Moderators isaac42 Posted January 12, 2015 Moderators Share Posted January 12, 2015 Played a gig on the coast last night. Band leader told me it was a very small club, and he'd prefer I not bring a big rig. I have a couple of small cabinets, but they're actually PA cabs, and aren't really tuned for low bass. So, what to do? Short answer: modify an old cab to suit. Sounded great! Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 12, 2015 Author Moderators Share Posted January 12, 2015 Back around 1976 or so, I built some cabinets. A couple of 2x15"s for bass and a 1x15 as a guitar extension cabinet so that I could hear the guitarist on the other side of the stage. Later, I modified the 1x15 to use for bass, but I made it a sealed cabinet. Worked all right, but didn't go really low. No problem, really; most bass cabinets don't go as low as we might think or expect them to. I took that homemade cabinet on tour to Canada and Alaska. Just a box with a driver in it, no wheels, no handles. 24"x24"x18". It's been beat to hell over the years, but it's still pretty solid. ⅝" plywood with ¾" bracing. The driver in it was a JBL 2032H. Great driver for low bass, but needs a much larger cabinet. In my relatively small cab, it was flat down to 80Hz or so, then rolled off smoothly. Solid for the lowest 2nd harmonic, which is usually sufficient. A little bit of bass boost and it was always up to the task. Lately, however, I've been getting into the real low end, wanting that last octave of fundamentals. The bands I play in have liked the results, too. In this band, the leader's been vocal about liking a lot of lows from the bass. So I did some calculating. The cabinet was over 4.5 ft^3, closer to 4 when you take into account the space displaced by the driver. Porting the cabinet with the 2032H in it didn't yield anything like smooth results. But I'm a hoarder. I have 8 or 10 15"s laying around in my pile o' junk. One is a JBL 2205B (reconed to 8 ohms, which would make it a 2205A, if the cone is the right one; mine has a smooth cone, not ribbed, so I don't think it's quite right). Anyway, a 2205 in a 4 ft^3 box tuned to 40 Hz looks really good. I have a few heavy gauge cardboard tubes laying around, so I decided to cut a hole sized for adding a tube later. Turned out that a 3⅝" hole the depth of the baffle tunes the cabinet to around 44 Hz, which is pretty close. Convenient! I opened the cabinet, took out the fiberglass stuffing, and took out the 2032H. Then I cut the hole (after spending an hour or two searching for my hole cutter, which I eventually found in what should have been the first place to look!), attached casters and a handle, installed the 2205, and put it all back together. Forgot to test it, but that turned out to not be an issue. Got to the club, got set up. Sounded good. But once the band started playing, oh man! with the full band, the low end was much more obvious. Solid, not at all boomy. And deep! With the rack rig, which doesn't roll off the lows at all, the low end was as good as any I've ever had. Saweet! Link to comment Share on other sites More sharing options...
Members DeepEnd Posted January 12, 2015 Members Share Posted January 12, 2015 Happy New (Old) Cab Day. I salute your ingenuity. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted January 12, 2015 Members Share Posted January 12, 2015 Back when I first started playing I used to hang around with older musicians. I knew a bass player ( he actually sold me my first good electric) who was always switching gear out. For awhile he used a Hoffner Bass playing through an Altec A7 PA cab using a Traynor head. He used the Horn as well too. The bass sounded great through it. As deep as an SVT with the extended highs. Those cabs have allot of air in them and can produce those lows with their reflex action. On the other hand he sold me a home made cab with the two Traynor 15's he had. The cab was the size of a Traynor 2X15 cab. Well made and all, but it produced pathetically weak lows. The cab was just too shallow to produce good lows. I eventually bought some A7's for a PA and those speakers sounded pretty good in them. I have a Traynor cab now a budding found on the side of the road and gave it to me. I put some good Celestion 15's in it and its got the same issue. Overly compressed bass tones and a lack of bottom end. I thought I might try venting it but I think it would be fruitless. The cab depth needs to be about 18" deep if you want those lows. Guitar will sound great with 12" deep, but bass just needs more air volume and if its tuned, so the speakers resonant frequencies are correct, it can sound massive. Something like this would produce the full sued long waves without folding them into 1/2 or 1/4 sized waves as most cabs do today. These will produce frequencies as low as 75hz at 102db. The question is where would you have the space for these or who would want to move them. You'd need a flatbed truck and fork lift just to get them into the club. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 12, 2015 Author Moderators Share Posted January 12, 2015 I wrote about this same cabinet 8 years ago! http://www.harmonycentral.com/forum/forum/Bass/acapella-17/475231- Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 12, 2015 Author Moderators Share Posted January 12, 2015 WRGKMC, you have a few notions about speakers that I think are mistaken. The depth of the cabinet has no necessary effect on bass production. Your talk about folding waves doesn't even make sense to me. The interior volume of a cabinet makes a big difference on bass production, though, and the depth of a cabinet can make a big difference in the interior volume. Porting your Traynor would likely not yield good results. The drivers in it are probably just not suited to low bass production in a compact cabinet. And Ampeg SVT's aren't particularly good at producing deep bass. They're loud and punchy, but not deep. Link to comment Share on other sites More sharing options...
Members DeepEnd Posted January 13, 2015 Members Share Posted January 13, 2015 . . . On the other hand he sold me a home made cab with the two Traynor 15's he had. The cab was the size of a Traynor 2X15 cab. Well made and all, but it produced pathetically weak lows. The cab was just too shallow to produce good lows. . . . . . . I have a Traynor cab now a budding found on the side of the road and gave it to me. I put some good Celestion 15's in it and its got the same issue. Overly compressed bass tones and a lack of bottom end. I thought I might try venting it but I think it would be fruitless. The cab depth needs to be about 18" deep if you want those lows. . . . As isaac42 pointed out, cabinet volume is much more important than depth. As long as the cab is deep enough to accommodate the speaker, you're fine. I have no idea of the specs of your Traynor 2X15 but let's make some assumptions for grins. Let's say it has an interior volume of about 9,150 cubic inches or about 150 liters. A cabinet with interior dimensions of 35"X22"X12" would qualify. Since you didn't specify, let's take the specs for a Celestion BL15-300X (http://celestion.com/product/35/bl15300x/) and plug them into a Thiele/Small calculator (http://www.micka.de/org/en/index.php#ideal). With a cabinet of 150 liters, we get usable bass response down to about 50 Hz with a mild peak at around 95 Hz, which is pretty good. A 3" (7.6cm) diameter port the depth of the baffle, say .75" (1.9cm), would give a slightly higher peak at about 85 Hz but the usable bass wouldn't change appreciably. As they say, your mileage may vary. A Thiele/Small calculator is a great way to experiment with ports and whatnot without actually cutting up your cab. BTW, here's a pic of an old Traynor 2X15. Is this close to yours? Link to comment Share on other sites More sharing options...
Members WRGKMC Posted January 13, 2015 Members Share Posted January 13, 2015 WRGKMC' date=' you have a few notions about speakers that I think are mistaken. The depth of the cabinet has no necessary effect on bass production. Your talk about folding waves doesn't even make sense to me. The interior volume of a cabinet makes a big difference on bass production, though, and the depth of a cabinet can make a big difference in the interior volume. Porting your Traynor would likely not yield good results. The drivers in it are probably just not suited to low bass production in a compact cabinet. And Ampeg SVT's aren't particularly good at producing deep bass. They're loud and punchy, but not deep.[/quote'] I wasn't being overly technical here. Well I was getting at air volume, which I hoped you would have understood. The Traynor is about the same size as say an Ampeg B52 in height and width except the depth on the Traynor is only say 14" deep at the most, maybe 12" inside. A B52 on the other hand is much deeper so of course there will be more air volume and deeper tones. You can read upon the ability of cabs fold waves on your own. It deals with different types of ports used in speaker cab designs. I'll find you more details on it later when I have time but found this quick bit on Wiki but its not exactly what I meant by smaller cabs being able to fold waves. Transmission line enclosure A perfect transmission line enclosure has an infinitely long line, stuffed with absorbent material such that all the rear radiation of the driver is fully absorbed, down to the lowest frequencies. Theoretically, the vent at the far end could be closed or open with no difference in performance. The density of and material used for the stuffing is critical, as too much stuffing will cause reflections due to back-pressure, whilst insufficient stuffing will allow sound to pass through to the vent. Stuffing often is of different materials and densities, changing as one gets further from the back of the driver's diaphragm. Consequent to the above, practical Transmission Line loudspeakers are not true Transmission Lines, as there is generally output from the vent at the lowest frequencies. They can be thought of as a waveguide in which the structure shifts the phase of the driver's rear output by at least 90°, thereby reinforcing the frequencies near the driver's Fs. Transmission lines tend to be larger than ported enclosures of approximately comparable performance, due to the size and length of the guide required (typically 1/4 the longest wavelength of interest). The design is often described as non-resonant, and some designs are sufficiently stuffed with absorbent material that there is indeed not much output from the line's port. But it is the inherent resonance (typically at 1/4 wavelength) that can enhance the bass response in this type of enclosure, albeit with less absorbent stuffing. Among the first examples of this enclosure design approach were the projects published in Wireless World by Bailey in the early 1970s, and the commercial designs of the now defunct IMF Electronics which received critical acclaim at about the same time. A variation on the transmission line enclosure uses a tapered tube, with the terminus (opening/port) having a smaller area than the throat. The tapering tube can be coiled for lower frequency driver enclosures to reduce the dimensions of the speaker system, resulting in a seashell like appearance. Bose uses similar patented technology on their Wave and Acoustic Waveguide music systems.[10] Numerical simulations by George L. Augspurger and Martin J. King have helped refine the theory and practical design of these systems.[11][12] Tapered quarter-wave pipe[edit] The tapered quarter-wave pipe (TQWP) is an example of a combination of transmission line and horn effects. It is highly regarded by some speaker designers. The concept is that the sound emitted from the rear of the loudspeaker driver is progressively reflected and absorbed along the length of the tapering tube, almost completely preventing internally reflected sound being retransmitted through the cone of the loudspeaker. The lower part of the pipe acts as a horn while the top can be visualised as an extended compression chamber. The entire pipe can also be seen as a tapered transmission line in inverted form. (A traditional tapered transmission line, confusingly also sometimes referred to as a TQWP, has a smaller mouth area than throat area.) Its relatively low adoption in commercial speakers can mostly be attributed to the large resulting dimensions of the speaker produced and the expense of manufacturing a rigid tapering tube. The TQWP is also known as a Voigt pipe and was introduced in 1934 by Paul G. A. H. Voigt, Lowther's original driver designer. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted January 13, 2015 Members Share Posted January 13, 2015 As isaac42 pointed out, cabinet volume is much more important than depth. As long as the cab is deep enough to accommodate the speaker, you're fine. I have no idea of the specs of your Traynor 2X15 but let's make some assumptions for grins. Let's say it has an interior volume of about 9,150 cubic inches or about 150 liters. A cabinet with interior dimensions of 35"X22"X12" would qualify. Since you didn't specify, let's take the specs for a Celestion BL15-300X (http://celestion.com/product/35/bl15300x/) and plug them into a Thiele/Small calculator (http://www.micka.de/org/en/index.php#ideal). With a cabinet of 150 liters, we get usable bass response down to about 50 Hz with a mild peak at around 95 Hz, which is pretty good. As they say, your mileage may vary. A Thiele/Small calculator is a great way to experiment with ports and whatnot without actually cutting up your cab. BTW, here's a pic of an old Traynor 2X15. Is this close to yours? That's the cab, except mines a bit older and missing the front grill cloth frame. Its a pathetic sounding cab even with the pair of 300W Celestion's in there. Has plenty of mids and Sounds fantastic for guitar though. You can skip the basics however. I'm sure you're read dozens of my posts on how to calculate the proper cabinet size to match the speaker resonance if you're building a cab. Today all you have to do is Google up an on line calculator and punch in the speaker specs and it will tell you what you need for cab dimensions/air volume. You can just shift the dimensions and keep the same air volume to get different shapes. My point was I had the cab already and it just sucks for bass tones. I've tried 4l different sets of speakers in it and it sounds anemic as can be for all of them. I suppose I could calculate the volume the cab has and work the problem in reverse to find the best speakers to match it, but I'm not that ambitious. I have 4 other bass cabs I can use and this one is just an extra. Maybe the Traynor heads pump allot more lows. I do remember them sounding very dark. The choice of speakers must be a factor too Link to comment Share on other sites More sharing options...
Members DeepEnd Posted January 14, 2015 Members Share Posted January 14, 2015 That's the cab, except mines a bit older and missing the front grill cloth frame. Its a pathetic sounding cab even with the pair of 300W Celestion's in there. Has plenty of mids and Sounds fantastic for guitar though. . . . . . . I've tried 4l different sets of speakers in it and it sounds anemic as can be for all of them. I suppose I could calculate the volume the cab has and work the problem in reverse to find the best speakers to match it, but I'm not that ambitious. I have 4 other bass cabs I can use and this one is just an extra. Maybe the Traynor heads pump allot more lows. I do remember them sounding very dark. The choice of speakers must be a factor too For grins, I tried parameters for a small number of Eminence and Jensen 15" speakers with a hypothetical 150 liter cab which ought to be similar to yours and they all had usable response (about -3 dB) down to 50 Hz or so, below the fundamental of the A on a bass. One possibility is that those big old cabs sometimes were constructed in such a way that they were essentially two smaller cabs put together with a partition in the middle. Cutting the cab volume in half would reduce the low end and make them sound compressed. Is that the case with yours? As you say, it could also be that Traynor heads were EQed to have more lows. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted January 14, 2015 Members Share Posted January 14, 2015 The cab is much shallower then I thought. Taking into consideration the thickness of the wood. Its about 9" deep inside x 22" wide x 35" tall. That should be about 6930 Sq inches if I remember my math for volume. No separate partitions in this case. Both of my Sunn cabs and EV cabs are double the depth of 18". The EV has a single 18" and a partition like an SVT for a pair of 10's. The single 15" Sun is a folded horn cab so the speaker shoots to the back of the cab before reflecting out. The air volume inside the sealed portion is very small. The cab acts like a horn so the speaker acts more like a high compression horn driver. I have a 300w JBL in there right now but it barely fits in there with its large magnet. Not sure is it really sounds that much better then the stock speaker that used to be in there given the magnet consumes more air space. It dies produce better mids and highs so I left it in there. I only had One JBL anyway so having it in a single 15" cab was the best answer. If I find another to match I may put the pair in my PA cabs and put the lower end 15" back in the cab. I have another Sunn which has 6X12's. Its an oddball with two angled baffles mounted in the back corners of the cab angles about 45 degrees or so. There is an air gap in the center between the two baffles to act as a reflex port. The actual air volume in back of the speakers is small compared to the entire cab size. I wouldn't even begin to try and reverse engineer the dimensions to figure out the actual speakers needed. Just finding the right speaker impedances is a challenge. I believe the cab had 12 ohm speakers which comes out to a 16 ohm cab wired series parallel. I've never had it loaded with 6 matching speakers but it does sound very natural considering its unusual design, and its angled baffels produce a super wide sound dispersion on stage. I just gave up trying to move the thing. Its truly a beast for weight. The EV 18" could actually use a little more air volume. It doesn't sound too bad Bi Amped though. I'm not a big Fan of 18's but the 10's help balance it. Its a straight bass reflex cab with the 3" port at the bottom and does produce the most normal, uncolored lows. I do like the folded Sunn the best. I've used it live and it sounds great out in the audience. I wish I could find another one to match because that would be just right for my preferences. I'd easily dump all the others. Finding another B52 cab would be my next option. I prefer it over an SVT which I also owned for about 10 years. The only reason I got rid of the Ampeg was because I moved from NJ to TX and it was either my record collection or the bass cab when it came to weight in the van. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 14, 2015 Author Moderators Share Posted January 14, 2015 Six 12 ohm drivers in parallel is 2 ohms. The Sunn 612S was wired series-parallel (three series pairs in parallel), which would give you 8 ohms. However, IIRC, they were rated at 6 ohms, not 8, and used 8 ohm drivers. That calculates out to 5.3 ohms, but 6 is close enough. The older 6x12 cabinets from the 60's did use 12 ohm drivers, but they were 48" tall and 30" wide, with a flat baffle. Link to comment Share on other sites More sharing options...
Members DeepEnd Posted January 14, 2015 Members Share Posted January 14, 2015 The cab is much shallower then I thought. Taking into consideration the thickness of the wood. Its about 9" deep inside x 22" wide x 35" tall. That should be about 6930 Sq inches if I remember my math for volume. No separate partitions in this case. . . . 6,930 cubic inches is 113.56 liters. For the Celestion BL15-300X, that gives a slight peak at about 95 Hz and -3 dB at about 54 Hz. With a 3" vent, that gives a slightly higher peak at 90 Hz and -3 dB at about 52 Hz, not worth the effort IMHO. . . . I have another Sunn which has 6X12's. . . . Just finding the right speaker impedances is a challenge. I believe the cab had 12 ohm speakers which comes out to a 16 ohm cab wired series parallel. . . . isaac42 is correct. With 6 X 12 Ohm speakers wired series/parallel, you could have 18 Ohms or 10.67 Ohms but not 16. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted January 14, 2015 Members Share Posted January 14, 2015 Six 12 ohm drivers in parallel is 2 ohms. The Sunn 612S was wired series-parallel (three series pairs in parallel), which would give you 8 ohms. However, IIRC, they were rated at 6 ohms, not 8, and used 8 ohm drivers. That calculates out to 5.3 ohms, but 6 is close enough. The older 6x12 cabinets from the 60's did use 12 ohm drivers, but they were 48" tall and 30" wide, with a flat baffle. My bad. Did the math before my first cup of coffee. You can wire three 12's in series for 36 ohms, then two sets of those in parallel is 18 which is close to 16. I'm not real sure what was in that cab because it had some speakers missing when I got it. I found the 4 original speakers in there read 11 ohms on the ohm meter. There was one with a open coil and one missing so I couldn't measure those. I had a couple of 8 ohms I wired in with the 11 ohm speakers to get 15 ohms. I know the original owner and he didn't swap anything around other then to remove the bad ones and abandoned it when he found he couldn't find any 12 ohms to replace them. I believe this was the cab, but for some reason I seem to remember an air gap in the middle. I don't remember the corner blocks between the sets of speakers either, but maybe I need to look at it again. I've had it in storage for several years. http://s141.photobucket.com/user/great_sscott/media/6x1202.jpg.html Its hard to find info on the older Sunn amps. I do know its a bass cab though not the flat front guitar/keyboard version. He used the 1982 Coliseum 300 on the cab. http://music-electronics-forum.com/attachments/2687d1215064307-sunn3.jpg He offered to sell me the head later after I had repaired and refurbished it for $150 but I didn't have the cash and he sold it to someone else. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 15, 2015 Author Moderators Share Posted January 15, 2015 6,930 cubic inches is 113.56 liters. For the Celestion BL15-300X, that gives a slight peak at about 95 Hz and -3 dB at about 54 Hz. With a 3" vent, that gives a slightly higher peak at 90 Hz and -3 dB at about 52 Hz, not worth the effort IMHO. isaac42 is correct. With 6 X 12 Ohm speakers wired series/parallel, you could have 18 Ohms or 10.67 Ohms but not 16. Oops. 10.67 vice 8. My bad. Although 18 is close enough to 16 for all practical purposes. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 15, 2015 Author Moderators Share Posted January 15, 2015 My bad. Did the math before my first cup of coffee. You can wire three 12's in series for 36 ohms, then two sets of those in parallel is 18 which is close to 16. I'm not real sure what was in that cab because it had some speakers missing when I got it. I found the 4 original speakers in there read 11 ohms on the ohm meter. There was one with a open coil and one missing so I couldn't measure those. I had a couple of 8 ohms I wired in with the 11 ohm speakers to get 15 ohms. I know the original owner and he didn't swap anything around other then to remove the bad ones and abandoned it when he found he couldn't find any 12 ohms to replace them. I believe this was the cab, but for some reason I seem to remember an air gap in the middle. I don't remember the corner blocks between the sets of speakers either, but maybe I need to look at it again. I've had it in storage for several years. http://s141.photobucket.com/user/great_sscott/media/6x1202.jpg.html Its hard to find info on the older Sunn amps. I do know its a bass cab though not the flat front guitar/keyboard version. He used the 1982 Coliseum 300 on the cab. http://music-electronics-forum.com/attachments/2687d1215064307-sunn3.jpg He offered to sell me the head later after I had repaired and refurbished it for $150 but I didn't have the cash and he sold it to someone else. Not necessarily. FWIW, I'm a bit Sunn fan, and know a bit of Sunn history. This site is a good place to get Sunn info: http://sunnforum.ampage.org/index.php/board,1.0.html The 612S came out during Sunn's "mix'n'match" period. Amps and cabinets were all available separately, and could be used for whatever the used wanted. In general, though, the cabs with 12"s were used for guitar. The flat front 6x12 cabinet which came with the 1200S amplifier, both designed for guitar. If you want info on old Sunn amps, go to that site, or just ask me. If I don't know, I know where to look or who to ask. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted January 16, 2015 Members Share Posted January 16, 2015 Using two 8's and the rest 12's I was able to get a few different ohm ratings out of the cab. The problem with some of those wiring configs was with the Speakers DB levels I found the best results with one 8 and 2 12 ohms in series vs having three sets in series and paralleling the three sets. Anyway, I did like the sound of the cab but a few of the speakers were flappy with bass. I pulled the speakers out and put 4 in the Peavey 4X12 and another 2X12 cab I have. The speakers are still good enough for guitar even with the surround repairs I've done. Some of the cones were beginning to crack so I repaired them. If I ever pull the Sunn cab out of storage, I'd likely get some good budget speakers to put in it. Link to comment Share on other sites More sharing options...
Members Mr Temporary Posted January 17, 2015 Members Share Posted January 17, 2015 While we're posting pictures of cabs that are too damn big and heavy to use, I thought I'd post one of mine. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted January 17, 2015 Author Moderators Share Posted January 17, 2015 Were we posting pictures? Lately I've been playing through a Sunn Model 215. Sometimes the Model 215 on one side of the stage, and a Model 410H on my side. The 215 is the cabinet the bandleader said was too large, though it would have fit just fine where the new/old cabinet went. It's footprint is only slightly larger. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted March 10, 2015 Author Moderators Share Posted March 10, 2015 Weird. I opened the cabinet yesterday to pull the 2205 and replace it with a K140, only to find that it was actually a 2220. The 2220 is a high efficiency driver, though rather different from the 2032. Anyway, the K140 should sound pretty good. I'll find out this weekend. Link to comment Share on other sites More sharing options...
Moderators isaac42 Posted March 16, 2015 Author Moderators Share Posted March 16, 2015 K140 was sweet. There are lots of good, even great drivers out there, but I don't know of anybody making any like those old JBLs. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted March 16, 2015 Members Share Posted March 16, 2015 Some of the new speakers aren't bad but they don't hold a candle to the quality of some of the older JBL and Altec builds. Link to comment Share on other sites More sharing options...
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