"Conversation" with PS Audio's Scott McGowan and speaker designer Chris Brunhaver on the new "Sprout" loudspeaker

One of the reasons I truly love and admire PS Audio is that they are so customer driven. No, I've never purchased their renowned BK Amplifiers but as per my earlier post, truly admire the brilliance in conceiving the Sprout, which is revolutionary in PS Audio's commitment to bring "Audiophile" or High Fidelity or HD Sound--whatever you prefer--within reach of a person who isn't in the 1% or 0.5% economic profile.

And so they don't discriminate among customers and treat all of us like family, even the poorer relations, which is remarkable in this day and age; amazingly, Scott and Chris took the time to write to me after I saw this video (this is the link to the site post), which discusses and shows the Sprout loudspeaker prototype. Chris is designing the drivers; I don't know much about him but he'll be doing videos on his work that will post very shortly.



First, Paul McGowan himself emailed me:

Chris is starting his own series on YouTube to help teach about speaker design and get into depth on the subject.

Stay tuned.

Scott McGowan wrote me and offered an apology when one of course wasn't needed:

Thanks for your kind email and I’m glad you are receiving well my personal outreach. It’s great to have you in the Hi-Fi Family! Sorry about a tardy reply, my fault and you deserve better. We are eager to release the Sprout Speaker, which I hope happens in the next year or so.
Chris, PS Audio's Chief Speaker designer, wrote me the following about designing his own drivers:

Yeah, I’m looking forward to the YouTube videos and have begun to record a few things.  

My goal is to, even at this high performance and pricing, offer superior value, as PS Audio has been able to do with other products, and the drive units are certainly a part of that effort.

***

Responding to a follow-up email from, Chris (with great patience and kindness) wrote:


I haven’t really spent any time with EPI or Human speakers, other than my friend's dad having a pair [EPI]. They did have a great tweeter for their era (similar construction to the Focal tweeter, where the dome isn’t driven at its periphery). However, there is a very non-flat response to [that] tweeter and there are now tons of fantastic domes available on the market, if you want to go that direction.
I would check out this book (summarizing 30 years of research funded in part by the Canadian government) on the topic.  
https://www.amazon.com/Sound-Reproduction-Psychoacoustics-Loudspeakers-Engineering-ebook/dp/B074CHY128/ref=as_li_ss_tl?ie=UTF8&qid=1512975526&sr=8-1-fkmr0&keywords=Sound+Reproduction:+The+Acoustic+and+Psychoacoustics+of+Loudspeakers+and+Rooms,+3rd+Edition&linkCode=sl1&tag=audioholics-20&linkId=74f7166b944a2e6e97300372ca9da566
Well, even the very best speakers deviate from the ideal orders of magnitude more than something like a DAC or power amplifier and so it then comes down to which kind of error is acceptable where you want to put your design budget.  As such, every engineer has to make informed value judgments in the design trade-offs to try to get the best sound quality. 
Measurement and simulation are very important tolls in loudspeaker design but the final arbiter is listening.  It’s not that we don’t measure, it’s just that the listening greatly informs the measurement and vice versa. 
I design the drive units that we use here for a number of reasons. I have a lot of expertise in driver design and enjoy it immensely and feel like I can offer our customers more for their money (or versus other small speaker companies using off-the-shelf components). 

I truly am excited about the Sprout Speaker and am looking forward to Chris' YouTube videos.

However, I found an opposing view on potential directionality of a large tweeter and that may explain why I preferred the venerable dual Dynaco A10 with SEAS drivers and my A25s reproducing music and voice compared to the Elac B6 etc. that I reviewed earlier on this site.

See this piece on "Large Tweeter Domes" and the author's review of the Sonnet, in which he writes:

BTW: If we go to the Copenhagen dealer on Chario speakers we find 93 dB sensitivity and F3 = 50 Hz. Chario website (and manual) states 90 dB/2.8V and F3 = 55 Hz. I guess this is what we can expect from an Audio Note dealer...... http://www.audioconsult.dk/.

"Frequencies below about 700 Hz are processed by determining the arrival time to each earpinnae and this is referred to as IT ). Frequencies above about 1,400 Hz are processed by determining the energy flow delivered to each era-pinnae and this is referred to as IAD (inter-aural amplitude difference). We soon recognize Duplex Theory not to be exhaustive because it fails to correctly explain the localization process within the missing 700-1,400 Hz range. At these frequencies head & torso are enough obstructive to modify the incoming wavefront (diffraction) so that the crossover from ITD to IAD is not linear and localization cues are not flawless."

What appears to be the long and the short of it, is this: The ear detects sound in two ways as described above. I've checked Wikipedia and this seems sound knowledge. http://en.wikipedia.org/wiki/Interaural_time_difference. So, between ~700 and ~1400 Hz our brain has trouble finding out what the heck is going on, so by placing the point of crossover between these two frequencies, we fool the ear/brain and we can't find out whether the sound comes from one driver or the other. Result: Perfect driver integration! Does this make sense to you? If not, please post me your interpretation. By the way: In the laboratory where I work, we have three incubators side by side. Whenever an alarm (~1 kHz sine wave) goes on, it's impossible to hear from which incubator the damn sound comes, so maybe we have trouble localising sounds from this frequency range). Just a thought.

Engineers, experts, hobbyists, feel free to weigh in.

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