[Vinnie R.]

Newbie questions:

What awg is appropriate for the inductor?
What wattage is appropriate for the resistor?

Thank you.

EP

Hi EP,

I'm not sure what is the best inductor value.  I think I'm using 18 awg air-core at the moment, but I'll probably try other types. 

As for the resistor, you should be fine with 10 watts.  Mine doesn't even get warm.

Best,

Vinnie
 

[JohninCR]

Something no one has mentioned is placement.  For the perfectionists at heart, coils don't belong near the driver since it isn't shielded.  The magnetic field can interfere with the coil, which also creates a magnetic field.  If close proximity is unavoidable the 2 fields should be perpendicular to each other to cause the least interference.

[EProvenzano]

Thanks for the clarification Vinnie.

Something no one has mentioned is placement.  For the perfectionists at heart, coils don't belong near the driver since it isn't shielded.  The magnetic field can interfere with the coil, which also creates a magnetic field.  If close proximity is unavoidable the 2 fields should be perpendicular to each other to cause the least interference.

I was also considering this very thing.  More for convenience though.
Is is appropriate to wire the parallel bundle at the + terminal of the amp? 

I assume this is ok because the bundle is still in series, only at the other end of the speaker wire.  Can this cause similar interference with the amp?

Thanks again!

[JohninCR]

Something no one has mentioned is placement.  For the perfectionists at heart, coils don't belong near the driver since it isn't shielded.  The magnetic field can interfere with the coil, which also creates a magnetic field.  If close proximity is unavoidable the 2 fields should be perpendicular to each other to cause the least interference.

I was also considering this very thing.  More for convenience though.
Is is appropriate to wire the parallel bundle at the + terminal of the amp? 

I assume this is ok because the bundle is still in series, only at the other end of the speaker wire.  Can this cause similar interference with the amp?

Thanks again!

No problem at the amp other than the increased potential for short circuits messing around back there.  Also, it's more difficult to make changes than at the speaker (one of the non-sonic beauties of OB), if you plan to tweak at all.  Also, you'd have 2 inductors near each other (2 speakers), so the same issue arrises, seperate or mount them perpendicular to each other.

[scorpion]

I think I was trying to be too funny in my last paragraph.

I plan to put my B200s in flat baffles 45 x 100 cms. Actually one side will be 100 cm the other 110 cm. I will mount them 80 cm high for the middle of the element slightly off center to the small side. According to the Edge program (http://www.tolvan.com/edge/) this will give a little boost from 300 to 700 Hz were B200 has a slight dip. The LR-filter was also calculated with this in mind. Good points by JohninCR regarding component placement, when you try you have everything on the floor and lots of 'crocodile' wire.

Konut,
The LR-circuit was calculated especially for the B200 and its frequency rise. It is also impedancedependent. It might be good for other speakers but that is sheer coincidence in that case.

I have been using big airwound inductors from 1.4 mm wire, I think that translates to AWG 16, AWG 18 would be as good.

Yes Vinnie, I think I am enjoying the B200's as much as you and hopefully everybody else ! As you say it is strange that this kind of filter never was tried before. I think there was one post in the DarkStar thread but componentvalues were not the right ones.

/Erling

[konut]

scorpion,

The Omega Aperiodic 8 utilizes the B200 in a triple constrained layer cabinet. I would imagine the loading would change low end response but not in the area where the circuit takes effect. Am I wrong?

[scorpion]

Konut,

No, it would certainly be worth a try.

/Erling

[markC]

Not wanting to be closed minded, I figured I'd give the BSC filter a try. And because between me and my friend we had the parts at hand. I must admit, you guys are right. Way smoother presentation and it took the annoying sting out of the upper midrange. We had a couple of  1 mH 18ga inductors, 4- .47 auricaps and a couple of old Ohmite 7 ohm resistors. Even with the thin wire coils and the old resistors, the improvement is substantial.
Running the BSC circuit on psice, it would appear that a very low dcr coil,( such as a 12ga alfa), will keep the bass more pronounced as the filter starts to kick in. Also, a .72 mH coil will hold on to the bass longer than a 1mH as attenuation begins. Attenuation starts @ about 100 hz,( unfortunatlely), but it's only down about .1 db. With an 8 ohm R the psice shows your down about 2.25 db @ 500 hz., 3.5 db @ 800hz., and bottoms out @ Just shy of 1100 hz. @ -5 db. Then it starts to rise again and by the time you get to 9.5 khz. it's back to 0 db. From there up it rises to + .5 db @ 20khz., (which the driver can't do anyway), but any reinforcement above 10khz. should be good.
I should have tried this sooner, 'cause that circuit is staying! I'll order a couple of 12ga Alfas and a couple of Mills 12W R's and the sound should be even sweeter than with the old crap we had laying around. Probably keep the Auricaps though, as I find them to be a pretty decent cap.

[scorpion]

markC,

Interesting to read about your findings. I read it during a walking vacation in Turkey. Now at home again I have compared your simulations with mine. What circuit did you use for your simulations ? In the low end our simulations are exactly equal. Baffle impact usually counteracts the early fall by augmenting frequences between 300 - 800 Hz depending a bit on bafflesize. Welcome in the club ! I certainly would like to hear about your experiences with the very low resistance coils. I have provisionally exchanged my Ciares for the B200s in my 100 x 60 cm baffles, including wings 12.5 and 17.5 cm width, main baffle 100 x 30 cms. Elements now sitting 70 cms above floor, mid of element. Placing them there I immediately lost some 8-10 dB in bass. I have equalized this and am pleased by the result. But bass augmentation for high Spls are now mandatory. Two B200s on the same baffle is a very natural solution, the other element placed low on baffle it would certainly contribute more than the theoretical 6 dBs. Achieving 100 dB would be impossible without more bass augmentation.

/Erling

[markC]

The circuit was modeled on my friends software, a P-spice program. It's apparently very accurate. He was over last night and we had a 3+ hour listening session. He was totally blown away. Kept saying "this is the best I've ever head, this system is perfect." I was grinning and chuckling to myself. Although the speaks go loud enough for any normal person, I can't help but want to add another pair of drivers. That way, I could really show them off. These things are so unforgiving that you can immediately hear the differences in recordings of different cds. I haven't got around to ordering the parts yet, but will post my findings when I finally get around to it and get them in the circuit.

[Vinnie R.]

Hi MarkC,

As I posted ealier, I am completely in love with my OBs with the BSC circuit in place and cannot go back. 

I did not yet try using a capacitor with my BSC circuit consisting of a 1mH inductor and 10-ohm resistor. 

I was just curious if you tried it with and without the capacitor.  I assume that you are using two 0.47uF Auricaps in parallel to make an approx 1uF cap that you place in parallel with the BSC circuit components? 

As much as I love what I am hearing, it seems very easy to try adding (and removing) the cap and giving it a good listen to see how the top end changes.  I think I'll give it a try when I get a chance this weekend.  I might even have some 1.0uF Auricaps...

So what are your current BSC circuit componenet values (R, L, and C) ?

Thanks for sharing.  I'll be sure to post my findings as well when I get a chance.

Best regards,

Vinnie

[markC]

Hi Vinnie,
I haven't listened to the circuit without the caps in place, only looked at the simulated chart. I have a feeling that I would'nt be able to hear a difference as it only raises the response 0.5db around 14khz on up. With the caps, (according to the simulation), response is only up 0.25 db at 11khz. I doubt I could hear that. I will cut the caps out 1 at a time this weekend and report  my findings.
My current "throw together" circuit consists of a 1 mH 18g inductor, a 25W 7 ohm Ohmite resistor and 2 0.47uf, (in parallel), Auricaps. The components are, of course, all in parallel and the cicuit in series with the + of the driver. Very smooth sound and I had to turn my IB sub way down in volume and a little down in the x-over. I'm currently crossing at around 100hz. I'm going to order a few different value R's to see which one I like the best b4 I make the final circuit.

[ChuckT]

I tried the 1mH as well, sound now is much more balance.

For the additional parallel cap, a large value like 4uF is required to let the high fz (around 10k) through

[Vinnie R.]

Hi MarkC and ChuckT,

Thanks for your posts.

-Vinnie

[markC]

Have to agree with Chuck that that small of a cap value doesn't make much difference. I listened last night for about an hour then I cut one of the caps out. Couldn't detect a difference in the highs, but the mids, especially vocals, became more fleshed out and natural sounding. This proves once again to me that the fewer components in the signal path, the better the sound. Even quality components. Next up is to do it again, this time cutting the remaining .47 cap out of the circuit.

[mcgsxr]

I hope that I can make it up to MarkC's house one day in the near future, I would be interested to hear what this circuit does.

Then again, I am working with 3-5wpc, and he is playing with 300wpc... so the drop in efficiency might not be as pronounced in his system!

[markC]

So there you are mcgsxr, I was beginning to wonder where you were. Yes, you can definatly percieve the drop in efficiency with this circuit in place. Just a guess, but I'll bet it drops from the stated 96db to about 90 db. This would be quite signifigant with your SET amp.

Yes, we must try to work out a day for a visit.

[jkelly]

I think the BSC makes a major improvement in the sound of the B200.
My wife who is the expert on harsh HF loves the improvement of the
filter.  I am still breaking in the B200's and have been looking for the magic,
and today listening to Muddy Waters Folk Singer, I got it. 
Big soundstage, sounds coming from all over the place.

The OB B200's are moving into the primary slot.



Jeff

[markC]

My wife who is the expert on harsh HF loves the improvement of the
filter.

I think that that pretty much says it all. With a filter in place, these drivers are the best I've heard. Not that there aren't better, but as for now...

[scorpion]

markC,

Very interesting software, P-Spice. I downloaded it and have been able to perform some simulations. I am an economist by profession so I had a little difficulties in getting it to work, but this program is probably also what is behind the 'Edge' - simulations that I worked with.
However by combining several simulations I think this will give a good picture of the effect of the simple 1 mH//8 ohm LR-filter for the B200:

Freq         Effect

100           - 0.1 dB
200           - 0.5
500           - 2.5
1000         - 5.0
2000         - 6.2
4000         - 5.7
6000         - 5.5
8000         - 5.0
10000       - 4.1
15000       - 3.9
20000       - 3.5

Effects are greatest were most required and lessening a bit in the highest octave. And as I said before the initial fall will be counteracted
by baffleeffects.

/Erling