Hey fellas. This morning I've decided that I want to try an inexpensive build using the Dayton RS180 7" woofer and the Vifa XT25 that I've grown to like quite well.
I've attached what I've come up with so far on the crossover, but bear in mind I'm not used to making proper crossovers yet, so any comments or fun-picking are more than welcome.
What do you think?
I've attached what I've come up with so far on the crossover, but bear in mind I'm not used to making proper crossovers yet, so any comments or fun-picking are more than welcome.
What do you think?
Attachments
We are in a week-end time...
I think you should make a steeper slope for the RS180 to suppress the resonance peaks. Hard cone are hard to work, the result could be superb.
See a similar projects :
RS180-RS28 MTM
HTGuide Forum - RS180 Modula MT - you asked for it, you got it!
I think you should make a steeper slope for the RS180 to suppress the resonance peaks. Hard cone are hard to work, the result could be superb.
See a similar projects :
RS180-RS28 MTM
HTGuide Forum - RS180 Modula MT - you asked for it, you got it!
Hey Jerome
I think I might try a little steeper. One of the things I was concerned with was the peaks. I wasn't sure if they'd be down far enough like this or if I should go steeper.
Steeper it is! One question though, if I make that slope steeper, maybe I should move the crossover point up a little bit? I suspect that the XT25 might be better off a little higher as well.
I'll tinker with it a little bit and post another one later today before I order parts tomorrow or Monday.
It isn't the peaks as per say that need to be so far down. The issue is the peaks created in the distortion profile. Lets say a peak occurs at 9khz in the frequency response. If the driver produces a 3khz tone, then it will naturally create 6khz and 9khz etc as the 2nd and 3rd order distortion products. In this case as the cone rings at 9khz, the 3rd order product will be amplified by the cone and thus you get a peak in the third order distortion product at 3khz. Hence cross before it.
You can see this in action on Zaph's website with his measurements of metal cone drivers. The RS180 wants a steep, low xover. The XT25 doesn't want low, but it can do 2khz with a 4th order slope.
You can see this in action on Zaph's website with his measurements of metal cone drivers. The RS180 wants a steep, low xover. The XT25 doesn't want low, but it can do 2khz with a 4th order slope.
Aha, makes sense. Commence more fiddling! lol.
Edit: I haven't ordered the drivers yet, is there a tweeter that you guys know of that might be a better mate..maybe a little lower where I could simplify the network a little? Maybe I should look at what Zaph used in his :S
Edit2: Meh, the RS28 tweeter is a little too much money.
Last edited:
I'd rather use the Vifa DQ25 over the DC28F. Or rather I've used the DQ25 with the RS125 with great results.
The DQ wont go down low as comfortably as a SEAS 27TDFC will. As Jerome says the vifa DX25 is rather good for the money too.
The crossover is very important however as any tweeter will be working close to it's operating limits. In this regard the DX25 has the most extended low end response and could well make designing the crossover a little bit easier. Whatever tweeter you use you want to use 4th order acoustic slopes no higher then 2khz as this will provide reasonable attenuation for the 3rd order distortion peak in the RS180.
If you've extrapolated the phase response decently then flipping the polarity on any even order network will show a symmetrical notch at the xover frequency if the drivers are well integrated with respect to phase.
The DQ wont go down low as comfortably as a SEAS 27TDFC will. As Jerome says the vifa DX25 is rather good for the money too.
The crossover is very important however as any tweeter will be working close to it's operating limits. In this regard the DX25 has the most extended low end response and could well make designing the crossover a little bit easier. Whatever tweeter you use you want to use 4th order acoustic slopes no higher then 2khz as this will provide reasonable attenuation for the 3rd order distortion peak in the RS180.
If you've extrapolated the phase response decently then flipping the polarity on any even order network will show a symmetrical notch at the xover frequency if the drivers are well integrated with respect to phase.
Why would it make any difference what the cone material is as to when the driver 'gives up'. This is entirely determined by the xmax of the driver and how efficiently it can get rid of heat from the voice coil. A metal cone driver should be slightly better with regards to cooling as the cone can act as a heat sink.
I really wouldn't recommend crossing the tweeter over at 1khz unless you only listen at really low volumes. The DX25 will hit it's linear excursion at around 90dB @ 1khz and while a 1khz xover point with 24dB slopes should keep distortion acceptably low, who's to say how it will handle greater signal levels? Xmax is commonly rated at a point where the driver will produce 10% THD. I don't know about you, but I want to crossover way before that happens.
Adding to this, I have done reasonably high power tests of some quite robust tweeters in the past and they tend to rattle and vibrate at lower frequencies (500-1500hz) when driven hard - enough to make me want to keep any 1" dome on the safer side of 1500hz with steep slopes.
I really wouldn't recommend crossing the tweeter over at 1khz unless you only listen at really low volumes. The DX25 will hit it's linear excursion at around 90dB @ 1khz and while a 1khz xover point with 24dB slopes should keep distortion acceptably low, who's to say how it will handle greater signal levels? Xmax is commonly rated at a point where the driver will produce 10% THD. I don't know about you, but I want to crossover way before that happens.
Adding to this, I have done reasonably high power tests of some quite robust tweeters in the past and they tend to rattle and vibrate at lower frequencies (500-1500hz) when driven hard - enough to make me want to keep any 1" dome on the safer side of 1500hz with steep slopes.
By "giving up" I meant audibility of metal cone resonances(ear piercing sound).
RS180 has 85db sensitivity, after baffle step correction applied, it will be ~82db or less.
XT25 is 90db sensitive, and after it's matched to woofer's level, it's job will be much easier.
It's not going to be a high output speaker anyway, and IMO it's better to keep from woofer's breakup as far as possible, even if a notch filter is used.
RS180 has 85db sensitivity, after baffle step correction applied, it will be ~82db or less.
XT25 is 90db sensitive, and after it's matched to woofer's level, it's job will be much easier.
It's not going to be a high output speaker anyway, and IMO it's better to keep from woofer's breakup as far as possible, even if a notch filter is used.
Yes it is possible but the tweeter is very stressed.
I did it DX25/27TDFC/27TBCG @1kHz : http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-13.html#post1989499
Best in this case is the metal dome... This metal dome also gave better result than an seas excel tweeter T25CF001 in an other project @1500Hz. The metal dome is also more pistonic in the low range ?
This looks a little steeper. I tried to keep it centered around 1900hz or so but tinkering with components pushed it up a bit.
I don't have much experience listening to 4th order though, I've always thought simpler was better. Are these types of crossovers still open sounding?
Edit: And damn that phase shift...should I be concerned?
Something tells me the driver selection process is not over, but I've got itchy fingers and I need to build something, my garage is too clean!
Edit2: What do you guys think about planar tweeters? Parts Express claims this one can be used LR2 as low as 1800.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=297-402
Meh, scratch that, Zaph said their distortion sucks below 2k.
I don't have much experience listening to 4th order though, I've always thought simpler was better. Are these types of crossovers still open sounding?
Edit: And damn that phase shift...should I be concerned?
Something tells me the driver selection process is not over, but I've got itchy fingers and I need to build something, my garage is too clean!
Edit2: What do you guys think about planar tweeters? Parts Express claims this one can be used LR2 as low as 1800.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=297-402
Meh, scratch that, Zaph said their distortion sucks below 2k.
Attachments
Last edited:
Hi,
Your c/o is getting too overcomplicated,
You should be going for 4th order L/R acoustic.
http://www.rjbaudio.com/Audiofiles/FRDtools.html
Take a look at the bass mid c/o topology used here : Zaph|Audio
Its basically first order (set for BSC) followed by a notch
filter, that makes it an elliptical filter but only electrically.
Jay_WJ actually did this for the RS180 ages ago, so I know
it will work but the links to his website no longer work.
I severely doubt than planar works well c/o at 2KHz.
See the tweeter used here : Zaph|Audio - ZMV5 - MCM / Vifa 5" System
rgds, sreten.
http://sites.google.com/site/undefinition/diy (see FAQs)
http://www.zaphaudio.com
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.rjbaudio.com/
http://speakerdesignworks.com/
http://www.htguide.com/forum/showthread.php4?t=28655
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.humblehomemadehifi.com/download.html
http://www.quarter-wave.com/
http://www.frugal-horn.com/
http://www.linkwitzlab.com/
http://www.musicanddesign.com/
Your c/o is getting too overcomplicated,
You should be going for 4th order L/R acoustic.
http://www.rjbaudio.com/Audiofiles/FRDtools.html
Take a look at the bass mid c/o topology used here : Zaph|Audio
Its basically first order (set for BSC) followed by a notch
filter, that makes it an elliptical filter but only electrically.
Jay_WJ actually did this for the RS180 ages ago, so I know
it will work but the links to his website no longer work.
I severely doubt than planar works well c/o at 2KHz.
See the tweeter used here : Zaph|Audio - ZMV5 - MCM / Vifa 5" System
rgds, sreten.
http://sites.google.com/site/undefinition/diy (see FAQs)
http://www.zaphaudio.com
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.rjbaudio.com/
http://speakerdesignworks.com/
http://www.htguide.com/forum/showthread.php4?t=28655
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.humblehomemadehifi.com/download.html
http://www.quarter-wave.com/
http://www.frugal-horn.com/
http://www.linkwitzlab.com/
http://www.musicanddesign.com/
Last edited:
Sexy, but expensive B&G. Anyone have experience with these?
Bohlender Graebener Neo8-PDR Planar Transducer
Bohlender Graebener Neo8-PDR Planar Transducer
Thats what I was thinking as well. Thanks for the links, time for more reading.
Edit: this picture actually helped substantially Sreten, thanks!
Attachments
Last edited:
I'm trying some of the stuff from Sreten's link. From what I can make out, it looks like this is the idea. The resulting chart looks like the tweeter is going to need way more padding, but I guess that's the idea behind BSC.
I will learn this sh if it's the last thing I do!
I will learn this sh
if it's the last thing I do! Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.