Philharmonic Audio BMR Philharmonitor Bookshelf Speaker Review

Swerd

Swerd

Audioholic Spartan
The only components which are questionable are the iron core inductors. For an overall slightly higher cost of the project, air core inductors are by far superior because they don't saturate and provide a more linear crossover transition. I guess that a prospective buyer could have them substituted by Meniscus.

Several years ago at Solen, I saw a reliable demonstration with proper testing equipment, by the late Denis Ouellet then president of the firm, of the undeniable superiority of an air core inductor.
In addition to what Dennis pointed out, I always want to know if those comparisons between air core & iron core inductors were based on measured electronic behavior or were they based on listening tests?

It is true that air core inductors saturate less easily, but if steel laminate inductors are used in woofer circuits they do not seem to be audibly different than air core inductors. Their advantage in lower DCR is significant over the physically larger air core inductors.
 
Verdinut

Verdinut

Audioholic Samurai
Was that comparison between an air core and a steel laminate? or just with a standard iron core? The engineers I know (including two well known crossover experts) swear by steel laminate core inductors for the woofer circuit. Not only are they cheaper (though not really inexpensive),they have lower dcr and perfectly satisfactory saturation points. I explicitly specified the steel laminates, and I used them in all of my BMR's.
I agree with you that steel laminate core inductors can be used in series with woofers. I know that it is impractical and very costly to use high value air core inductors for subwoofer filter frequencies and when you need low AWR ga wire to maintain the DCR at an acceptable percentage of the driver's impedance. However, when building speaker systems with woofer crossover frequencies at 600 Hz or over, I prefer to use air core inductors when reasonably feasible.
 
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D

D Murphy

Junior Audioholic
I agree with you that steel laminate core inductors can be used in series with woofers. I know that it is impractical and very costly to use high value air core inductors for subwoofer filter frequencies and when you need low AWR ga wire to maintain the DCR at an acceptable percentage of the driver's impedance. However, when building speaker systems with woofer crossover frequencies at 600 Hz or over, I prefer to use air core inductors when reasonably feasible.
Fair enough. But there are two inductors in the BMR woofer circuit, so dcr is an issue unless you go to super big super expensive air cores that will use up limited cabinet volume.
 
Verdinut

Verdinut

Audioholic Samurai
When it's not reasonably feasible to use an air core inductor, which is the case with a massive expensive high value coil, I have been using the Jantzen P-Core inductors. They have a low DCR, will handle 400 watts before saturating and are reasonable priced.
Parts-Express sells them and I understand, after talking to a Jantzen rep several years ago, that P-E can order on special demand from the manufacturer values that they don't stock:

http://www.jantzen-audio.com/iron-powder-cored-coils-with-disc/
 
D

D Murphy

Junior Audioholic
When it's not reasonably feasible to use an air core inductor, which is the case with a massive expensive high value coil, I have been using the Jantzen P-Core inductors. They have a low DCR, will handle 400 watts before saturating and are reasonable priced.
Parts-Express sells them and I understand, after talking to a Jantzen rep several years ago, that P-E can order on special demand from the manufacturer values that they don't stock:

http://www.jantzen-audio.com/iron-powder-cored-coils-with-disc/
They certainly look interesting, and I'm sure people could work something out with Meniscus Mark to substitute them, but I'm not convinced that the steel laminates have any audible issues.
 
Verdinut

Verdinut

Audioholic Samurai
They certainly look interesting, and I'm sure people could work something out with Meniscus Mark to substitute them, but I'm not convinced that the steel laminates have any audible issues.
Both Rod Elliott (Elliott Sound Products) and Vance Dickason who wrote the Loudspeaker Design Cookbook, have the opinion that metal core inductors, and that includes steel laminate inductors, have a propensity to saturate and cause distortion at higher operating levels, which is not the case with the air core ones.

I think that serious concern has to do with sound levels found with public performances which are much higher than the typical SPL experienced in a home environment.
 
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Swerd

Swerd

Audioholic Spartan
ER18 or BMR? Hmmmmm ...
A real dilemma. Considering your existing Dennis Murphy Speaker Museum, do you need either of these? Maybe you need a Speaker Junkie's Intervention :rolleyes:.

On the other hand, I did say more than a year ago that I really liked the BMRs.
Dennis pays great attention to how his speakers present an audio image, the so-called soundstage. This is directly related to how widely they disperse sound, especially in the midrange. All his speakers share this sound quality, this “voicing”. I own or have owned several of Dennis’s designs, a DIY design, the CAOW1, Salk SongTowers from 2007-16, when I replaced them with the Salk Veracity STs. I’ve also heard a number of his other designs over the years, DIY, Salk, or Philharmonic Audio. (It’s nice to live 15 miles away from him.) All his speakers share that common midrange clarity and openness, with the convincingly realistic soundstage. In that regard, the BMRs belong among the best of his work. I can confidently say that the BMR actually presents a more detailed and realistic sounding soundstage than my Veracity ST speakers do. They sound close, but I have to say the BMRs did this just a little better.
There, I hope that makes things more clear for you ;).

Edit: Your woodwork on past jobs has always looked very good. If you did build a pair of BMRs, they would look very good.

I strongly recommend the Full Kit with the extra parts just to get those flared Precision Ports.
 
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Matthew J Poes

Matthew J Poes

Senior Audioholic
I just want to weigh in with my opinion on the whole steel core vs air core business.

I don’t think there is any debate that adding a metallic core to a coil of wire provides an opportunity for that core to saturate. I think the question in speaker design is whether the core will saturate sufficiently to cause an audible detriment in practical use. To this question, I think that the answer is “no” with the right kind of inductor.

steel laminate inductors saturate at much higher levels and have lower levels of distortion when they do start to saturate. More importantantly, the saturation is based on a certain current point. It doesn’t just saturate once it’s powered up or over time. Once sufficient current is passed through, it begins to saturate. Most speaker inductors have a core saturation point that is actually above the wire current limit. The exception are those cheap little 20 gauge or smaller types with cheaper powder ferrite cores.

the Erse superQ steel laminate inductors are rated at 500 watts. They won’t actually saturate until after that point and what happens is that the inductance drops slightly. Not enough to make a big difference. A slight amount of harmonic and Intermodulation distortion is also created. At the same time, at more than 500 watts, the woofer is also distorting as smoke comes out.

on the other hand, fixing that problem with an air core would mean accepting a substantial loss of sensitivity and addition of series dc resistance and loss of power handling in the inductor, or an inductor that would be way more expensive. In my speakers the SuperQ inductors were ~$20 each. I have 2 in each speaker. I have three speakers. That is $120 in inductors for the three speakers. The DC resistance is something like .16 ohms each. .32 for the pair.

now if we go to a 14 gauge air core, price is $60 each, the size is about 4 times larger, DCr is .4 each, about .8 for the pair, power handling is about the same. This upgrade then is $360 vs the original $120. That’s a lot of money. And I would pay it if I thought it made a difference but I don’t.

in the place where it might make a difference. A very high powered pro audio speaker, we still see metallic core inductors primarily used.

my opinion is that whatever audible benefit they might have is being outweighed by their detriment. Not all metallic core inductors of course, but once you start getting into values greater than 1mh, good metallic core inductors become attractive. You usually don’t want to add a lot of excess series resistance in your speaker, it kills needed sensitivity and wastes precious power as heat. It also kills the amplifier damping factor (many Class D amplifiers have very low damping factors to begin with, some class AB designs aren’t so hot either.)
 
Matthew J Poes

Matthew J Poes

Senior Audioholic
Just to add to this with some more numbers. Adding .8-1 ohm of additional series resistance (you also have the speaker cable contributing) would lead to between a 1.5 and 3dB loss in output depending on an 8 or 4 ohm speaker on the end. This would drop the system damping factor from say 200 on a good amplifier to just 4-5. The target minimum DF is 20 typically. That would be the detriment of air core inductors I mentioned.
 
Verdinut

Verdinut

Audioholic Samurai
my opinion is that whatever audible benefit they might have is being outweighed by their detriment. Not all metallic core inductors of course, but once you start getting into values greater than 1mh, good metallic core inductors become attractive. You usually don’t want to add a lot of excess series resistance in your speaker, it kills needed sensitivity and wastes precious power as heat. It also kills the amplifier damping factor (many Class D amplifiers have very low damping factors to begin with, some class AB designs aren’t so hot either.)
Also, as stated in my post #145 above, the Jantzen P-Core inductors represent another valid option for higher values in passive crossovers because of their low DCR and their high power rating.
 
Matthew J Poes

Matthew J Poes

Senior Audioholic
Also, as stated in my post #145 above, the Jantzen P-Core inductors represent another valid option for higher values in passive crossovers because of their low DCR and their high power rating.
those are not better than steel laminate inductors. They are one of the cheaper (good) metal core inductors. I would actually take a steel laminate inductor over a permite core inductor. They have a higher saturation point.

probably the most interesting would be the toroidal inductors. They cool better and tend to handle more power for their size. Their very expensive but if I was to use something other than a steel laminate inductor, it would probably be that.
 
Swerd

Swerd

Audioholic Spartan
I want to set up a third system for the bedroom. Size had me leaning toward a CAOW1. Killer tweeter.
If I recall, Dennis has a crossover for this design but with the SEAS ER15 mid woofer instead of the CA15. Ask him.

As far as steel laminate core inductors vs. air core, here's a simple comparison of 2 mH inductors from Madisound:

Sidewinder 2.0 mH Air Core Inductor 16 AWG
costs $20.40
weighs 1.09 lbs
the bobbin is 67mm diameter × 34mm tall
DCR is 0.52 ohm

Steel Laminate 2.0 mH 15 AWG Inductor
costs $15.30
weighs 0.90 lbs
34mm × 47mm × 77mm
DCR is 0.156 ohm
 
O

oivavoi

Audiophyte
Hi y'all, new member here! The BMR monitors brought me here. Looks like this might be the community to be concerning those.

I'm very tempted to get a pair and see if I can build the cabinets myself. Two questions to the resident Philharmonic Audio veterans, though:

1) Do you think it's possible and/or a good idea to run them with an external active crossover? Active crossovers can confer benefits - but would it do so in this case?

2) If I build the cabinets myself, do you think it would be possible to do so with the front baffle tilted slightly backwards? Or would it change the acoustic properties of the speakers? I can for example imagine that the raal tweeters, with their limited vertical dispersion, would "bounce off" inferior off-axis sound towards the listener if it's tilted too much. Or it may work out just fine.
 
everettT

everettT

Audioholic Ninja
Hi y'all, new member here! The BMR monitors brought me here. Looks like this might be the community to be concerning those.

I'm very tempted to get a pair and see if I can build the cabinets myself. Two questions to the resident Philharmonic Audio veterans, though:

1) Do you think it's possible and/or a good idea to run them with an external active crossover? Active crossovers can confer benefits - but would it do so in this case?

2) If I build the cabinets myself, do you think it would be possible to do so with the front baffle tilted slightly backwards? Or would it change the acoustic properties of the speakers? I can for example imagine that the raal tweeters, with their limited vertical dispersion, would "bounce off" inferior off-axis sound towards the listener if it's tilted too much. Or it may work out just fine.
Active crossovers have been discussed with Dennis before and IIRC there would need to be a complex redesign to achieve it with little benefit. With the number of elements in the design to achieve the driver integration I'd leave everything as is.
In regards to the sloped baffle, that to I'd leave alone as I'd assume a crossover redesign is needed and based on the NRC measurements of the speaker there is no need. The "spinorama" measurements are very good.
 
O

oivavoi

Audiophyte
Active crossovers have been discussed with Dennis before and IIRC there would need to be a complex redesign to achieve it with little benefit. With the number of elements in the design to achieve the driver integration I'd leave everything as is.
In regards to the sloped baffle, that to I'd leave alone as I'd assume a crossover redesign is needed and based on the NRC measurements of the speaker there is no need. The "spinorama" measurements are very good.
Thanks! Good to hear.

Concerning actives: This is a long-standing debate in the audiophile community of course... I'm in the camp which thinks that all things being equal (which they often aren't),active crossovers are the better choice. Does't work if the crossover settings need to be reworked though.

As to the sloping baffle: For me it's not about improving measurements (which indeed are superb),but simply that the only possible placement for the speakers are somewhat too low, below two windows, so I would like them tilted slightly upwards so they'll point at my ears at my listening position. But might not be a good idea.
 
Swerd

Swerd

Audioholic Spartan
Hi y'all, new member here! The BMR monitors brought me here. Looks like this might be the community to be concerning those.

I'm very tempted to get a pair and see if I can build the cabinets myself.
Have you ever built speaker cabinets before? I think it would be wise to first see the cabinet build plans supplied by Meniscus Audio before you decide.
Two questions to the resident Philharmonic Audio veterans:
1) Do you think it's possible and/or a good idea to run them with an external active crossover? Active crossovers can confer benefits - but would it do so in this case?
I personally would advise against that. Perhaps Dennis Murphy can give us his insight on this.

As with all speakers designed by Dennis Murphy, these speakers have exceptionally well-designed and well-performing crossovers. I wonder if you or others could reproduce his efforts with an external crossover. Do you have particular benefits in mind when you propose an active crossover, or are you speaking of general benefits that active crossovers are said to have?
2) If I build the cabinets myself, do you think it would be possible to do so with the front baffle tilted slightly backwards? Or would it change the acoustic properties of the speakers? I can for example imagine that the raal tweeters, with their limited vertical dispersion, would "bounce off" inferior off-axis sound towards the listener if it's tilted too much. Or it may work out just fine.
You should definitely not tilt the front baffle backwards. These speakers probably have crossovers with 4th order acoustic properties. As such, they are already phase correct. Any further effort at "time alignment" such as tilting the front baffle, will not produce the desired effect, and may have a negative effect. The BMR speakers were designed with the front baffles, speaker positions, port location, and cabinet dimensions exactly as they appear in the plans. Don't change them.
 

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