Gravity Well Of A DarkStar

mcgsxr · « **Reply #1240 on:** 11 Jan 2007, 01:55 pm »

Good point about the $ value proposition. Only the Bolder modded Teac was more than $200... all the others were inside that mark.

It is always rewarding to find a great amp!

nodiak · « **Reply #1241 on:** 11 Jan 2007, 05:00 pm »

Hi Mark, no guilt applies of course, I find it educational. Interesting we're both enjoying vintage el84 amps now!
Don

scorpion · « **Reply #1242 on:** 11 Jan 2007, 05:24 pm »

Shep,

I see you asked me a question. I know too little about switching amplifiers to be able to explain their good virtues. Witness was not a very good phrasing.

PS. New ver 1.1 is something like "Shep - 2/3". aa

/Erling

Wind Chaser · « **Reply #1243 on:** 25 Jan 2007, 03:57 am »

The Anatomy A DarkStar - 4 months later - don't ask!

mgalusha · « **Reply #1244 on:** 25 Jan 2007, 04:07 am »

Oh that's ugly. I've torched some drivers over the years and have killed VC's that bad but never seen a magnet literally go to pieces.

JohninCR · « **Reply #1245 on:** 25 Jan 2007, 04:41 am »

That's the kind of result I was cautioning against when I disputed Dan's post about the B200 handling plenty of power.

opnly bafld · « **Reply #1246 on:** 25 Jan 2007, 04:58 am »

Quote from: JohninCR on 25 Jan 2007, 04:41 am

That's the kind of result I was cautioning against when I disputed Dan's post about the B200 handling plenty of power.

And everybody knows you are always right John.

Lin

Russell Dawkins · « **Reply #1247 on:** 25 Jan 2007, 05:26 am »

So, I won't ask about the rest of it - but what happened to the magnet?

-Richard- · « **Reply #1248 on:** 25 Jan 2007, 06:11 am »

Hi Wind Chaser ~

It would be most helpful if you can indulge all of us with an explanation of what you believe was
responsible for what looks like a total deconstruction of your B200's.

I have had mine playing every day for at least one year... at varying sonic levels... sometimes
quite loud... so far I do not see any evidence of material or construction failure.

Are we seeing, at least in part, the results of moisture that may have been present in your
dedicated basement listening room?

Thanks for any insights that may help us to avoid this kind of calamity ourselves.

Incidentally... I am glad to see everyone who used to contribute to this thread willing to come
together again to form our amazing community of collective intelligence. Let me say that I
admit that last year I was quite uncharacteristically critical for which I humbly apologize.

I am very interested in contributing to our AC community with affection and sensitivity.

So let me wish everyone the greatest happiness imaginable in the new year... and let me
also say how deeply grateful I am to everyone for sharing their insights and wisdom
with all of us which is a constant source of help, enlightenment and fascination.

Warmest Regards ~ Richard

JohninCR · « **Reply #1249 on:** 25 Jan 2007, 06:44 am »

Richard,

I've missed you too. You paint a picture with words of the OB sound unlike anyone else. I didn't really understand what happened, but I apologize for my part in it.

-Richard- · « **Reply #1250 on:** 25 Jan 2007, 09:29 am »

Hi JohninCR ~

I have always deeply respected your creative and systematic approach to your investigations
into what is possible with DIY OB implementation... and you are most certainly a man
of your word... you followed through quite ethically in our mutual dealings together...
for which I further respect you.

I have always read with great interest anything you write about OB's, John.

We all owe you a great deal of respect and acknowledgment for your dedication to furthering
the art and science of Open Baffle speaker design.

For me, Open Baffle sonics, is nothing less than a revolution in bringing music to life
in ones home.

Warmest Regards ~ Richard

JohninCR · « **Reply #1251 on:** 25 Jan 2007, 07:13 pm »

Regarding the failed driver, I wonder what went first. It looks like maybe the spider broke from over-excursion. Based on the duct seal, I guess that's one of your phased plug drivers. I worry that could be part of the cause, because I noticed on my B200 with the dustcap cut off that there appear to be vent holes on the voice coil former to allow air flow in the area under the duct cap. It seems that filling most of that otherwise open air space with a solid phase plug could restrict the airflow designed to help cool the voice coil.

I find that the B200 sounds better by filtering out the low frequencies, which will also increase power handling while reducing the risks of over-excursion. I believe that increasing the complexity of the system has benefits that outweigh the compromises by a significant margin.

Wind Chaser · « **Reply #1252 on:** 26 Jan 2007, 12:53 am »

Unfortunately that was one of the modified drivers. I wish I could tell you this was the work of thermo-nuclear power amp John Iverson was testing at my place; but that was just a dream I had back in 1982. The driver was neither pushed too hard nor overdriven. It simply fell prey to a faulty amplifier. Had I known, that amp never would have entered my house. First I noticed a foul order. Then a cloud of smoke ascended from the right baffle. Shit, this can’t be happening. Too bad I didn’t take a picture. The voice coil literally went up in smoke. 120 volts of AC will probably do that every time. Oh well, better a B200 then me.

A few weeks later I attempted to dismember the damaged driver in the hopes of salvaging an expensive fridge magnet. So I took an Exacto Knife among other tools to it but that didn’t go so well; hence the ugly magnet. But hey, at least it looks like it was powered with an atomic amp!

Regarding the spider, it has more than enough travel so no concerns are warranted there. And the phase plug does not create a heat issue as it fits inside the chamber leaving a gap of about one millimeter around the perimeter for ventilation and unimpeded movement of the VC.

John

jrebman · « **Reply #1253 on:** 26 Jan 2007, 03:02 am »

Quote from: Wind Chaser on 26 Jan 2007, 12:53 am

Regarding the spider, it has more than enough travel so no concerns are warranted there. And the phase plug does not create a heat issue as it fits inside the chamber leaving a gap of about one millimeter around the perimeter for ventilation and unimpeded movement of the VC.

I'd be really interested to hear what you and others think about phase plugging the B200s. I'm assuming you're using the plugs available from Planet 10?

I have a pair of Omega Revolutions that are still breaking in so I won't be doing anything to them until I hear them in final form (which I figure is still quite a way off), but I'm intrigued by the idea of the phase plugs anyway.
I would love to try the OB thing, but there is just not room enough in this house to get anything more than 2 feet out from a wall, and I just don't think that would cut it for an OB.

Thanks,

Jim

-Richard- · « **Reply #1254 on:** 26 Jan 2007, 04:40 am »

Hi Jim ~

There is probably an absolute, or perfect relative spacial mathematical pattern or series of
proportions one can apply to OB's for every room... taking in the particular and peculiar
characteristics of that rooms geometry and damping factor.

That said... OB's are very adaptable!!!

You could compensate for the closeness your OB's may need to be in their relative
position to the listening wall by making your baffles a bit narrower for example... or
designing a baffle that has the B200 driver closer to the floor... which is one option that
Louis Chochos is seriously considering.

Tow-in is yet another variable that could help to make your OB's work in the position
they must fit themselves in. I have had my OB's about 2 feet from the listening wall
and the sound was quite satisfying. Now they are still less than 3 feet and the sound
stage is rather impressive.

I also use my OB's when I view film... the sound I get creates an entirely different
visual space... and it sounds better to me than a commercial cinema. Voices are rich and
full of emotional depth with incredible nuances... music melts your heart bringing tears
to the eyes... my OB's create an effervescent filmic experience!!!!

An analogy: imagine yourself in a room with live music. Perhaps you are a bit closer or a bit
further away from the actual instruments that are playing. Still... the effect of hearing that
live sound reverberate in that room will not be diminished in its "essence" by the alteration of
your sitting position... the "thereness" of the sound still resonates all around you.
That is what you can expect from your OB's... even if they are a bit closer to the wall than
someone else, who has their OB's a bit further out into the room. That penetrating dipole
effect will still create the impression that you are hearing music that is "alive"... free to
saturate your room with its reverberant warm rich detailed and enveloping sonic characteristics.

Warmest Regards ~ Richard

corloc · « **Reply #1255 on:** 26 Jan 2007, 07:31 pm »

Wind Chaser,
Sorry for the loss, I had my chip amp kits go DC on me twice and thankfully didn't do damage.

Richard,
I have gone from listening in my living room to a spare bedroom. I was using fixed wing, and now using a 4' x 12" plank with the driver mounted at 38" from the floor. What amazed me the bass its still produces with a notch filter. Not as deep and the fixed wing, but good. The only drawback I can find is the imaging isn't as good with the flat plank.

jrebman,

I use Planet 10's phase plugs. I like them a lot. It helps smooth out the treble a little, but helps more with beaming. I would be interested in your impressions of the Revolutions. I'm really curious of the difference in sound from OB to A****.. ( can't remember the plasted word) cabinets.

-Richard- · « **Reply #1256 on:** 26 Jan 2007, 08:32 pm »

Hi Corloc ~

Given the extraordinary amount of creative exploration you do with your audio system
I assume you have experimented with tow-in and distance variations of your narrow/tall
OB's... so you have probably found the best placement... considering your current
listening space.

Here is an interesting link to the low version I mentioned in a previous post to Jim:

http://members.myactv.net/~je2a3/open.htm

probably too wide for your room... it roughly follows the parameters of the original Quads ESL57,
and a very early iteration of an OB available by Wharfedale, designed by G.A. Briggs
(scroll down for photos and more information).

And that was from 1956!!!!!!!!!!

Note the tilt-back of this low OB design... Roger Modjeski believes that 7% tilt-back represents
a golden-mean of sorts... that is yet another option, Corloc, that might help with your
imaging concerns.

Warmest Regards ~ Richard

Scotty · « **Reply #1257 on:** 26 Jan 2007, 11:27 pm »

Fuse? Anywhere? Guess not.
Scotty

Dmason · « **Reply #1258 on:** 27 Jan 2007, 12:00 am »

Yes, I stand by the observation they will take alot of Music Power, I cannot vouch for their ability with alternating current. Using a [properly working] high power solid state amp I was amazed at what they will take, and the sheer amount of acoustic output.

It looks like it was crushed by an unimaginable gravitational force.

You have joined the "electrician's club."

Scotty · « **Reply #1259 on:** 27 Jan 2007, 12:13 am »

Assuming an 8 ohm load ,voltage divided resistance equals amperage.
The driver saw 15amps of current which when multiplied by the voltage equals 1800watts at 60 Hz. Speaker fuse anyone?

Scotty