Gravity Well Of A DarkStar

scorpion · « **Reply #780 on:** 17 Jun 2006, 06:40 pm »

JohninCr wrote:

Quote

whatever D (flat baffle width/2)

.

I would rather estimate the effective pathdifference D as (baffle with * 1).
Using wings makes it considerably easier to achive bigger effective pathdifferences.

And I do not think that the analysis on the MusicandDesign-webb when it comes to damped U-baffles has much to do with pure dipole design and its advantages.

But I agree, you have to move a lot of air to produce 100 dbC at 30 Hz with OBs.

/Erling

scorpion · « **Reply #781 on:** 17 Jun 2006, 09:40 pm »

JohninCr,

Very good points. I agree 100 %.
However I define a U-baffle as a box without a back, an OB with wings is a folded baffle. The wings should be used so as not to create unneccesary resonances.

/Erling

Dmason · « **Reply #782 on:** 18 Jun 2006, 02:18 am »

John

Any word on you know who's prototype 10 inch coaxial? 10, to me seems the ideal diameter driver for this.

I still like the idea of the coaxial with Xmax, and the ability to bi-amp with SS/T on the cone, and SET on the C/D to me represents the best of ALL worlds. All of the good, all at the same time. None of the bad.

The Flintstone cabinets are my all time favorite. Something very compelling about that design. Maybe the downward waveguide factor. Made alot of sense to me.

sonicpete · « **Reply #783 on:** 18 Jun 2006, 09:33 am »

i built a pair of BIBs using fostex speakers and while waiting for them to break in, had a pair of goodmans twin axion 8 inch speakers to hand. so using the japanese panel measurements, slotted them into a three-layer panel of chipboard, plywood and a face plate of thin hardwood ply. -- drive em with a pioneer universal audio dvd player, a decware csp preamp and a sonic super t-amp -- it's an amazingly listenable combination. bass is down at low volumes but crank it a little and it blooms out so on that front i hv no complaints. what i really enjoy is just how articulate music is through these speakers. for example, the springsteen dvd, live in barcelona, the bass used to be a muddy drone but now i can actually hear the bass player sliding or hammering his notes clearly. lots of inner detail can be heard and instruments sound more realistic. all that despite the fact, thanks to my understanding and tolerant other half, the audio setup is in the bedroom! and the speaks are certainly not ideally placed -- just plonked out of our path.
where female vocals used to be sibilant, that-s greatly reduced. and the al di meola, stanley clark, jean luc ponty cd is superb. can't think just how good it could be with a better cd player
now a question for those who may have tried this and your reccomendations -- i also have a pair of 10 inch goodmans twin axioms . the difference between them and the 8 inchers is that the eight inchers are rated 40hz-16000khx while the 10s are 50-15000. any advantage in me sticking the 10 inchers in along with the eights -- side by side or top and bottom, which to try? and how should i wire them up? in parallel?
i occasionally listen to the BIBs which are still running in -- and while i like some aspects of them, the OBs have stole my (audio) heart!

Vinnie R. · « **Reply #784 on:** 18 Jun 2006, 04:32 pm »

Quote from: Vinnie R.

I didn't get time yesterday to try turning my OBs upside down, but hopefully later tonight. The workload has been a little crazy here and I want more hours in the day so I can sit back and listen!
.

Hi Guys,

I forgot to post my findings:

With my OBs turned upside down, I didn't get as much of an increase in bass as I was expecting. Yes, I found *some* increase in bass output, but the quality of the bass was not nearly as good. The notes became less distinct and less controlled. The soudstage also dropped, as if I was sitting higher up in the concert and the stage was lower. I tried tilting the baffles back and it helped this aspect of the sound somewhat, but the bass was still not to my liking. Upon returning the baffles to the way I orginally had them, it became very clear to me that I liked the sound this way a whole lot more this way. EVERYTHING sounded better to me!

I'm sure these results are very dependent on the baffle dimensions as well as the interaction with the room.

I also have a 2nd pair of B200s coming sometime next week. I am thinking of mounting them close to the upper B200 instead of mounting them closer to the floor. I can also ask Louis to make me two different versions of the center baffle....one with the drivers next to each other and one with one driver closer to the floor.

Now I need to order those coils. I am going to try setting the LPF at 80Hz.

One more thing... running the two B200s in parallel gives a pretty difficult 3-ohm load. How are your amps responding to this? I was thinking that it might be worth trying a 2-ohm resistor in series with each driver and then connecting them in parallel to give a total 4-ohm load. Didn't someone mentioned that adding a resistor in series with the driver will also change the Q of the driver?

Or, I can run one Sig 30 for one OB (one channel per driver) and one Sig 30 for the other OB....I'm sure that is the better approach!

-Richard- · « **Reply #785 on:** 18 Jun 2006, 05:22 pm »

Hi Vinnie,

I am driving my parallel connected double B200 OB's with
the Signature 30's and do not notice any problems in spite of the
less than ideal 3 ohm load ~

Please keep us informed Vinnie, of your results ~

I honestly feel that your investigations with your own Open Baffle
experiments may yield the most important findings on this thread ~

So I am extremely interested in your observations...what you finally
wind up with may well be the prototype many of us will base our own
OB designs on ~

Warm Regards ~Richard~

opnly bafld · « **Reply #786 on:** 18 Jun 2006, 06:09 pm »

Welcome sonicpete,
I would suggest getting a cheap piece of wood and cutting several baffles so you can try various positions.
You only need to make one of each at first, to determine pros and cons.
BTW we KNEW you would like the sound

Lin

Dmason · « **Reply #787 on:** 18 Jun 2006, 06:44 pm »

Vinnie

I mounted one back firing and wired out of phase, works okay, and the back wave from the back firing driver is "in phase" for listening. Seems okay. Besides, those little T amps are no good for this big dog OB stuff anyway.

I read the work on the physical impossibility of Bumblebee flight. Fascinating. Speaking as a man of science, it is stuff like that that proves to me mankind ain't real good with Science.

-Richard- · « **Reply #788 on:** 18 Jun 2006, 06:59 pm »

Nice suggestion opnly bafld!!!

A bit of simple experimentation yields interesting dividends in the
exploration of how different designs affect all-over performance ~

Vinnie's Signature 30 and Open Baffles are a tremendous combination...
stunning bass response with just 2 B200's per panel...perhaps not
the final solution...but a very effective and successful temporary
design...deeply satisfying ~

I am very interested to hear what Vinnie discovers with his further
experiments ~

Warm Regards ~Richard~

scorpion · « **Reply #789 on:** 18 Jun 2006, 07:04 pm »

JohninCr,

Amazingly, your Flintstone cabs seem to be exactly like what I am experimenting with for my bass-dipoles. Slightly angled sidewings and a slightly upward angled top. On what thread-page are they presented ?

I came into this thread from diyAudio where someone drew my attention to it with a favourable mention.

/Erling

opnly bafld · « **Reply #790 on:** 18 Jun 2006, 08:59 pm »

In one of my posts I almost mentioned not ever using my system in a corn field, of which we have plenty around here.
Maybe I should put together a RWA all battery system and try it out in a soybean field. (corn is getting too tall)
I know it would not be as fun as listening at the beach.
My boombox on the beach near Naples Fl.(low 80s in Feb? that is not fair!) sounded better than the best stereo I have ever heard.
A lot of that must have been the beach.

Lin

scorpion · « **Reply #791 on:** 18 Jun 2006, 09:49 pm »

JohninCr,

Yes, I think the Flinstone would be a great design for the B200. There is, however, an 8 mm cutout difference. It would be nice if you could try it.
What is approximately the size of the Flintstone ? Judging by element size I can have a qualified guess only.

/Erling

Vinnie R. · « **Reply #792 on:** 19 Jun 2006, 01:30 am »

Quote from: sonicpete

i built a pair of BIBs using fostex speakers and while waiting for them to break in, had a pair of goodmans twin axion 8 inch speakers to hand. so using the japanese panel measurements, slotted them into a three-layer panel of chipboard, plywood and a face plate of thin hardwood ply. -- drive em with a pioneer universal audio dvd player, a decware csp preamp and a sonic super t-amp -- it's an amazingly listenable combination. bass is down at low volumes but crank it a little and it blooms out so on that fro ...

Hi sonicpete,

Welcome to Audiocircle and the world of OB!

Are you interested in adding the 10" drivers to your OB for a boost in the bass response? You can run them in parallel and put an inductor in front of the 10 incher to LPF it, but if you run in parallel be careful of the lower impedance load.

Hi JohninCR,

I can't wait to hear your impressions of the B200s in the Flinstones cabs....those looks great! The bass manifold ideas is also very interesting. How is the bass quality using the cheapie 6" drivers? Are they powered by a separate amp?

Thanks,

Dmason · « **Reply #793 on:** 19 Jun 2006, 01:45 am »

It would be good to discover some 6X9 car speakers of high quality. All of them are designed for free air performance, and I am betting there are some diamonds amongst the rubble.

These could be fitted into smallish manifolds making for some serious potential I would think. Any thoughts?

Wind Chaser · « **Reply #794 on:** 19 Jun 2006, 03:09 pm »

For the record, those of you who have dual B200’s… what are you using as a means to crossover the lower driver? Richard and Dmason have already explained what they are using, but what about the rest of you?

I was thinking of mounting a Charlize on each baffle using one channel for the top driver and the other channel to power the bottom drive with one of the coils Richard recommended. But I have some sub amps with a variable 2nd order crossover adjustable from 60Hz to 200Hz that I'd like to try first. Apart from digital EQ, what are the options?

John

opnly bafld · « **Reply #795 on:** 19 Jun 2006, 06:06 pm »

Wind Chaser,
I have used 12dB/oct and 24dB/oct electronic crossovers with good results.
Your sub amps have good x-over range, so you should be able to find a setting that works pretty good.
Currently I am biamping with a 12mH inductor (@80hz 6dB/oct) on the lower driver.
Put the lower driver near the floor and I think you will like what you hear.

Lin

Wind Chaser · « **Reply #796 on:** 20 Jun 2006, 03:32 pm »

Lin,

Of the three options you have tried, which is your preference and why?

Perhaps the sub amps might be the best way for me to go in that they offer a wide range of crossover points and a significant amount of adjustable gain. Those are two big advantages for a cost effective solution. That means I’ll have to buy 2 more sub amps for the Augies.

Scorpion Corloc and JiffyBoob , I thought you guys were all doing dual DarkStars? If so, what are you using to crossover the lower driver?

John

corloc · « **Reply #797 on:** 21 Jun 2006, 02:33 am »

Quote

[/b]Scorpion Corloc and JiffyBoob [/b], I thought you guys were all doing dual DarkStars? If so, what are you using to crossover the lower driver?

John

I'm not useing two B200's, (cost prohibitive). I'm using the Madison "Warrior 15", and a 5uH coil. Crossover around 200Hz. I like this set up. It adds a good foundation to the music, without overtaking the B200. I will be trying a lower crossover point later on just for giggles.

Chris

JiffyBoob · « **Reply #798 on:** 21 Jun 2006, 03:01 am »

hi

I am using a Behringer DCX2496, lower driver rolled in around 175Hz. I am using right now the Signature 30 on top, and a Samson "pro" audio cheapie amp on the bottom. Ordinarily I have an Art Audio PX-25 for the main driver.

This system exhibits a more agile and sophisticated sound than the DarkStar set up with the 4X15 bass drivers. Both are great, I have decided I prefer the 2XB200.

opnly bafld · « **Reply #799 on:** 21 Jun 2006, 03:25 am »

Hi Wind Chaser,
The 4th order x-o was sounding OK. Two reasons why I stopped using it are, I wanted to try a more gentle slope to try and offset the response of the B200, and I had one more component to turn on and off.

With the 2nd order x-o I was only able to have a mono signal to the lower drivers. I would like to try 12dB/oct stereo like you have the ability to do.

The inductor seems to be working well even though I had (have) concerns about the lower driver playing to high. I have not really noticed any problems. I have thought about using the inductor and the Rane 24 dB x-o higher up to cut off the midrange more sharply, but like I said I have noticed no problems with just the 12mH inductor and less is more right.

Lin