Metal domes always sound a bit metallic, of course, but the Zobel tames them a lot. They do have high end detail. A polycone bass should be easier. Probably won't need the notch, perhaps more pure rolloff instead.
This is the hobby. Trying stuff with a reasonable expectation of success.
I do like Class A preamps rather than opamps, and I suppose we just have to put up with less than ideal Class AB power amps unless we shell out big bucks for Class A. Interestingly, the old CD DACs (Like my ancient Sony 18 bit 4Xoversampling) sound better than cheaper modern bitstream from my comparisons. CD can actually sound very good on occasion, I think it gets too compressed in the mix sometimes.
Speakers aren't witchcraft at all, IMO. But I think people rely on flat on-axis frequency response too much. And some of the so-called experts talk about it like it's some exact science.
Here's a no-nonsense view of cabinets:
http://www.diyaudio.com/forums/multi-way/223174-interesting-read-i-found-lossy-cabinet-designs-harbeth.html#post3234256
Now to focus on your next build, possibly with a 6" polycone, we should talk about BW3 and a classic design like the Heybrook HB2 "Classic" designed by Peter Comeau:
http://www.diyaudio.com/forums/multi-way/92628-q-heybrook-hb2-xo.html
The circuit is a bit muddled IMO, but take from it the 3rd order electrical design, because polycones roll off steeper than paper. The crossover is quite low. 2 or 2.5kHz. The exact design and tweeter is a matter of taste, and of what sort of impedance you want.
Hope it helps.
Speakers aren't witchcraft at all, IMO. But I think people rely on flat on-axis frequency response too much. And some of the so-called experts talk about it like it's some exact science.
Here's a no-nonsense view of cabinets:
http://www.diyaudio.com/forums/multi-way/223174-interesting-read-i-found-lossy-cabinet-designs-harbeth.html#post3234256
Now to focus on your next build, possibly with a 6" polycone, we should talk about BW3 and a classic design like the Heybrook HB2 "Classic" designed by Peter Comeau:
http://www.diyaudio.com/forums/multi-way/92628-q-heybrook-hb2-xo.html
The circuit is a bit muddled IMO, but take from it the 3rd order electrical design, because polycones roll off steeper than paper. The crossover is quite low. 2 or 2.5kHz. The exact design and tweeter is a matter of taste, and of what sort of impedance you want.
Hope it helps.
Attachments
I've been looking at the polycone Peerless 830874 in detail.
Peerless 830874 6-1/2" PPB Cone HDS Woofer
It's a low inductance (Le 0.42mH) closed box driver with Qts of 0.43 and Vas of 12.5L.
Impedance Equalization (L-Pad) Circuit Designer / Calculator
Electrically its very similar to the paper 830875 (Qts 0.36, Vas 21.78L which says reflex). I think the chassis is identical.
Less of the typical breakup around 4.5 to 5kHz. But not much different in fact. The main issue is the bass response in a reflex cabinet. That will need some thought. I think it will sound bassier.
Peerless 830874 6-1/2" PPB Cone HDS Woofer
It's a low inductance (Le 0.42mH) closed box driver with Qts of 0.43 and Vas of 12.5L.
Impedance Equalization (L-Pad) Circuit Designer / Calculator
Electrically its very similar to the paper 830875 (Qts 0.36, Vas 21.78L which says reflex). I think the chassis is identical.
Less of the typical breakup around 4.5 to 5kHz. But not much different in fact. The main issue is the bass response in a reflex cabinet. That will need some thought. I think it will sound bassier.
Attachments
You could stuff the ports with drinking straws, which is an old and neat trick. Makes them more resistive. Approaches the half-way house between 12dB/octave closed box and 24dB/octave reflex, AKA aperiodic or damped reflex.
AVI Hi-Fi Legacy - Duo Loudspeaker
Closed box lets you use stuffing to reduce standing waves too. That white BAF wadding is good stuff. It's used in air-conditioning air filters. So is cheap as chips. Fill the box with the stuff so it presses on the back of the metal chassis, which might reduce metal chassis ringing a bit too.
I've already quoted the Harbeth thread on damping panel resonances with rubbery stuff glued to the walls. Rubber backed carpet or carpet tiles will do, IMO. It's just how it works on panels, but thicker is a better absorber.
http://www.diyaudio.com/forums/multi-way/223174-interesting-read-i-found-lossy-cabinet-designs-harbeth.html#post3234256
For an initial experiment, I don't see why you couldn't use your current filter for the 830875 and see how it works.
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I haven't followed the entire thread but if attempting to build something with the sound quality of the Duos (or other AVI speakers as they have a neutral sound balance), and assuming the original drivers aren't available, bear in mind
- AVI's designer has a preference for paper or treated paper cone bass/mid drivers
- soft dome tweeters, usually fabric doped
- uses straightforward, text-book 12dB/octave filters
- doesn't use baffle step or other compensation networks
Some good indication of AVI's quality can be found in reviews on the SoundonSound website, which is aimed at pro audio users. Of course, if aiming for something different to neutral and/or relatively straightforward, the above may not be of use.
- AVI's designer has a preference for paper or treated paper cone bass/mid drivers
- soft dome tweeters, usually fabric doped
- uses straightforward, text-book 12dB/octave filters
- doesn't use baffle step or other compensation networks
Some good indication of AVI's quality can be found in reviews on the SoundonSound website, which is aimed at pro audio users. Of course, if aiming for something different to neutral and/or relatively straightforward, the above may not be of use.
The tweeter model is identical and actually "borrowed" from my AVI Nunetreons. The Midwoofer is different though. They went with the 830874 rather than the 830875. In my naivety I assumed "more expensive innit, must be better then". Still, they sound rather nice at the minute. Still breaking in the woofers, but they're coming on nicely
I'm not familiar with them but any differences in parameters in the two drivers may adversely effect the bass loading as cabinet and port will have been designed to match the driver. But if the drivers are close enough in spec, follow the AVI principle of keeping it simple and you should be ok. There are crossover calculators online.
Steve, Tony,
Bought this little lot to do the final crossover build. Not cheap, but everything else was, so I thought "why not"...
All built up and installed this evening. I didn't bother with the zobel on the tweeter in the end as I felt it attenuated the top end a bit too much for my tastes. The end result is nothing short of stunning! They were really nice before with the temporary "hashed up" crossovers, but this.... Just WOW! Love em. Thanks again for all your help.
Bought this little lot to do the final crossover build.
Not cheap, but everything else was, so I thought "why not"...
All built up and installed this evening. I didn't bother with the zobel on the tweeter in the end as I felt it attenuated the top end a bit too much for my tastes. The end result is nothing short of stunning! They were really nice before with the temporary "hashed up" crossovers, but this.... Just WOW! Love em. Thanks again for all your help.
TBH, I've completely lost track of what we are doing here.
Tristan, this has been a great thread by a guy who actually builds stuff. I think you are using that flame-resistant paper Nomex woofer:
Peerless 830875 6-1/2" Nomex Cone HDS Woofer
And I'm not clear at all what tweeter you are finally using.
Could I ask for a crossover schematic and some driver and box details? Maybe some photos? 6" bass is the hardest driver in the repertoire IMO. But it has something on the detail front.
Tristan, this has been a great thread by a guy who actually builds stuff. I think you are using that flame-resistant paper Nomex woofer:
Peerless 830875 6-1/2" Nomex Cone HDS Woofer
And I'm not clear at all what tweeter you are finally using.
Could I ask for a crossover schematic and some driver and box details? Maybe some photos? 6" bass is the hardest driver in the repertoire IMO. But it has something on the detail front.
I'm always building stuff Steve. Made a nice passive preamp the other day too (not for me though). I've got another pair of boxes here so will do my best to get some accurate measurements of them for you.
Crossover schematic is much easier though. The only change from the one below is that I substituted the zobel on the tweeter section for a 22r 10w resistor. I used all Jantzen parts from HIFI Collective and the total cost came to about £146 for xo, Peerless 830874 were about £97 delivered, cabinets £25, other bits and bobs (spikes ports etc) about £30, the tweeters I already had. Under £300 all in.
Crossover schematic is much easier though. The only change from the one below is that I substituted the zobel on the tweeter section for a 22r 10w resistor. I used all Jantzen parts from HIFI Collective and the total cost came to about £146 for xo, Peerless 830874 were about £97 delivered, cabinets £25, other bits and bobs (spikes ports etc) about £30, the tweeters I already had. Under £300 all in.
Ah, now it comes back to me! Tony modelled the 4.5kHz LCR notch accurately! Hence 5.6uF and 0.2mH and 2R.
The second order tweeter filter is rather Lynn Olson Ariel.
I have been fiddling about with a design like this. But struggling with an undersize box and some lumpy bass, and a pure guess where the notch should go on an unknown driver:
http://www.diyaudio.com/forums/multi-way/221923-upgrading-mordaunt-short-ms15-bookshelves-3.html#post3860811
But it's interesting that in general, designs with smaller bass coils and a bit of resistor damping in the shunt sound more musical. I may have to consider using second order tweeters too.
A fine project, Tristan.
Best Regards, Steve.
The second order tweeter filter is rather Lynn Olson Ariel.
I have been fiddling about with a design like this. But struggling with an undersize box and some lumpy bass, and a pure guess where the notch should go on an unknown driver:
http://www.diyaudio.com/forums/multi-way/221923-upgrading-mordaunt-short-ms15-bookshelves-3.html#post3860811
But it's interesting that in general, designs with smaller bass coils and a bit of resistor damping in the shunt sound more musical. I may have to consider using second order tweeters too.
A fine project, Tristan.
Best Regards, Steve.
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