Gravity Well Of A DarkStar

-Richard- · « **Reply #760 on:** 15 Jun 2006, 04:34 am »

Hi John in CR,

"It's great to talk people into stepping into what they perceive as the Twilight Zone and
giving OB's a try. We just need to be careful to not create unrealistic expectations."

An entirely reasonable approach John...I agree with you ~

Here is where I perceive the misunderstanding to have originated:

When Dmason started the Dark Star thread he suggested that everyone who
had a spark of adventure could experience a paradigm shift of music reproduction
by doing a simple DIY experiment...which consisted of cutting a simple plywood baffle,
cutting a hole in it and placing a Visaton B200 driver in the hole and listening to the
sound it generates ~

That is what I did...or rather had my neighbor, Jim McCarthy, do for me here in Ojai...
I am shy of DIY tools at the present ~

Like many who took Dmason at his word I was amazed at the result...nothing I had
ever heard compares to the sound I was getting until recently when I placed another
B200 driver on the baffles ~

Naturally...I would like as many audio enthusiasts to experience this same
revelation that I am experiencing...even as I write this ~

All they need to do is what I did...buy 1 or 2 B200's, cut a simple plywood board
and place the drivers in the board...admittedly...this is not a very scientific
approach...as you have sagely observed...but it works...and that is the point
Dmason, opnly bafld, myself and others are pointing out here ~

You are suggesting that if we apply a more thought out approach with the application
of some fundamental science we could have a much better experience that would
be remarkably better than that simplistic "rough" approach...we have no argument
there at all...I entirely agree with you ~

But that is not the spirit and intention of the original premise of this thread...which was
to get as many people involved in the Open Baffle experimentation as possible ~

Perhaps it is time this thread evolved out of the simple approach that originally
shaped its intention...and I await the findings that will move us all closer to a definitive
version that satisfies a more profound longing many of us have for a transcendent
musical experience...I am quite sincere here ~

And it would not at all surprise me if you, John, are able to help all of us to get closer
to that lofty goal ~

I am very glad I followed Dmason's suggestion to just jump in and DO SOMETHING!!!

My musical life has not been the same since...and Deb just loves what our OB's do
for the music...thanks Dmason!!!!...you have given us the gift of music that I thought
it would take thousands of dollars to purchase from super expensive audio
manufactures that cater to the rich...and the gullible ~

So here we are...those of you who have not yet tried to build your own OB's and
are reading this thread and are not sure what to do...here is your choice...
you could take what Dmason says as a kind of challenge knowing that it will
not be the ULTIMATE OB solution...which is what I and so many others have done...
or you can implement a more thorough OB approach which John in CR is
recommending...based on a more careful study of what the "best" approach would
be that will get you closer to the ideal ~

I am a bit simple minded I suppose...if I can get 70 percent "there" with a simple
implementation of OB building principles...that seems good enough to me...especially
if I can get there immediately...down the road...as ideas shape themselves more
accurately around the best approach...I will change what I have and integrate the
new approach to my OB's...meanwhile my enjoyment is startlingly good ~

The choice is yours ~

Warm Regards ~Richard~

JLM · « **Reply #761 on:** 15 Jun 2006, 10:21 am »

I highly recommend to any audionut who hasn't, to play with an spl meter and test tone CDs to learn what 30 Hz, 15,000 Hz, 90 dB, etc. sounds like because some of the statements made here make no sense.

Go to a piano:

Low C = 128 Hz (what most would consider midbass)
Middle C = 256 Hz (midrange)
High C = 512 Hz (almost midtreble)

No one in the last 30 years would accept a speaker as audiophile if it couldn't produce the top (10,000 - 20,000 Hz) octave, but many (perhaps most) easily accept loss of some or most of the bottom (30 - 60 Hz for music) octave. IMO this is due to all the problems associated with trying to reproduce bass correctly at home (mostly room acoustics related) and the striving for high efficiency (bass typically takes more power, more drivers, bigger cabinets). From my experience the small amp/single driver crowds are most susceptable to this bias. It is easy to be conditioned in time into believing music doesn't include fundamental bass.

Wind Chaser · « **Reply #762 on:** 15 Jun 2006, 06:16 pm »

Quote from: JohninCR

Wind Chaser,
You'll want and easily achieve a lot better than 100hz. I can't wait for a full report on the effects of the phase plugs, whether it's purely subjective or not.

If I can get dual B200’s reasonably flat from 100Hz on up with a small baffle and no EQ then I'll be pretty happy. The Augies can competently deal with anything that matters below 100Hz.

Last year I had a Clari-T mated with my stainless steel Jordan’s and there was an unacceptable lack of bass. I thought the problem was with the speakers. Eventually I tried a different amp from a friend and suddenly there was some of the most tuneful bass I had ever heard! The quality and quantity of this bass far exceeded anything one could reasonably expect from a mini monitor. This led to the discovery that the Clari-T’s bottom end begins to roll off at 200Hz. Even with a decent sub engaged to its upper limit of 120Hz to help fill in the bottom end didn’t complete the picture. The mid bass suck out from 120 to 200Hz was painfully obvious and as a result I didn’t listen to much music.

To be fair, Vinnie does offer further modification to resolve this particular issue, however I have taken the Clari-T out of the loop and replaced it a pair of amps more suitable to my needs. The point is any aberration in a systems ability to flesh out a balanced bottom end will take its toll on the enjoyment of everything else.

As for the phase plugged B200’s, I am anxious to hear them myself. Even though Dave completed the modification some time ago I told him to hang on them for a while. I’ll soon have a stock version of drivers to compare them with, but they’ll need a few hundred hours to catch up. In any case I won’t have to rely on my memory, as it has been quite a while since I last heard them; so I should be able to give a more accurate report on the differences between the two. It should be mentioned that the modified drivers entail more than just phase plugs. Dave has a few tricks up his sleeve and I gave him permission go for it!

John

Dmason · « **Reply #763 on:** 15 Jun 2006, 09:37 pm »

I look forward to your reported experiences with the plugs installed in the B200. Dave D did a nice job, and says that off axis response is increased greatly, and beaming issues are apparently greatly improved. This type of modification really completes the picture of the "finished" transducer.

Dmason · « **Reply #764 on:** 15 Jun 2006, 11:14 pm »

My thoughts exactly. I have long thought Visaton needed to get off their asses and finish developing the driver, which would include a plug. And a better response plot. Now that sales have ramped up both here and in Europe, I doubt it furthers the cause. It is a DIY darling in Germany, apparently. However, it looks like there will be some more choices on the horizon

coming from The Green Scene. Hint:

I am supposed to know more around the end of the month, according to what I have been told.

Vinnie R. · « **Reply #765 on:** 16 Jun 2006, 12:42 am »

Quote from: Dmason

However, it looks like there will be some more choices on the horizon coming from The Green Scene. Hint:

I am supposed to know more around the end of the month, according to what I have been told.

The Green Scene, eh?

I WANT, I WANT!

Please keep us posted, Dr.

Wind Chaser · « **Reply #766 on:** 16 Jun 2006, 04:18 pm »

Quote from: -Richard-

...the bottom drivers cut off at 100Hz with a 10mH 18 gauge air core coil
inductor (-2 db according to Roger...so I am ordering the 15 gauge tomorrow= –1db)...

Richard,

I thought the 10mH 18 AWG produced a 6db per octave roll off? Could you elaborate a little more on the above?

Thanks,

John

Vinnie R. · « **Reply #767 on:** 16 Jun 2006, 04:27 pm »

Quote from: Wind Chaser

Quote from: -Richard-

...the bottom drivers cut off at 100Hz with a 10mH 18 gauge air core coil
inductor (-2 db according to Roger...so I am ordering the 15 gauge tomorrow= –1db)...

Richard,

I thought the 10mH 18 AWG produced a 6db per octave roll off? Could you elaborate a little more on the above?

Thanks,

John

Hi John,

I think he is referring to the added attenuation due to the resistance of the inductor.

-Richard- · « **Reply #768 on:** 16 Jun 2006, 05:07 pm »

Hi John/Wind Chaser,

Vinnie is correct (as he always is...thanks Vinnie)...

Roger Modjeski has pointed out to me that different thicknesses or gauges of
the copper wire attenuate the all-over strength of the signal differently
as it moves through the coil: 18 gauge = a factor of 2db, 15 gauge = a factor of 1db.

Also: All copper coiled (wire) inductors have a 1st order slop of 6db.

An inductor of 10 mH, or milli Henries, used with a 6 ohm driver, like the B200,
should give us a cut off at 100 Hz with a 6 db fade that should disappear at 1000 hz.

Parts Express has what seems like a good deal on 15 gauge coiled inductors:

http://www.partsexpress.com/webpage.cfm?DID=7&WebPage_ID=3&Start=5&Filter=Jantzen%2Binductors&searchorderby=1&sm=1&so=1&search_type=main&desc=ASC

For the record: there are several ways to accomplish a crossover. I am still
researching other options: an L-pad variable potentiometer, Zobell crossover network,
and the "active" crossover units from Berhinger and Rane which are very versatile
but contain op amps that may affect the quality of the signal.

For now a simple "choke" or coiled copper inductor works its magic very nicely.

Warm Regards -Richard-

Wind Chaser · « **Reply #769 on:** 16 Jun 2006, 05:10 pm »

Thanks Vinnie, that makes sense.

Wow, looks like Parts Express has become INFLATION EXPRESS. In just 4 days the prices have gone up like a rocket!

10mH 18AWG part no 255-294 went from $14.81 to $24.52

10mH 15AWG part no 255-448 went from $26.76 to $47.36

I'd rather not have to do it myself but in this case I'm suddenly motivated. Thanks to JohninCR for providing the link... http://www.colomar.com/Shavano/inductor_info.html

John

Wind Chaser · « **Reply #770 on:** 16 Jun 2006, 05:19 pm »

Richard,

Not that I doubted Vinnies answer, but thanks for confirming. As for managing the crossover point, cost effective solutions that get the job done is what I am especially interested in.

John

Vinnie R. · « **Reply #771 on:** 16 Jun 2006, 05:23 pm »

Quote from: Wind Chaser

Wow, looks like Parts Express has become INFLATION EXPRESS.

I wonder how many lurkers here on the Darkstar thread are buying them? Maybe the demand has really increased and they are jacking up the prices?

We did it to ourselves!

Wind Chaser · « **Reply #772 on:** 16 Jun 2006, 05:37 pm »

I just got off the phone with Inflation Express. They said the price increase took effect today because their vendors raised the price. I asked them what about the ones in your inventory that are still sitting on the shelf from yesterday? They said sorry… Yeah, right. Whatever…

scorpion · « **Reply #773 on:** 16 Jun 2006, 10:03 pm »

JohninCr,

You are of course very familiar with Siegfried Linkwitz' Webb-pages.
You might also be familiar with his Excel-model to calculate SPL for OBs under the following link: http://www.linkwitzlab.com/spl_max1.xls.

With this you could calculate under what conditions 4 B200s would be able to produce for instance 90 dBC in the 30 - 40 Hz region.

Now 90 dBC is very seldom reached in a middle seat in a properly constructed Consert Hall with a full Symphony Orcestra playing.

/Erling

Wind Chaser · « **Reply #774 on:** 16 Jun 2006, 10:08 pm »

Quote from: JohninCR

The price of copper has doubled in the past year, so inductor prices will likely go even higher. Plus a 10mH coil requires over 300ft of wire.

Reality check. According to the DIY inductor link, a 10mH 14AWG would require 2 X 356' of wire. A 10 lb spool with 800' of wire sells for $189.60 @... http://www.powerwerx.com/product.asp?ProdID=2094&CtgID=3727

In light of these facts Parts Express is giving the product away even at the significantly new higher price. As JohninCR suggests, it's not unreasonable for the price of these inductors to go up further.

So then, what are the alternatives?

John

chadh · « **Reply #775 on:** 16 Jun 2006, 10:21 pm »

A reasonably irrelevant post - but I think that copper prices have fallen considerably in the past week or so. They're still up in excess of 70% over the past 12 months though.

Chad

-Richard- · « **Reply #776 on:** 16 Jun 2006, 10:28 pm »

Hi Scorpion,

"Now 90 dBC is very seldom reached in a middle seat in a properly constructed
Consert Hall with a full Symphony Orcestra playing."

Your insights are a breath of fresh air...
thanks so much for posting THAT reality check!!

Warm Regards ~Richard~

opnly bafld · « **Reply #777 on:** 17 Jun 2006, 02:00 am »

JohninCr are you saying my 20"w baffles with 2 Bs can't reach 90dB @40hz at say 2m?
What about 50hz?
Lin

opnly bafld · « **Reply #778 on:** 17 Jun 2006, 03:50 am »

Are these numbers including any room gain?
Thanks,
Lin

opnly bafld · « **Reply #779 on:** 17 Jun 2006, 12:04 pm »

Thanks again John.
I have been on both sites and would have to agree with you that Music and Design is a little easier to follow.
Lin