formica

Ok... I might have a similar problem... I have a set of Cornwalls that sounded dull tonight, so I checked up close... and surely enough... one tweeter wasnt working. It seemed to have stopped working with a very low signal, does this sometimes happen? Age? Bad x-over? Or some kind of spike? 1) I opened the rear, and disconnected the tweeter... and tested its resistance, and I got infinity. 2) I noticed that if I check the x-over, I get 4ohms at the woofer, 1ohm at the mid, and 1ohm at the tweeter... obviously if the tweeter was connected, I would have gotten the 1ohm too... right? 3) Now I wasnt sure if I should check it connected or not so I also tested it with a AAA battery to see if it had any reaction... and nothing. (woofer and mid made sounds) 4) Figuring that it was blown, I opened the unit to see if I could see anything unusual and it doesnt look dead, but should it show? 5) I noticed that the front horn, which came off when I unscrewed the back, was originally glued the diaphragm plate with a little bit of glue. Does this matter if it isnt attached by anything other than the screws? Ive got the K-77-M (with the square magnet), so should I just order the piece for the EV T-35 from Simply Speakers? thanks guys... Rob

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wish we could load multiple pictures at once...

Through my surfing, I have collected 6 images (plans) for what is supposed to be a Klipschorn (or equivalent) but I can't guaranty their accuracy, as I dont have one to compare with. I thought Id post them anyways... maybe theyll be of use to someone... and if anyone knows, please post if they are accurate? HDBRbuilder, I noticed that the plans you posted are the same as a set I have, but in what appears to be German ... do you know about these and their history? It just seems odd, even the panel numbers are the same... Rob

One thing i would like to add to this is the importance of "leaks" or "bridges" which occur in standard construction. Even though the composition chosen may have a respectable STC rating it is very often compromised by its weak points. A good example is at the floor joist level where the joists run over the supporting shared wall and the next floor's wall sit on top of them. Even though the wall may have been designed for acoustics, the joist junction was not. I unfortunately don't have my design guide with me, but USG may have some info online for the STC ratings for different compositions. http://www.usg.com/Design_Solutions/2_3_4_acoustictips.asp The composition you mentioned probably won't have a very high STC even though you have two sets of studs. Adding some mass in-between the two would help (a block wall? extra gypsum? etc...) and having at least one of the two unit's exposed gypsum panel attached to resilient furring as well. Does the home have a basement? The foundation wall would help performance greatly. If not, i guess you can try having your neighbor over to watch some movies with you... it apparently works wonders. Bass unfortunately carries... there is no magical solution...

- When used scientifically: it can be an arbitrary known point to compare other points (eg: freezing point of water is the reference point for Celsius ---> 0o Celsius, and all other temperatures are compared back to it... room temp 20oC ) - When used by an audio equipment reviewer: it can be an arbitrary known piece of equipment to compare other equipment. eg: the Velodyne HGS-15 can be the reference sub ---> and all other subs are compared back to it (Flatter, boomy, faster, louder....) but you can also use a KSW-15 because its typical 500$ sub (like http://www.hometheaterhifi.com/volume_8_4/subwoofers-12-2001.html did... - When used as part of the name of audio equipment ---> : it can be an arbitrary marketing ploy, as it does not guarantee any minimum performance point (unlike THX, etc...) - I used my 10year old Tercel as a reference car when I went shopping for a replacement... ;-P

QSC do make some of the more musical pro-amplifiers... but there is a lot of different opinions on using pro-amplifiers for critical full frequency listening. I guess a lot of it is a question of taste. The small differences between one amplifier and another are a lot less distinguishable at lower frequencies, which is why they are so common as sub amps. You have to also consider, as was mentioned earlier, most pro-amps has internal fans which may be audible when listening at lower volumes. But to drive your SVS or DIY subwoofer, they fit the bill perfectly.

I did verify with JBL about whether they are 230V units and the fact that the brochure mentions they are not configurable... they responded: "Hi Rob You can change the units to 120V!!! Do you have a Fax # I do not have the mod in a pdf sorry..." I also have the fax (which I can scan and post) about the modification... ironically it's a QSC document for the CX4 and CX6, but he (JBL) explains that they are basically the same model. I haven't tried the modification yet, but it's basically moving 2 connectors and a new power cable. I can let you guys know how it works out. Sorry about the typo you are right that the 225W is into 4ohms x 2 channels and I also realise that the 700W x 1 @ 4 ohms is very optimistic. The thing I found interesting is the unit is rated for a 450W x 1 @ 8ohms with 0.1THD and from 20 to 20kHz. I'm guessing about 600W x 1 @ 4ohms clean? This can be very useful for people looking into some of the new subs like the Stryke AV15. I guess it's more of an economical option to the QSC RMX850 than a competitor to the PA #300-794 plate amp (you would need two PA-300-794 to produce that power... or one Adire A750 plate amp). Like you also mentioned, it's got screw-down terminals just like my klipsch It's definitely not for everyone, but I think that could be said about most passive subwoofers. Later... Rob

Just thought Id give you guys a heads up on the JBL amps on liquidation... the prices are incredible (and include shipping) and they would make great sub amps as they are bridgeable... but there are catches: The amplifiers in question are JBL MPC200 (200Wx2 @8ohms 143$ shipping included) and MPC300 (300Wx2 @8ohms 193$ shipping included), which were originally manufactured by QSC and are the same as the QSC-CX4 and QSC-CX6. They are unfortunately 220V units for the export market but can easily be rewired for 120V as they are internally equipped to handle both 120V and 220V. I posted the question on the QSC tech forum at http://www.qscaudio.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=2;t=000006 JBL is liquidating these amps directly at their Tent Sale as Harmon now sells (owns) Crown amps. They have about 90units left... as well as two slightly higher end (but still 220V) MPA275 and MPA750. I don't know if the MPA series can be as easily rewired though. The link is: http://www.jblpro.com/Tent_Sale/sale_items.htm The other catch is that the sale is for US mailing addresses only, which could be a pain in the butt for us Canadians. I hope this can be of some use to someone... I've ordered a MPC200 and probably will get a Tempest although the AV-15 still isn't out of the picture. Later... Rob.

Fiveliter: Cant you plug the plate amp into the soundcard line-level output... and then plug the Promedia into the plate amps pass through line-level outputs... without using any Ys? Youd have to make a couple of cables and your Promedias will be fed full frequency but it should work without the gap in the frequency range. (no high pass out on the AVA250, right?) Dustin: Actually, isnt the Tempest/AVA250 more or less what you got Dustin? I was considering a Tempest sub as well since Im also in Canada so Adire is quite attractive because of CSS. I remember seeing your comments (I think at HT forum) about what youd do differently but I cant seem to find it now... Having lived with your setup, what would you do differently? Ive already ordered a pro JBL power amp on liquidation (a realistic 225Wx2@8ohms or an optimistic 700Wx1@2ohms). Seeing that the Tempest runs 225$cnd shipped versus ±330$cnd shipped for the Stryke AV15, do you think the Stryke is worth the cost difference? Thanks... Rob PS: excuse me if i'm sometimes overlapping my HTF posts, but i'm learning tons of stuff...

I dont know on what it does to the collector value, but refinishing them usually does great things for their WAF. Ive done this on my set of Cornwalls... they were originally purchased unfinished, stained and varnished in brown, and then painted black before I bought them. They can be stripped and finished in a stain which is of similar darkness or darker without much problem. Id recommend first carefully chemically stripping them, steel wool, and then finish sanding. The veneer is not that thin, but care should be taken all the same. As with any veneered wood, never sand cross grain, as it will delaminate and chip the edges. You might get slight unevenness in the finish if they are birch, but this is a characteristic of the wood and not the refinishing. Walnut, oak, and cherry should be no problem. Here is a picture of an almost finished Birch Cornwall in red oak stain... I havent gotten around to getting some digital pics of the finished units. Rob B. PS: the colour will look quite different from screen to screen, but they are just a little bit more red than the copper logo.

You forgot to mention a couple of basic specs for your shivas... such as voice coil setup (dual in your case), power-handling (650W combined), efficiency (87.2db 1W@1m), resistance (4ohm nom in each VC)... The Shivas are actually good SQ subs for room use, so you can use it successfully for both car and home. As you already know, they do require somewhat of a large box for car use though. Im quite sure that your carpeted box will not affect the SQ of your sub even for interior use... as long as its well built (sealed and VERY well braced). For your other question, Im assuming your asking which 120V amp would be able to pump out ±1200W into 2 ohms in your home? If youll be using it with your ProMedia, I dont think youll need to push your sub very hard (ie: 1200W) to overpower your main speakers. Actually this would represent an in-room SPL at 1m of about 130db for your vented enclosure or 137db for the sealed one! Even a 300W would give you phenomenal performance versus your klipsch. If you install a plug on the rear of your box for each voice-coil, you will be able to modify the wiring to accommodate your power amp (ie: 2,4,8,16ohms) and whether it can be bridged or not. If youd like an amp that can be bridged and put out decent power into 2ohms you will have to buy a pro-amp such as the QSC RMX series which are very popular with the DIY crowd right now. http://www.qsc.com/products/amps/rmx/rmx.htm and the RMX 850 sells for under 300$ hope it helps some... Rob B.

Interesting thread... I hope klipsch execs read this thread. Personally I share a lot of wants with theEAR. First off, they should offer two models with similar performance... but priced quite differently... bang-for-the-buck (abbreviated as $) should be priced a little more than a similar SVS (ummm... about 1000$) and price has almost no limit (abbreviated as $$$) should be priced less than the top of the line Velodyne (less than 3000$?)... - Flat to about 18Hz (both $ and $$$ versions ) - Impressive high SPL capability surpassing SVS / Velo (with the $$$ one having a 6db advantage) It basically requires large drivers, long excursion, and plenty of power. A look at Adires Tumult, Strykes AV-15, Adire Tempest, etc... shows what can easily be done. - A built in auto EQ like the new Velos (I believe this is the future of subwoofers, and is essential in the $$$ unit but should be in the $ sub as well. Considering the cost of the BFD 1124, I cant believe they cant integrate a powerful parametric unit for a cost of less than 100$ to 150$?) - Im also for the plain but strong pulp/Kevlar woofers (esp in the $ version) - Choice of NICE Real wood only for the $$$ units - Cheap box/tube for the $ unit... after all... form follows function at this price. I think the cost and the two first points are the main deciding factors when buying / testing a sub. If they want reviewers to rave about their subs, they have to blow them away literally... with the $$$ sub As cool as having a horn-loaded sub would be, physics pretty much rules out this option. Tuning it low like 18Hz or 20Hz would make the box (and cost) huge!! That is why most commercial horn loaded woofers really excel in mid-bass rather the sub-bass. Adding wildly flanged ports could help give the subs a brand / heritage look though... but its more marketing in this case. Ok... I think that was my 2 cents... Rob B.

---------------- On 3/1/2003 10:02:00 AM Dustin B wrote: There is absolutely no difference between a well built tube and a well built box sub with the same allignment (ie same net internal volume, same port(s)/tuning, same driver and same power). The only difference is the box is heavier and more expensive to make. The PB1 is essentially a 25-31PCi tuned to 22hz. ---------------- As Dustin said, the shape of the box shouldn't change it's sound... the PB1 could have been called PB 22-21PCi i guess... It's more of a convevience factor (and a WAF) That is one of the beauties of actually building your own sub... you can give it any shape or finish you like!

Actually the Behringer Feedback Destroyer Pro DSP1124P contains 24 bands of fully parametric equalization... so you can adjust the centre frequency as well as the slope for each of the bands. As you mentioned you could technically put all 24 bands in the subwoofer range ... but you probably won't need them all. It does give you excellent flexibility in taming room resonances... more than any 1/3 octave eq.

All the sub EQ talk these days seems to be about the Behringer Feedback Destroyer Pro DSP1124P which is actually isn't primarily designed as an EQ. It's own description at http://www.behringer.com/02_products/prodindex.cfm?id=DSP1124P〈=eng describes it as "locates feedback frequencies immediately and sets extremely narrow notch filters to destroy them". The beauty of it is that it contains 24 bands of fully parametric equalization with a 20hz low frequency limit for less than 150$ US. In other words you cans use all 24bands in the 20 - 80Hz subwoofer range. There is a good info page at http://www27.brinkster.com/jmag999/ let us know what you decide... Rob B

I was planning on doing a similar project (building a centre using heresy pieces)... but this does involve more work and planing than just buying a prebuilt unit. On the other hand it's the only way to get an exact match for a heritage speaker.

I agree with dustin... Its definitely easier to high SPL in a car than HT, but these SPL cars / audio systems become nothing more than trailer queens... no longer serving the purpose they were originally designed for (transport and music listening). Im not criticizing the sport, but like many other sports you have to put 110% in order to win. If Im not mistakened, car interiors often have a strong mid bass peak... which is often why people feel their car has muddy bass but with a lot of punch. I dont agree that you cant get good sound in a car... it just requires a lot of design and experimentation to get there. I have heard several SQ systems which sounded very good, but they were designed as a whole and parametrically EQed for cabin gains. Which one has advantage in low end impact at high SPL levels? ... Id say the one that was adapted for its environment. If neither one is, the room gain will be less pronounced in the HT because of its larger volume. But that is just my opinion... Rob B.

You can also try refinishing or replacing the veneer yourself. Neither requires any special equipment... just alot or elbow grease and some patience. It should cost you between 40$ to 75$ of supplies and materials.

But don't forget, as with any trade-in offer, the asking price for the new units should come into the equation!

I would recommend new parts... The problem with reusing existing (non DIY) parts is it's very hard to find the Thiele/Small parameters in order to design a new box. The only info you do know is the current design! There is some info on how to measure some of these parameters at http://www.diysubwoofers.org/sbc/sbc2.htm ... actually www.diysubwoofers.org is a good site overall covering many aspects of DIY subwoofer design http://www.linearteam.dk/ offers a free software to design enclosures based on the T/S para. www.hometheaterforum.com has a great DIY forum enjoy... Rob

Ive been considering the same thing... either DIY dual shiva subs or a single tempest. Im looking into a JBL MPC-200 pro amp at the moment... if the deal is right, Ill definitely go DIY. Another option I've been considering is just one SVS PCi 20-39 sub, although the SVS is more expensive initially (esp with duty and brokerage fees), it does have a much better resale value when I eventually upgrade. Has anyone tested (measured) a DIY Vented Adire versus a SVS unit? Is there a web page where we can find response curves and max SPL for both under the same test conditions? I realise that it's very enclosure dependant... I'm just trying to get a general idea on how they compare... We seem to be quite a few canadians on this board... I had already come across the Canadian www.creativesound.ca web site (by the way the shiva has had its price dropped to 169.00$cnd) as well as www.solen.ca (many of the madisound brands) as Dustin is right about brokerage and duties really adding $$ to a project... Thanks... Rob