i should have taken the time to qualify my earlier statement.
lets assume we have a common 6" 2 way
the XO is usually around 3k. sometimes a bit lower.
will a 1st order XO still offer adequate proection for the tweeter.
assume that the woofer does not break up and the tweeter has an Fs of about 1000-1200Hz.
i am trying to draw general conclusions about protection here not trying to tie down a specific formula.
lets assume we have a common 6" 2 way
the XO is usually around 3k. sometimes a bit lower.
will a 1st order XO still offer adequate proection for the tweeter.
assume that the woofer does not break up and the tweeter has an Fs of about 1000-1200Hz.
i am trying to draw general conclusions about protection here not trying to tie down a specific formula.
should be fine.
assumming you use a very good tweeter - dynaudio, morel, scanspeak, focal, better vifa or seas units, etc. i know the morels and dynaudios for sure handle plenty of power, the others probably too. the ones with high power ratings and low Fs - at least 80W RMS or so and below 1kHz Fs (i've seen as low as 750Hz on a 1" dome). i've seen them crossed over as low as 2.5KHz with a first order and still handle some decent power. this doesn't mean you still can't blow it out with a distorted signal or a 500W amp, but i think it'll be reasonably safe.
assumming you use a very good tweeter - dynaudio, morel, scanspeak, focal, better vifa or seas units, etc. i know the morels and dynaudios for sure handle plenty of power, the others probably too. the ones with high power ratings and low Fs - at least 80W RMS or so and below 1kHz Fs (i've seen as low as 750Hz on a 1" dome). i've seen them crossed over as low as 2.5KHz with a first order and still handle some decent power. this doesn't mean you still can't blow it out with a distorted signal or a 500W amp, but i think it'll be reasonably safe.
This might be the tweeter for the job: http://www.d-s-t.com/scs/data/d2904_980000d.htm
The data sheet states fs at 500 Hz, in reality it even seems to be less then that.
The data sheet states fs at 500 Hz, in reality it even seems to be less then that.
You guys don't like metal domes do you? 
I think the time has come to take them for serious. That one above or the Focal Tioxids - In my opinion there's nothing to worry about any more.
I know the Scan Speak from spending some weeks with the Revel sub/sat system and really loved it.
Ferrofluid? I don't know at the moment.
I think the time has come to take them for serious. That one above or the Focal Tioxids - In my opinion there's nothing to worry about any more.
I know the Scan Speak from spending some weeks with the Revel sub/sat system and really loved it.
Ferrofluid? I don't know at the moment.
metal domes have gotten a lot better the last the last several years but i still have not heard one that is as natural as a good soft dome (morel, scanspeak, dynaudio). the titanium ones seem a little better than aluminum but it's a case-by-case basis depending on the tweeter, many more factors other than the dome material of course. Focal Tioxid is a really excellent tweeter, love the highs, but i do not consider it a "pure" metal dome (it's treated, vapor deposited titanium oxide no?). i haven't really observed ferrofluid vs. no fluid, however the Morel MDT30 in my Merlin TSM speakers has a little fluid and it is a good tweeter.
i *think* soft domes are also a little better behaved when you cross them in low but i could be wrong. most metal domes i've seen in commercial designs are usually used with at least a 2nd order crossover; the time-aligned 1st order minimalist designs tend to use soft domes, at least the ones i've seen.
i'm not familiar with the Revel sat/sub system but i recently heard the Ultima Salons (US$15,000) and thought they sounded extremely mediocre at best. metal drivers, high order crossovers - blech. there are speakers for a fraction of the price which sound far more musical to me.
i *think* soft domes are also a little better behaved when you cross them in low but i could be wrong. most metal domes i've seen in commercial designs are usually used with at least a 2nd order crossover; the time-aligned 1st order minimalist designs tend to use soft domes, at least the ones i've seen.
i'm not familiar with the Revel sat/sub system but i recently heard the Ultima Salons (US$15,000) and thought they sounded extremely mediocre at best. metal drivers, high order crossovers - blech. there are speakers for a fraction of the price which sound far more musical to me.
Andy Graddon said:
Thank you all very much, I'm getting far more response than I hoped for. Indeed some things are too difficult for me. But I'm learning fast!
Still I got a question.
Andy,
You said
But I thought (please correct me if I'm wrong), the mid-frequency band is one of the main reasons to opt for a 6db XO. Because the crossover-point is usually in the frequency-range where our hearing is most sensitive. So it would seem better if the drivers blend in smoothly.
Another question about the protection of the tweeter. Isn't true that the efficiency of the speaker is generally speaking higher with only the capacitor for the tweeter. Then it would take less power to produce a certain soundlevel.
TIOXID DIOXINE
Dorkus,
It is Titanium Dioxid.
Ferrofluid sucks,better take a more efficient design alltogether and you won't need these high PR no more.
Personally I like these ribbon tweeties a lot.
They're usually healthy,present a flat impedance curve (mostly purely resistive) and some go way up into the 40 to 60 KHz range.
Lightweight by nature they're also very quick off the mark.
Cheers,
Dorkus,
It is Titanium Dioxid.
Ferrofluid sucks,better take a more efficient design alltogether and you won't need these high PR no more.
Personally I like these ribbon tweeties a lot.
They're usually healthy,present a flat impedance curve (mostly purely resistive) and some go way up into the 40 to 60 KHz range.
Lightweight by nature they're also very quick off the mark.
Cheers,
i think human hearing acuity starts dropping above 2kHz or so, which is why people try to keep the crossover points above there. certainly phase acuity drops at that frequency. the primary reason for 1st order xover is phase linearity. most higher order xovers are not linear phase and tend to ring more. gradual blending of the drivers is actually undesirable as they tend to interfere with each other, which is why theoretically steep crossovers are better (along w/power handling and bandwidth reasons). in practice they have the aforementioned problem though.
frank, ribbon tweeters sure are lovely-sounding, just that crossing them over with a dynamic driver requires a lot of skill (and a good driver). i've heard ribbon/dynamic hybrids that have great highs but a discontinuity of character in the crossover region. my editor recently reviewed a big VMPS loudspeaker that uses ribbon tweeters and midrange panels however, and loved the sound. the ribbon panels cross over to a 10" woofer at 166Hz, 1st order.
frank, ribbon tweeters sure are lovely-sounding, just that crossing them over with a dynamic driver requires a lot of skill (and a good driver). i've heard ribbon/dynamic hybrids that have great highs but a discontinuity of character in the crossover region. my editor recently reviewed a big VMPS loudspeaker that uses ribbon tweeters and midrange panels however, and loved the sound. the ribbon panels cross over to a 10" woofer at 166Hz, 1st order.
Dorkus,
I absolutely agree to your statement concerning the Revel Salon - not my cup of tea either. But the "Gem" is a completely different thing - although it shares the same tweeter.
One reason for the sound of the Salon may be the 24 dB low pass for the woofers - certainly not easy with a passive filter.
I absolutely agree to your statement concerning the Revel Salon - not my cup of tea either. But the "Gem" is a completely different thing - although it shares the same tweeter.
One reason for the sound of the Salon may be the 24 dB low pass for the woofers - certainly not easy with a passive filter.
MATING AND MATCHING
Hi,
Absolutely.
You run into the same kind of trouble with any kind of hybrid really.
That's one reason they often use an array of smaller diameter woofers,they respond often a lot faster.
Bringing the lower x-over point also helps to even out perceived differences.
Once done right they're absolutely addictive though.
I use a pair of the older SD1 at home for reference and it's pretty good.
In case any of you want to take a look:
http://www.interads.co.uk/sdacoustics/
Cheers,
Hi,
Absolutely.
You run into the same kind of trouble with any kind of hybrid really.
That's one reason they often use an array of smaller diameter woofers,they respond often a lot faster.
Bringing the lower x-over point also helps to even out perceived differences.
Once done right they're absolutely addictive though.
I use a pair of the older SD1 at home for reference and it's pretty good.
In case any of you want to take a look:
http://www.interads.co.uk/sdacoustics/
Cheers,
Re: CHOICE
Is it a good idea to use the Vifa 10BGS and to cross it over at 3KHz or more? Then it shouldn't be very difficult to find a suitable tweeter. I really like the idea of a ribbon tweeter as well.
It would require a subwoofer for the low frequencies though. This comes close to what I would consider the ideal speaker setup.
fdegrove said:
Is it a good idea to use the Vifa 10BGS and to cross it over at 3KHz or more? Then it shouldn't be very difficult to find a suitable tweeter. I really like the idea of a ribbon tweeter as well.
It would require a subwoofer for the low frequencies though. This comes close to what I would consider the ideal speaker setup.
MASSIVE ATTACK?
Hi,
Looks like a decent speaker to me.
You could cross it at around 6Khz on first look.
With the right type of housing it would still go quite low though.
I never was a big fan of subs,they're often more trouble than they're worth especially for the average Euro lving room.
The ribbon tweeter will likely be more efficient then this woofer so it will need some padding down.
Cheers,
Hi,
Looks like a decent speaker to me.
You could cross it at around 6Khz on first look.
With the right type of housing it would still go quite low though.
I never was a big fan of subs,they're often more trouble than they're worth especially for the average Euro lving room.
The ribbon tweeter will likely be more efficient then this woofer so it will need some padding down.
Cheers,
Vifa 10BGS
is that a kevlar cone? if so, beware nasty breakup modes. check the impedance plots. i've heard kevlars need to be crossed over carefully or they can get unpleasant. on the other hand, the response plot on this one is commendably smooth, with a controlled roll-off, so it may be ok. makes me wonder if they fudged the plot though...
frank that speaker looks very nice. i like multi-midrange speakers, if done right. they usually energize more air and have a fuller, richer sound than single-midrange speakers. lemme guess what it sounds like... sparkling highs, full and rich midrange, good power in the lower midrange and upper bass. pretty close? one concern i have is the xover point (3.6kHz), which is very high for a 6" cone, particularly in an over-under array. i would think the upper midrange/lower treble detail would be diminished somewhat compared to the higher treble... might lose a bit of harmonic detail with some acoustic instruments? also, how do you get away with a 1st order crossover with dual over-under midrange? aren't there lobing effects?
check this speaker out:
http://www.vmpsaudio.com/rm40Pic.htm
is that a kevlar cone? if so, beware nasty breakup modes. check the impedance plots. i've heard kevlars need to be crossed over carefully or they can get unpleasant. on the other hand, the response plot on this one is commendably smooth, with a controlled roll-off, so it may be ok. makes me wonder if they fudged the plot though...
frank that speaker looks very nice. i like multi-midrange speakers, if done right. they usually energize more air and have a fuller, richer sound than single-midrange speakers. lemme guess what it sounds like... sparkling highs, full and rich midrange, good power in the lower midrange and upper bass. pretty close?
one concern i have is the xover point (3.6kHz), which is very high for a 6" cone, particularly in an over-under array. i would think the upper midrange/lower treble detail would be diminished somewhat compared to the higher treble... might lose a bit of harmonic detail with some acoustic instruments? also, how do you get away with a 1st order crossover with dual over-under midrange? aren't there lobing effects?check this speaker out:
http://www.vmpsaudio.com/rm40Pic.htm
FORGOT TO TELL YOU
Dorkus,
Mine is an original SD1 one.
X-over is done at around the same 3.6 Khz but with a second order 12 dB slope.
The tweet is a Viston ribbon and also crossed with a second order
at 12 or 14 KHz.
Other then that it only used one stiff big Audax midrange (can't remember the ref.)
You make a pretty accurate description though .
I hate slow speakers. If you catch my drift.
They match my OTL amps very well.
Probably right but as far as I know Steen Doessing he usually knows what he's doing.
He likes fast and open speakers too and that's haw we got acquainted.
See you,
Dorkus,
Mine is an original SD1 one.
X-over is done at around the same 3.6 Khz but with a second order 12 dB slope.
The tweet is a Viston ribbon and also crossed with a second order
at 12 or 14 KHz.
Other then that it only used one stiff big Audax midrange (can't remember the ref.)
You make a pretty accurate description though .
I hate slow speakers.
If you catch my drift.They match my OTL amps very well.
Probably right but as far as I know Steen Doessing he usually knows what he's doing.
He likes fast and open speakers too and that's haw we got acquainted.
See you,
L-Padding the tweeter.....
can often allow a variation from the "rule of thumb" I spoke of earlier.
For instance, if a 6ohm tweeter has a 12 ohm resistor parallel to it, it will only draw 2/3 of the hi-freq signal through it, so you can lower the x-o point etc
And since in a lot of cases the tweet will have a higher sensitivity than the woofer and need padding anyway, the right L-pad can allow you to cross significantly lower than indicated in my previous statement.
As for that speaker that crosses at the tweeter res point, I don't know about ribbons, but its certainly not something I would be keen to try with a dome tweeter. (not saying you can't though) If anyone knows of a speaker that does that I'd be very interested!
A parallel resistor can also have quite a large effect on the res freq impedance value of the tweeter as seen by the crossover. Suppose a tweeter has an Fs impedance of 30 ohms (some non ferro tweets go this high!) and you pad it with a 10 ohm parallel resistor, then the most the x-o "sees" is about 9 ohms, and the resistor takes a "large amount" of the signal, at that point (so you gotta use high power resistors). nearly as good as using an LRC !!!
This can be a particularly useful technique in the series x-o cos you can push the value of the capacitor up to rebalance the whole x-o !! Jon Rische and Jeff B on Mad have also mentioned this way of taming a tweeter res peak in a few posts, simpler, way cheaper, and less other problems than an LRC ( but not as accurate cos it is not aimed at a particular frequency)
can often allow a variation from the "rule of thumb" I spoke of earlier.
For instance, if a 6ohm tweeter has a 12 ohm resistor parallel to it, it will only draw 2/3 of the hi-freq signal through it, so you can lower the x-o point etc
And since in a lot of cases the tweet will have a higher sensitivity than the woofer and need padding anyway, the right L-pad can allow you to cross significantly lower than indicated in my previous statement.
As for that speaker that crosses at the tweeter res point, I don't know about ribbons, but its certainly not something I would be keen to try with a dome tweeter. (not saying you can't though) If anyone knows of a speaker that does that I'd be very interested!
A parallel resistor can also have quite a large effect on the res freq impedance value of the tweeter as seen by the crossover. Suppose a tweeter has an Fs impedance of 30 ohms (some non ferro tweets go this high!) and you pad it with a 10 ohm parallel resistor, then the most the x-o "sees" is about 9 ohms, and the resistor takes a "large amount" of the signal, at that point (so you gotta use high power resistors). nearly as good as using an LRC !!!
This can be a particularly useful technique in the series x-o cos you can push the value of the capacitor up to rebalance the whole x-o !! Jon Rische and Jeff B on Mad have also mentioned this way of taming a tweeter res peak in a few posts, simpler, way cheaper, and less other problems than an LRC ( but not as accurate cos it is not aimed at a particular frequency)
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