I drew up a quick schematic of what I'm listening to now. For speed I did it on paper and scanned. It looks complicated when it's put on paper but I think it might be about the bare minimum for an open baffle with several wildly different drivers...
The "brilliance" filter is not very well tested yet, I just chucked some semi-random components on there to see what it sounded like.
By the way I like the principle of simple designs so I'm aware there's some irony of how this is going. It won't be long before I look at bi-amping in order to address the huge sensitivity mismatch between woofers and top end and then it'll become even more complex, but hopefully rather good too. Jennifer Warnes is sounding fine, and that's in the kitchen on one speaker and a Sherwood amp and mildly modified cd player!
The "brilliance" filter is not very well tested yet, I just chucked some semi-random components on there to see what it sounded like.
By the way I like the principle of simple designs so I'm aware there's some irony of how this is going. It won't be long before I look at bi-amping in order to address the huge sensitivity mismatch between woofers and top end and then it'll become even more complex, but hopefully rather good too. Jennifer Warnes is sounding fine, and that's in the kitchen on one speaker and a Sherwood amp and mildly modified cd player!
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I just did another little tweak. I put some anti-slip furniture discs on the inside of the frame on the Beta 8 mid. I'm sure it won't do any harm. At mid-high levels the sound is superb now! I also added 0.47uF to my tweeter cap as I felt I was probably listening to a dip in the response.
At low levels the sound is a tiny bit dull but that's how I like it. Tuned for a warm, full sound that can be played very loud without a trace of harshness. This is something I hate with some other speakers I've heard or owned and the number one thing to get right for me.
I'm going to build the other speaker up to this spec now and have a listen.
At low levels the sound is a tiny bit dull but that's how I like it. Tuned for a warm, full sound that can be played very loud without a trace of harshness. This is something I hate with some other speakers I've heard or owned and the number one thing to get right for me.
I'm going to build the other speaker up to this spec now and have a listen.
Looks like progress!
I'm surprised you need such a complicated crossover. I've hear the Beta-8 in semi open baffle and all it needed was a small value coil to tame the top end. Sounded great.
Maybe the full open baffle changes things enough to warrant the fancier crossover.
I'm surprised you need such a complicated crossover. I've hear the Beta-8 in semi open baffle and all it needed was a small value coil to tame the top end. Sounded great.
Maybe the full open baffle changes things enough to warrant the fancier crossover.
It's not all strictly needed but it DOES need padding down a lot and does need the top end reducing, at least so far it seems to. The bottom end really needs bringing up to my ears and it's no doubt largely due to the steep dipole roll off. How on earth could it otherwise reach down to meet the 12" woofers which are rolled off with a 12mH coil? It certainly sounded like there was a gap!
The cap to limit LF excursion seems a good idea on paper in some ways but I'm yet to decide how important it is, given how padded down the driver is. It's not going to have issues regularly hitting xmax but I don't want it to get strained unnecessarily...
The cap to limit LF excursion seems a good idea on paper in some ways but I'm yet to decide how important it is, given how padded down the driver is. It's not going to have issues regularly hitting xmax but I don't want it to get strained unnecessarily...
Open baffle woofers with a 12mH coil play higher up than you might think. 😉 I can understand the pad on the 8", for sure.
To be fair, I heard the beta-8 in a cardioid, not open baffle. So it would have more low end and a flatter response. With your baffle, you gotta do what you gotta do.
To be fair, I heard the beta-8 in a cardioid, not open baffle. So it would have more low end and a flatter response. With your baffle, you gotta do what you gotta do.
Yeh, I'm "playing it by ear" but some measurements will come as I know they're needed to be sure I'm not missing anything obvious.
My 7" woofers on my mk1 open baffles seemed to play much higher than these 12" woofers. Perhaps these are a lot more inductive.
I have toyed with the idea of running one 12" coming in at about 60hz and the other coming in at something like 200hz, to help fill the gap.
My 7" woofers on my mk1 open baffles seemed to play much higher than these 12" woofers. Perhaps these are a lot more inductive.
I have toyed with the idea of running one 12" coming in at about 60hz and the other coming in at something like 200hz, to help fill the gap.
The crossover points are very misleading and frustrating because when the acoustic slopes are factored in it's all a nice big mess!
Linkwitz suggests a notch filter at around 3 kHz.
There seem to be parts missing in the T-Bass circuit, namely the capacitor in parallel with the output choke and the Zobel. Without them the woofers will probably still contribute more in the midrange than you would want.
Didn't you have some measuring equipment?
Good to hear you're getting the sound how you like it. Measurements will help confirm everything is "right" I suppose 🙂
I hope you'll do it soon. Some little R & C are all you need for passive line level filter. They won't be any more complex than the coil(s). I always feel it's much easier to build and more predictable in line level.
And, maybe it's only me, an irrational obsession, I don't like a big choke in the path. Maybe it's because the bad experience at the first try... 😱
Hi guys,
Thanks for the compliments and advice. I will be sure to check the T-bass thread to make sure I've not missed things.
I now have the speakers playing in my room. There doesn't appear to be too much mid coming from the woofers. There is, however, slightly too much bass. It doesn't overwhelm the room, it doesn't boom, it just sounds a bit louder than everything else and the sound probably isn't as open and lively as it should be.
When cranked up these baffles gently rock the room with LF, and soothe the ears. It's probably a little too tame, even for my tastes! I've never heard Dr Dre sound so amazing though...
Thanks for the compliments and advice. I will be sure to check the T-bass thread to make sure I've not missed things.
I now have the speakers playing in my room. There doesn't appear to be too much mid coming from the woofers. There is, however, slightly too much bass. It doesn't overwhelm the room, it doesn't boom, it just sounds a bit louder than everything else and the sound probably isn't as open and lively as it should be.
When cranked up these baffles gently rock the room with LF, and soothe the ears. It's probably a little too tame, even for my tastes! I've never heard Dr Dre sound so amazing though...
Gorgeous! I really like the look of those woofers. Overall very high-end and exotic looking. Well done!
Thanks very much! I'm pleased with how they look and the sound is coming along nicely.
I've upped the mid level a bit and altered the tweeter crossover too. I've also installed some foam behind the mids. The sound is getting quite close to excellent now.
I played some Michael Jackson and I have to say I've not heard that album (Bad) with such superb bass reproduction before. The notes are very low, very loud and stop and start instantly. Usually a speaker/room will either not play it strongly enough or it will be muddy and boomy. Here I have pretty much everything. Ok, not everything - it's probably still a little over-ripe, but just needs a little more fine-tuning.
I am happy with the fatigue-free nature of the sound. It's possible to turn my preamp up to nearly 3 o'clock and not hear any hardness or harshness, it just sounds very loud and very smooth with no peakiness. Of course I may actually be missing some frequencies to achieve this. I will learn more when I break out the little mic capsule and preamp etc.
I've upped the mid level a bit and altered the tweeter crossover too. I've also installed some foam behind the mids. The sound is getting quite close to excellent now.
I played some Michael Jackson and I have to say I've not heard that album (Bad) with such superb bass reproduction before. The notes are very low, very loud and stop and start instantly. Usually a speaker/room will either not play it strongly enough or it will be muddy and boomy. Here I have pretty much everything. Ok, not everything - it's probably still a little over-ripe, but just needs a little more fine-tuning.
I am happy with the fatigue-free nature of the sound. It's possible to turn my preamp up to nearly 3 o'clock and not hear any hardness or harshness, it just sounds very loud and very smooth with no peakiness. Of course I may actually be missing some frequencies to achieve this. I will learn more when I break out the little mic capsule and preamp etc.
A minor criticism [considering the price] of these Skytronic woofers is that they have flimsy plastic cones and they sound a bit like flimsy plastic cones. The bass, although really satisfying, has a slightly soft quality that I associate with plastic-coned woofers. They're superb value though. If I can find some good quality paper or metal woofers that will fill the baffle holes neatly I may upgrade at a later date.
Before that I am very likely to change the tweeters for something better. There's something about the top end that isn't quite right to my ears. Part of me wishes I'd just used normal hi-fi tweeters, but then I know I'd be restricted to that typical dull samey treble most home speakers have... I would like to use the compression drivers De Earl Geddes recommends, a B&C model. They are £120 each though, which I can't afford for a while.
Before that I am very likely to change the tweeters for something better. There's something about the top end that isn't quite right to my ears. Part of me wishes I'd just used normal hi-fi tweeters, but then I know I'd be restricted to that typical dull samey treble most home speakers have... I would like to use the compression drivers De Earl Geddes recommends, a B&C model. They are £120 each though, which I can't afford for a while.
They look great! Impressive work 😎
Can you hear vent noise at high excursion with these woofers in OB? Always a risk, even some high quality woofers can have a bit of vent noise at high excursion and it's much more audible in OB.
Perhaps ribbon/planar tweeters might offer a more exciting sound character? I've not used compression drivers but use Hi-Vi planars and like them a lot, really dynamic treble whilst also detailed, very restrictive vertical dispersion though which can be a plus or a minus point really!
Getting the tone exactly right is a tough job, make sure you take lots of breaks and return to them as you make adjustements, doing it by ear it's too easy to get used to changes in tonality after a while.
Can you hear vent noise at high excursion with these woofers in OB? Always a risk, even some high quality woofers can have a bit of vent noise at high excursion and it's much more audible in OB.
Perhaps ribbon/planar tweeters might offer a more exciting sound character? I've not used compression drivers but use Hi-Vi planars and like them a lot, really dynamic treble whilst also detailed, very restrictive vertical dispersion though which can be a plus or a minus point really!
Getting the tone exactly right is a tough job, make sure you take lots of breaks and return to them as you make adjustements, doing it by ear it's too easy to get used to changes in tonality after a while.
Thank you. I'm pretty committed to these waveguides now, they really took a lot to make and to fit perfectly to the baffles. The treble from them is very exciting, no problems there. I probably need to add a spacer to make these transition into the throat more appropriately and perhaps that will help. I also badly want to try the Earl Geddes foam trick! He claims is makes waveguides with compression tweeters the best thing since sliced bread! Another tiny tweak is to use better resistors as I've just used whatever I could find for testing. I will eventually use nicer parts and some more exotic caps. Nothing wrong with the basic Mundorf MKPs but I would prefer Supremes, which I love!!!
I don't hear vent noise. If I overdo it it's possible to hear voice-coil rubbing type noises. They have pretty limited xmax.
I don't hear vent noise. If I overdo it it's possible to hear voice-coil rubbing type noises. They have pretty limited xmax.
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