North Creek Rhthym Revelator

**ThomasW** · 11 October 2004, 13:05 Monday

Next to our own JonMarsh, George Short is one of the better loudspeaker designers around. He's light years above the designers that post on the MAD board. :wink:

We buy his hand made and baked large inductors, and they cost a TON!

That kit is using some of the finest components available. In comparison one would probably pay $5K+ for it's equal at a B&M store.

That being said, I'd put a 'tricked-out' and upgraded M8a MTM design up against it anytime..... :B

**Bing Fung** · 11 October 2004, 15:08 Monday

Thanks Thomas, so then I take it the matched drivers and big dollar matched components for the XO's would be a worth while upgrade from the base kit?

-Rhythm - North D25 Project ...$999.00 per pair
-Upgrade to the D28-06S tweeter for $120 per pair

-Rhythm - North D28 Unlimited Project ...$1,489.00 per pair

-Rhythm/Revelator Project ...$1,799.00 per pair

-Rhythm/Revelator Signature Project ...$2,299.00 per pair (everything matched)

When you are buying George's Large inductors, is he custom winding them to your own specifications? (must be)

What is the Tricked-out and Upgraded M8a comprised of from the original design?

Are you basing the challenge on paper specs, or because you have heard the Rhythm Revelator? just curious... I have heard neither

**ThomasW** · 11 October 2004, 15:25 Monday

No I haven't heard Geroge's design, but I'm certainly familar with all the drivers used in it.

Driver matching is interesting and a great marketing tool. Have you had your ear tested to see if they're 'matched'. :B Most pairs of ears are much further off than the normal unmatched pairs of production loudspeakers, let alone drivers matched to +/- a fraction of a dB... :E

We use his inductors because they are the 'best' large inductors we've found.

The tricket out M8a MTM will be the MTM section of Jon's Arvo. So SS9800 tweeter, high-end caps, Kimber braided wire, North Creek inductors in critical places

**Bing Fung** · 11 October 2004, 17:15 Monday

I'll take the matched componets versus cost as a "No" then...

I remember back when I had a set of Energy Pro 22 Monitors. They were a 8-1/2" 2 way speaker, that sounded very nice. My friend bought a set a few months after hearing mine, however he bought the Pro 22 Reference. It was the same speaker, however His were marketed as "Matched" components, in the same way as the North Creek. I forget the price difference, however it was about $400 more.

We never did any side by side comparitive tests, however I remember being at his place once, and I really though the Reference had a lot more jam at the upper end and sounded smoother than my regular Pro 22's. I realize there may have been a lot of things such as the room, etc that would have added to it. I really noticed he could get a lot smoother "Loud volume" sound than I could. He had a Luxman integrated amp driving it that was about 70 WPC. I had the Luxman CO2/M02 Separate Pre amp/Power Amp that was rated at 150WPC, Both our electronics were of the same model year, yet his system seemed so much smoother. We had planned to do side by side, however it never materialized.

I would like to know more about the "Tricked-out M8" or even more I would like to know more about the Avro :yesnod:

So would you say the M8 is using better (nicer) drivers than the Scan Speaks in Rhythm Revelators?

Or is it Jon's cross over designs that are superiour?

**ThomasW** · 11 October 2004, 19:02 Monday

I'd really need to actually hear a shootout between a max'ed out M8a-MTM and George's Rhythm Rev's to say for sure.

These are both state of the art systems but using completely different technologies with regards to the actual radiating elements.

As a result there would certainly be audible differences, that wouldn't necessarily be attributed to one system actually being 'better'.

It would be apples vs oranges type of comparison. Chose the one you like 'best'.

There's not much more to tell about the 'tricked' out Arvo. Jon used the high-end AudioCap Theta Film and Foil caps in the tweeter section, George's coils in the woofer section, and the braided Kimber 4TC speaker wire to wire up the drivers. At this point his very happy about those choices.

Jon has tickets to fly out to Denver Oct 6th -14th. I'm going to buy some of the caps and the Kimber cable. Then we'll do a side-by-side comparison between one of my old Arvo's and one with the upgrades.

I'm not going to use George's inductors. Since my Arvo's are actively bi-amped, so there is no passive bass XO.

When one has the opportunity to compare products like different Energy speakers, A/B/X testing generally proves interesting. Placebo effect is very real........:wink:

All the current Arvo info is HERE

Or is it Jon's cross over designs that are superiour?

Jon's XO topologies are certainly unique. And mandatory given his choice drivers and crossover points. The drivers George is using are more forgiving of variances in XO design

**JonMarsh** · 11 October 2004, 19:50 Monday

Originally posted by ThomasW

I'd really need to actually hear a shootout between a max'ed out M8a-MTM and George's Rhythm Rev's to say for sure.

These are both state of the art systems but using completely different technologies with regards to the actual radiating elements.

As a result there would certainly be audible differences, that wouldn't necessarily be attributed to one system actually being 'better'.

It would be apples vs oranges type of comparison. Chose the one you like 'best'.

There's not much more to tell about the 'tricked' out Arvo. Jon used the high-end AudioCap Theta Film and Foil caps in the tweeter section, George's coils in the woofer section, and the braided Kimber 4TC speaker wire to wire up the drivers. At this point his very happy about those choices.

Jon has tickets to fly out to Denver Oct 6th -14th. I'm going to buy some of the caps and the Kimber cable. Then we'll do a side-by-side comparison between one of my old Arvo's and one with the upgrades.

I'm not going to use George's inductors. Since my Arvo's are actively bi-amped, so there is no passive bass XO.

When one has the opportunity to compare products like different Energy speakers, A/B/X testing generally proves interesting. Placebo effect is very real........:wink:

All the current Arvo info is HERE

Jon's XO topologies are certainly unique. And mandatory given his choice drivers and crossover points. The drivers George is using are more forgiving of variances in XO design

My main "beef" with the Northcreek Revelator is the same as for it's predessor, the NorthCreek Rythm. He uses the ScanSpeak carbon fiber/paper woofers up to ~2.5 kHz, and the first cone mode is at ~800 Hz. The Scanspeaks have a "kink" in the response at ~800Hz (rising resopnse above this to ~ 3 kHz) to simplify crossover design for achieving baffle step; a single first order function at ~ 250-300 Hz is only needed to get BSC to 800 Hz, and flat above that. George explained in detail how he used this in the design of the Rythm, and hasn't materially changed it since.

Having used Scan 7" and 8" in sysems in the early 90's myself, I'm familiar with this characteristics; problem is, it contributes to what I hear as a smear in the midrange response and a sort of "ehh" charactersistic that you can't get rid of. SL uncovered the reasons also, using his shaped sine burst testing, which is why HE no longer uses Scanspeak woofers either, but just the Excel.

At this point, I still think a M8 MTM as we've done for Tibor would stand up well to the NorthCreek, with the SS9800 tweeter; with the possibility of using the Dayton reference 8" woofers, I really doubt it would be much of a contest. The ScanSpeak 7" have a slight Xmax edge on the M8a, but the M8a has a huge Sd edge, so in some ways, pitting an M8 MTM against the NorthCreek wouldn't really be "fair".

Except when you consider price....

Part of what that price from NorthCreek gets you is a pretty carefully put together package, backed up by good technical support.

But then, we're not too bad on the technical support end at HG Guide, either, and we don't charge for it... I guess we're not very clever fellows, eh?

~Jon

~Jon

**Bing Fung** · 11 October 2004, 21:05 Monday

Hey Jon, I think you may have to dumb all that down for me....

ops:

ops: Sorry, however I'm nowhere near speaking intelligently to you about this :loser:

Originally posted by JonMarsh

My main "beef" with the Northcreek Revelator is the same as for it's predessor, the NorthCreek Rythm. He uses the ScanSpeak carbon fiber/paper woofers up to ~2.5 kHz, and the first cone mode is at ~800 Hz. The Scanspeaks have a "kink" in the response at ~800Hz (rising resopnse above this to ~ 3 kHz) to simplify crossover design for achieving baffle step; a single first order function at ~ 250-300 Hz is only needed to get BSC to 800 Hz, and flat above that. George explained in detail how he used this in the design of the Rythm, and hasn't materially changed it since.

What I could get out of that is the Scans Speaks have some frequency problems at 800 hz, creating other anomales. There was suppose to be a fix in the mix, however it hasn't happen yet?

I don't know what baffle step is or BSC :scratchhead:

Can you explain it to me using George's posted Graph?

Having used Scan 7" and 8" in sysems in the early 90's myself, I'm familiar with this characteristics; problem is, it contributes to what I hear as a smear in the midrange response and a sort of "ehh" charactersistic that you can't get rid of. SL uncovered the reasons also, using his shaped sine burst testing, which is why HE no longer uses Scanspeak woofers either, but just the Excel.

Who is SL? and does this mean the Scanspeak Woofers are "not so good"?

At this point, I still think a M8 MTM as we've done for Tibor would stand up well to the NorthCreek, with the SS9800 tweeter; with the possibility of using the Dayton reference 8" woofers, I really doubt it would be much of a contest. The ScanSpeak 7" have a slight Xmax edge on the M8a, but the M8a has a huge Sd edge, so in some ways, pitting an M8 MTM against the NorthCreek wouldn't really be "fair".

Except when you consider price....

I take it Daytons are used in the M8 design (sorry I haven't full looked into the M8

ops: ) So in the "Fair" consideration, who is the underdog?

Part of what that price from NorthCreek gets you is a pretty carefully put together package, backed up by good technical support.

But then, we're not too bad on the technical support end at HG Guide, either, and we don't charge for it... I guess we're not very clever fellows, eh?

~Jon

OK, now I gon and done it... If you guys (Dynamic Duo) start chargeing huge dollars for your excellent technical knowledge as support, I'm going to be pelted by sticks and stones from the other members. :smackbutt: :nutkick: :throwat:

Well, not sure where to take this now as it seems, it's a dead end.....

Were is the parts list for the M8's and the various designs that can be applied to it?

Does a person buy preassembled cross overs form you or would I have to build them myself?

I'm not going to even think about replicating yours and Thomas's Avalon design :lol:

Don't get me wrong, I'm all for saving good money (if M8 is less) and building a superiour design, so I'm sorry I didn't mean to ask Porsche if I should build this commuter car, As I said. I just don't know anything.

**ThomasW** · 11 October 2004, 21:42 Monday

To 'see' the problems with the SS woofers you need to look at the impedance plot not the frequency response. The cone itself becomes non-pistonic in it's operation. That causes problem with the sound quality above 800Hz. There is no 'fix' other than for SS to redesign the cone.

SL = Siegfried Linkwitz, you know the guy that helped invent the Linkwitz/Riley (LR) crossover topology.

If Andrew can build the crossovers so can you .... (just kidding Andrew

) We will build them for you, but we charge $1000/hr, and there's a 10hr mininium ..... :E

No the Daytons aren't used in the M8a design. Jon is getting in some to evaluate their performance.

There are 3 working designs using the M8a speaker
1) M8a-MKIV =8" ported box 2-way
2) MTM sealed or ported box design with a pair of M8a drivers
3) Avro = dipole 3 way with M8a MTM at the top and a pair of 12" woofer at the bottom .

You can find REAMS of posts about each design right here in the DIY forum.

**Dennis H** · 11 October 2004, 21:44 Monday

I guess we're not very clever fellows, eh?

Nah, Jon, you guys have it figured out just right. George has to be nice to his customers, even if they are jerks. You can be irascible and tell them to f*** off if they don't like it. :lol:

**Paul H** · 11 October 2004, 22:19 Monday

I'm glad I wasn't drinking anything when I read that last post - lol.

Paul

**JonMarsh** · 12 October 2004, 20:09 Tuesday

Hah! You know, I think Dennis "Got it"!

Seriously, Bing, one of the critical things for clarity (low distortion and energy storage) is doing one's best to use drivers just in their pistonic range. But many drivers, as a matter of design philosophy/compromises, have made choices to try to extend the working range of the driver, by decoupling parts of the radiating area from other parts, or trying to build in flexible decoupling in the cone with increasing frequency. You know, though, there's reasons Whizzer cones don't sound as good as good dome tweeters. Similar problems can occur in the lower range.

As Thomas pointed out, One of the easiest ways to detect "gross" mechanical discontinuities is to look at the impedance curve- if you see a glitch/bobble somewhere in the 500 Hz to 3 kHz area, that's a dead giveaway, IMO. You can figure out more about the problem by looking at it with nearfield testing at multiple points on the cone, with shaped sine burst testing as SL does, or if you've got a big fancy dancy well funded laboaratory, something more fancy like a laser interferometer. OK, sorry for the big word; I'll try to cut that out!

One also has to be careful to look at the region near where the obvious glitch/problem occurs; often at frequencies below the main cone breakup mode, there may be energy storage that leads to problems- for example, SEAS W22 is fairly flat up to 1 kHz, then above that has a big dip, then a big spike at the main break up mode. That big dip is where a lot of energy storage from out of phase behavior of part of the cone is occuring- it also tends to smear the transient definition, so, should be kept away from (in designing the speaker) .

YMMV, and there's no truly perfect speaker or driver. But as much as I like the Scanspeak motor in the 8" and 7" models (low distortion, great bass), the cone modes relegate them to below 700 Hz duties.

And, according to Mark K's tests, the new Dayton Reference series better them in LF distortion. This I gotta see, which is why I ordered some! :B

Mit gruessen aus Singapore.

~Jon

**ThomasW** · 12 October 2004, 20:50 Tuesday

I'm going to start a new thread. Loosely based on "Where's Waldo?" concept, the thread will be called "Where in the world is Jon today?" .......... :wink:

**Andrew Pratt** · 12 October 2004, 21:32 Tuesday

If Andrew can build the crossovers so can you

Very true indeed

Bing if you want to hear the stock M8a's you're more then welcome to drive down for a weekend etc. Drag Trev along in his Vette and you'd be hear in no time

**mante** · 15 October 2004, 08:49 Friday

Hi Thomas,

"Jon has tickets to fly out to Denver Oct 6th -14th. I'm going to buy some of the caps and the Kimber cable. Then we'll do a side-by-side comparsion between one of my old Arvo's and one with the upgrades." I'm salivating and saving for the Arvos. I really hope you meant November and not Oct. 2005 ;>)

Craig

**Bing Fung** · 15 October 2004, 17:27 Friday

I was kinda of fired up about possibly building a set of these (one day) as the size is just right and the performance is around the range I'm looking at. However, now I suppose not... :scratchhead: Avros :huh:

Jon, thanks for your input, really I do know what a Interferometer is

While all these anomalies/glitches may affect the system on paper or test equipment, how does that convey to real world performance? Would a ludite like me be able to detect that while I was listening?

Andrew, I would really like to hear your speakers one day.

**ThomasW** · 15 October 2004, 18:58 Friday

I really hope you meant November and not Oct. 2005 ;>)

Yes, oops my bad, Nov 6th. For some reason I'm still stuck in September. Probably a function of old age ......... :B

Would a ludite like me be able to detect that while I was listening?

Nope a Ludite can't hear those things at all.
But a normal person with a good quality stereo can. ... :wink:

**Bing Fung** · 15 October 2004, 19:22 Friday

Originally posted by ThomasW

Nope a Ludite can't hear those things at all.
But a normal person with a good quality stereo can. ... :wink:

Well, I certainly would not hear it then, on both accounts

:

**JonMarsh** · 20 October 2004, 10:38 Wednesday

Bing, it's like the difference between a two way system I did with Scanspeak midwoofers and Seas aluminum tweeter, versus the top module of my X1 clones- yes, the frequency response of the completed system on an RTA looked similar, but there was no comparing the clarity and inner detail - the Eton midwoofers, which had their first poblem area at 1600 Hz, instead of 800 Hz, just blew the Scanspeak 7" away in ternms of clarity, inner detail, and naturalness.

Believe me, you can hear the difference.

**Bing Fung** · 20 October 2004, 11:01 Wednesday

Jon, No doubt if a driver displays it's weaknesses in a range where it was not intended to work, it would be cleaner than one that displays anomalies in it's working range... I understand now.

I can't say I'm a big fan of the look of the random mashed paper look of the Scan Speak Drivers anyway :B The Seas, and Etons look very nice... Going by looks only, as I really don't know enough speaker specifications to apply them in a Virtual enclosure in my head, and know how they should sound. :unsure:

I was just poking fun at my knowledge and my midfi system, indicating I would not hear a difference on because of both factors. :lol:

North Creek Rhthym Revelator

North Creek Rhthym Revelator

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