[Brian Cheney]

Prototype CD waveguide for the RM/X is not finished.

[ScottMayo]

Prototype CD waveguide for the RM/X is not finished.

Well, no problem, you've got a week.

[James Romeyn]

B you gotta call me when you get the CDWG for the X.

I am searching for either a new guitar or possibly to have the neck replaced on my favorite acoustic.  We've all had the following experience, but it's still fun to encounter: Walking up to my favorite acoustic guitar sallon & hearing a live guitar playing from outside well before I entered (mediocre skill/nice guitar).  It's so easy to identify live music.  In fact it helped me find the place because it's one narrow & confusing storefront after the other in this boutique area.  

We all know the following, but it might be worthwhile to repeat here.  The sound we all identify immediately as a live violin is composed of its peculiar qualities, including attack/decay, dominant & secondary steady-state overtone structure, etc.  But another primary identifier is its polar radiation pattern, which cause a specific tonal quality when bouncing off nearby surfaces, especially the floor.  

Suppose you got a super narrow polar radiation pattern in your favorite speaker.  Is it not true that that speaker is not capable of reproducing some of the polar response of a source that was actually quite wide?  

Conversely, let's say an original recorded source captured a wide polar output at 1kHz & 3kHz.  Let's say that well recorded source is played on a speaker with extremely wide polar output at the lower frequency, but very narrow response at the higher frequency.  Would it not alter the reproduction in a negative fashion, detracting from the original instrument's peculiar identity?  It's not known how audible it might be, but depending on the source, it could possibly make a big difference.

[clarkjohnsen]

Let's not, at least for the moment, use that ugly word "tweak". Let's say instead, "fine tuning".

There are those who believe that manufacturers, those devoted souls, give us the best possible product, and others who think that they can make it better.

I happen to fall into the latter camp, especially as regards CD.

CDs need all the fine tuning they can get!

Or put it this way: A system with bare-bones CDs is unlistenable.

Ironically for Scott, my introduction to this very area occurred on a 1980 visit to VMPS, when I was shown some grand Len Hupp speaker cables, the VPI Magic Brick and various duded-out John Curl electronics. Now, to me, the audio hobby is only about doing what one can to improve performance oneself.

Equipment per se is boring.

clark

[ScottMayo]

Let's not, at least for the moment, use that ugly word "tweak". Let's say instead, "fine tuning".

There are those who believe that manufacturers, those devoted souls, give us the best possible product, and others who think that they can make it better.

I happen to fall into the latter camp, especially as regards CD.

That's why I'm looking forward to this.  

Media is the one place I do think tw- fine tuning holds some promise.

The manufacturer of a high end amp or speaker (we're not talking mid-fi here) - he's going to know how to make his product works the best it can. And since he's selling to audiophiles, he has no incentive to cut corners to save pennies. Audiophiles already spend big money for small improvements. We'd happily spend an extra $50 for the manufacturer to use better caps, more linear transistors, or silver wire. So my take is, at these prices, if it helps, they've already offered it (or if they haven't, they will end up with a bad rep.)

But that doesn't apply to mass market stuff, like CDs. Manufacturers are saving pennies there, any way they can. There's no hope they've gone all out to make it perfect.

Of course, for CDs in particular, I don't see much hope. If the player is reading the bits off accurately and clocking through them cleanly, it's doing all that can be done. Waving magnets, cold air or bits of plastic at a CD isn't going to change any of the bits - and the bits are all there are. Clean the disk and it's as good as it will get. I look forward to seeing a technology that can help.  

The good news is, someday, CDs are going away. We'll get our stuff over the internet, store it digitally on magnetic media, and the idea of reading bits will be consigned to sealed disk drives with error rates of 1e-25. I'm not going to miss jewel cases, personally. But it will mean the end of, um, fine tuning. I mean, who's going to put a disk drive in a freezer?    

[John B]

I agree, tweaks really are where it's at in getting the most out of your audio system.  Though for me I don't call them tweaks, I call them system enhancing devices    Some work, some don't.  Wire being the most important of all the SEDs, can make or break your sound.  For example I've had a devil of time finding an IC that would work on my TT outputs to where it didn't enhance one portion of the frequency spectrum at the expense of another.  I finally found my solution with an IC I had relegated to my "snake pit".  I'd found other wire that I felt outperformed it, and so sent it out to pasture     However, as with all things in audio, it does come down to a synergy thing, and this particular IC turned out to be the perfect match for my TT output.

I've heard from B that my production model RM30C, which get's delivered today     !! Whooo Hooo!!!, has benefited from a hookup wiring upgrade; this particular wire product was used in my tube preamp, and it's effects there were extremely musical.  Now for the real test...having thoroughly enjoyed the stock version of the RM30 w/CD device, just how much improvement will I hear with the production models and all of its SEDs  

[skrivis]

When you are invited to someone's house for a meal (the public VMPS forum here), you don't volunteer an unsolicited & unwelcome comment that you would have spiced the meal differently. Especially when you are a novice cook who has never entered a meal into any competition, & you are visiting a master chef who has been making people happy with his meals for oh, about three decades.

I kind of think that some criticism should be welcome here. Otherwise it just becomes a fan club where everyone congratulates each other on having had the wisdom to acquire VMPS speakers.

I find myself agreeing with BC on some points, and having some real questions about others. I would hope that I'd be able to ask rather pointed questions, or maybe even offer up a different approach that has impresssed me. (BC is free to answer or not, and I certainly wouldn't expect him to write a book in response to my points.)  

[skrivis]

First order networks sound more natural to me than higher order slopes, which is the main reason I use them.

I would agree with this. I've been using speakers with 1st-order series x-overs (not quasi-second...) for the last 20 years or so. I just finished assembling new ones and am extremely pleased.

[Brian Cheney]

skrivis:
If I wanted character-building criticism and contrarian views based on uninformed opinion, I'd still be with my previous administration.

And lest I forget, my current spouse reminds me daily of the blessed, enlightened estate I now enjoy.  You wouldn't want to spoil that, would you?

[Brian Cheney]

skrivis:
The series first order filter is also referred to as a "quasi second order" configuration since it features a 12dB highpass from only 2 elements.

If you have used series first order crossovers for the past 20 years (as I have), then you have been enjoying the sound of "quasi second order" filters.

[skrivis]

We all know the following, but it might be worthwhile to repeat here. The sound we all identify immediately as a live violin is composed of its peculiar qualities, including attack/decay, dominant & secondary steady-state overtone structure, etc. But another primary identifier is its polar radiation pattern, which cause a specific tonal quality when bouncing off nearby surfaces, especially the floor.

Suppose you got a super narrow polar radiation pattern in your favorite speaker. Is it not true that that speaker is not capable of reproducing some of the polar response of a source that was actually quite wide?

I'm not sure I go for that. A live acoustic guitar is immediately heard as live even out in the middle of a cow pasture.

What the speakers need to be able to do is reproduce what the microphones heard, and the polar response of the original source may or may not be relevant.

[clarkjohnsen]

Clean the disk and it's as good as it will get.

Have you proof of that assertion? Any, at all?...

Moreover you seem to dismiss the CD-R phenomenon, where the bits are all the same but the disc sounds different, usually way better. An impossibilty, you would claim.

[John Casler]

I can see you two are gonna have fun

[skrivis]

skrivis:
The series first order filter is also referred to as a "quasi second order" configuration since it features a 12dB highpass from only 2 elements.

If you have used series first order crossovers for the past 20 years (as I have), then you have been enjoying the sound of "quasi second order" filters.

AFAIK, these have a Zeta near 1, so have a Butterworth response.

[skrivis]

skrivis:
If I wanted character-building criticism and contrarian views based on uninformed opinion, I'd still be with my previous administration.

Previous? I thought the Republicans were still in power?

And lest I forget, my current spouse reminds me daily of the blessed, enlightened estate I now enjoy.  You wouldn't want to spoil that, would you?

No, not when you put it that way. hehe


But, as an example, I've heard "line source" speakers in the past and found their treble to be not quite right. Planar speakers ("large source?") speakers kind of strike me the same way.

I'm skeptical of your designs because of your use of multiple drivers for a given frequency band. It doesn't seem ideal, and my past experience with this type of thing didn't thrill me. I lean towards a point source being ideal, and most like a microphone (since we're sort of trying to reverse from what the mics hear).

I won't go so far as to say you're wrong, and I will certainly reserve judgement until I can hear some of your more recent speakers. But I do kind of think of "those big speakers with upmteen drivers."

I try to keep an open mind, and if your designs sound better to me, then I'll admit I was all washed-up and start saving for a pair of VMPS speakers.

[skrivis]

Clean the disk and it's as good as it will get.

Have you proof of that assertion? Any, at all?...

Moreover you seem to dismiss the CD-R phenomenon, where the bits are all the same but the disc sounds different, usually way better. An impossibilty, you would claim.

I would tend to conclude, in this case, that the bits are _not_ the same.

[John Casler]

But, as an example, I've heard "line source" speakers in the past and found their treble to be not quite right. Planar speakers ("large source?") speakers kind of strike me the same way.

...

Hi Skirvis,

I know what you're talking about and I too hear "problems" with typical "line source" designs due to the interaction of the "dynamic cone" drivers at each end of the line with the drivers in the center.

However, I don't hear this on Brian's multiple panel designs.  I think in actuall listening practice the "panel line" is limited by the vertical dispersion charachteristics of each panel which is limited

So, in fact, you hear the panel at ear level, which makes it closer to point source than line source.  Again, this is not true with Line Source designs that use multiple higher dispersion drivers in the line.

I could be wrong,  and Brian can offer the "real" answer.    

Have you heard VMPS speakers recently?

[skrivis]

Hi Skirvis,

I know what you're talking about and I too hear "problems" with typical "line source" designs due to the interaction of the "dynamic cone" drivers at each end of the line with the drivers in the center.

However, I don't hear this on Brian's multiple panel designs.  I think in actuall listening practice the "panel line" is limited by the vertical dispersion charachteristics of each panel which is limited

So, in fact, you hear the panel at ear level, which makes it closer to point source  ...

Ok, I can see I'll have to listen to a pair before jumping to any more conclusions. And, no, I haven't listened to any VMPS speakers recently, although I hope that will change.

[John Casler]

Hi All,

We got off topic a bit to a very interesting subject, so I "split" it into a second thread titled:

Burned CD's vs Regular and CDP's vs PC CDP's

[BrunoB]

skrivis:
The series first order filter is also referred to as a "quasi second order" configuration since it features a 12dB highpass from only 2 elements.

If you have used series first order crossovers for the past 20 years (as I have), then you have been enjoying the sound of "quasi second order" filters.

According to John Kreskovsky,  first order series crossovers with a zeta of 0.5 are quasi second order filters:
http://www.geocities.com/kreskovs/Series-1.html

Are the VMPS speakers with a series crossover really QSO ("quasi second order")?

I am asking this question because I  made a computer simulation of the crossover (woofer to mid panel) using the capacitance and inductance found in my single wire   QSO 626R.   I have found that the calculated  zeta is 1.35 using the formula zeta = sqrt(L/(C * R1*  R2)) where L is the inductance in Henry, C the capacitance in Farrads and R1 and R2 are the impedance of the drivers in Ohms.  A zeta higher than 1.0 means that  there is a  broader overlap region around the crossover frequency than for a Butterworth first order crossover (zeta  = 1.0).  I performed a simulation with  the help of SoundEasy  using flat 8 ohms impedances for the drivers.The shape of the simulated  crossover slopes  look  more like a quasi first order than a quasi second order crossover.
Note that I am not an  expert in this field  (I learned from Kreskovsky's  paper cited above) and that the simulation might be different from  the actual crossover slopes ( I don't have  a standard 626R to measure them).

Bruno