Dev R Posted July 23, 2023 Share Posted July 23, 2023 Hi. I am building my own 2 x10" bass cab and used the WinISD programme to design it. I am using 2 x Celestion BN10-300X watts speakers at 8ohms each wired in parallel making the cab 600 watts in total at 4 ohms. My question is, What compression tweeter and crossover unit should I put in my cab to match? Do I need to buy a tweeter that is rated 4 ohms and 600 watts? The same question with the crossover unit. I see a lot of tweeters and crossover units on the market that all seem to be rated at 8 ohms. I will be powering the speakers through a Markbass amp at 500 watts. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 23, 2023 Share Posted July 23, 2023 With bass cabs I use the Eminence BGH25-8. It's rated at 25 watts, because that's all there is above 2kHz with 500 watts program. There are few, if any, off the shelf 4 ohm crossovers, but off the shelf crossovers aren't very good. I design my own. This is an 8 ohm 2kHz 4th order high pass filter, which you can't buy from anywhere in the UK. The capacitors are poly or mylar, rated for at least 100 volts. The coils are air core, of the smallest available wire gauge with no more than 0.5 ohms DCR. A plus/minus 10% tolerance of the component values is permissible. This is a 4 ohm 2kHz 2nd order low pass filter. The capacitor is a non-polar electrolytic (NPE), rated for at least 50 volts. The coil may be solid or air core; what’s critical is that the DCR (resistance) of the coil for a 4 ohm system be less than 0.2 ohms. A plus/minus 10% tolerance of the component values is permissible. Being 4 ohms you can't buy one of these either. I always build my filters on separate boards, it's too easy to get confused with the layout and wiring putting them on the same board. 3 2 Quote Link to comment Share on other sites More sharing options...
Dev R Posted July 24, 2023 Author Share Posted July 24, 2023 Thank you very much Bill for answering my question. Great stuff. I will now look into obtaining all the components needed. Quote Link to comment Share on other sites More sharing options...
Dev R Posted July 24, 2023 Author Share Posted July 24, 2023 Hi Bill. So you wouldn't recommend an off the shelf crossover like this example? Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 24, 2023 Share Posted July 24, 2023 That only has a 2nd order high pass, which is totally inadequate. 3rd order is the minimum acceptable for pro use. The 4th order I use reduces the power to the tweeter an octave below the knee frequency by an additional 12dB compared to a 2nd order. That makes the difference between clean and distorted, as well as between functioning and blown. 1 Quote Link to comment Share on other sites More sharing options...
Dev R Posted July 24, 2023 Author Share Posted July 24, 2023 Thank you once again. I will use the same design and components you have given me above for the crossover! Cheers Bill Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted July 25, 2023 Share Posted July 25, 2023 @Bill Fitzmaurice Y'know Bill, I have been reading your posts both here and the dreaded TalkBass for many years. I, for one, appreciate the time and effort you invest to help folks with their loudspeaker problems. Thank you sir for what you do. 5 Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 25, 2023 Share Posted July 25, 2023 Aside from playing golf I've nothing else to do. 😄 1 5 Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted July 26, 2023 Share Posted July 26, 2023 23 hours ago, Bill Fitzmaurice said: Aside from playing golf I've nothing else to do. 😄 Take up fishing. I find it a great way to while away my twilight years. 1 Quote Link to comment Share on other sites More sharing options...
Dev R Posted July 28, 2023 Author Share Posted July 28, 2023 Hi Bill. Just about to order the parts for the crossovers. Would you recommend an L-Pad Attenuator to go with this build or not? And one more question. Is it right that you have to wire one speaker (tweeter) backwards (+ to -) because of 180 degree phase shifting? Thanks Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted July 30, 2023 Share Posted July 30, 2023 The LPad can't hurt, but since you have dual woofers at 4 ohms that will even things out a bit. You usually have to reverse wire the tweeter with a 2nd order/2nd order crossover, another reason why I never use them. But it doesn't hurt to run a 2kHz tone through the system before you button it up, trying the tweeter wiring both ways, going with whichever is louder if there is any difference. 1 Quote Link to comment Share on other sites More sharing options...
Dev R Posted August 3, 2023 Author Share Posted August 3, 2023 Thank you again Bill Quote Link to comment Share on other sites More sharing options...
Dev R Posted August 5, 2023 Author Share Posted August 5, 2023 I shall obviously use the L Pad to control the tweeter volume. Would I have to get an L Pad rated at 8ohm to match the Eminence BGH25-8 tweeter or 4 ohms to match the woofers?. That is my final question on this matter....I promise!! Thanks Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted August 5, 2023 Share Posted August 5, 2023 The LPad goes between the high pass filter and the tweeter, so it's 8 ohm. Besides, you can only find them in 8 ohm. Where questions are concerned better to ask than to have a problem. 3 Quote Link to comment Share on other sites More sharing options...
Dev R Posted November 25, 2023 Author Share Posted November 25, 2023 Hi Bill. Before I solder the components on the board, I just wanted to be re-assured that you're happy with this layout. Cheers 1 Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted November 25, 2023 Share Posted November 25, 2023 It looks fine. Much ado is made about inductor orientation, but it's moot with that much spacing. 2 Quote Link to comment Share on other sites More sharing options...
stevie Posted November 29, 2023 Share Posted November 29, 2023 (edited) As it happens, I have a pair of 8-ohm Celestion BN10-300X drivers here, with measurements saved on my PC. Having run these through a crossover simulation program, I'd recommend that you do not use a low pass filter because the driver rolls off naturally quite early anyway and you don't want to run the risk of dropping the impedance too much below 4 ohms. Just run the driver full range. I see you've already bought the components - so try it with and without and see which you prefer. Edited November 29, 2023 by stevie 1 Quote Link to comment Share on other sites More sharing options...
Dev R Posted December 24, 2023 Author Share Posted December 24, 2023 Thank you for your input Stevie. I will try it both ways! 1 Quote Link to comment Share on other sites More sharing options...
JohnDaBass Posted January 27 Share Posted January 27 On 24/12/2023 at 11:50, Dev R said: Thank you for your input Stevie. I will try it both ways! Which sounded the best? Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted January 27 Share Posted January 27 On 24/12/2023 at 06:50, Dev R said: Thank you for your input Stevie. I will try it both ways! Wot? and risk having kids? 1 Quote Link to comment Share on other sites More sharing options...
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