PMC vs. ATC

Hi. Another supposition! You assume I have a friend who knows about speakers - because otherwise your "story" about me just doesnt fit. Well sorry to have to tell you this but you are just plain wrong. I did this all alone and unassisted. What's more it was easy ;-). All you can do is make false assumptions and sling labels hoping they will fit as you have no technical argument to fall back on. All your suppositions are contradictory - you are just clutching at straws hoping something will stick. Consequently your remarks about my not coming out and saying what I have to say are so bizarre as to be inance beyond any hope of my making a sensible answer to such nonsense. I have clearly surpassed your presumptions about my level hence your need to invoke an imaginary speak expert who is whispering in my ear. Come on be serious. Do you think I am calling pmc or something?? I have no connection other than the speakers I bought.

I didn't temper my comments - if you read carefully I have not backed down on or moderated a single claim. If you beleive I have then show me which one.

As for my semantics they are perfectly sufficient and accurate though for truth I was dumbing down the concepts somewhat until you proved that you were taking things to a higher level. Please show me exactly where I was ducking in and out and I will be happy to clarify.

As for the atc measurements I have seen such on numerous occasions and you yourself admitted a treble peak of 1dB broadband!! Given that we both agree this fact then certain physical laws lead inexorably to my conclusion. You are hoist by your own petard. If I was fabricating "BS" then it's the same BS you also produced. I happen to know something about anechoic chambers as they were necessary for research work I did many years ago. No need for an imaginary expert - I have a research engineering phd and my own expertise is quite sufficient. Specifically I worked in speech recognition and monitoring systems - nothing to do with audio or sales but an area of engineering which distinctly overlaps in a lot of ways. A lot of use of anechoic chambers and frequency response measurements for speakers. So I know what reproduces human voice best and it is PMC not ATC - voices just don't sound the way the atc presents them tonally. Or do you still think I am a junior salesperson??? Given you have corroborated my assertion from your own mouth then surely the issue is beyond any contention.

People don't listen in anechoic chambers and the design should reflect this. The same as a speakers anachoic bass response does not match real world siting as you noted - so it is with the treble. ATC themselves rely upon rear wall reinforcement - this is a strengthening of lower bass response that would not be present in the anachoic measurement. However they factor it in for real world performance. That is just good engineeering practice and applies to the treble as much as the bass. No-one says you have to cut the treble but a reasonably directional tweeter and a flat response rather than a peaked response would be a good start. Got it? PMC are hardly dull sounding they are still brightish due to the FLAT response. In a treated room their inherent neutrality would be more apparent, just as it made the atc treble more palatable, though not quite neutral still due to the treble lift under anechoic conditions.

Sure you have to be careful with a TL - you need a big room I don't dispute that. I keep mine 2m from the rear wall and 1.5m from the side walls. Problem solved. Yes likely in a smaller room atc might sound better due to bass room interactions. However given a large enough room the TL will give much better results. Again I point you to the issue of acoutic impedance matching to the air mass - sealed or reflex boxes just can't compete. If you have technical papers that claim otherwise I will be happy to view them. In a large room with appropriate positioning the TL will give a flat response to an appropriate level and will do so more effectively in terms of dynamics and detail than a sealed box or reflex design. Which is exactly what I heard. There is no isssue of pmc ignoring room gain. You are off on a flight of fancy.

The issue here is the treble response not impulse response.

You claim to KNOW beyond any shadow of doubt quite a few things about me - many of which you have already abandoned as they proved to be wrong. You then move onto the next guess you absolutely KNOW is right. :S

"Voicing" is a non-technical description of interpreting test measurements in order to engineer a flat frequency resposnse taking into account room effects. Just a colloquial way of descrbing the R&D process. Happy now? ;-) I used these non-technical terms so as not to alienate other readers by trying too hard too look like an expert. Likewise with "sharp". Stop nitpicking it is irrelevent and petulant. We are not pretending to be hifi designers here. At least I am not ;-).

I suggest you read a techical book regarding TL, the theory is pretty clear - I have explained the issues but you don't seem to have grasped them. They are only boomy if poorly implemented or sited. It is very hard to make a good TL so usually sealed box or reflex is better implemented. However the failure is implemtantion not fundamental theory - and PMC have got it right. They provide a better match to the air mass of the room - that is established fact and the theory is outlined in even the most basic texts. The back pressure on the bass driver also improves control over the bass effectively as if it were increasing the damping factor of the driving amplifier. We can discuss amp design as well if you like - all my electronics is currently being converted to DIY kit - eventually only the speakers and turntable wil remain and I will convert the PMC to active using diy active crossovers and using my own in-room measurements. I am sure the atc crossover is very good - it is only the treble peak I take issue with. It's a preference not a flaw of the design. "Sharp" refers to a treble boost nothing to do with distortion. I think the PMC sounds cleaner myself but I think this is a knock on effect into the midrange of the TL driver.

The PMC midrange driver spec is not in the public doman so far as I know as it is an in-house design. contrary to your beleifs I don't have inside access at PMC. Nice try to trap me but no good I am afraid.

Your sub idea sounds good - it will doubtless work well when room size is limited. I have a huge listening area so I don't need to consider it. I have not observed any particular modal problems (except for one piece of organ music) so it isn't an issue for me. So long as you just use the sub low down and don't intefere with the mid then it's a good idea in principle.

I don't lump atc with B&W - atc are much better. I just don't like listening to either of them if the truth be told. I have no axe to grind why would I? You seem to think I have a vested interest but I do not. I found that atc and pmc sounded very different to me. Doubtless each excels in some areas relative to the others and maybe you prefer that designs compromises and I prefer PMC. They are designed for different things and their different tonal balance reflects that. For me tonal neutrality is the most improtant thing. I am certainly not dogmatic. I like bryston amps. However I prefer the older ST series - the SST range don't do much for me. So maybe they have sold out ;-). Maybe PMC will too. If soemthing better comes along I will happily buy it. If that happens to be ATC then all well and good. FYI most of my comments apply to the 100s.

By the way - which pmc models are you actualy talking about? My comments are restricted to the larger three way designs like the MB2.

Hey brizon,

Well I don't doubt we could swap systems and go on enjoying ourselves, I'm glad we (I) had a holiday weekend to sort this out.

All do respect to what you were saying, I get it now but you were talking like two people, and I appreciate you dumbing it down but to me it was deceptive (not intentional I know) I wanted to have a discussion not a fishing expedition :). Look if you studied speech intelegibility then let me know, part of my film degree (25%) of my classes were devoted to speech intellegibility and "noise" in communication. I still study it today, independently. I was just fishing to see who you were and I must say, the combination of semi-promotional speak (fastest growing speakers...on the back of domestic sales) SOLD!!!!, words like sharp and etc, with an obvious clear understanding of how things work, I'm like "who is this guy can I go here, lets poke him and call him a tourist if he's educated I'll get a response!" I knew you were playing me, So I kept poking you with those crazy SUP's and traps so you'd tell me to clarify my petulant ways. :)

Hey check these out, these kind of support my argument but they were the only ones I could find if you can direct me to others I want to see because the speaker is what it is and I can't change what the ATC is and You can't change what the PMC is....so i'd like to know what I can.

http://lib1.store.vip.sc5.yahoo.com/lib/transaudiodirect/65
eratc.pdf, "this is kind of sketchy I know."

http://www.guidetohometheater.com/speakersystems/5/index5.html

I have a new mic preamp coming in and when I get it if you're interested I'll take some measurements of my 150's and I'll run them through the psychoacoustic filter and compare the straight in room response, take a quasi-anechoic then with the psycho-acoustic filter see what we get.

I must admit that I took sharp as more of an adverb and an adjective, or a dynamic problem. So that's why I jumped to impulse response or IMD because I assumed if it drove you from the room it had to appear by surprise not as a consistent character or you wouldn't have played it that loud. LOL! But maybe I'm taking you too literally.

Fact is after all this we still disagree on magnitude and I still percieve your hearing like the Princess and the Pea :)....still, I guess it is what it is. Thanks for the kind words on my sub design and since I work typically in 8X12X3 meter rooms max, you understand my philosophy.

I sold the Bryston St series the SST's seem a bit softer, that's probably because so many speakers are sharp...I guess that's the best way to go to catch a few more flies if you're building amplifiers these days.

Have a good week. look forward to chatting again hopefully more constructively now that we know each other a little better.

I had MB2's, Those are the only big three way PMC's I have heard.

Doug

PS: "The PMC midrange driver spec is not in the public doman so far as I know as it is an in-house design. contrary to your beliefs I don't have inside access at PMC."

Actually it was wishful thinking. I'm a curious dude when it comes to these things ;(

Haha thats ok, doubtless having a treated room makes the top end quite a bit more palatable. However this is something usually only studios or very dedicated individuals can commit to. I rent so it's not an option for me. Most rooms are very reverberent in the Uk due to wooden floors and even with carpets the treble just gets too strident especially with small rooms.

My first research job was working in speech recognition systems of which testing things like hearing and speaker systems is a very important part. One of the things I looked at was computer speech recognition in high noise and distortion environments like fighter cockpits. I then moved into RF engineering which also involved listening tests for radio intelligibility. I then went into nonlinear signals processing and analysis before jacking it all in to work in finance 5 years ago. My interest in diy just comes out of the fact I am interested in everything technical.

I have also rountinely had to have my hearing tested up to 20 KHz. My hearing extends flat past 16 kHz which is extremely unusual in a person of my age. I often find I can hear high pitched sounds that others can't and this is partially way high frequency treble boosts annoy me so much. To others they probably dont care. The person who complained the most when I took them to atc dems were female. They usually have better high frequency hearing too. She actually liked hifi (especially if it was big, bulky and black!) so she wasn't just petulant about being dragged in. ;-). She liekd the pmc best and I managed to convert her from cd to vynil in that dem (she thought there was soemthing wrong with the cd player initially!).

Are you using active crossovers with the atcs?

Nick.

Im impressed!

"The person who complained the most when I took them to atc dems were female."

If I get ever get past my Masters, my doctorate thesis is on why women do not participate in audio the physiological and psychological factors. Audiophiles? give me woman anytime to judge the sound of a system.

My ATC's are active, infact the speakers I build have room correction and response shaping built in with their amplification and Blue Sky, Meyer and ATC are all active speaker lines (ATC has a mix as you know), Most passive speakers simply cannot get to the level of performance active speakers can without using very expensive amplification, which makes them more expensive for the same performance. The reason I don't have PMC is they are more expensive and not a strong a line at more modest price points as ATC and DALI, so they had to slide on the priority scale a little but their time will come.

Have a good one.

PS: Checkout the lake technology crossover @ www.lake.com