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Affordable Accuracy Monitor Review

CDMC

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#61
Amazing what can be done for the price. Dennis no longer makes speakers under Philharmonic Audio, but nearly all of Jim Salk's speakers are designed by Dennis, although unfortunately none in this price range. I have a pair of Salk WOW1 monitors on the way and may send to Amir to review.
I for one would love to see the Wow1 measured.
 

wwenze

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#62
The BS22 was my desktop speaker setup for a year or two, and a quartet of the AJ FS52 plus the center were my first "big" home theater speakers. It took a while to understand what I was hearing but it eventually became clear that I wasn't imagining it and the tweeter was horrible. I not only swore off many of the AJ designs, but also all of the audio reviewers who lavished praise on those speakers. (Overreaction? ¯\_(ツ)_/¯)

I'm absolutely blown away at how much Dennis Murphy was able to transform these speakers. Unreal.
Well, not intending to disrespect anybody especially the people who are actually getting paid to design speakers, but I feel mentioning designer names just make things overblown than what things would have been. Henry Kloss is another name that people like to mention but speakers today have already overtook his designs. Partly because he already died in 2002 but I'm not sure if Tivoli could be considered stellar for its time.

John Romero made Doom, but he also made Daikatana.
And for something that hits close to home here, Rob Wyatt is, quoting wikipedia article, system architect for the original Xbox and designer of PlayStation 3's graphic systems, yet he couldn't smell the gong show mission-impossible that Atari VCS is.

Not to mention, designers are also working with $$$ and time constraints. Maybe better tweeter and crossovers would have helped, but this may not be the goal. I know it's that AJ we're talking about here - The one who said he wouldn't mind increasing part cost by $1 or something like that. I also think this way when I design stuff. But it's not that simple in practice, and when you increase $1 here and there, it eventually adds up and then you have to rethink the idea and start removing stuff. The Vifa tweeter costs $17 each, too.
 

Dennis Murphy

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#63
Comparison with the Pioneer it's modded from:
Don't even ask me how long it took me to figure out how to create GIFs and have them displayed in-sync (this site doesn't play them in-sync, so I had to combine them)
  • Sensitivity is decreased by 2dB (Claimed the same 85dB, for shame Dennis:p)
Caught me. All of my sensitivity specs from back in the day were a little inflated because I know so little about DIY home improvement projects. I thought the little diamond symbol on measuring sticks and spools indicated 1 meter. Instead, it's there to help locate wall studs and is almost an inch shorter than one meter. Plus, measuring sensitivity is inherently tricky with the software I use. Even without all of those lame excuses, my spec was closer to reality than those of a certain speaker company located in Indiana.
 

Dennis Murphy

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#64
Here is a cache of the AAM listing:
http://web.archive.org/web/20140624210748/http://philharmonicaudio.com/folio-me/html/Phil Pages/AALS.html

@Dennis Murphy, since you excluded shipping from the price, and to have it be somewhat accurate with price comparisons, I put the speaker as $190 in my spreadsheet, is that somewhat accurate?
He also had a Slim tower that isn’t listed on his legacy offerings.
Close enough for retired government work. They sold for $165/pair and shipping usually brought that up to $185 - $190.
 

andreasmaaan

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#65
The latest affordable accuracy wouldn't measure as well in the upper treble because the Dayton "silky" tweeter has a fairly prominent peak at 15kHz and has less-than-stellar quality control. Parts Ex;press reverse engineered a more expensive Morel tweeter with stricter tolerances, and I offered the real-deal Morel as an upgrade. Either speaker would measure with much greater bass extension and power handling than the BS22 Mod. PE assigned me a new account rep and I'm going to forward this review to him to see if I can get them to change their minds. Maybe it will give me more credibility. The Dayton woofer has amazing bass performance--far better than the woofers used in other budget speakers. It does have to be crossed at around 1900 Hz, which is why I couldn't use the Vifa tweeter I used in the 22 mod.
@Dennis Murphy just to clarify, which Dayton woofer are you referring to here please?

I presume you're not talking about this woofer linked earlier in the thread by @MZKM (which is obvs not a Dayton).
 

Dennis Murphy

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#67
Is this the original design or the revision when you had to use different cabinets?

As for the Purifi woofer:
https://hificompass.com/en/reviews/purifi-audio-ptt65w04-01a-midwoofer

Really weird looking surround, looks like it got melted in the sun.
Pretty good performance, especially the IMD. It starts to beam ~1.5kHz.
NRC measured a slightly different and earlier version, which had the mids and tweets offset in mirror-image fashion. I got all kinds of push back on the aesthetics of that, and when I commissioned the Chinese cabinets I converted to in-line drivers to simplify production, improve their fashion appeal, and suppress questions about how the speakers should be oriented. I did have to monkey with crossover to avoid a peak in the off-axis response, but the in-line version ended up measuring at least as well as the original; Audioholics tested the latest version with in-line drivers.

I'll be crossing the Purifi in the 500 Hz range, so any beaming in the upper mids won't be an issue. They are ugly, but the current Scan 8545 won't win any beauty contests either.
 

Dennis Murphy

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#68

Dennis Murphy

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#70
Curious if this mod also works on the FS52 towers which are doing L/R duty in my home theater.
I've developed separate mods for the towers and the center channel, all using the same tweeter. Of the three AJ Pioneer designs, the towers are the most problematic. I've lost track of how many of those I've modded and sold, but the stock versions consistently measured worse than the center or monitor and sounded the murkiest. Although I have documented the mod for the 52 in fairly great detail, it's a bear to implement. I don't really recommend that anyone take it on unless they're really really bored and have an electronics background.
 

HooStat

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#72
Just a random question about the BMR since I was considering trying to build one -- is the port required or can it be a completely sealed design?
 

Dennis Murphy

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#73
So in practice he takes the pioneer, changes the tweeter, the woofer (is he using the Dayton audio 6.5" from part express?) and the crossover?

Am I missing something or maybe it would be better to also build a case by himself to save money instead of modding pioneer?
Fortunately, PE sells the BR-1 cabinets separately at a very reasonable price, at least before the trade war. So there was no need for me to buy the crossover parts, and I could buy the drivers on my commercial accounted with discount pricing. I've specialized in modding kits and finished speakers because it solves the otherwise insurmountable cabinet problem. I can't build them, having them built to order in the U.S. is too expensive, and meeting the minimum order for Chinese cabinets requires a huge up-front investment and more storage room than I have. For awhile Parts Express had a line of fairly high-quality and reasonably priced cabinets that made it possible for me to start selling the BMR's, but they had so many problems finding reliable Chinese factories that they dropped the line. I had much better luck dealing with Bennic for the Chinese cabinets I used in the most recent BMR's, and they've become much more flexible and eager for business since the tariffs and the virus left their mark. My business partner is currently selling Bennic BMR's in Taiwan, and will soon offer a mini I just designed. Hopefully I'll be able to get the BMR's back into the domestic market in the not-too-distant future.
 

Dennis Murphy

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#74
Question for Amir and Dennis: do you reckon one could get a good chunk of the way by applying EQ to the stock Pioneer speaker instead of making physical mods to the driver, crossover and cabinet?
No--I started this project by redoing the stock crossover, thinking it was just a matter of building in more baffle step compensation and smoothing out the treble a little. That was fairly easy to do, but the new crossover sounded almost as foggy as the stock. That's when I realized the tweeter itself was the problem. I think it's was wave-guide coloration, others think it's harmonic distortion, but whatever the cause, any meaningful improvement requires a tweeter transplant.
 

Dennis Murphy

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#75
Looking at the crossover, Dennis added a 0.5 mH low pass inductor. Looking up the Jantzen used, it adds a dc resistance of 0.5 ohms right in series with the woofer. From @amirm measures of the originals, the original system impedance was ~ 5 ohms below the BDC frequency range and above port tuning frequencies. So, this added inductor will add ~ 0.8 dB loss to the ~ 200 to 400 Hz range. The rest of the difference in the bass will be due to
  • Dennis added sonic barrier which will somewhat lessen port coupling efficiency, reducing sensitivity below 200Hz. This probably is the main contributor to getting rid of the 70Hz peak as well
View attachment 65662
  • if not from the same production batch, raw drivers could easily have unit to unit variation of a dB, making up the rest



The vertical off axis dip in the response curve gives away the crossover frequency as ~ 2.7 kHz (eyeballing it from the graph):
View attachment 65665

Its also a fairly steep notch, also giving away a fairly steep high pass.

The crossover schematic confirms this, being 3rd order electrical (18 dB/octave asymptotic). The 2.2uF cap helps get rid of the tweeter impedance peak at resonance, keeping the crossover rolling off:

View attachment 65666

Checking out the hificompass test shows that the Vifa tweeter's distortion @ 4V takes off below ~ 2.5 kHz:

View attachment 65663

4V would be ~ 96 dB at one meter. From the data sheet: View attachment 65664
(above a few kHz, the tweeter operates in half space on the baffle)

So, putting this all together, the third order crossover at 2.5kHz to 3 kHz is a very sensible choice to keep the tweeter distortion in check all the way to quite high playback levels.

I think Dennis made another really good choice elevating the on axis slightly from 800Hz to 3 kHz, to help compensate for the woofer's off axis roll in this range (as shown by the DI curve). I find this definitely helps make the spectral balance a bit more neutral in my designs. This is where allot of Dennis' voicing black magic comes in, because there are no hard and fast rules how much extra on axis response is needed to compensate for the roll off off-axis (and it can depend on room placement a bit), but IME and looking at the dispersion, I would expect this to be about perfect.
View attachment 65669

I also think its great that Dennis was able to keep cost down by not replacing any big inductors, just adding one small lower cost one. This choice would have reduced the amount of design freedom he had available, so it makes this result even more impressive.

Looks like a collection of great design choices, but no surprise there.
What a great post. I'm not sure I deserve all of that imputed wisdom, but you certainly know your stuff. Just one comment--i didn't really start out to increase the output from 800 Hz to 3kHz. I actually brought it down compared with the stock 22. What you're not seeing on the Klippel measurements is the impact of the room on the response below 800 Hz or a little lower. Actually, it's getting late and I'll add to this post tomorrow to explain what I'm after here. But in the meantime, thanks for clarifying the crossover point. I targeted 2600 Hz, and I came out pretty close. Although the crossover slopes are 18 dB electrical, as I'm sure you know, the more important acoustic slopes are 24 dB.
 

Dennis Murphy

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#76
Are some of the Salk Sound speaker crossover designs from Dennis Murphy? Even though he is retired I assume they still follow his template for each speaker. If this is true I would love to see some Salk speakers on the test bench.
I'm not really retired. I just had to get out of the pressures of running a growing business single-handed. With the exception of the last round of BMR's, I had to assemble all of the speakers I sold, including building the crossovers, installing everything, and getting stuff packed up and shipped. I'm still doing lots of crossover work, including all of Jim Salk's designs and custom one-offs. The main difference is that I can sleep at night and I'm not losing money.
 

Bruce Morgen

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#77
I'd love to see a GR research design here. He does come in a mixed bag that is for sure, some artists are just odd (no way on those tube connectors) but seeing the results here would be interesting for sure.
I've just come from U-Toob, where I encountered this gem of a Danny Richie statement in his latest mod-touting video:

"I hate PVC-jacketed wire. It just has a sound that I just can't stand." :facepalm:

All that aside, seeing how his mods measure up and sound "here would be interesting for sure."
 

Dennis Murphy

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#78
I am still learning here but have always wondered with these cheaper speakers - if the crossover is always such a compromise why not go active with something like a minidsp and some cheap class D amps? Would that not be a better way to solve crossover errors than with passive components and crossover redesign?
I get here that the tweeter replacement also made a huge difference.
You're being way too rational. People still seem to prefer stand-alone passive speakers. Go figure.
 

andreasmaaan

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#79
No--I started this project by redoing the stock crossover, thinking it was just a matter of building in more baffle step compensation and smoothing out the treble a little. That was fairly easy to do, but the new crossover sounded almost as foggy as the stock. That's when I realized the tweeter itself was the problem. I think it's was wave-guide coloration, others think it's harmonic distortion, but whatever the cause, any meaningful improvement requires a tweeter transplant.
Where in the measurements do you believe the waveguide colouration you mention is apparent? Looking at the on- and off-axis responses of the BS22, I don't see anything that stands out above 4-ish kHz:



Feel free not to weigh in deeper on this ofc ;)
 

Dennis Murphy

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#80
Just a random question about the BMR since I was considering trying to build one -- is the port required or can it be a completely sealed design?
Dennis, your affordable accuracy speakers have one of the highest preference ratings (used with a subwoofer) on the site so far. I assume you feel your BMR is the superior speaker. Would you expect a similar preference rating? And if so, what, besides bass performance/power handling, would you attribute the upgrade in sound quality to? (Once again assuming a high preference rating for the BMR as well - basically I'm asking if 2 speakers both have similarly high preference ratings, what factors would cause one to sound better than the other?)
Other than bass reach and power handling, the main difference between the BMR and the little BS22 mod is in the breadth and evenness of the off-axis response. I'm not sure what that would do to the preference scores, but in terms of sound staging the BMR's would throw a much taller, deeper, and wider sound stage on good recordings with natural ambiance. On studio recordings there would be much less difference, and some people might prefer the more up-front sound of the 22 mod.
 
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