopefully!) give you a well-designed speaker box with a pretty flat response.  

If you used crap drivers, the crossover will have tons of notches, weigh a ton cos of all the inductors, and would have cost a small fortune in copper wire.  If you used crap drivers, there will also be lots of phase issues because of all the crossover stuff â€" if you plug them in at the same time as anything else (even the other speaker), you will have that awful comb effect where the bass changes loudness depending on where you stand in the room.

Your bog standard el-cheapo PA speaker has a plastic encosure for the mid which lets the bass wave in and you get intermod distortion from the mid driver, porting that lowers the frequency response and raises the sensitivity at low frequencies to give the box 'more bass', giving it huge peaks at 50Hz, 100Hz, 200Hz, 400Hz etc, a tweeter that's twice as sensitive as the woofer and has a huge peak at 8kHz, and huge holes in frequency response around the crossover.

If you start with good quality, well matched components and some cheap MDF, you can build a pair of speakers that have a crossover that's easy and cheap to design and build, wonderfully smooth frequency response, and very few phase problems.

If you're doing this for a guitar cabinet, everything becomes easier â€" it's an open cabinet and there is no crossover.  The sound is determined by the speaker and that's the end of the story!  Nicer speaker = nice sound, crap speaker = one-note syndrome and general 'listening fatigue' caused by resonant peaks.

I'm not writing this to show off how much i know about speakers, in fact i've only done this once (and it was a lot of fun!) - i'm writing because it's a path i already walked and it goes nowhere.  Like has been said, speaker design is an art and it really, really does make a difference on the drivers you choose.

HTH  :)

http://speakerbuilding.com/
http://www.diysubwoofers.com/
Title: Check this speaker out!
Post by: javacody on February 17, 2004, 11:48:50 PM
I would just buy a couple of jensens and be done with it if I were you. I have an 8" Ceramic Jensen (c8Q?) that cost $20 that I put into a speaker box that I bought premade from Walmart for $20. It sounds awesome! My next speaker project is to buy 3 more 8" Jensens and build myself a mini half stack.
Title: Check this speaker out!
Post by: smoguzbenjamin on February 18, 2004, 02:31:48 AM
Thanks Darren, that's made a lot clear to me. I

'll have to check out the amp man here but he had a cabinet with 2 celestion 6.5" 50W speakers in it, covered with green leather and it cost a whopping 175 euros! :shock: I don't have that kind of money! I have a 10W practice amp with a 30W rated speaker in it but I want to leave that as it is, so when I finally start building my tube amps I'm gonna need a cab :D

Whatabout old proper HIFI loudspeakers, will they sound good for guitar?

edit: hey javacody where'd you get those jensens from?
Title: Check this speaker out!
Post by: javacody on February 18, 2004, 09:07:31 AM
http://www.vintagespeaker.com

They take paypal and are about the cheapest place for Jensens I have found. I guess that the Jensen reissues are made in Italy though, so I'm wondering if you could find a European source for these and pay less shipping?

Anyway, I've ordered an 8" and a 10" (both ceramic) from them. They pack the speaker very well (still in its original Jensen factory box) and ship quickly. I get them in usually 3 days. They also are very quick to confirm your order via email.
Title: Array...
Post by: petemoore on February 18, 2004, 03:41:54 PM
Cone surface area is one subject we've all probably experimented with...bigger cone area means generally higher volume usable tone with more bass.
 Having more than one driver also has tonal impact.
 I think your 4x8'' Jensen choice should sound choice.
 Even in mono, and at the same amplitudes for comparison, multiple speakers make for an 'ambience', certainly the phase is slightly shifted [unless you are standing square in front of them],.
 There's just something different about having 1, 2,  4, or 8 speakers. Even small ones.
 Possible it's the way the air is 'treated' between them, as the waves are broken around the edges of the soundboard, and merge again a short way in front of the cabinet.
Title: Check this speaker out!
Post by: smoguzbenjamin on February 18, 2004, 04:07:06 PM
I was actually thinking of ordering 2 8" speakers (midrangers, right?) and putting them in a diagonal 2x8, and then ordering 2 extra speakers at a later date and making it a 4x8 cab. It'll get me far enough :) Man I wish I had more money :|
Title: Check this speaker out!
Post by: javacody on February 18, 2004, 07:11:40 PM
Me to smoguzbenjamin. By the way,what the heck is a smoguz?
Title: Check this speaker out!
Post by: Jered on February 19, 2004, 06:07:21 AM
Try the Jensen "Mod" series speakers, they're cheap and sound great. I put a 6" in my Vox BM Special ten watter and the sound improved dramaticaly over the original speaker. I've also bought 8" and 10" for my Fender SF Champ and both sound great clean or when pushed into OD.
  You can get two 10" speakers, shipping included for around $50.00 from this place http://www.tubesandmore.com/new/scripts/silverware.exe/catalog@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?SEARCH_PAGENO=0&SEARCH_KEYWORD=GENERAL%20AND%20ELECTRIC

 Designed FOR guitar, no keeping your fingers crossed hoping a used hi-fi speaker might sound good.
   Jered
Title: Check this speaker out!
Post by: casey on February 19, 2004, 10:43:08 AM
www.partsexpress.com  

these guys have every speaker and accessory available.

at good prices as well.
Title: Check this speaker out!
Post by: smoguzbenjamin on February 19, 2004, 11:09:03 AM
'smoguz' doesn't mean anything. It was a band name and I thought it sounded cool so I included it in my webname. I've used that name for about 3 years now and I have so many sign-ons on websites etcetera that I don't want to change it. It's just too much trouble.

$50 for 2 10" speakers AND shipping?! :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen:  SWEEEEEEEET! I'm gonna check that out for sure! Wow I can blow my neighbours' butts off with that! :mrgreen:
Title: Check this speaker out!
Post by: smoguzbenjamin on February 19, 2004, 11:18:22 AM
Oh and by the way... There's two power ratings here in the specs, 50W rated power, and 100W musical power. What number should I take into acount if I build/buy an amp head?