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power amp questions [message #2312] Mon, 06 January 2003 09:10 Anonymous I know its a matter of perception..but I'm really struggling here... many of you know I run my small band PA consisting of a pair of 3x15 sirens for my mains, and a pair of 2x15 bass cabs for my subs. the siren cabs have the original heavey Jensons in them and they are not the issue..its my bass cabs.. I have them loaded with eminence 150 watt rms each drivers and I like the tone...in the past, as a matter of budget I've powered these cabs with original kustom 400 amps throwing 100wattsrms per side at the 4 ohms. I've been impressed with the amount of punch I get from those amps...I've tried rigs like PV power rated at over twice the rms and the result was a mushier bottom...the kustoms just seemed tighter...I borrowed a new Macike 1400 power amp for this past weekend..and yeah...there is a diff hitting those cabs with 450rms per side in terms of volume and a bit more chest thump..but I swear I was expecting significant difference...and it really wasn't there.. I'm guessing its more about my speakers and the cabs... I was shoulder to shoulder with a DJ system running a pair of PV black wido loaded 2x15 cabs..he was hitting them with a PV2000 amp and he could go places I can't...that's ok cause I really don't need that kind of sound pressure...but I swear, I'm not sure the Mackie is worth the money.. I'd like to try a QSC1400...they're cheaper...but even at that... I'm not sure I've got a reason to stop running my 400s.other than the rackability...can someone smarter than me (that's most of ya'll)...tell me what it is about the kustom amps that makes them sound tighter, punchier...and since I'm not able to go up to say an Eminence KAppa pro series (the kustom mounting posts are too short to make it through the speaker frame ) so I don't see me changing out my speakers...I"m using an nice AShley 3 way/sub electronic crossover which really lets me find the sweat spot in the cabs...I just think I'm looking at a whole different game to get into massive wattage solutions to get more bass...anyway.. as always I'm rambling...my whole point is really to say that 30 years on, I'm still way impressed with what comes out of my kustom amps..I've read the whole input voltage from signal source, dampening ratings...and the effect of planetary alignment on amp rms ratings...in the end..my ears and chest are still hearing good things from my tuck n roll...somebody 'splain it to me...ET Report message to a moderator

Re: power amp questions [message #2313 is a reply to message #2312] Mon, 06 January 2003 12:55   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member The problem not your speakers or power amps you have tried, but the cabinets them selves.Those original kustom cabs where small for two 15s, thats why I think the latter 69 and 70 cabs did away with the slanted front, they made it straigth to get more cab internal volume. The new but resently discontinuted kustoms from HHI inc where about 1.5' taller still, compared to my originals, for the same reason more and lower bass responce.As you drive your speakers with more watts ,even though they can take it the cab does not have the air volume to match that much speaker cone movement.Remember if you where using two 15s and wanted to double your bass output, you could add two more speakers or you would have to quaduple your wattage. Hope this helps guys. Report message to a moderator

Re: power amp questions [message #2319 is a reply to message #2313] Tue, 07 January 2003 01:11 KustomBlues Messages: 490 Registered: June 2001 Location: Michigan Senior Member Et, make a new back (just the wood, no vinyl necessary to experiment) for your cab and cut a 3" hole in the bottom corner area of the cab. It will allow for some more venting. If necessary, make the hole bigger. Let me know what you think. Report message to a moderator

Re: power amp questions [message #2321 is a reply to message #2319] Tue, 07 January 2003 07:52   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member If you wnt to try added venting, go on line to parts plus and order a vent tube that is bigger on the ID size than the OD size of the tube in the cab now. use clear silicone to mount it to the old tube, cut its length so that it is no closer than 6" os so to the back of the cab. The stock port tube suffers from air sheering because the stock port tube has no radius leading into the port, this extention will cure that. On my cabs when I measuered the difference, A/B them it was worth a 2DB gain in output. Thas a difference you will hear in low freq responce. Report message to a moderator

Re: power amp questions [message #2324 is a reply to message #2321] Tue, 07 January 2003 10:59 Anonymous great advice all...see , I knew someone would have the edge up on this....I do like the excuse of having a reason to get 2 more 2x15 cabs....but I guess I'll try getting some more air into these for now....budget ya know....ET Report message to a moderator

Re: power amp questions [message #2325 is a reply to message #2312] Tue, 07 January 2003 12:42   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member Sorry, I forgot. If you go to a auto parts store get some permatex or similar brand radiator repair epxoie, its a clay like epoxie. Get 2 or 3 packs of it, and use it to make a smooth transition from the larger new inner port tube to the original kustom tube. Report message to a moderator

Re: power amp questions [message #2327 is a reply to message #2325] Tue, 07 January 2003 15:54   RoyC Messages: 97 Registered: April 2000 Location: East Central Illinois Member How would it work to use a hard rubber hose (like non-pleat radiator hose or ridgid pump suction hose) held on by a simple worm-screw type hose clamp? Report message to a moderator

Re: power amp questions [message #2330 is a reply to message #2327] Tue, 07 January 2003 23:55 KustomBlues Messages: 490 Registered: June 2001 Location: Michigan Senior Member Roy, I think that idea tells me you must be a Tim the tool man Taylor, or a farmer :-) Which is it? Ha ha :-) Report message to a moderator

Re: power amp questions [message #2331 is a reply to message #2330] Wed, 08 January 2003 07:49   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member The main reason for the added airflow, and in turn lower frequency responce and incresed DB output, is the radius on the inlet side of the extention tube I recommended adding from parts plus. If you have some idea of how you can get at least a 3/4" radius inlet on the hose, then have at it! Report message to a moderator

Re: power amp questions [message #2333 is a reply to message #2331] Wed, 08 January 2003 15:40   RoyC Messages: 97 Registered: April 2000 Location: East Central Illinois Member Can't blame a guy for wanting to save a buck ..... :D Report message to a moderator

Re: power amp questions [message #2335 is a reply to message #2333] Thu, 09 January 2003 19:42 KustomBlues Messages: 490 Registered: June 2001 Location: Michigan Senior Member You just want to have more $ to buy more Kustoms, that's all. Nothing wrong with that Roy! :-) Report message to a moderator

Re: power amp questions [message #2481 is a reply to message #2312] Tue, 25 February 2003 00:16 Bill Messages: 64 Registered: March 2002 Location: Kansas Member Not wanting to risk ruining my 2x15 JBL cabinet with the following experiment, this is what I did to my homemade 2x15 Kustom wannabe (loaded with Carvin PS15's) cabinet to get it to throw more lows..... I built a 5 inch deep extension insert which lays inside the original cab one inch. The original back screws into the insert just as it did on the original cab. The port tubes are 12 inches, with the overall cab depth 19 inches now. Anyway, the idea of this endeavor was to come up with something that could be added to a normal cabinet, and be removed if it didn't work out, with out ruining a nice Kustom cabinet. It is on the back of the amp, so it is not really noticeable, unless a Kustom Krazy should happens by, and wonders what the deal is. By the way, I will be playing in Chanute next Saturday, with a pair of K200 amps. Thrill Bill Report message to a moderator

Re: power amp questions [message #2484 is a reply to message #2312] Tue, 25 February 2003 08:02   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member Hi. Your basic problem at this point is the 2-15 cabs, they need to be alot bigger internal volume wise than they are for those speakers.One thing you might try would be to remove the wheels from the bottom and let the cabs coulple to the floor this will provide some level of improved low end.You can get wheels from parts plus that are the kustom style but are removable and load into a socket installed in the cab bottom.The larger wattage power amps you have tryed may be putting out more bass than the kustoms, depending on their power supply design, but your cabs cant give any more.A better A/B check at this point might be to run your kustom rig through better bass bins and then check the diff from you kustom amps and other power amps. Some new power amps, as you have noted just do not have the kick not matter how much wattage they have. Their distortion specs are great, they put out the goods due to their power supply.You might be better off making new baffel boards and putting in 18 inchers if they can be made to fit( you may have to front load them)but at least they would have more of the needed cab volume to work better than the 15s are now.You could even change the internal design of the cab to a folded horn loaded cab instead or the ported style it is now.That would for sure bring up the low end kick. Report message to a moderator

Re: power amp questions [message #2485 is a reply to message #2484] Thu, 27 February 2003 10:56 Anonymous thanks again for the input guys..my 2x15s are not mint...but only a bit rough around the lower edges and look great on stage...I have to give em credit they do well for most every gig our band plays.. I just remember seeing rigs like little 1x15 PV cabs..not big ones..but loaded with a single black widow getting slammed with high wattage and it would slap my chest big time..I don't think it had as much coverage or throw as my old cabs..but it was tighter and punchier and I figure a big part of that is the higher wattage..and with the PV cab not really affording much air space I'm wondering how much diff a set of really hi watt speakers powered with a ton of wattage would do..but then I tried loading an EMinence Kappa400 in my cab...but the speaker's rim is so thick that the mounting bolts on my kustom baffle aren't long enough to go all the way through! so I backed down to my good old 150 rms drivers. I guess these ol gals will hang with me for the next few years that I have of viability on stage...after that I'll be happy just to be a sideman guitar player and my kustom PA will retire to mystudio where late at night I'll drop an old Joe Cocker Mad Dogs CD on the system and throttle up my tuck n roll stereo Report message to a moderator

Re: power amp questions [message #2486 is a reply to message #2485] Thu, 27 February 2003 12:42   stevem Messages: 4733 Registered: June 2004 Location: NY Senior Member Hey! I forgot. Here is a posibilty for you.Eminence has come out with a 12 driver that I saw in the new parts plus catalog. They say that two of them will replace 6 to 8!! 18 inchers. The cone travel rating is huge on them. You could make a adpter baffel to bolt on the baffel now.They only handle 200 RMS, but even if they have more punch than 4 18 inchers thatsb alot of kick! Report message to a moderator

Re: power amp questions [message #2487 is a reply to message #2486] Fri, 28 February 2003 13:25 Anonymous pretty bold claims... I gotta think they are going for the aural perception factor that I am struggling with...that ability to "smack" your chest with bass. Hopefully they'll come out with a similar driver in the 15 size and I can just do a straight replace....or hey...maybe I can make some custom kustom cabs for single 12s to stack on top of my 2x15s...naw..too much trouble..everybody'd want some and I'd have to go into business for myself making them..I mean..think about it..spending all day creating cool tuck n roll rigs...when I could be sitting at my desk stuck in this crappy job....I suppose some bass player in the bunch will try those new speakers in the little 2x12 cabs.. I only have two of those cabs right now and they are dedicated to guitar.. I'd have to buy more cabs to load the emi's in ...gee..wonder what's on ebay.....best go lool.. Report message to a moderator

Re: power amp questions [message #2488 is a reply to message #2487] Fri, 28 February 2003 16:29 C4ster Messages: 686 Registered: June 2001 Location: Mukwonago, WI (Milwaukee... Senior Member Well, here goes my 2 cents worth. I know the anti JBL contingent will be out but I have 2 E140's in a 3x15 siren cabinet and I have 2 cabs on either side of the stage. By themselves they give the kick you are looking for. The E's are very tight with a 100 dB sound pressure level measured at 1 meter with a 1 watt input. That isn't too bad. Also the 140's have a frequency range of 40-2500 Hz. These are in the siren cabs so I have more internal volume than the 2x15 cabs. I think that helps the frequency response and projection. The only problem is I need to cover the high bass region before I cross over to the horns. I have 4x12 columns with JBL E120's and the horns have to do very little work. I hit the cabs with 1100 watts on the 15's and 800 on the 12's. The sound is quite good. The 12's have excellent clarity. The only drawback to the system is the price of the speakers. I probibly spent $1000 on all of the speakers alone. Plus I had to recone 2 E140's because the knob who sold them to me, didn't know how to pack them. I should have sent them right back and demanded my money. Oh well, live and learn. Conrad Report message to a moderator

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