What I said was correct as I know my limitations with 3-ways. BTW, thanks for the kind words.
I have opened my mouth a bit more than I intended to give the thread a gentle nudge forward.
Navin it seems like anything between 66L and 113L will be OK for a sealed box, the XO may need small changes however.
Not really, I've used info from an old Madisound pricelist. I prefer air core inductors, I was looking at a 5mH Solen 14AWG air core, although I would prefer a 12AWG, I see they list polypropylene caps with values that high.
A very good idea, that's if you want to turn your own coils. Build myself an electric motor with a foot switch to turn my own coils but decided afterwards it is much easier to buy them.
Thanks, I will try it.
Just note Navin were talking about the 6mH inductor in series with a 3 Ohm resistor, so its not directly in the signal path.
How would you allow for BSC with only one woofer?
Andre
The only thing I would add is the polarity of the drivers and from my simulation using your values the mid is reversed polarity and others are normal. Is that right? The tweeter may need a slight bit of padding (maybe) with a 1R resistor before the filter. Nice job and well done!
Yes I forgot to mention polarities, you are right, the mid must be reversed.
WinISD show the boxed SPL of the midrange close to 90dB. On xoversim, the contribution from the woofers and tweeter is enough to lift the midrange also to 91dB, thus no need for padding, that is if the sims are correct of course.
Thanks.
Right so
But mind you, with double 10" you need a mid with pretty good sensitivity, I would say not a fraction less than 90db
There is a risk of getting too much pounding bass, and having no means to get it down
And I dont trust manufactors specs on that subject
I like to know how the driver works in a real time design
In a future design I sure would like my woofers being driven by their own amp, and have easy and precise level adjustment
Otherwise the only option is to passively attenuate the mid
As said, you may avoid it, but you really need to know your drivers, and may go through several design changes, and lot of work
Im not being negative, not at all
Neither do I suggesting directly to just go build Zaphs new 3way
But it would be naive to think this is going to be easy
Like say just calculating BSC theoretically, it aint as simple as a db more or less
It will depend on actual design, and its nature, bass "tightness" etc
In reality, a simulation only really works if you have real time response measurements to plot into the sims
And simulations are in reality nothing but a convenient tool fore those who also do real time measurements as well
I believe rabbitz said the same, but in single more easily unnoticed sentense, or someone else
This is just to make sure all of you realise what its about
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Hi Andre,
your right my bad I thought he was talking about the 5mH one
Should have read more carefully! I almost added a bit about BSC in my post, but I left it out... generally from what I've read the full 6db baffle step compensation is too much in most cases, and 3db is usually the most that is needed, If we cross at 300Hz it is still going to be an issue with the Mid's as well, so I would think that the Mids would need to be doubled up as well... as it is, a single woofer and Mid are closely matched, so applying baffle step compensation (if desired) to the two and then padding down the tweeter appropriately would I think do the trick. If you don't double up the mid's as well I think (and could well be wrong as I haven't done any ** simulations) we will end up with a very bass heavy speaker. I'm only going off my experience with my three ways which have no BSC, just Lpads...
My woofer and Mid are matched pretty well sensitivity wise (within 1db) crossed at 500Hz, and If I attenuate the mids even a little bit, the speakers start to sound bass heavy (to my ears)... My tweeters are a different matter, and are attenuated around 6-7 db but they are much more efficient than the woofer and mid... All this may however be irrelevant as my current speakers have quite a wide baffle (probably close to 85cm) so the baffle step freq will be quite low compared to the narrow baffle we are looking at here!
Tony.
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Yes, and will also depend on which amp is used, and the room etc
Thus I think it would be nice if each builder would be able to at least adjust mids and tweeter level to their own needs and taste, without affecting crossover too much
That to me is one of the best advantages of diy speaker building, to be able to adjust it to suit my own needs
Thus I think it would be nice if each builder would be able to at least adjust mids and tweeter level to their own needs and taste, without affecting crossover too much
That to me is one of the best advantages of diy speaker building, to be able to adjust it to suit my own needs
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Hi Tinitus
If I understand you correctly you are advocating adjustable "L-pads" on the mids/tweeters as part of the XO design??
Perhaps not a bad idea except for the added expense of the components, and if this is going to be part of the design is the make/manufacturer of the L-pad important?
If I understand you correctly you are advocating adjustable "L-pads" on the mids/tweeters as part of the XO design??
Perhaps not a bad idea except for the added expense of the components, and if this is going to be part of the design is the make/manufacturer of the L-pad important?
I wasnt exactly thinking of L-pads
But why not
But even they can be difficult to adjust correctly
But still better than nothing
Its a delicate balance than can make it like day or night
I have a friend who really cant adjust them properly
In my ears his adjustments sounds way off
And he is never happy with my adjustment
Funny thing
L-pads were used in a 2way Snell with good result
But I dont know how to best implement L-pads
And Im sure that every time I returned to the shop, they were adjusted wrong
Whatever, I love adjustable things
And I hate stuff I cant change the least bit
My problem is I cant keep my fingers away
L-pads may also have a bad habbit of going bad after a while
And adjustments are probably not fine enough
I would expect any builder of these speakers should be able to adjust a few resistors internally
But why not
But even they can be difficult to adjust correctly
But still better than nothing
Its a delicate balance than can make it like day or night
I have a friend who really cant adjust them properly
In my ears his adjustments sounds way off
And he is never happy with my adjustment
Funny thing
L-pads were used in a 2way Snell with good result
But I dont know how to best implement L-pads
And Im sure that every time I returned to the shop, they were adjusted wrong
Whatever, I love adjustable things
And I hate stuff I cant change the least bit
My problem is I cant keep my fingers away
L-pads may also have a bad habbit of going bad after a while
And adjustments are probably not fine enough
I would expect any builder of these speakers should be able to adjust a few resistors internally
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Exactly you've hit the DIY nail on the head. It's a more important consideration than cost IMO.
For my use I've generally only needed 2-3dB of BSC. It would be different for each user due to room, placement and partnering equipment.
For a single woofer speaker, a little room loading and some work in the crossover does the trick. You do however lose some SPL as you have to drop the SPL in frequencies above the baffle step. Placed close to the rear wall and you don't have to worry about BSC but can lose out in other areas like mid presentation.
Some L-Pads aren't too bad and I tried some Visaton a couple of years ago and worked well with no nasties. I think all speaker designs would have to be tweaked for mid and top end levels to suit the user and room and not too difficult with some resistors. I've done one recently which changes the tweeter level by a switchable damping resistor across the tweeter and was done to suit different systems in use. It used a series resistor before the tweeter filter to do the main padding and a 15R parallel damping resistor is an addition for when the level needs reduction. This system worked better than using a resistor L-Pad network just before the tweeter.
For a single woofer speaker, a little room loading and some work in the crossover does the trick. You do however lose some SPL as you have to drop the SPL in frequencies above the baffle step. Placed close to the rear wall and you don't have to worry about BSC but can lose out in other areas like mid presentation.
Some L-Pads aren't too bad and I tried some Visaton a couple of years ago and worked well with no nasties. I think all speaker designs would have to be tweaked for mid and top end levels to suit the user and room and not too difficult with some resistors. I've done one recently which changes the tweeter level by a switchable damping resistor across the tweeter and was done to suit different systems in use. It used a series resistor before the tweeter filter to do the main padding and a 15R parallel damping resistor is an addition for when the level needs reduction. This system worked better than using a resistor L-Pad network just before the tweeter.
And my two year old calls it fun!!! It took me a while to work out what had happened, but she had turned the tweeter attenuation to max on one of the speakers....
I'm not necessarily an advocate of using adjustable lpads, but they certainly are great for finely adjusting levels. I tried doing it using measurements but in the end I redid it by ear... something I would have found very difficult if using fixed resistors!
Also I didn't really make it clear in my previous post, but lpad's aren't really suitable for trying to achieve baffle step compensation due to the shape of the baffle step curve, but can be useful for adjusting absolute level mismatches. I think the exception to this would be when the crossover between the mid and the woofer is at the baffle step freq, meaning the woofer wouldn't necessarily need any bsc and it would only need to be applied to the mid/tweeter... this is the approach I'm taking with my own project, but I will be biamping so any level mismatch will be taken care of before amplification. I'm also wondering if with this setup the higher level of the woofer may be enough to boost the freqs on the high side of the crossover enough to "fill in" without compensation on the mid but for that I will need to wait and see....
Tony.
your right my bad I thought he was talking about the 5mH one
If we cross at 300Hz it is still going to be an issue with the Mid's as well, so I would think that the Mids would need to be doubled up as well...
My woofer and Mid are matched pretty well sensitivity wise (within 1db) crossed at 500Hz, and If I attenuate the mids even a little bit, the speakers start to sound bass heavy (to my ears)...
the 5mh inductor is in the signal path. I would never do that!
doubling up on the mids means that we will have comb filtering effects (in the upper mid) to contend with.
while baffle step will start at 80Hz or so the baffle step compensation will be needed mostly between 300 and 1000Hz all of this in the working range of the midrange. hence we can use the 10" woofers to compensate for the baffle step loss in the midrange. This means that we just roll the woofers of slower than theory would dictate.
it is indeed funny how sensitive ears can be trained to be. my sister (who used to be my tester) could detect very small changes (0.5db in and around 300Hz). I remember clearly that she and my wife noticed what LspCAD showed to be only a 0.5db change in the BSC. I suppose in the midrange the ear is terribly sensitive.
perronal preference. most of my friends think my settings are "laid back".
bi-tri-amping is a great option. I too will be tri-amping (if and when I get the time to build this). I'll be following your progress closely.
That's exactly what I did.
With the double woofers, my filter start to work at about 90Hz to adjust the amount of BSC, if less is needed a larger coil could be used. What I like about this is that the two woofers add together at the lower frequencies, thus effectively lower the FR.
Exactly!
The only reasons I prefer sealed over BR or TL using 2 10" woofers are:
1. Box size (65-70 liters sealed for 2 woofers will work well compared to 100-120 liters required for BR).
2. for my room and location (read as close to rear wall) sealed speakers that roll off at 50Hz or so seem to integrate better
For the midrange, TL (what Troels did with the cyclops Midrange) is what I am leaning towards.
about half way down the midrange used is a MH15
W26 Classic
to quote Troels....
"So, I've tried to design a box where the rear energy is absorbed as good as possible and due to the slots in the rear, we have an aperiodic system, reducing impedance peak at resonance frequency."
You are right, it can become a fine balancing act.
I'm working on a 3way active speaker with a friend, I'm thinking of using the CA18RNX for a midwoofer to keep the bass XO freq lower, seems difficult to do that with a passive XO.
For sure, it's only a starting point.
I also think 3 dB would be enough, some say 4dB though?
I like to do BSC as part of the XO freq selected and filter slopes. I'm really not a fan of two midrange drivers. I prefer to use as little as possible (rather no) series resistance in a XO, maybe that's the biggest reason why I'm leaning towards using two woofers.