Hi Sreten,
Very much appreciated, thank you! ( I do value your replies! - you have helped me before)
Your recent reply re: baffle step was truly 'illuminating' - turned the lights on!
I was beginning to think DIY was too hard till I read that! (And of course such great
encouragement and amazing input from Omni - thanks Omni!) I was considering
'canning' the whole idea, and cutting my losses untill then!
(Sreten I realise you are very busy replying to everyone in this forum...but a Q or 2? is OK?)
From a beginners perspective, I assume 'partial Zobeling' means 'derr' that the impedance rise
is only partially compensated - probably say about 50%? For example, say a woofer has, as an
example, an impedance of about 16 Ohms at 3Khz, does that mean that partial Zobeling in this
(50%) case would be half of that, ie an 8 Ohms reduction at 3K? I really don't know what it
means - but it seems realistic? - unfortunately its not in the 'Cookbook' I have, (old 1997print).
As to how to calculate the 'partial' values for C & R, I guess I'll have to figure it out -somehow!
Re: (quote) "Personally I'd say partial zobelling of woofers is the best option,
if zobelling is needed for the crossover design." ......
This raises lots of questions and leaves a beginner like me a tad perplexed!
From my viewpoint now, the midrange (from reading Vance D. 1997) will need full Zobel.
Sreten, could you please elaborate a little why partial Zobeling of woofers is the best option?
Please don't get me wrong, I'm only trying to understand your comments, thats all.
Like I said, your replies are truly inspirational!, but some of us 'plebs' might have a bit of difficulty
comprehending things, like the 'why and wherefors'.
Absolutely no offence intended, only kindest regards, and many thanks....Grant
Very much appreciated, thank you! ( I do value your replies! - you have helped me before)
Your recent reply re: baffle step was truly 'illuminating' - turned the lights on!
I was beginning to think DIY was too hard till I read that! (And of course such great
encouragement and amazing input from Omni - thanks Omni!) I was considering
'canning' the whole idea, and cutting my losses untill then!
(Sreten I realise you are very busy replying to everyone in this forum...but a Q or 2? is OK?)
From a beginners perspective, I assume 'partial Zobeling' means 'derr' that the impedance rise
is only partially compensated - probably say about 50%? For example, say a woofer has, as an
example, an impedance of about 16 Ohms at 3Khz, does that mean that partial Zobeling in this
(50%) case would be half of that, ie an 8 Ohms reduction at 3K? I really don't know what it
means - but it seems realistic? - unfortunately its not in the 'Cookbook' I have, (old 1997print).
As to how to calculate the 'partial' values for C & R, I guess I'll have to figure it out -somehow!
Re: (quote) "Personally I'd say partial zobelling of woofers is the best option,
if zobelling is needed for the crossover design." ......
This raises lots of questions and leaves a beginner like me a tad perplexed!
From my viewpoint now, the midrange (from reading Vance D. 1997) will need full Zobel.
Sreten, could you please elaborate a little why partial Zobeling of woofers is the best option?
Please don't get me wrong, I'm only trying to understand your comments, thats all.
Like I said, your replies are truly inspirational!, but some of us 'plebs' might have a bit of difficulty
comprehending things, like the 'why and wherefors'.
Absolutely no offence intended, only kindest regards, and many thanks....Grant
Omni, thanks re: all, especially <rant> its very late here, be back soon!
Will reply in more detail then, thanks mate (as we say in AU!)...grant
Will reply in more detail then, thanks mate (as we say in AU!)...grant
omni said:
Hi,
A full Zobel for a 6R (8 ohm) woofer would use 6R + a capacitor.
However what you are trying to control is the effect of the (lossy)
inductance of the driver. Partial zobelling is using something like
10r to 15R and a capacitor, controls the effect and maintains a
higher impedance.
Zobelling bass drivers is more useful for odd order (1,3, etc) electrical
parallel filter ands even order (2, 4 etc) series filters, less useful for
the opposite cases.
Also discussing the bass behaviour of a mid without its high pass
crossover is fairly pointless, the end result is what matters, Qbox
=1 and filter =0.5 gives the same result as Qbox =0.5 and filter =1.
🙂/sreten.
Hi,
I'd also reccommend downloading the free trail of Svante's Basta
program. Cookbook crossover design is exactly that, far too simple,
and only applicable when the simplifications are valid, trouble is
the simplifications are not explained. Practical filter design uses the
minimum necessary, and you have to know what you are doing.
The Basta trail will allow you to model the crossover, especially
the mids box alignments interaction with its high pass filter, the
behaviour generally is not what you'd expect, things get very
hairy if the box frequency and filter frequency are close.
🙂/sreten.
http://www.tolvan.com/basta/
or
http://www.rjbaudio.com/Audiofiles/FRDtools.html
I'd also reccommend downloading the free trail of Svante's Basta
program. Cookbook crossover design is exactly that, far too simple,
and only applicable when the simplifications are valid, trouble is
the simplifications are not explained. Practical filter design uses the
minimum necessary, and you have to know what you are doing.
The Basta trail will allow you to model the crossover, especially
the mids box alignments interaction with its high pass filter, the
behaviour generally is not what you'd expect, things get very
hairy if the box frequency and filter frequency are close.
🙂/sreten.
http://www.tolvan.com/basta/
or
http://www.rjbaudio.com/Audiofiles/FRDtools.html
Hi sreten,
Your comment (quote): "Also a mid units bass alignment can have quite a high Q, combined with its high pass filter, it can be near irrelevant." shows great insight and puts the mid alignment into perspective for me. Great stuff! thanks
Your comment (quote): "Also a mid units bass alignment can have quite a high Q, combined with its high pass filter, it can be near irrelevant." shows great insight and puts the mid alignment into perspective for me. Great stuff! thanks
an apology....
My comment re 'plebs' was made in a jocular way. I was referring to myself only as a 'green' beginner and no one else here. I hope I didn't offend anyone.
My comment re 'plebs' was made in a jocular way. I was referring to myself only as a 'green' beginner and no one else here. I hope I didn't offend anyone.
Alright Sreten............... I humbly offer to you that now it seems you are startin to put up.............I checked out the link pertaining to FRD toolbox and it looks like it may be useful, It was late, so I have to study it further when time permits............. I say this to you in the most humble manner I can when I say that there are a lot of us out there who don't have measurement tools other than, perhaps a multimeter. Problem is, and I can only be fair to speak for myself, that when I read posts on this forum, it appears that many of those posts are coming from people who have full blown measurement setups, with costly implementation tools, and the information goes right over my head, not to mention the inability to duplicate the processes described...... It seems that these posters can become impatient with a person who wants to know the whats, whys and wherefors................. and sometimes they seem argumentative.......... real or imagined.........The only thing left to do is pour through tons of speakerbooks, search megabytes of websites, and learn by trial and error, hopefully learning along the way; AND to pester the experienced posters on this forum to milk as much experience, strength and hope from them as possible..lol..... It is a neat thing, and a joy to share the information with others, kind of like the kid who has just learned to ride a bicycle........... At any rate, you seem to be very active here, and I believe you garner much joy in your tutelage on this forum. For me, the joy in the speakerbuilding process is definately a thrill, with the added gratification of corresponding with other "like minds" such as you, Grant, and Tinitus, and others from across the world; What a treat!.............Thank you for posting that link. Maybe with its' help, combined with my old frequency generator, and multimeter and a lot trial and error, something beautiful will grow. I look forward to share. I got on this particular thread because Grant mentioned some of the drivers he's using, and might use, and they are the same ones I have committed to..... Grant, it seems we are going down similar paths..........."Off to see the Wizard"........ It's weird, but almost every thread I have been involved in on this forum, the likes of you and Tinitus have always shown up...............Hey Grant, I think we are in good company!.............Respectfully................Omni
Hi Omni,
Your last message was wonderful! Especially this "the added gratification of corresponding with other "like minds" such as you, Grant, and Tinitus, and others from across the world; What a treat!".
Beautiful thoughts that I so much relate to, thanks Omni it made me smile, I'm so happy to read that! (I was wondering if I was pestering people!)
I hope your project is progressing well. How are the enclosures looking?
For mine: the more I think about a full 2order network (LR2 my original plan B) the more appealing its becoming. Only a few days ago I had dismissed the idea as the required high mH value (and low DCR air-core) coils were way out of my budget. I presume you are using good quality ones eg Solen.
But if I could use cheap, stock ferrite core coils for the woofer and the mids large one, this all changes.
I've heard that ferrite cored inductors produce more distortion. Is this true? And if so, I'm wondering how noticible it would be to me at around 300Hz. I guess subwoofers use them, as commercial air cores at maybe 30-60Hz would be incredibly expensive.( I once saw a sub design using homemade air cores, admittedly thick gauge wire, which were roughly the size of 2 house bricks!)
From the Lalena calculator ( xo 290) the mids coil is 9mH and the woofers 8.9mH, so close (1%) that I could just use stock ones without unwinding! and only $14AU (DCR 0.95 Ohm). The Solen air cores (DCR 0.87) are $112AU! - so you can see why I'd like to be able to use the cheapies. As my project is a cheap and cheerful (probably non-optimal) upgrade, using some ferrite inductors might OK. Any thoughts please Omni?
A full LR2 also has a bandpass gain of 2dB which would make the CA a better match SPL-wise to our other drivers, I presume.
I'll have a go at downloading the WinIsd's tonight, while Sreten's Basta link looks very promising also. I've just been browsing its user guide - very comprehensive, but I'm not sure how much functionality the 'locked' version provides but it could definitely be worth buying if I can afford it, lol.
The 'FRD Consortium' programs over at Roman Bednarek's site look very useful too but most use Excel spreadsheets. I don't think they would work for the free 'StarOffice' which I have.
Lastly, how did you design your XO? Software package/calculator or by hand from formulas? I'm also wondering if baffle step and its correction is an issue with your design? Thanks Omni, best regards....grant
Your last message was wonderful! Especially this "the added gratification of corresponding with other "like minds" such as you, Grant, and Tinitus, and others from across the world; What a treat!".
Beautiful thoughts that I so much relate to, thanks Omni it made me smile, I'm so happy to read that! (I was wondering if I was pestering people!)
I hope your project is progressing well. How are the enclosures looking?
For mine: the more I think about a full 2order network (LR2 my original plan B) the more appealing its becoming. Only a few days ago I had dismissed the idea as the required high mH value (and low DCR air-core) coils were way out of my budget. I presume you are using good quality ones eg Solen.
But if I could use cheap, stock ferrite core coils for the woofer and the mids large one, this all changes.
I've heard that ferrite cored inductors produce more distortion. Is this true? And if so, I'm wondering how noticible it would be to me at around 300Hz. I guess subwoofers use them, as commercial air cores at maybe 30-60Hz would be incredibly expensive.( I once saw a sub design using homemade air cores, admittedly thick gauge wire, which were roughly the size of 2 house bricks!)
From the Lalena calculator ( xo 290) the mids coil is 9mH and the woofers 8.9mH, so close (1%) that I could just use stock ones without unwinding! and only $14AU (DCR 0.95 Ohm). The Solen air cores (DCR 0.87) are $112AU! - so you can see why I'd like to be able to use the cheapies. As my project is a cheap and cheerful (probably non-optimal) upgrade, using some ferrite inductors might OK. Any thoughts please Omni?
A full LR2 also has a bandpass gain of 2dB which would make the CA a better match SPL-wise to our other drivers, I presume.
I'll have a go at downloading the WinIsd's tonight, while Sreten's Basta link looks very promising also. I've just been browsing its user guide - very comprehensive, but I'm not sure how much functionality the 'locked' version provides but it could definitely be worth buying if I can afford it, lol.
The 'FRD Consortium' programs over at Roman Bednarek's site look very useful too but most use Excel spreadsheets. I don't think they would work for the free 'StarOffice' which I have.
Lastly, how did you design your XO? Software package/calculator or by hand from formulas? I'm also wondering if baffle step and its correction is an issue with your design? Thanks Omni, best regards....grant
Hi,
I don't have a measurement set up of any sort. But I do understand most
of the in's and out's of speaker design, and I do find it frustrating when the
fundamentals seem to be being ignored at the cost of debating some dubious
aspects of what people think is the right or wrong way to do things.
Perhaps this is what is being referred to as "seems you are startin to put up".
3-ways are notoriously difficult to design, because there are conflicting issues
regarding the bass / mid crossover, if one of these issues is ignored its almost
impossible to get it right by accident, generally it will be wrong.
The paper cone 3-ways on troels site are a good starting point for research.
Loads of sites have misinformation - I recommend being familiar with pretty much
the total content of the following, though each one has its individual limitations :
http://www.zaphaudio.com/
http://www.humblehomemadehifi.com/
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.rjbaudio.com/projects.html
🙂/sreten.
I don't have a measurement set up of any sort. But I do understand most
of the in's and out's of speaker design, and I do find it frustrating when the
fundamentals seem to be being ignored at the cost of debating some dubious
aspects of what people think is the right or wrong way to do things.
Perhaps this is what is being referred to as "seems you are startin to put up".
3-ways are notoriously difficult to design, because there are conflicting issues
regarding the bass / mid crossover, if one of these issues is ignored its almost
impossible to get it right by accident, generally it will be wrong.
The paper cone 3-ways on troels site are a good starting point for research.
Loads of sites have misinformation - I recommend being familiar with pretty much
the total content of the following, though each one has its individual limitations :
http://www.zaphaudio.com/
http://www.humblehomemadehifi.com/
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.rjbaudio.com/projects.html
🙂/sreten.
Hi sreten, thanks so much for your clarification on partial Zobeling.
I've actually got the calculator out here and by hand! getting Xc's for various caps in series with 10 and 15 ohm resistors at various frequencies! And plotting the resultant Z in parallel with the drivers appropriate impedance at appropriate octaves.
I presume the resulting impedance rise might be desirably 50% of non Zobeled.
If I had the 'Basic' program language on this PC I could write a little routine, it would be a lot easier! thanks Grant
I've actually got the calculator out here and by hand! getting Xc's for various caps in series with 10 and 15 ohm resistors at various frequencies! And plotting the resultant Z in parallel with the drivers appropriate impedance at appropriate octaves.
I presume the resulting impedance rise might be desirably 50% of non Zobeled.
If I had the 'Basic' program language on this PC I could write a little routine, it would be a lot easier! thanks Grant
Hi Sreten,
Thanks! I do agree that a 3way may be nearly impossible for me as a beginner, I think I did say that in my opening post?. But, as you (or I) don't have any measurement facilities, then, just maybe, I could possibly and eventually achieve (either by trial and error tweaking..arrrggh or by your Basta link) an acceptable result for me, well hopefully better than what I have currently. And maybe even emulate a FRACTION of your success and insight. So what limits me now is my knowledge and my possible capacity to understand!
This is why I have been reading (for a while now) all of those 4 sites you kindly listed and others like Rod Elliot etc. (Maybe I'm a bit too slow for this now? - at 54 I'm certainly not as sharp as I used to be!
but I definitely like a challenge). To get a 'feel for' the fundamentals, so that when kind, benevolent and very knowledgable people like you offer to help and provide information at least I know when to sit up and pay due attention and follow it up by study because its important enough for you to mention it!
I've said many times that I very much appreciate and value your help and comments. This is true.
Could I please therefore VERY RESPECTFULLY comment on this (quote)... "and I do find it frustrating when the fundamentals seem to be being ignored at the cost of debating some dubious aspects of
what people think is the right or wrong way to do things". Um, as a beginner, I'm desperately trying to become an intermediate! This is a very complex hobby, especially 3ways. And sometimes (for me as a novice) its very difficult 'to separate the wheat from the chaff', ie to identify whats important and whats not. There is SO much information out there and as you acknowledge "loads of sites have
misinformation". So this is my dilemma. There can be many different points of view, and arguments rage about some things, like the specially named (I'm sorry I can't recall the name now, I think Lyn
Olson was opposed to it, maybe Mr Linkwitz) minimalistic crossovers. So what is a beginner to do?
Find a person who is believable and trust them!
Sreten, I trust you! (aw shucks, LOL)
Your advice to me has been/is still entirely reasonable, believable and also helps greatly facilitate my learning, provided I follow up your insights by study, but that usually raises more questions of course. I certainly don't want to waste your time, because if you kindly offer good information, I'm sure that you would want your audience to appreciate (and make the most of) it. I do! I'm sure you realise these comments are sincere.
I will revisit Troels 3way paper cone in my quest for knowledge! ....respectfully...grant
Thanks! I do agree that a 3way may be nearly impossible for me as a beginner, I think I did say that in my opening post?. But, as you (or I) don't have any measurement facilities, then, just maybe, I could possibly and eventually achieve (either by trial and error tweaking..arrrggh or by your Basta link) an acceptable result for me, well hopefully better than what I have currently. And maybe even emulate a FRACTION of your success and insight. So what limits me now is my knowledge and my possible capacity to understand!
This is why I have been reading (for a while now) all of those 4 sites you kindly listed and others like Rod Elliot etc. (Maybe I'm a bit too slow for this now? - at 54 I'm certainly not as sharp as I used to be!
but I definitely like a challenge). To get a 'feel for' the fundamentals, so that when kind, benevolent and very knowledgable people like you offer to help and provide information at least I know when to sit up and pay due attention and follow it up by study because its important enough for you to mention it!
I've said many times that I very much appreciate and value your help and comments. This is true.
Could I please therefore VERY RESPECTFULLY comment on this (quote)... "and I do find it frustrating when the fundamentals seem to be being ignored at the cost of debating some dubious aspects of
what people think is the right or wrong way to do things". Um, as a beginner, I'm desperately trying to become an intermediate! This is a very complex hobby, especially 3ways. And sometimes (for me as a novice) its very difficult 'to separate the wheat from the chaff', ie to identify whats important and whats not. There is SO much information out there and as you acknowledge "loads of sites have
misinformation". So this is my dilemma. There can be many different points of view, and arguments rage about some things, like the specially named (I'm sorry I can't recall the name now, I think Lyn
Olson was opposed to it, maybe Mr Linkwitz) minimalistic crossovers. So what is a beginner to do?
Find a person who is believable and trust them!
Sreten, I trust you! (aw shucks, LOL)
Your advice to me has been/is still entirely reasonable, believable and also helps greatly facilitate my learning, provided I follow up your insights by study, but that usually raises more questions of course. I certainly don't want to waste your time, because if you kindly offer good information, I'm sure that you would want your audience to appreciate (and make the most of) it. I do! I'm sure you realise these comments are sincere.
I will revisit Troels 3way paper cone in my quest for knowledge! ....respectfully...grant
Hi,
Tina-ti allows you to directly plot / simulate impedance, very quickly.
(it has an impedance meter)
Partial zobelling limits the rise of impedance to the Zobel resistor value.
Non-zobelled carries on increasing so they are not % comparable.
🙂/sreten.
http://focus.ti.com/docs/toolsw/folders/print/tina-ti.html
(to get passive circuits to work just add an unconnected op-amp)
Tina-ti allows you to directly plot / simulate impedance, very quickly.
(it has an impedance meter)
Partial zobelling limits the rise of impedance to the Zobel resistor value.
Non-zobelled carries on increasing so they are not % comparable.
🙂/sreten.
http://focus.ti.com/docs/toolsw/folders/print/tina-ti.html
(to get passive circuits to work just add an unconnected op-amp)
grantnsw said:
Hi,
I'm mostly talking about the people giving advice, not the people asking for it,
🙂/sreten.
Omni, I've been re-reading your last message 3 times! It makes me smile! You are so eloquent! Even artful and so refreshing! I once read that speaker building was an art and a science - I think you cover both! ....grant
Hi,
May sound a stupid question but are you sure you don't like the D75's ?
Who made the original speakers / designed the crossovers ?
What is the original crossover ?
If a speaker doesn't sound good it doesn't necessarily mean poor drivers.......
🙂/sreten.
May sound a stupid question but are you sure you don't like the D75's ?
Who made the original speakers / designed the crossovers ?
What is the original crossover ?
If a speaker doesn't sound good it doesn't necessarily mean poor drivers.......
🙂/sreten.
Grant, Thank you for your comments.............I got a real kick out of your statement about desperately trying to become an intermediate..............Hells Bells, man, shoot for the stars!.....lol. Sreten, thank you for acknowledging my post. I think we all have similar goals in mind.........At any rate, Grant, the questions you ask are about issues I have given serious thought and research to, along with actions and decisions made. The iron core vs. air cored inductors debate continues, and probably will continue to continue, but a line in the sand had to be drawn. Firstly, I have read that there IS a difference between Ferrite coils and Iron Core coils, and recommendations seem to point the way to stay away from Ferrite. Not sure exactly why. But also, some people suggest that Iron core inductors are fraught with saturation distortion and histerysis...........I think my spelling is wrong here...... Then there are those who have said that the Iron cores wont distort at the powers that home audio amplifiers produce. Again, I'm not sure.........Air cores appear to be the preferred choice, albeit more expensive, and with higher DCR than the Iron core inductors for a given inductance in the higher inductance values. That being said, I am going to use Iron cored inductors in the woofer section , and in the lower portion of the midbass leg of the crossover. I am putting my emphasis on lower DCR for now, and hope that the theorists who report that there are no problems with saturation distortion are correct. In addition, there is a HIGHLY respected individual who goes by the name of ZAPH, who uses Iron cored inductors in his designs. Maybe an endorsement, maybe not..............For the rest of the crossover I am going to use 14 gauge air core Solens. Even in the tweeter section. There are various reports that this may be overkill, as such, that some people believe that a bit of DCR in the tweeter leg is negligible. Again, I am not certain here. Capacitor research is an entirely different beast, which right now would turn my verbosity on this post into "mega verbosity".........lol.......The approach I have taken so far, with crossover design, has been a great amount of study in Dickasons Cookbook, Weems book and internet research. The APC formulas in Dickasons' book have appeared to be the most reasonable alternative, so what I have been doing is : making impedance measurements in free air and comparing them to published specs: ie manufacture specs and specs found on Zaphs website. My next step is to get the drivers mounted in the finished cabinets, and make actual impedance measurements, again, to use for the data for the APC formulas in Dickasons book. BTW, the Lalena formulas, I believe, are very similar to Dickasons'. The Zobels for my midbass and tweeter were designed as per the manuscript Rod Elliot wrote..... The next step is to assemble the crossover and do listening tests by ear, and tweak if need be................HOWEVER..........Sreten has posted a link we both have found that might be useful, so I believe it would be remiss of me not to incorporate this into my thinking.............So, I am going to do some experiments with that information here shortly.............As far as baffle step goes: At this time I am not going to worry about it for a few reasons: I designed my cabinets to be wide at the bottom, where the woofer is, and taper up into the midbass, tweeter region. Pyramid. The baffle width is also wide enough at the midbass, that I shouldn't lose a significant amount of SPL, but slender enough at the tweeter to facilitate good dispersion and imaging. Even if I do lose a little SPL in the woofer, it may bring it closer in line with the CA15RLY, which has a lower reported SPL at 86dB, where my woofer has a SPL reported as 92dB. The baffle is also slanted at about 7-8 degrees to bring voice coils into line on the vertical plane. I did this, not by math, but by actual physical measurements, given the driver placement distances between them. Rounded baffle edges to help eliminate diffraction.......... Back to the crossover: 2nd order electrical, at 300-3000 Hz, with sealed enclosures bringing it to 4th order acoustically...........I hope. Zener diodes paralleled across tweeter for protection? Maybe. I have used it in the past..... Any comments from anyone out there about the Zeners?..........At any rate, I hope your efforts continue to burgeon, and lets keep in touch...........Respectfully.....Omni
Hi Sreten,
re D75's: I think they were damaged when the amp blew up. Amazingly the D25's still seem OK.
I think the D75's were a very poor driver. Although the on-axis looks superficially great on paper, +-1.5dB 600-7000Hz, the off-axis is very poor. Then 60deg off plummets a whopping 40+dB one
octave from 2K while the on axis is only 2dB down at 7Khz. Cone breakup begins in the late 5000's I think which would necessitate a 3rd order at only 2K. I read somewhere, that its not advisable to xo where the 'off' is dropping rapidly.
Similarly for HP a 3rd order would be required. From 800 its only 2dB down at 400. Resonance at 350Hz. So for all the increased complexity I'd only be getting a usable range from 800+ to 2K.
Which are spaced way too close to minimize interference?. The xo complexity, if it could be done at such close spacing, is well beyond me. Hardly seems worth it considering their age und unknown condition.
I think it was Lyn Olson, in one of his essays who said that nearly all dome-mids were rubbish that shouldn't have been built! But I didn't know any of this when I bought them.
The project was concieved by an AU audio magazine at the time 1998! and offered as a kit. I made the boxes and built the xo's. I no longer have the original article but I think the xo was a mix of orders 1,2 and3.
I was looking to replace the D75's initially with Peerless 832873(830873) but the CA15's seem like better performers for less money here. grant
re D75's: I think they were damaged when the amp blew up. Amazingly the D25's still seem OK.
I think the D75's were a very poor driver. Although the on-axis looks superficially great on paper, +-1.5dB 600-7000Hz, the off-axis is very poor. Then 60deg off plummets a whopping 40+dB one
octave from 2K while the on axis is only 2dB down at 7Khz. Cone breakup begins in the late 5000's I think which would necessitate a 3rd order at only 2K. I read somewhere, that its not advisable to xo where the 'off' is dropping rapidly.
Similarly for HP a 3rd order would be required. From 800 its only 2dB down at 400. Resonance at 350Hz. So for all the increased complexity I'd only be getting a usable range from 800+ to 2K.
Which are spaced way too close to minimize interference?. The xo complexity, if it could be done at such close spacing, is well beyond me. Hardly seems worth it considering their age und unknown condition.
I think it was Lyn Olson, in one of his essays who said that nearly all dome-mids were rubbish that shouldn't have been built! But I didn't know any of this when I bought them.
The project was concieved by an AU audio magazine at the time 1998! and offered as a kit. I made the boxes and built the xo's. I no longer have the original article but I think the xo was a mix of orders 1,2 and3.
I was looking to replace the D75's initially with Peerless 832873(830873) but the CA15's seem like better performers for less money here. grant
Hi Omni, thanks for the information, much appreciated as usual.
Re: hysteresis of solid cores causing saturation, is what prompted my question. I guess if Zaph uses iron cores, then thats good enough for me!
This is great news!, my full LR2 version is now viable and in my budget so this project now looks to be a 'goer'. Excuse my ignorance but I didn't at first realise there was a difference between ferrite and iron. Evidently its an alloy(allotrope) of pure iron, which is why iron core could induce the distortion you mention I suppose.
Re: capacitor testing, there's a great review over here ---> www.humblehomemadehifi.com/Cap.html
...you probably have read it. I'll just be using the cheapest polys, and poly shunted bipolar electros for the larger values.
Your impedance testing seems very methodical and essential if one has the means.
Yes, Lalena 3way are APC LR2 just like Vance's formulas, because I think the only 2nd order APC types are in fact LR2's.
It will be interesting to see what results you get with Sreten's Basta link. I'll try it when I've finished reading the 'doco'.
Nice pyramid design! and OK re baffle step. The full LR2 xo evidently also gives a 2dB overall gain for the mid? Also good idea re the slanted cabinet for 'ZDP' issues. I'll effectively be able to do the same if I build seperate tweeter&mid boxes.
Are quick acting polyswitches an alternative to Zeners?
Thanks Omni! grant...."shooting for the stars'! LOL
PS: I just had an idea re a tweaking method. Obtain dual-mono from amp by 1) simply combining channels in the 'Audacity' WAV-editor on the PC or 2) using a stereo to mono adapter cable from CD to amp. Building my simpler xo for one speaker and the full LR2 design for the other speaker. Compare by toggling the balance control. Tweak 'ad-nauseam'! Guess I could try it.
Re: hysteresis of solid cores causing saturation, is what prompted my question. I guess if Zaph uses iron cores, then thats good enough for me!
This is great news!, my full LR2 version is now viable and in my budget so this project now looks to be a 'goer'. Excuse my ignorance but I didn't at first realise there was a difference between ferrite and iron. Evidently its an alloy(allotrope) of pure iron, which is why iron core could induce the distortion you mention I suppose.
Re: capacitor testing, there's a great review over here ---> www.humblehomemadehifi.com/Cap.html
...you probably have read it. I'll just be using the cheapest polys, and poly shunted bipolar electros for the larger values.
Your impedance testing seems very methodical and essential if one has the means.
Yes, Lalena 3way are APC LR2 just like Vance's formulas, because I think the only 2nd order APC types are in fact LR2's.
It will be interesting to see what results you get with Sreten's Basta link. I'll try it when I've finished reading the 'doco'.
Nice pyramid design! and OK re baffle step. The full LR2 xo evidently also gives a 2dB overall gain for the mid? Also good idea re the slanted cabinet for 'ZDP' issues. I'll effectively be able to do the same if I build seperate tweeter&mid boxes.
Are quick acting polyswitches an alternative to Zeners?
Thanks Omni! grant...."shooting for the stars'! LOL
PS: I just had an idea re a tweaking method. Obtain dual-mono from amp by 1) simply combining channels in the 'Audacity' WAV-editor on the PC or 2) using a stereo to mono adapter cable from CD to amp. Building my simpler xo for one speaker and the full LR2 design for the other speaker. Compare by toggling the balance control. Tweak 'ad-nauseam'! Guess I could try it.
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