RAAL ribbon with Scan midbass computer monitors
Maybe I should have title this thread "How would YOU choose to utilize the 64-10 OEM ???"
Because you MUST design the speakers around the RAAL ribbon. Not the more correct way of starting with the mid driver. This is because RAAL already has a partial xover built on to the ribbon, in the transformer. RAAL suggests 3000, others who have used it say no lower than 3400. This is ALL I can get from RAAL about the 64-10 OEM:
[/url]RAAL4 by Cullen Graham, on Flickr[/IMG]
So now we know our xover point and slope for the tweeter. I'm thinking I may want to build a pair of upgraded Speedsters, using the RAAL. How would YOU go about building a pair of computer monitors under these situations ?
Maybe I should have title this thread "How would YOU choose to utilize the 64-10 OEM ???"
Because you MUST design the speakers around the RAAL ribbon. Not the more correct way of starting with the mid driver. This is because RAAL already has a partial xover built on to the ribbon, in the transformer. RAAL suggests 3000, others who have used it say no lower than 3400. This is ALL I can get from RAAL about the 64-10 OEM:
So now we know our xover point and slope for the tweeter. I'm thinking I may want to build a pair of upgraded Speedsters, using the RAAL. How would YOU go about building a pair of computer monitors under these situations ?
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One thing to ask about is if the sensitivity of either is equivalent. If so, then go with the 8 Ohm version, as smaller cap values sound better, are less expensive, and require less bypassing. If sensitivity forces you to use the 4 Ohm version consider a pair of caps in parallel (like 2x 4.7uF) to achieve the equivalent size.
Raal is a huge fan of simple crossover designs, which is why he only recommends a single cap as a crossover. That doesn't mean higher order filters and higher crossover points are not possible, but it is not the pattern he wants you to listen to.
I also don't think you are that limited in midrange. You can pick any mid that goes past 3kHz, and in the 4" format there are a lot of choices. I know Raal likes Scanspeak, so you can't go wrong there.
Best,
E
Raal is a huge fan of simple crossover designs, which is why he only recommends a single cap as a crossover. That doesn't mean higher order filters and higher crossover points are not possible, but it is not the pattern he wants you to listen to.
I also don't think you are that limited in midrange. You can pick any mid that goes past 3kHz, and in the 4" format there are a lot of choices. I know Raal likes Scanspeak, so you can't go wrong there.
Best,
E
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OH, also, one last thing. The baffle step compensation of a desktop speaker is not the same as free-field / stand mount. Don't bother designing that until you have measurements in hand. You may get a few extra DB of sensitivity this way.
Best,
E
I've been fishing quite a lot lately. Trying to get a handle on this. But I'm not even considering baffle step. I can't design my own xover properly at this point. But I know for a fact the speedster is a proven design. I'm figuring I would build the Speedsters, minus the tweeter section of the xover, and use the RAAL with it's proprietary xover, and just adjust the volume levels independently with an AVR to balance the levels. THAT is about where my building level is at this point
I just REALLY hate it that I was given a pair of unobtanium OEM RAALs, and can not figure a way to use them. My thoughts were to get a woofer that needs almost zero help other than an inductor and a capacitor. I've read the 5.5 Rev is known for that.
Maybe I should blend it with these. They play nicely to 5000hz.
Flaxxer,
I'm a little sad actually. I love this hobby and want you to as well. Rather than being frustrated, I really wish you would see this as a great learning opportunity. If that's not something you can do, maybe sell your tweets and make a fully-baked design.
Truth is, there's a lot to this, but I really find it fun and exciting and hope you approach it the same way. If you approach this as "merely" a way to save money I'm afraid you won't feel your investment will return.
Best,
E
I'm a little sad actually. I love this hobby and want you to as well. Rather than being frustrated, I really wish you would see this as a great learning opportunity. If that's not something you can do, maybe sell your tweets and make a fully-baked design.
Truth is, there's a lot to this, but I really find it fun and exciting and hope you approach it the same way. If you approach this as "merely" a way to save money I'm afraid you won't feel your investment will return.
Best,
E
Only problem, as you say, is that you can't design your crossover properly - because the task should be easy.
Tang Band 4w-1337sdf or Tang Band 75-1558SE should be easy to blend with RAAL 64-10. RS51AN should work to.
I wouldn't use anything above 4" because directivity od 10mm ribbon at 3KHz is quite wide.
Tang Band 4w-1337sdf or Tang Band 75-1558SE should be easy to blend with RAAL 64-10. RS51AN should work to.
I wouldn't use anything above 4" because directivity od 10mm ribbon at 3KHz is quite wide.
The RAAL datasheet recommends an LR4 circuit. I suspect an LR2 circuit would be "ribbon safe" for modest listening levels, but LR4 will protect the ribbon and reduce beaming and cone breakup with a 5" cone desired for a 2-way monitor.
CONSIDER: Using LR4/LR4 circuits at 3kHz to the Tang Band W5-2143 full range - very smooth SPL from bamboo fiber paper cone and soft surround.
-- 90db sensitivity
-- Fs = 55Hz
CONSIDER: Using LR4/LR4 circuits at 3kHz to the Tang Band W5-2143 full range - very smooth SPL from bamboo fiber paper cone and soft surround.
-- 90db sensitivity
-- Fs = 55Hz
Attachments
for reference, high-pass filter in-place as seen on second amplitude graph/picture:
New Raal 64-10 ribbon?
I'm guessing an Audax HM100Z0 mid (depending on diffraction sig.) + a more efficient midbass driver..Dayton Audio PM180-8
New Raal 64-10 ribbon?
I'm guessing an Audax HM100Z0 mid (depending on diffraction sig.) + a more efficient midbass driver..Dayton Audio PM180-8
Hi Flaxxer,
How far down the rabbit hole did you want to go? If you want to do passive crossovers REW outlines an impedance box that can be used to measure a drivers impedance over frequency (cost is minimal). Armed with this and a mic you could use the very good xsim program (free) to create crossovers.
If you could make a few measurements and post them to the forum, their are a number of people that could help come up with a crossover that would work but some learning curve is involved.
Requirements:
1. Choose woofer. Wideband fullranger might be good just in case things start to get hard.
2. Build impedance box.
3. Build enclosure, get the mid and tweeter spaced as close a possible.
4. Measure drivers impedance and frequency in enclosure and post to forum.
If you don't want that hassle of the above, pick a fullranger and do first order crossover around 5khz? Play with the tweeter polarity, one way will have a higher perceived tweeter level than the other, use that polarity. Then set tweeter level as per taste.
With that nice tweeter it would be great to do it justice though and create your first 2-way speaker! If you don't want to monkey around with an enclosure the parts express cabs are nice and you can probably get free shipping.
How far down the rabbit hole did you want to go? If you want to do passive crossovers REW outlines an impedance box that can be used to measure a drivers impedance over frequency (cost is minimal). Armed with this and a mic you could use the very good xsim program (free) to create crossovers.
If you could make a few measurements and post them to the forum, their are a number of people that could help come up with a crossover that would work but some learning curve is involved.
Requirements:
1. Choose woofer. Wideband fullranger might be good just in case things start to get hard.
2. Build impedance box.
3. Build enclosure, get the mid and tweeter spaced as close a possible.
4. Measure drivers impedance and frequency in enclosure and post to forum.
If you don't want that hassle of the above, pick a fullranger and do first order crossover around 5khz? Play with the tweeter polarity, one way will have a higher perceived tweeter level than the other, use that polarity. Then set tweeter level as per taste.
With that nice tweeter it would be great to do it justice though and create your first 2-way speaker! If you don't want to monkey around with an enclosure the parts express cabs are nice and you can probably get free shipping.
That little Audax could measure better. I really don't like the ridges in waterfall:
AUDAX HM100Z0 (Mid-range 4", 8 Ohm, 80Wmax)
While the W4-1337SDF is somewhat better in that regard, but lower sensitivity:
TB SPEAKERS W4-1337SDF (Full-range 4", 8 Ohm, 50 Wmax)
The ripple's not bad for something that will be down in pressure almost 9 db before the ripple begins (..with a net 4th order LR). (..assuming 3.1 kHz for the crossover.) Decay before then is very nice and excepting the ripple and its consequence with decay, is still rather good at higher freq.s..
Even the directivity loss for the Audax mid. between 2-4 kHz should sum reasonably well with the tweeter.
Even the directivity loss for the Audax mid. between 2-4 kHz should sum reasonably well with the tweeter.
I'm looking at Zvu's actual measurement with cap. ref. of 4.7 uf on 8 ohm tap.
-6db from average looks like 3.1 kHz to me.. how about you?
..and remember, we aren't talking about the high-pass filter of the ribbon (which we assume is set by the recommended 4.7uf cap) - rather the high-pass filter of the mid..
-6db from average looks like 3.1 kHz to me.. how about you?
..and remember, we aren't talking about the high-pass filter of the ribbon (which we assume is set by the recommended 4.7uf cap) - rather the high-pass filter of the mid..
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I'm looking at Zvu's actual measurement with cap. ref. of 4.7 uf on 8 ohm tap.
-6db from average looks like 3.1 kHz to me.. how about you?
..and remember, we aren't talking about the high-pass filter of the ribbon (which we assume is set by the recommended 4.7uf cap) - rather the high-pass filter of the mid..
Oh, ok. Understood now.
The crossover point should be arround 3.5KHz. There are 2 ridges, one just bellow 2KHz and other is the main breakup. I am not worried about amplitude but about time domain because it rings only 9dB bellow fundament lasting almost 3 times longer than other frequencies in the pass band. If we are looking at distortions that are -40dB as relevant, why should we avoid to look at resonance ridges the same way - and they are much more detrimental to the sound.
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..and that's the problem.
On top of that there is the issue with respect to baffle diffraction - assuming a small box the rising response of the Audax usually results in an easier crossover. (..flat response is great for a wider baffle though.)
Why would lower sensitivity be a problem for computer monitors, that op said he wants to design ?
If easier crossover is the one with less components, than i say - it depends.
I'm looking at Zvu's actual measurement with cap. ref. of 4.7 uf on 8 ohm tap.
-6db from average looks like 3.1 kHz to me.. how about you?
..and remember, we aren't talking about the high-pass filter of the ribbon (which we assume is set by the recommended 4.7uf cap) - rather the high-pass filter of the mid..
I measured it's response in that small loudspeaker with recommended crossover just to see what Aleksandar wanted for us to hear. I listened that way for some time, then i changed it.
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