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Old 11th October 2009, 02:42 AM   #11
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Originally Posted by wintermute View Post
Hey Terry straight from the horses mouth! I didn't think you frequented the forums! I just checked your profile and found you are the person I alluded to in my previous post in this thread

I can't believe it is nearly six years since I first contacted you about the morel drivers! I'm going to get there eventually... Was starting to gain momentum again but have hit a wall for a little while, hopefully in a month or two will be back into it and get these things finished! and start enjoying them!

Tony.

edit: Nice to know when I did my prototype that I wasn't going crazy when I thought it sounded brilliant with just a cap on the tweeter and the mw144's running full range too!
Thanks Tony, these combinations are rare. When you find one, enjoy. I am now designing a 3 way using these two as the mid / tweeter. Bass may be Morel.s Neolin 222mm (8")

Terry
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Old 11th October 2009, 04:24 AM   #12
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Most DIYers seem to want to put the best of this with the best of that. They fail to realise that what they are doing is to try and marry this mid to this tweeter. How the individual drivers perform is a small part to consider. The larger question should be how will my drivers marry. If they marry perfectly then and only then will you get a top class system. The DMS37 rebate mounted with the MW142/144 surface mounted are a near perfect match. So perfect that when you design the crossover you will be in for a surprise. I did up a nice 1st order xover, put in a whole lot of components and when measuring and listening I started taking out components. In the end I had one high grade cap left (5.6uf from memory) and the woofer was just taking it's feed straight from the amp. These two drivers just love each other. The relationship is much more important than the individual drivers.

Terry
To each his own. I would never run any midwoofer without a lowpass, breakup is an issue in any driver as is directionality at the upper end, especially in the breakup area. I also beg to differ on the individual driver response. That is crucial to making any design choices. You can't know how they'll "marry" without knowing how they act individually.

"Most" DIYers are not as you assume. Matching drivers is, in fact, generally high on their list in my experience, as is mine. Wanting the best or best bang-for-the-buck combination, yes, but not blindly selecting as you imply. I'm not sure why you even injected that into the discussion.

That aside, that system has to be something on the order of a 2nd order lowpass (or whatever the native driver has) using the midwoofer's lowpass and an approximate 3rd order highpass by adding a cap to the tweeter's 2nd order natural highpass. That type of system is not going to pass square waves without distorting them, but then I'm not usually doing transient-perfect designs myself, preferring LR2 in general. Looking at the quasi-IEC measurement, how is baffle step taken into account? With a fairly flat driver as that one appears to be, there's no getting around the step loss unless it's used in a 3-way with a highpass that handles it. In a 2-way, it's going to lose 6db before any boundary reinforcment comes into play. Even then, 3-4 db correction would not be unusual.

It would appear that my comment about adjusting for phase was accurate, since it's not a crossover type for which time is as critical. Phase is the issue, especially with the woofer lowpass not being controlled in any way with its impact on the passband phase.

The native lowpass looks to be down 3db at 10K, so I'm unsure as to what is being used for the highpass Fc. 10K would be exceedingly high, but would be what is indicated by the Morel graphs. 5.6 uF isn't going to result in a very high tweeter Fc, however, so it seems like there must be a lot of overlap and possibly a fair amount of destructive interference.

Dave

Last edited by dlr; 11th October 2009 at 04:37 AM.
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Old 11th October 2009, 04:34 AM   #13
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To each his own. I would never run any midwoofer without a lowpass, breakup is an issue in any driver as is directionality at the upper end, especially in the breakup area. I also beg to differ on the individual driver response. That is crucial to making any design choices. You can't know how they'll "marry" without knowing how they act individually.

"Most" DIYers are not as you assume. Matching drivers is, in fact, generally high on their list in my experience, as is mine. Wanting the best or best bang-for-the-buck combination, yes, but not blindly selecting as you imply. I'm not sure why you even injected that into the discussion.

That aside, that system has to be something on the order of a 2nd order lowpass (or whatever the native driver has) using the midwoofer's lowpass and an approximate 3rd order highpass by adding a cap to the tweeter's 2nd order natural highpass. That type of system is not going to pass square waves without distorting them, but then I'm not usually doing transient-perfect designs myself, preferring LR2 in general.

It would appear that my comment about adjusting for phase was accurate, since it's not a crossover type for which time is as critical. Phase is the issue, especially with the woofer lowpass not being controlled in any way with its impact on the passband phase.

Dave
I will certainly agree to disagree. No problem. I like first order crossovers. Yes I have lots of experience at other orders. You like yours, I like mine.

A well executed design using first orders, with the right drivers in a point source array has lots of benefits. There are many very famous speakers using this approach. Duntech used this approach with great response and great sales.

Terry
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Old 11th October 2009, 05:44 AM   #14
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The only speaker I've ever heard that fooled me into thinking a real live trumpet was playing in front of me was a custom built wide range single driver fully omni-directional prototype speaker.

When I first put on a Miles Davis track I nearly jumped out of my skin. But, without a crossover and without a tweeter, and without a subwoofer, that speaker was somewhat of a one-trick-pony.

DLR - he does actual time alignment first, with only a cap on the tweeter for protection. Once he has time alignment, then he starts designing the crossover.

Terry, I'm always wanting to hear more speakers with "just a cap on the tweeter", but, my favorite commecial speakers that I've heard in the last 10 years or so were the Madrigal Revel Salon Ultimas. I don't think any of the DIY speakers I've heard at events compare to them, but, I can't fairly say, because I haven't liked the listening conditions at the DIY events I've seen thus far. I would like to attend some smaller gatherings and "just listen to speakers" with a few guys sometime soon. I was invited to such a gathering last month or so, but my second child was coming at about the same time so I couldn't go.
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Old 11th October 2009, 06:01 AM   #15
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The only speaker I've ever heard that fooled me into thinking a real live trumpet was playing in front of me was a custom built wide range single driver fully omni-directional prototype speaker.

When I first put on a Miles Davis track I nearly jumped out of my skin. But, without a crossover and without a tweeter, and without a subwoofer, that speaker was somewhat of a one-trick-pony.

DLR - he does actual time alignment first, with only a cap on the tweeter for protection. Once he has time alignment, then he starts designing the crossover.

Terry, I'm always wanting to hear more speakers with "just a cap on the tweeter", but, my favorite commecial speakers that I've heard in the last 10 years or so were the Madrigal Revel Salon Ultimas. I don't think any of the DIY speakers I've heard at events compare to them, but, I can't fairly say, because I haven't liked the listening conditions at the DIY events I've seen thus far. I would like to attend some smaller gatherings and "just listen to speakers" with a few guys sometime soon. I was invited to such a gathering last month or so, but my second child was coming at about the same time so I couldn't go.
I'm sure that was a wise choice! Not supposed to miss the actual birth day. I agree that the listening environment is so important! I've designed a great many speakers some with great sales. For my own pleasure I like point source.

Terry
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Old 11th October 2009, 01:22 PM   #16
dlr is offline dlr  United States
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Originally Posted by pheonix358 View Post


I will certainly agree to disagree. No problem. I like first order crossovers. Yes I have lots of experience at other orders. You like yours, I like mine.

A well executed design using first orders, with the right drivers in a point source array has lots of benefits. There are many very famous speakers using this approach. Duntech used this approach with great response and great sales.

Terry
With all due respect, what you have done with running a midwoofer full range and a cap on a tweeter bears no resemblance to anything Dunlavy did at Duntech or later and is in no a way a first order system. Dunlavy's were true first order system responses, yours cannot be. The electrical characteristics of the crossover do not in any way define the acoustic system response.

I'll also point out, for those who do not understand, running a flat midwoofer with no crossover results in a large step loss when stand mounted (6db before boundary reinforcement) that then emphasizes the upper midrange andtreble. This emphasis is to some preferred, to many and I would venture to say most, it would not be.

But again, to each his own.

Dave

Last edited by dlr; 11th October 2009 at 01:33 PM.
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Old 12th October 2009, 12:28 AM   #17
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With all due respect, what you have done with running a midwoofer full range and a cap on a tweeter bears no resemblance to anything Dunlavy did at Duntech or later and is in no a way a first order system. Dunlavy's were true first order system responses, yours cannot be. The electrical characteristics of the crossover do not in any way define the acoustic system response.

I'll also point out, for those who do not understand, running a flat midwoofer with no crossover results in a large step loss when stand mounted (6db before boundary reinforcement) that then emphasizes the upper midrange andtreble. This emphasis is to some preferred, to many and I would venture to say most, it would not be.

But again, to each his own.

Dave
Dave, I don't need to convince you. Continue with what you like in xovers. I like discussions. I hate when people knock others with out understanding what they themselves are saying.

Terry
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Old 12th October 2009, 01:11 AM   #18
dlr is offline dlr  United States
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Dave, I don't need to convince you. Continue with what you like in xovers. I like discussions. I hate when people knock others with out understanding what they themselves are saying.

Terry
You don't need to convince me, you won't if what you say is incorrect, but you should be cognizant that others read these posts. Your statements equating your design to those of Dunlavy were not just wrong, they mislead others who might accept them as factual. You want to discuss, let's discuss. Explain how you think that a full range midwoofer with a 2nd order or higher acoustic lowpass and a tweeter with a 2nd order highpass and a cap that results in a third order acoustic highpass equates to the works of Dunlavy who went to great lengths to achieve well integrated first order acoustic responses.

Point out what I've said that is wrong, discuss it, don't make claims of what I may or may not know when you have no idea of what I may or may not know. Refute with facts, not supposition. A simple set of two measurements, woofer and tweeter, is generally sufficient.

This started off as a simple thread on a good idea of a DIY version of an MDT-37 and has morphed not due to my inserting claims that so far are unsupported by facts. Either you can back up your claims or you can't, I leave that to you. But I will challenge when I see what I believe to be erroneous claims.

Dave
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Old 12th October 2009, 01:41 AM   #19
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Ok Dave,

"You can't know how they'll "marry" without knowing how they act individually".

When looking at how they Marry you need to consider what one does to the other. Yes you need to look at their individual operation but only as it affects the other driver. The relationship is important, not how good an individual driver is perceived to be.

"and an approximate 3rd order highpass by adding a cap to the tweeter's 2nd order natural highpass." " 5.6 uF isn't going to result in a very high tweeter Fc,"

Actually it is 6000 Hz. For the entire xover region this tweeter is 1st order. It is not 3rd order as you state.

"however, so it seems like there must be a lot of overlap and possibly a fair amount of destructive interference."

Why are you assuming it is destructive interference?

I stated quite clearly

"Thanks Tony, these combinations are rare. When you find one, enjoy."

You have taken no notice of this quite clear statement. You hav'nt tried it, you have not listened to it, you just come out of the gate at full steam. You don't like 1st order! That's fine. Enjoy what you like. Be careful not to set yourself up as an expert in an area where clearly you don't have experience.

You also have not clearly understood that this system is time aligned.

"That aside, that system has to be something on the order of a 2nd order lowpass (or whatever the native driver has) using the midwoofer's lowpass and an approximate 3rd order highpass by adding a cap to the tweeter's 2nd order natural highpass. That type of system is not going to pass square waves without distorting them,"

How do you know what this system will do. Try it. Remember it is rare to find two drivers that will do this.

FYI I did consulting work for Duntech after Dunleavey sold the company. I know their designs.

Enough, A question, have you ever designed a system based on 1st order.

Terry
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Old 12th October 2009, 02:36 AM   #20
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EDIT: Dave was replying as I wrote this, looks like my post wasn't needed, I think the discussion is back on track, after almost getting derailed (perhaps).

Let me just take a moment to suppose that... Had you two been sitting in the same room together discussing these topics, I for one, would be willing to bet that there would have been no insults felt or implied - at least not to the point where anyone would feel one's "feathers ruffled"...

So, let me ask, do please continue your discussion about "first order" crossovers, just... pick up a little Zen attitude and even if "he started it first" be the bigger man, and graciously dismiss any insult that may have been meant, or not. Any questions or implications that may have implied insult - let's take them as if they hadn't, and simply respond sincerely.

I'm not saying anybody has been childish here - I just see an opportunity to further a discussion, rather than one person or the other maybe feeling that its headed down a negative path that will end up without much merit.

--
"Two roads diverged in a wood, and I—
I took the one less traveled by,..."

Last edited by critofur; 12th October 2009 at 02:41 AM.
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