The Dropbox folder includes a zip file of impulse responses for various configurations, including a 15/6/1 with T3W and CBG crossovers. XD125 tweeter. With a suitable impulse convolver (e.g. Audacity, foobar2000 and probably any DAW) you can check on how they sound.
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True 3-way fEARful bass enclosures
- Thread starter 12bass
- Start date
A friend and I built our 15/6s at the same time, his without the tweeter. I described the difference in the OP. The biggest difference is that with the CBG crossover, there's a harsh cone resonance peak around 4kHz in the midrange driver, which is removed with the T3W using a bandpass filter. Comparing the two, the CBG sounds more harsh and peaky in the treble, while the T3W is much flatter across the range. I found it difficult to deal with the CBG peakiness, requiring significant EQ to tame. The T3W is more like a studio monitor.
Thank you for all the replies!
The truth of the matter is that if I had never heard of the T3W, I probably wouldn't have any questions at all. But, I have noticed - especially when playing the 15/6/1 alone (as opposed to pairing it with my 12/6/1) - that there is a very "crunchy" resonance which can become tiresome. Sometimes I like it, but sometimes I find it "too much".
I have also found that, compared to my 12/6/1 (also CBG), the 15/6/1 sounds a bit more "hollow" in the low mids. I have always put that down to the driver and cab differences, but I have often wondered if it could be the crossover.
So, most of my inferences come from comparing the two cabs. I don't notice the "crunchiness" as much with the 12/6/1, which is why I'm focused on the 15/6/1 (for now).
I ran some isolated bass lines that I have recorded through these impulse responses, as well as some fully recorded music, and - wow! - the T3W sounds very different than the CBG! The difference is far greater than I expected. I found that I much prefer the T3W sound to the CBG sound in every example I tried. Based on these listening tests, it looks like I'm going to try the T3W.
...time to contact Leland!
I do have one more question for all you crossover experts: Is making the change from CBG to T3W difficult? ...or is it something that a simpleton, like me, can do? (I have lots of experience soldering, but I'm no EE!)
Thanks, again, everyone!
What an outstanding question.
The truth of the matter is that if I had never heard of the T3W, I probably wouldn't have any questions at all. But, I have noticed - especially when playing the 15/6/1 alone (as opposed to pairing it with my 12/6/1) - that there is a very "crunchy" resonance which can become tiresome. Sometimes I like it, but sometimes I find it "too much".
I have also found that, compared to my 12/6/1 (also CBG), the 15/6/1 sounds a bit more "hollow" in the low mids. I have always put that down to the driver and cab differences, but I have often wondered if it could be the crossover.
So, most of my inferences come from comparing the two cabs. I don't notice the "crunchiness" as much with the 12/6/1, which is why I'm focused on the 15/6/1 (for now).
The "blank canvas" and "studio monitor" aspect are what I would like to achieve, also.
Thank you for this info, sclift!
I ran some isolated bass lines that I have recorded through these impulse responses, as well as some fully recorded music, and - wow! - the T3W sounds very different than the CBG! The difference is far greater than I expected. I found that I much prefer the T3W sound to the CBG sound in every example I tried. Based on these listening tests, it looks like I'm going to try the T3W.
This 4k peak must equate to the harsh crunchiness I have heard. ...and, I agree: when I played my music through the impulse response files, the CBG changed the sound dramatically, while the T3W seemed very clear across the spectrum.
...time to contact Leland!
I do have one more question for all you crossover experts: Is making the change from CBG to T3W difficult? ...or is it something that a simpleton, like me, can do? (I have lots of experience soldering, but I'm no EE!)
Thanks, again, everyone!
If you load an impulse response into Room Equalizer Wizard, it will show you the corresponding frequency response, which might be interesting. Note that the responses are not reliable below about 200 Hz because of measurement artifacts.
If your 12/6/1 uses an Alpha for the mids, that's probably why it sounds less crunchy than the 15/6/1. The 6ND410 is very efficient, but there is a price to pay for that - a pronounced cone-breakup response peak around 4 kHz. The amplitude varies from unit to unit, but 6 dB is typical IIRC. The Alpha cone-breakup is not so pronounced, so it sounds more polite.
Don't know about hollow low mids. What frequency is "low mids"? The T3W changes apply above about 600 Hz. Below that the damping material in the box can have quite an effect on the sound.
If you can solder you should be OK. The schematics are not too complicated and help is available if you post photos. The existing LF network can be converted by soldering a 9 uF cap in parallel with the 30 uF cap. The mid and tweeter networks will have to be replaced. There are one or two components that can be salvaged and re-used. Leland sells assembled boards or loose parts if you want to do your own assembly. Or, if you are really cheap, you can make your own boards. I made several using 1/4" ply and brass nails for soldering points, which works well. For the last one, inspired the innards of my old Bassman, I used ply and brass eyelets - very classy!
If your 12/6/1 uses an Alpha for the mids, that's probably why it sounds less crunchy than the 15/6/1. The 6ND410 is very efficient, but there is a price to pay for that - a pronounced cone-breakup response peak around 4 kHz. The amplitude varies from unit to unit, but 6 dB is typical IIRC. The Alpha cone-breakup is not so pronounced, so it sounds more polite.
Don't know about hollow low mids. What frequency is "low mids"? The T3W changes apply above about 600 Hz. Below that the damping material in the box can have quite an effect on the sound.
If you can solder you should be OK. The schematics are not too complicated and help is available if you post photos. The existing LF network can be converted by soldering a 9 uF cap in parallel with the 30 uF cap. The mid and tweeter networks will have to be replaced. There are one or two components that can be salvaged and re-used. Leland sells assembled boards or loose parts if you want to do your own assembly. Or, if you are really cheap, you can make your own boards. I made several using 1/4" ply and brass nails for soldering points, which works well. For the last one, inspired the innards of my old Bassman, I used ply and brass eyelets - very classy!
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Thanks, sclift (and everyone else)
After looking at the parts list which Leland has sent, and perusing the threads here and over at greenboy's forum, I'm very nearly convinced that this project is beyond me. I'm going to dig a little more before I decide, but at this point, I just don't feel confident enough to jump in.
After looking at the parts list which Leland has sent, and perusing the threads here and over at greenboy's forum, I'm very nearly convinced that this project is beyond me. I'm going to dig a little more before I decide, but at this point, I just don't feel confident enough to jump in.
Hi sclift, I hope you are well today, and everyday. I am building a 121261 and am using the T3W crossover you approved. I ordered the parts from Leland, and got some components drop shipped. The Low frequency components are for the CBG. The inductor coil is 1.5mH, instead of the 1.6mH as approved. Leland says it will only affect about 5hz, but didn't say in what direction. The 1.6mH coil is listed on the mfg website, but indicates it will take up to 90 days to get.. Do you think I should wait and get a 1.6mH, or use the 1.5mH.. Any guidance will be greatly appreciated.. Thanks
I'm fine, thanks. Hope you are too. Using 1.5 mH will push the LF crossover frequency up a little, resulting in more overlap with the midrange driver. That might create a small bump in the response around 800 Hz, but I doubt that it would be very noticeable. The difference between 1.5 mH and 1.6 mH is about 6 turns of wire. I would get the 1.5 and, if you are worried about it, add 6 turns of similarly-sized insulated wire to the outside of the coil. I think the coil is glued together, so you could cut the zip ties, add the turns and then add new zip-ties.
