Hey Paul,
Nah I'm at the city store - but getting the kit sent up from Frankston. I totally agree with you on the baffle - I'm going to set them close together when I make mine, but I wonder if there's such a thing as too close? Obviously I'll need to leave enough wood so that the woofers don't shake the tweeters out, but are there any other probs with putting them too close?
I've seen some baffles which move the tweeter to the side, but as you said the tweeter in this kit is perfect for mounting in the middle.
By the way, what do you think of making the baffle narrower like these guys did? They say it gives better polar response - but I'm wondering why SL wouldn't have thought of that in his original design....
I can't find anything on these boards or google on Nao passive dipoles, or a user called John K. Am I missing something? I know the VAF DC-series speakers I currently own just use a cap to roll the tweeter off at 12dB/octave but then they use box tuning to tame the mids - would the equaliser in (say) a JVC RX-F10 receiver be able to do the necessary correction?
Thanks,
Adam F
Nah I'm at the city store - but getting the kit sent up from Frankston. I totally agree with you on the baffle - I'm going to set them close together when I make mine, but I wonder if there's such a thing as too close? Obviously I'll need to leave enough wood so that the woofers don't shake the tweeters out, but are there any other probs with putting them too close?
I've seen some baffles which move the tweeter to the side, but as you said the tweeter in this kit is perfect for mounting in the middle.
By the way, what do you think of making the baffle narrower like these guys did? They say it gives better polar response - but I'm wondering why SL wouldn't have thought of that in his original design....
I can't find anything on these boards or google on Nao passive dipoles, or a user called John K. Am I missing something? I know the VAF DC-series speakers I currently own just use a cap to roll the tweeter off at 12dB/octave but then they use box tuning to tame the mids - would the equaliser in (say) a JVC RX-F10 receiver be able to do the necessary correction?
Thanks,
Adam F
I'm pretty sure those narrow baffles didn't work out-I think this was the final design- http://home.pacbell.net/donwm/Digital_SEAS_Winged_Phoenix_Final.htm
NaO- http://www.geocities.com/kreskovs/John1.html
NaO- http://www.geocities.com/kreskovs/John1.html
Thanks for the info guys.
I had a look at the Nao site - for someone who doesn't have the skills to build an EQ circuit, would the equalisation built into receivers such as the Panasonic and JVC be able to do the job?
Obviously something like a Behringer DCX2496 would be better but those are too expensive for me.
//Adam F
PS Paul - yes I'm one of those Jaycar guys who knows more about gadgets than components, oh the shame
I had a look at the Nao site - for someone who doesn't have the skills to build an EQ circuit, would the equalisation built into receivers such as the Panasonic and JVC be able to do the job?
Obviously something like a Behringer DCX2496 would be better but those are too expensive for me.
//Adam F
PS Paul - yes I'm one of those Jaycar guys who knows more about gadgets than components, oh the shame
Adam,
The ideal with driver spacing is to have a point source - all sounds coming from one location. So you should aim to get as close to this as possible. I prefer the look of drivers aligned, rather than offsetting the tweeter to one side. In your case I would allow a small space between the tweeter and midbass drivers - say 5mm, with the drivers flush mounted to avoid edge diffraction problems.
You might wish to experiment with your eq on your receiver as a temporary measure, but for long term use you should make up a filter.
Different designs with the baffle regarding width and the use of wings gives a different mix of characteristics, including factors such as size (the obvious), matching the size of the bass, polar response, frequency response in the passband, imaging and the sense of transparency. Therefore there is not "best" mix, it's a matter of trade offs. Linkwitz designed his for what he considers the best mix of what performs well and is domestically acceptable.
I heard the latest VAF DXC speakers on a recent trip to Adelaide - not very impressive. The top end was a little harsh and unrefined to my ears. I don't think their minimalist approach to crossver design in that speaker works very well. I found their other speakers more impressive, in particular the Signature series!
One challenge with your speaker is getting the tweeter to handle the low crossover point that will be required to mate it with 8" midbass drivers. In their DCX speaker, vaf now use two small tweeters and a pair of 8" midbass drivers. This reduces stress on the tweeters due to what is probably a low xo point and gives higher efficiency. It has approx 2x the SD of a typical MTM with 6.5" midbass drivers. I like the idea, but something went wrong in the execution in my view.
What do you plan to do for the bass? ... might be a good idea to either start a new thread or move to email if you wish to discuss further, as it's getting a bit off topic.
The ideal with driver spacing is to have a point source - all sounds coming from one location. So you should aim to get as close to this as possible. I prefer the look of drivers aligned, rather than offsetting the tweeter to one side. In your case I would allow a small space between the tweeter and midbass drivers - say 5mm, with the drivers flush mounted to avoid edge diffraction problems.
You might wish to experiment with your eq on your receiver as a temporary measure, but for long term use you should make up a filter.
Different designs with the baffle regarding width and the use of wings gives a different mix of characteristics, including factors such as size (the obvious), matching the size of the bass, polar response, frequency response in the passband, imaging and the sense of transparency. Therefore there is not "best" mix, it's a matter of trade offs. Linkwitz designed his for what he considers the best mix of what performs well and is domestically acceptable.
I heard the latest VAF DXC speakers on a recent trip to Adelaide - not very impressive. The top end was a little harsh and unrefined to my ears. I don't think their minimalist approach to crossver design in that speaker works very well. I found their other speakers more impressive, in particular the Signature series!
One challenge with your speaker is getting the tweeter to handle the low crossover point that will be required to mate it with 8" midbass drivers. In their DCX speaker, vaf now use two small tweeters and a pair of 8" midbass drivers. This reduces stress on the tweeters due to what is probably a low xo point and gives higher efficiency. It has approx 2x the SD of a typical MTM with 6.5" midbass drivers. I like the idea, but something went wrong in the execution in my view.
What do you plan to do for the bass? ... might be a good idea to either start a new thread or move to email if you wish to discuss further, as it's getting a bit off topic.
Hey Adam, if your drivers are the P21 and the D26, you should take a look at SL's prototype page where he has a couple of passive designs using those drivers. The only thing is he used the 8 ohm P21 so you'd need to make some changes in the crossover.
http://linkwitzlab.com/proto.htm
http://linkwitzlab.com/proto.htm
I have heard it briefly in the kit, but unfortunately it was on the radio with some crappy music and a not particularly flattering receiver, so I can't comment much based on that.
But the Vifa neo tweeter is very similar to the Vifa D26 (I think), except it has a much higher Q and hence sharper rolloff. Fairly low fs. It can't be crossed at 1.2k due to the rolloff, but more like 2k perhaps. I have heard the D26 and it's a nice tweeter.
It actually makes me wonder why neo isn't used more in tweeter magnets. It means you can use a compact faceplate. The conventional large faceplate isn't really needed for any acoustic reason when the driver is flush mounted. It makes the tweeter less flexible. I only wish they would make the Vifa neo with a round faceplate! What is it with speaker manufacturers making non-circular shaped face plates?
Steve, I have tended to agree with you about amps, but I'm moving away from that a little. After recently comparing a decent diy gainclone and a very nice rotel power amp, I have to say there is more in high end amps than I was inclined to think in the past. This is one of the issues you face with Orion and similar speakers. Chip amps are very tempting, but they are in my view less refined than a good Rotel. Still, I think you can make a great diy amp for slightly more than the cost of a chip amp and match the Rotel or better it.
My drivers arrived today, whoopee.
Now I have to decide on a crossover. Adapting Linkwitz's passive design for 4ohm drivers has proven harder than I thought, because of the notch filter (or whatever it is - some kind of bass boost?). Also, he seems to have the two 8ohm P21s connected in series - isn't that a little unusual?
I'm tempted to just go active, but I'm finding it hard to justify the cost. I don't suppose anyone here knows of an active crossover or Tripath amp for sale 2nd hand?
Thanks,
//Adam F
Now I have to decide on a crossover. Adapting Linkwitz's passive design for 4ohm drivers has proven harder than I thought, because of the notch filter (or whatever it is - some kind of bass boost?). Also, he seems to have the two 8ohm P21s connected in series - isn't that a little unusual?
I'm tempted to just go active, but I'm finding it hard to justify the cost. I don't suppose anyone here knows of an active crossover or Tripath amp for sale 2nd hand?
Thanks,
//Adam F
Adam, the tricky part with active is not the crossover but all the filters that you add, at least if you want to do Phoenix or Orion, or something that attempts to get close to their performance. Making an active crossover that merely divides up the signal to the drivers is not that hard. Jaycar even have a 3 way active xo kit with all the parts that you could probably get ridiculously cheap!
I understand Paul, and that would be nice but:
a) I haven't put iron to solder since 1996, and then it was to build a simple FM transmitter, which didn't work...and (b) equalisers are cheap and seem to do substantially similar work to these complicated bandpass filters.
I was reading about the DCX2496 (as used by sfdoddsy) in an old Audio Xpress at work yesterday - what an amazing piece of machinery. You can hook it up to your PC and play with the xover points/slopes etc, then compensate for room your room, add notch filters etc - all in software. Then I'd be in familiar territory.
The only small problem is that if i bought one, I wouldn't be able to afford amplification. There's always a catch
//Adam F
a) I haven't put iron to solder since 1996, and then it was to build a simple FM transmitter, which didn't work...and (b) equalisers are cheap and seem to do substantially similar work to these complicated bandpass filters.
I was reading about the DCX2496 (as used by sfdoddsy) in an old Audio Xpress at work yesterday - what an amazing piece of machinery. You can hook it up to your PC and play with the xover points/slopes etc, then compensate for room your room, add notch filters etc - all in software. Then I'd be in familiar territory.
The only small problem is that if i bought one, I wouldn't be able to afford amplification. There's always a catch
//Adam F
Ultradrive is great and I'd like to have a play with it as well but at AU $900 it would eclipse the cost of your drivers! Still, you could always upgrade the drivers later on and you could probably get hold of a cheap low power amp for the tweeter - you could get away with 10 - 20w. You could get one of those cheap amp modules until you can afford better.
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