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Philharmonic Audio - Dennis Murphy - Page 142

post #4231 of 4611
Quote:
Originally Posted by D54Smith View Post

Dumb question here… when you refer to mid bass, what frequency range (Hz) are you referring to? 130-260?


No--I would call that upper bass, lower midrange. I'm talking more in the range of 80 Hz to 130 Hz, or whatever range would include at the top end the spoken deep voice of a radio announcer. It's the area that can sound chesty or boomy on a bad speaker.
post #4232 of 4611
Quote:
Originally Posted by malinois1 View Post

Thanks very much for the feedback! Looks like I will be contacting Mr Dennis towards the end of the year for a pair of Phil 3's!

Anyone have any feedback on amps to use for these? I was thinking of using crown xls drivecore amp for these? Maybe the 1500 or 2000 series? All suggestions are appreciated, but I would rather not pay more for the amp than speakers if you know what I mean.

I have no trouble recommending an XLS drivecore amp for the Phils. I've used an AB International 800.2, Perreaux 6000B, Outlaw 755, Crown XLS 2500, Cinepro 1K2, Rotel RMB-1075, Onkyo 3009, and finally a Threshold S/300e with my Phil 3's and the Crown performed flawlessly with them. They're great amps, and for the price they're pretty tough to beat IMO.
post #4233 of 4611
Quote:
Originally Posted by Dennis Murphy View Post


I just dunno. I really would have to hear them before I could tell whether the limiting factor is the drivers or the crossover. Or both. What do they sound like?

They sound old and muddy.  Any electrolytics in the crossovers should be replaced.  The problem for me is just where to start.  The boxes are still nice I'm sure the passive radiator is good.  It would be a matter of just figuring out a pair of drivers to start with, refresh the crossover and start from there.  I'll see if I can create a schematic.

 

Frank

post #4234 of 4611
Quote:
Originally Posted by yonk View Post

They sound old and muddy.  Any electrolytics in the crossovers should be replaced.  The problem for me is just where to start.  The boxes are still nice I'm sure the passive radiator is good.  It would be a matter of just figuring out a pair of drivers to start with, refresh the crossover and start from there.  I'll see if I can create a schematic.

Frank

Well, the electrolytics won't mess up the sound unless they've gone out of spec. So I wouldn't waste money replacing those. I use poly's on all of my circuits, including the high value and very expensive ones for the woofer, but quite frankly that's only because I don't want to have to defend using NP electrolytics. No one would hear any difference if I switched to a good Bennic low loss NP, and I would save about $70 a pair.

The muddy sound may be due to an improperly tuned passive radiator. People were more or less guessing on passives back in that day. Do you remember them sounding much better? I guess we should probably switch this over to a private e-mail exchange. Cheers
post #4235 of 4611
Quote:
Originally Posted by Nethawk View Post

That's a fine choice in speakers!

There is at least one owner of Philharmonic Audio speakers using XLS Drivecore amp. Eternal Velocity has his powered by an XLS2500 and has sung its praises. While my Denon 4311 AVR provides ample power to mine, in a separate 2 channel system powering Ascend Acoustics speakers I am using an XLS1500 and am very happy with the balance of features, performance and price.

Thanks for the feedback nethawk. I knew you would recommend it. I see your post about them in quite a few threads and it is one of the reasons I was looking into them. I think the 1500 would probably be plenty for these speakers but I could swing the 2000 or 2500 if I had to. I am sure with 525 watts into 4 ohms of the 1500 should be more than I will ever need. Although I am pretty sure my Pioneer SC-1222 could power them as well with 190 watts per channel in stereo.
post #4236 of 4611
Quote:
Originally Posted by fuzz092888 View Post

I have no trouble recommending an XLS drivecore amp for the Phils. I've used an AB International 800.2, Perreaux 6000B, Outlaw 755, Crown XLS 2500, Cinepro 1K2, Rotel RMB-1075, Onkyo 3009, and finally a Threshold S/300e with my Phil 3's and the Crown performed flawlessly with them. They're great amps, and for the price they're pretty tough to beat IMO.

Thanks for the confirmation fuzz. I am pretty positive I will go with the drivecore series. I agree the price per watt ratio is tough to beat. I am pretty sure phil 3's with a drivecore amp will be a huge upgrade from my current setup. Sc-1222-k with Martin Logan Motion 12's! I just wish someone in my area had some phil's so I could hear them in person. There is no hi end audio dealers within 200 miles of me to demo hi end equipment...so no matter what I would buy almost would have to be bought sound unheard.
post #4237 of 4611
Quote:
Originally Posted by Saturn94 View Post

^^^ I'll be there. smile.gif

Once again I'm going to miss CAF. This is the same weekend as the 4 day music festival known as Floydfest. It was a tough call, but in just about every scenario my mind came up with, dancing hippie chicks outweighed the opportunity to meet Dennis. No offense, of course. biggrin.gif
post #4238 of 4611
Quote:
Originally Posted by Nethawk View Post

Once again I'm going to miss CAF. This is the same weekend as the 4 day music festival known as Floydfest. It was a tough call, but in just about every scenario my mind came up with, dancing hippie chicks outweighed the opportunity to meet Dennis. No offense, of course. biggrin.gif

Of course, you've never seen a dancing Dennis. But then neither have I. Sorry to hear you are so easily distracted. Perhaps next year?
post #4239 of 4611
^^ I could be persuaded, there's a first time for everything. You have no plans to don a hemp skirt at the Sheraton do you?
post #4240 of 4611
Quote:
Originally Posted by Nethawk View Post

Once again I'm going to miss CAF. This is the same weekend as the 4 day music festival known as Floydfest. It was a tough call, but in just about every scenario my mind came up with, dancing hippie chicks outweighed the opportunity to meet Dennis. No offense, of course. biggrin.gif

I bet Dennis smells better than the hippie chicks...so he does have that going for him.
post #4241 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

Of course, you've never seen a dancing Dennis. But then neither have I. Sorry to hear you are so easily distracted. Perhaps next year?

Quote:
Originally Posted by Nethawk View Post

^^ I could be persuaded, there's a first time for everything. You have no plans to don a hemp skirt at the Sheraton do you?

Quote:
Originally Posted by Jdgate View Post

I bet Dennis smells better than the hippie chicks...so he does have that going for him.

LOL!

Thanks guys, I needed a good laugh...... biggrin.giftongue.gif

If Dennis shows up in a Hemp skirt I'm taking pictures this time! eek.gifbiggrin.gif
post #4242 of 4611
now dennis doing the hula in a grass skirt with the phil slims and the olive 3z now that would be a priceless picture! i double dare you :-)
post #4243 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

No--I would call that upper bass, lower midrange. I'm talking more in the range of 80 Hz to 130 Hz, or whatever range would include at the top end the spoken deep voice of a radio announcer. It's the area that can sound chesty or boomy on a bad speaker.

Dennis - what range is it that normally requires BSC?

And how does planned placement close to a wall impact BSC design?
post #4244 of 4611
Quote:
Originally Posted by rick240 View Post

Dennis - what range is it that normally requires BSC?

And how does planned placement close to a wall impact BSC design?

Although the starting point depends on the baffle dimensions, a typical woofer's output will start to tilt up around 350 Hz, and reach a 6 dB peak around 1 kHz.. Somewhat surprisingly, placing a typical cabinet flush against the wall has a relatively minor effect on the baffle step. The only way
to eliminate it entirely without crossover compensation is to mount the cabinet with the front baffle flush with the wall, forming an infinite baffle. That's why I haven't felt the need to provide an adjustable bsc circuit in my designs. If, however, the cabinet is very shallow and meant to be hung on a wall, then I design a crossover that provides much less bsc.
post #4245 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

Although the starting point depends on the baffle dimensions, a typical woofer's output will start to tilt up around 350 Hz, and reach a 6 dB peak around 1 kHz.

Just to make sure I understand - for a speaker crossed to a sub at 80Hz, with a overall sensitivity of XXdb:

- from 80 - 350Hz it would need to be XX + 6db sensitive
- from 350 - 1kHz it would ramp from (XX + 6) to XX
- and from 1kHz up it would be XX

Quote:
Somewhat surprisingly, placing a typical cabinet flush against the wall has a relatively minor effect on the baffle step. The only way
to eliminate it entirely without crossover compensation is to mount the cabinet with the front baffle flush with the wall, forming an infinite baffle. That's why I haven't felt the need to provide an adjustable bsc circuit in my designs. If, however, the cabinet is very shallow and meant to be hung on a wall, then I design a crossover that provides much less bsc.

Interesting - so something like the Phil Slims, within 6 - 8" of the wall would still need full BSC. Did the WOW1s get slightly less than full BSC?

What would the effect on the design be if instead of 6db of BSC only 4db was allowed for?
post #4246 of 4611
Quote:
Originally Posted by rick240 View Post

Just to make sure I understand - for a speaker crossed to a sub at 80Hz, with a overall sensitivity of XXdb:

- from 80 - 350Hz it would need to be XX + 6db sensitive
- from 350 - 1kHz it would ramp from (XX + 6) to XX
- and from 1kHz up it would be XX
Interesting - so something like the Phil Slims, within 6 - 8" of the wall would still need full BSC. Did the WOW1s get slightly less than full BSC?

What would the effect on the design be if instead of 6db of BSC only 4db was allowed for?


I'm not sure I understand the math in the first part of your post. If the speaker has more or less full bsc, the sub would be set at the same level as the main speaker is producing at 1 kHz. The output there has already been brought down roughly to the 350 Hz level by the bsc.
Most designers don't use a full 6 dB of bsc, since it tends to produce heaviness on source material like the spoken voice. I use about 4 dB on speakers with full bass extension. I used closer to 6 dB on the WOW because I thought the little woofer needed it. This isn't really a science. Believe it or not, I still listen to a speaker after I've optimized a crossover.
post #4247 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

I'm not sure I understand the math in the first part of your post.

No, I'm sure it's me who's not quite understanding the math redface.gif

So, more specifically (and thanks for the patience)...

If designing a 3-way speaker with 4db of BSC, with these drivers:

- 94db sensitive woofer, crossed to mid at 600Hz
- 93db sensitive mid, crossed to tweeter at 3kHz
- 90 db sensitive tweeter

The woofer would have no padding up to 350Hz; then it would be padded to ramp to about 92db sensitivity (ignoring crossover - which is what, another 6db as both woofer and mid are playing at this point) at 600Hz.

The mid would be padded to 92db sensitivity at 600Hz and ramped to 90db at 1kHz, and stay at 90db to 3kHz.

The tweeter would need no padding.


Am I grasping the basic concept?

Would this speaker be called 90db sensitive or 94?
Quote:
This isn't really a science. Believe it or not, I still listen to a speaker after I've optimized a crossover.

Oh - I understand that it is definitely an art. Which is why i am very happy to leave design and implementation up to a master like you biggrin.gif

I'm just trying to understand the principles wink.gif
Edited by rick240 - 6/28/13 at 11:08am
post #4248 of 4611
Quote:
Originally Posted by rick240 View Post

No, I'm sure it's me who's not quite understanding the math redface.gif

So, more specifically (and thanks for the patience)...

If designing a 3-way speaker with 4db of BSC, with these drivers:

- 94db sensitive woofer, crossed to mid at 600Hz
- 93db sensitive mid, crossed to tweeter at 3kHz
- 90 db sensitive tweeter

The woofer would have no padding up to 350Hz; then it would be padded to ramp to about 92db sensitivity (ignoring crossover) at 600Hz.

The mid would be padded to 92db sensitivity at 600Hz and ramped to 90db at 1kHz, and stay at 90db to 3kHz.

The tweeter would need no padding.

Would this speaker be called 90db sensitive or 94?


Oh - I understand that it is definitely an art. Which is why i am very happy to leave design and implementation up to a master like you biggrin.gif

I'm just trying to understand the principles wink.gif

I really don't think it's a good idea to jump into explanations of 3-ways. Better to start with a 2-way that's crossed above the baffle step point, which virtually all 2-ways would be. Also--you never "pad" down woofers in the same sense that you would pad down a midrange or tweeter with a resistor or two resistors in an L-pad. That would adversely affect bass tuning and probably burn up the resistor. Finally, almost no one uses a dedicated bsc circuit anymore. You use the optimization program in your design software to choose inductor and capacitor values that will roll the woofer off at the top in a manner that will bring its maximum output down to its level in the 350 - 400 Hz range and achieve the desired crossover slope and frequency. . Then, if the tweeter is more sensitive than that level, which it almost certainly would be, you pad down the tweeter with a series resistor and usually also a parallel resistor. I've attached two measurements of the Seas woofer used in the WOW. One is without any crossover components. You can see the baffle step, which starts higher up for this speaker because the baffle is so small (I can explain that if need be) and you can see the ringing breakup mode of the metal cone centered at 10 kHz. The second measurement is with the crossover in place. The components achieve a shape and crossover point that eliminates the baffle step and achieves a 4th order crossover slope at 2200 Hz. Note the vertical demarcations on the graph are 10 dB, so the metal cone breakup is now 30 dB below the average output. SNAG-085.png 10k .png file SNAG-086.png 10k .png file
post #4249 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

… The components achieve a shape and crossover point that eliminates the baffle step and achieves a 4th order crossover slope at 2200 Hz. Note the vertical demarcations on the graph are 10 dB, so the metal cone breakup is now 30 dB below the average output.

I assume that the other part of this puzzle is to get the tweeters phase to align with the woofer's phase at 2200Hz. Is it important for the phase angles to be the same for an octave or so on each side of 2200Hz? Or do they differ slightly because of the different plane/distance from the listener that each driver is positioned?

On a related question, I assume there is a phase reason why Jim's tweeters are located off center of the woofer. That one hasn't made sense to me.
post #4250 of 4611
Quote:
Originally Posted by D54Smith View Post

I assume that the other part of this puzzle is to get the tweeters phase to align with the woofer's phase at 2200Hz. Is it important for the phase angles to be the same for an octave or so on each side of 2200Hz? Or do they differ slightly because of the different plane/distance from the listener that each driver is positioned?

On a related question, I assume there is a phase reason why Jim's tweeters are located off center of the woofer. That one hasn't made sense to me.

It's related to acoustic phase, but not the phase summation at the crossover.

An offset tweeter will alter the summation of diffraction, which on the forward axis can flatten out peaks and dips in frequency response caused by symmetrical edge diffraction.
post #4251 of 4611
Quote:
Originally Posted by Eternal Velocity View Post

It's related to acoustic phase, but not the phase summation at the crossover.

An offset tweeter will alter the summation of diffraction, which on the forward axis can flatten out peaks and dips in frequency response caused by symmetrical edge diffraction.


Right. But the key phrase is "on axis." If you move off axis to either side, the diffraction effects will change, and they won't be the same on the left as on the right. Most people don't listen directly on axis, and it's kind of a crap shoot whether the overall response will be better
with an offset tweeter or with a centered one. I use centered tweeters in my Philharmonic designs, and I've never run into any trouble. As for the phase question, whether or not the two drivers will be in phase at the crossover point depends on the type of slope chosen. For the popular Linkwitz-Riley 4th order slopes, it you do it right the two drivers will cross 6 dB down from the average output, and they will be exactly in phase over the crossover region, although not always a full octave on either side of the crossover point. Their combined output will be 6 dB higher at the crossover frequency than the individual driver output at that point, and that will get you back up 6 dB to the average output and a flat response.
post #4252 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

Their combined output will be 6 dB higher at the crossover frequency than the individual driver output at that point, and that will get you back up 6 dB to the average output and a flat response.

Woo-hoo, I understand a concept wink.gif

Really enjoying the education (and extreme mental stimulation) this conversation is causing.
post #4253 of 4611
Quote:
Originally Posted by rick240 View Post

Woo-hoo, I understand a concept wink.gif

Really enjoying the education (and extreme mental stimulation) this conversation is causing.

+1

I am having a hard time wrapping my head around the symmetrical edge diffraction answer though. Maybe someday the light will come on.wink.gif

Maybe this will help. What is the difference between the acoustic phase and phase summation at the crossover that EV refers to?
post #4254 of 4611
Quote:
Originally Posted by D54Smith View Post

+1

I am having a hard time wrapping my head around the symmetrical edge diffraction answer though. Maybe someday the light will come on.wink.gif

Maybe this will help. What is the difference between the acoustic phase and phase summation at the crossover that EV refers to?

I don't think there is any difference. EV was just pointing out that the position of the tweeter laterally wasn't related to output summation at the crossover point. People mess around with the tweeter to try and mitigate diffraction effects. Those are independent of the direct on-axis output of the drivers. Whether you offset the tweeter, round over the cabinet edges to reduce diffraction effects in the first instance, or both--you will still follow the same rules in targeting slopes that will cause the direct output of the drivers to sum properly. Diffraction is a fairly complex subject that is handled very nicely by Jeff Bagby in his blog on the SalkSound site. You have to read the whole blog, but here's what he says about tweeter positioning:

Sometimes you will see a tweeter offset from the centerline of a baffle. This asymmetric mounting is also a diffraction control technique. By offsetting the tweeter, the distance from the center of the tweeter to the left edge and the right edge are different distances. This means that the frequencies whose wavelengths correspond to these distances are different too. By offsetting these frequencies you can sometimes smooth the on-axis diffraction signature because the distances to each edge will produce ripples at different frequencies. If carefully designed, these can combine to smooth the response. When using this technique it is important to note that the diffraction signature is asymmetrical too and there is a greater difference in the response whether you move off-axis to the left or to the right compared to a centered tweeter that is symmetrical.
post #4255 of 4611
Thanks Dennis, I read that blog once… I should probably read that again. I am absolutely positive I didn't catch everything. eek.gif But, I did learn some…and will probably learn more this time through. wink.gif
post #4256 of 4611
This has been a fascinating few posts. Kind of scary, I even understand most of it now. One question:
Quote:
By offsetting the tweeter, the distance from the center of the tweeter to the left edge and the right edge are different distances. This means that the frequencies whose wavelengths correspond to these distances are different too. By offsetting these frequencies you can sometimes smooth the on-axis diffraction signature

Why only sometimes? Is the inconsistency based purely on the cabinet design and limitations on offset distance?
post #4257 of 4611
Quote:
Originally Posted by Nethawk View Post

This has been a fascinating few posts. Kind of scary, I even understand most of it now. One question:
Why only sometimes? Is the inconsistency based purely on the cabinet design and limitations on offset distance?

I think 'sometimes' is because it is still as much art than science. I read the diffraction blog on the Salk site again. I started thinking about how to computer model it. My head started to spin about radius dimensions, other driver edges.... Lots of fun if somebody would provide a 6 digit research grant. I don't think Dennis would do that. rolleyes.gif So, I will move on to more practical things like mowing the lawn. It is interesting and I am sure I will revisit it again.
post #4258 of 4611
Quote:
Originally Posted by D54Smith View Post

I think 'sometimes' is because it is still as much art than science. I read the diffraction blog on the Salk site again. I started thinking about how to computer model it. My head started to spin about radius dimensions, other driver edges.... Lots of fun if somebody would provide a 6 digit research grant. I don't think Dennis would do that. rolleyes.gif So, I will move on to more practical things like mowing the lawn. It is interesting and I am sure I will revisit it again.


Actually, Jeff has developed a program that will simulate diffraction effects for any given baffle geometry,driver size. and location. The physics are well known--the same effects hold for water waves, light waves, and sound waves.
post #4259 of 4611
Quote:
Originally Posted by Dennis Murphy View Post

Actually, Jeff has developed a program that will simulate diffraction effects for any given baffle geometry,driver size. and location. The physics are well known--the same effects hold for water waves, light waves, and sound waves.

You just took all of the fun out of it! Yes, I looked at web ad for the software. But, both you and him used the word 'Sometimes' when describing off center tweeters. This software also doesn't take into account strange steeple shaped boxes, beveled corners, and nearby woofer surrounds and speaker grills. Of course, I hope you realize, I have tongue firmly planted in cheek.

I wish you the very best, and thanks for the education. I think it is important to be a life long learner.
post #4260 of 4611
Good Afternoon All,

Just wanted to check in. I've had my Philharmonitors for almost 3 weeks now and today I picked up a new Rega Apollo R to replace my 1992 Kenwood CD player.

Ummm......WOW! What a difference! I played some Chris Botti,, Pink Floyd, Dave Brubeck and Stevie Ray Vaughn. Voices are much clearer and cymbals and snare drums seem more sizzling. The plunks from bass guitars are more prominent. Hope that makes sense. Again, still new to the hobby.

Anyway, I'm totally amazed with these speaker. I was planning for a sub but I don't think I need one. They play very deep. Thanks again Mr. Murphy. Next on the list is an integrated amp to replace the 1988 Kenwood pre and amp. Considering the NAD375BEE, Marantz 8004, Music Hall 70.2 and the Rogue Audio Sphinx. I've also been reading about Van Alstine equipment. Any recommendations are welcomed.


Having Fun!


Scott
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