Marvel

Hi all, Still working on this project, just have other projects in front of it for a while. I have two more questions for those who are far more knowledgeable than myself. The LS horn flare isn't very smooth at all (I know, it was an industrial speaker first). After the initial flare (left and right) the horn stays the same as it comes toward the front (about 7 1/2 inches). Then it flares again, to the the mouth. I figured up the area for these three different sections, and figured out I could have the flare be more constant (or continuous at least) when I build them. As TBrennan says, he thinks they will go high enough to then cross at 500Hz anyway, but would this help out any? Someone had mentioned that adding the corner reflectors caused some funny output in the upper end, but this might be a better solution. Couldn't do what I have in mind on a stock LS, but these are starting from the ground up. Also figured I could make the cabinet just enough wider to make those side parts be 3 inches across instead of 2 3/4. Perhaps I will make these and run some tests, before I get the mid/hi horns. The other is the wood I was going to use. What I had thought was birch that I had purchased before, turned out to be 'golden virola' a wood from South America. It has very clean grain, and has nine (count 'em: nine) plies. all the same wood. It is used for cabinet making and furniture, but wondered if anyone here has used it before. The birch here is running around $44 a sheet, while the virola is only $34 right now. Thanks for the input, Marvel BTW, I got to hear John Albright's LaScalas a few weeks go. Sweet! Took over a David "Fathead" Newman CD of Duke Ellington songs. Sounded like they were playing in the room. ================= After reading some of DJKs old posts on another forum, I realized the reason for the two different flare rates on the LS. Still wonder about the sides remaining constant. This message has been edited by Marvel on 10-16-2001 at 07:49 AM

Maybe just have some of Handel's 'Water Music' on hand! I know there are a lot of variables in any speaker, and magnet size is just one. My son worked at a movie theater that had those JBL compression drivers that weighs in around 30lbs. They will empty your wallet quicker than anything. Marvel

A 30 ounce magnet for the sub. It is funny how things change. My old JBL 4311 Studio Monitors have a 25 ounce magnet on the tweeter. The woofer has a 6.5 pound magnet. How is the amp cooled? Some subs have amp compnents inside the cabinet, and actually use air flow through the port to help cool the amp. Marvel

djk, You are a hoot! Slon, Pay close attention to what djk says. He KNOWS pro audio very well. He may sound opinionated (who isn't?), but he does know his stuff. Most people on this forum (wonderful, caring, helpful), are in this for home use. It is a whole other ball game when you move to PA use. I used some home built LS cabinets for PA use once, and they were made by djk. They rocked, but I also only used them within their limits. Actually, I never pushed them very hard at all. They sure weren't stock either. You want to use them in an 11' by 15' rehearsal space? Watch out for open mics. Almost lost my hearing once with feedback doing a small room like that. (That was from some EV Eliminators from djk. The horns ARE efficient.

gjp60, I'm pretty new here also, but am working on building a pair of LS bass cabinets with the generous help of those on this forum. I am attaching a jpg of the top view of the LS cabinet (just the bass part), with two possible mods. The original drawing was done by Tony Reed, another member here. The part in red, is the addition of two vertical corner reflectors, the idea of which is to help extend the upper bass response by smoothing out the air flow from the cabinet. The part in blue, was an idea that Gil McDermott was using to brace the side of some other cabinets he was building. It would sorta add a shelf in the mouth of the horn. I only drew one side, but it should be on both. this would keep the sides from vibrating. John Albright showed me a photo from Gil that had this done. John has said that certain male vocals cause the sides on his LS cabinets to vibrate a lot. If you notice from the drawing, the sides only have an opening of 2 3/4 inches, while the back is 3 inches. This makes the flare of the horn actually get smaller again. Tony measured more than one factory set of LS and found them to be the same. It doesn't appear to hurt the sound any. The only reason I have figured out is when laying out the dimensions on plywood, if the cabinets were wide enough to get the 3 inches on the side, I couldn't fit the pieces on one sheet of ply. No matter what, it will take three sheets just to build the bass boxes. My mid/hi horns will be separate. Hope this helps. Marvel This message has been edited by Marvel on 09-29-2001 at 09:04 AM

If you were to use a small piece of window screen (I'm thinking of the vinyl kind) on the end on the vacumm hose, so that it looks like a vegetable strainer in miniature, this would keep you from sucking the cap clear off. It would provide a limit as to how far the cap would come out. Don't know if what I'm saying makes sense, but I have it pictured in my head (very dangerous place). Marvel

My wife and I went to the opener of the Chattanooga Symphony & Opera this past Friday. The were doing a mostly Beethoven concert. Little did I know that they always open the season with the Star Spangled Banner. The theatre was packed, with probably fewer than twenty seats open. I couldn't sing I was so overwhelmed with emotion. They followed with America the Beautiful. I was devastated. Marvel BTW, while coming back from Atlanta on Sunday, a car passed us, full of folks who appeared to be from the Middle East. The passenger on the right side of the car was holding a small American flag out the window. They are in my prayers, as they looked scared.

johnny24c, I'm sure Trey could help, but it sounds like you have a 70volt transformer on your speaker. This is used in many commercial settings to adjust levels of different speakers. The different taps would be to adjust the levels. This makes it easier for a commercial installer to calculate the load on the amp. Who want to figure out how to add ten 8 ohm speakers on to a system? Works a lot like the transformer on the LaScala, used to adjust the squawker level. They wouldn't be used in normal systems. Marvel This message has been edited by Marvel on 09-22-2001 at 09:35 AM

Mike, There were actually albums produced that utilized DBX encoding. Many people liked it better than Dolby for tapes too, but you couldn't do that on vinyl. I think the DBX used a set compression/decompression ratio, unlike Dolby Labs having it vary depending on signal level and other criteria. The records generally played back with no surface or background noise. TEAC still uses DBX on their multitrack analog tape recorders. Marvel

I have started to write something all week, but haven't been able to get down in a short space all that is on my mind. How could I? It has been interesting where I work, a small Presbyterian college. I'm the only Catholic there, and I often find myself in sharp disagreement over matters of religion. If Christians can argue and disagree, what can we then make of all the world's religions? We can all be wrong, but we can't all be right. But right now, being right or wrong about our faith is not the issue. This nation is full of people of all faiths, Christian, Muslim, Jew, Hindu,... There are athiests, moralists, deists, ... And all of the varieties in each of those. We are human beings, created in God's image, trying to interact with the world around us, and right now, we are all hurting. Has the U.S. had the best foreign policy or always acted with the best intentions in the world? I think we would be wrong to say we are without sin (moral, ecological, business, political, whatever). But I for one, wouldn't want to live or be from anywhere else. So now we declare war on terrorism. That is about as vague a target as the war on poverty, and it didn't work. I am praying that our leaders will have wisdom, that our fellow citizens will have wisdom ... and compassion, mercy and forgiveness. I have a 30 mile drive to and from work. Not a day has passed that I have not wept as I have made that drive. Should something be done? Yes, but I pray it is the right, whatever it is. Marvel

I bought an ST-120 (solid state) and an ST-70 (tube) from an acqaintance around 25 years ago. I liked the ST-120, but sold it to another friend. I only paid about $60 for it then. I still have the ST-70 (paid $50 for it). It still has the original parts. It is finally getting upgraded. We have TVA power here, and a solid 125 volts coming out of the wall. I'm afraid it will just go up in smoke if I don't change out some parts. The ST-120 may have been the worst ever SS amp, but hey, if you like the sound and it isn't going to die and blow something, why not pick it up? Marvel

Lag, The idea of fiber handling higher data rates than Cat5e is not warranted. Multimode fiber can only handle 1 gigabit. Single mode probably goes higher, but most folks only deal with multimode. That is the cable most network cards use. One cable for transmit and another for receive, and they come paired together. But you are correct in that the short lengths used in a home wouldn't require exceptional cable. My ADAT can transfer eight 20 bit tracks at one time over the little fiber cable that came with it. NO degradation noticed. Marvel

If you search through the Audio Asylum files, you will find a post by DJK (who posts a lot here also). He put forth a mod for LaScalas that meant closing in the top part of the cabinet, making an opening from the sealed woofer enclosure into that, stuffing it with fiberglass and porting it. It kept the stock K-33E speaker, and gave you more bottom end out of the cabinet. He didn't say what size the ports should be. I think it pretty much doubles the internal volume off the sealed enclosure. I had calculated the volume recently, but I'm at work and not at home. Of course, you wouldn't want to do that to a brand new cabinet. If you didn't mind the added height, it would be easier to add on to the bottom of the cabinet since it already has an access point for the woofer. If djk has more info on that, I'm doing some drawings that I will post on my web site (no, it's not there yet. Only pages for my church) I am doing them in Caligari TrueSpace 4.3. I also want to post all the LaScala drawings I've collected from different people (if they don't mind). I'm still looking for the right plywood to use. Our local Home Depot had 9 ply birch, with almost all plys the same thickness. It was really nice and only $36 a sheet. When I went back to get some for this, they only had 7 ply available. Cheers, Marvel

Ya gotta love it. I have been doing audio editing at home on my PC. Bouncing tracks off the ADAT so I can do looping,etc. Haven't been able to afford great cables yet, but the same thing applies. I had very inexpensive 1/8" to two RCAs. They picked up no end of noise. Lots of RF around the PC to be picked up, that's for sure. I bought newer Radio Shack versions. THey are way heavier (not just the insulation) and the noise went away. Many older Radio Shack cables (interconnects) if you cut them open, don't have braid for the shielding, but wire that is twisted around the outside. Braid gives better shielding, and cable by Belden (or other similar type) with a foil shield and drain wire, will do even better. the connectors tend to be a real problem also. Almost all of the newer cables from Radio Shack, Wal-Mart, K-Mart, Lowe's, etc., are made in China. GE has some that cost too much for what they are. But good wires make a difference. This message has been edited by Marvel on 09-01-2001 at 01:08 PM

The DE45 has a 1 inch throat, but the RF7 says it is 1 3/4 inch. That doesn't make them look the same.

uh, Ray, Thanks for the refresher. I went back to my notebooks and of couse, you are correct. That's what I get for sending this from my office when I should be working. My memory only brought part of that back correctly. I have been trying to explain to my kids (aaghhh!!! They're young adults now), that almost everything in math has to do with ratios. I apologize for my error. Marvel

A drawing forwarded to me by Gil (many thanks), for the LaScala bottom, has reflectors in the back corners. I don't know if this is a mod or not, but thought they made sense. There was a link to those on the site, but it no longer functions. Would it help the response to have all those coners rounded? Getting the high end bumped up a bit out of the bass cabinet would certainly make it easier to find a useable mid horn. Is the stock LaScala mid horn driver still made by Atlas? I would also assume that the price from Klipsch is still reasonable. Are the Selenium drivers worth looking at or should I stick with the Klipsch or JBL drivers? Perhaps I should just get the bottoms done and see what the response is coming out of them. As far as PA use, most of it is strictly voice, speakers at conferences, or acoustic music. I think djk built his for some pretty hard core rock.

djk -- Shows you what I remember. They were, how should I say it, rather bright in a small room. I don't have a problem making them three-ways, so I'll probably go ahead and get the mid from Klipsch, unles someone knows of another mid horn driver that will work. For sure, most don't go down to 400Hz. This is more fun than stacking BBs is a corner. Bruce This message has been edited by Marvel on 08-27-2001 at 04:05 PM

djk -- Are you saying you used the KSN1016 as a tweeter along with the mid horn? I don't remember those being but a two way. Those are piezos aren't they? Bruce

Most preamp outputs for consumer gear are all high impedance and unbalanced. This causes the high end to pretty much short to ground due to the cable capacitance in a long cable run. For example, microphones use balanced lines, a ground with pos/neg voltage leads. You can run them hundreds of feet with no degradation in signal quality. Plus, emf and such that hits the cable run (for instance, crossing 60Hz AC wiring), gets cancelled out because of the two out of phase lines picking up the same signal. You could pick up some audio transformers and make the preamp have balanced outs, and reverse it on the other end, but good ones cost a bit of money. If you are using large gauge speaker cable, a long run isn't really too bad.

Randy, I emailed Eminence and asked for the specs on the K-33. This is what they sent back to me. SPEC 15162 PART # K-33 RE OHMS 3.39 LE MH .96 QM 7.39 QE .410 QT .390 XMAX MM 8.20 BL TM 11.88 EFF % 2.91 FS HZ 34.46 MMS GMS 78.59 CMS mm/N .2714 RMS NS/M 2.3037 VAS LTRS 301.66 SD SCM 889.59 EBP 84.4 SPL dB 96.6 Wattage 150rms

Chris, Here is another thing to consider. If you put fans at the bottom, to pull air into the cabinet, make a provision for some kind of air filter material. This way, you have positive air pressure in the cabinet, and will have air coming out around all the gaps, glass doors, etc. If you have fans at the top, sucking air out, that air will come through all of those same gaps, pulling dust into the cabinet. At the college where I work doing computer support, our grounds dept. had a computer that you could actually dump dirt out of when you opened it up. We had the carpentry shop build a cabinet for it, with a slot in the back to run cables out, with a fan/filter pushing air in. After months of running, there is almost no dust in the computer (or cabinet). We just used air filter material and have a clip of some kind to hold it over the fan (it is hidden in back, so it didn't have to be super neat). This way neither the front door to the cabinet nor the slot for cables had to be sealed. Most computers only have the fan in the power supply, pulling air through the computer case and exhausting out the back, creating negative air pressure in the case. They pull dust into the floppy drive and case, causing buildup on the cpu and other boards. Not very healthy for them at all. Bruce

A 1db increase is usually the smallest amount the ear can detect. A 3db increase is a doubling in volume but requires a ten times increase in power. So if you are cranking at 10 watts, to make it twice as loud would require 100 watts. The next step would be 200 watts. Some of this is also freq. dependent. Lower freq. require more than treble. That's why a large amp is sometimes required just for the headroom on the bass endeven though it won't seem louder.

Curious about different drivers. What is the response of the horn/bass cabinet with the K-33 driver in it. The crossover is stated to be at 500Hz, but most of the compression drivers I've seen are stated to have the crossover point be 700/800 Hz. In building these, I'm not looking to make an exact clone of a La Scala, but a two way that has the bass cab as close to genuine, the mid/hi horn can be anything else that is not too pricey. I realize it is a tradeoff, no matter what you do. DJK told me he had used an EV compression driver, but looking at their web site, if it is still the same model, where did all that great high end come from (it is a siren driver)? How about the Eminence PSD 3003 driver? The price for a new one is still not too outrageous. Or would the JBLs be better? Or does this just get into personal preference? How about making a tractrix horn? That really doesn't look to be too hard if you have the measurements. Since I will also on occasion use these for PA work (couple times a year), I want something pretty portable, hence the separate bottom cabinet. BTW, the specs for the K33 are listed below. Does anyone else make a woofer that would work in the cabinet without a major redesign? Be hard to beat the price for the K33 though. SPEC 15162 PART # K-33 RE OHMS 3.39 LE MH .96 QM 7.39 QE .410 QT .390 XMAX MM 8.20 BL TM 11.88 EFF % 2.91 FS HZ 34.46 MMS GMS 78.59 CMS mm/N .2714 RMS NS/M 2.3037 VAS LTRS 301.66 SD SCM 889.59 EBP 84.4 SPL dB 96.6 Wattage 150rms Again, thanks for the great response from you guys. Got some other things to buy and work on first (a video editing project), but this project WILL get started some day. Bruce This message has been edited by Marvel on 08-25-2001 at 12:03 PM

Thanks to the post from djk, and the help from some friends who have great woodshops and tools, I'm not afraid to tackle this. I do have an offer to buy some used ones (87s, with some mods along the way) for a price lower than I could build them. I still want to make ones with separate bass horns. This is what djk did with the multitude he made a few years ago. Found out I had used a pair, borrowed by his brother. They sounded great, and were easy to move around (P.A. use) with the parts separate. Time will tell. JBEK, if you have the plans, feel free to email them to me. And Gil, your plans seem pretty close to the mark from what else I've seen.