MOX in parallell with a 1 mH inductor for the B200

Danny Richie · « **Reply #20 on:** 20 Sep 2006, 03:03 am »

Quote

http://I spent 4 months listening to a set of DIY Cable WR125's run full range. Totally dead above 10K, and not good below 60Hz either, but oh baby, what mids!

I have a set of FR-125's setting on my desk as computer speakers. They have a more extended top end than the WR version, but close otherwise. They do have a nice mid for a small woofer, but nothing like what I am getting out of our M-130's.

I guess I need to give the FR-125's a shot in an open baffle and see what happens.

mcgsxr · « **Reply #21 on:** 20 Sep 2006, 11:41 am »

I have a set of the FR125's too, much better full ranger, and much better (in this one guy's opinion) than the KIT41, which mates a WR125 run full range, with a cheap tweeter brought in at 10K+.

All good fun, and better dispersion than the b200, but nothing like the lifelike sound of the Visaton.

Oh, and apologies to MarkC, I have stated before, and will repeat again, his monoblocks are unequivocally the best amps I have ever heard, with the open baffle b200. Period. But I don't own a set, so I did not include them in that earlier post about synergistic matches with my speakers.

foniton · « **Reply #22 on:** 20 Sep 2006, 02:23 pm »

Hi everybody.
I didn´t want to be offensive with my comments about Danny´s products. I´m very pleased with this new "open baffle speakers" forum. Thanks for it.
But I must confess I´m a bit annoyed with "objectivists" constant announcements of "OB disaster" around the corner. Yes, big cones beam, full range drivers are far from being linear and wings are for aeroplanes but, stressing about that, maybe you are missing the whole concept.
Fortunately, many things are changing in audio and, If you look at the recent audio history, one thing can be said about the OB approach: this is a "deconstructive" movement.

Best regards.

scorpion · « **Reply #23 on:** 21 Sep 2006, 11:02 am »

Hi all,

As I am somewhat responsible for originating this thread with my RL-circuit I would like to point out that I have posted some comments in the "Darkstar"-thread. Visatons' measurement are taken in their echo-free room. Recently published measuments i German DIY-magazines and my own rather primitive SPL-meter readings point to an even more steep frequency rise between 800 Hz and 2 Khz. To me, at least, this was quite annoying when I listened to the speakers. A RL-circuit is the simplest way of correcting this.

I am playing the speakers with an 845 SE tube amp and a NAD combo SS. They sound great with both !

/Erling

Vinnie R. · « **Reply #24 on:** 21 Sep 2006, 12:32 pm »

All,

I am using Scorpion's recommend BSC circuit -- a 1mH inductor in parallel with an 8-ohm resistor.

I am very impressed with the results and have plenty to write about it, but I'm extremely busy this week. I hope to go into some details about it over the weekend.

What I will say now is that I am getting a more seductive sound that has a hard time letting go of me. Playing at louder levels is a real treat. I am hearing more bass out of my OBs (without using my sub during my listening sessions with this new BSC circuit), more "meat on the bones," more tonal balance.

YES, you will lose some efficiency, but with my Signature 30 running the show it is not a problem at all. I'm not sure if flea powered amps would be good candidates for the B200 OBs using BSC circuits. My 6-watt Clari-T drove them, but the Sig 30 had quite a bit more drive, more control, and more dynamics. NOTE... I read a thread somewhere (Paul Joppa -- bottlehead forum?) that discussed using a line-level BSC circuit instead of one in front of the speaker. This would eliminate losing speaker efficiency, but I'm not sure how it would sound in comparison.

I hope to see this thread grow. I'd say Scorpion has a winner with this BSC circuit. Later I might try fine tuning it to my baffle/room/tastes, but right now I just wish I can listen all day and night (ain't gonna happen

).

[quote"mcgsxr"]Enjoyable? You bet, with the right amplifier, in my room.[/quote

Hi Mark,

I hope you get a chance to try this BSC circuit with your OBs using some of those amps that you had that you thought didn't sound as good with your OBs (e.g. the Teac AL700P and others). I think you'll find it to be a new ballgame.

I'll be posting more details when I get a chance...hopefully soon enough..

-Vinnie

EProvenzano · « **Reply #25 on:** 21 Sep 2006, 03:34 pm »

Quote from: Vinnie R. on 21 Sep 2006, 12:32 pm

I read a thread somewhere (Paul Joppa -- bottlehead forum?) that discussed using a line-level BSC circuit instead of one in front of the speaker. This would eliminate losing speaker efficiency, but I'm not sure how it would sound in comparison.

I'm not understanding this. If you shelf down the rise in the frequency response, whether done line level or speaker level, won't the over all efficiency be reduced?

Thanks.

Danny Richie · « **Reply #26 on:** 21 Sep 2006, 03:41 pm »

The other way uses a gain circuit kind of like a transform circuit to boost the lows up to the level of the rest of it. However this demands more power from the amp in the lower end making it work two or three times harder. If using small or single digit amps you'll be out of headroom real quick. It's a six of one and half dozen of the other deal.

mcgsxr · « **Reply #27 on:** 21 Sep 2006, 04:05 pm »

Perhaps the "free" way, is to use an old single ended amp, with low damping...

I say free, as it robs no efficiency, but of course you have to buy the amp!

That is what I mean by amp synergy - not finding an amp that has a stupendous rise in repoducing the lower registers, but finding one that works well with the unique attributes of the b200.

Absolutely not for everyone, like anything, but it sure sounds good when you find it, like anything!

JohninCR · « **Reply #28 on:** 22 Sep 2006, 05:35 am »

Scorpion,

Have you tried a notch filter vs a BSC filter? With the B200's somewhat limited top end, I don't think I'd want
to filter above 10khz. We need someone with the parts and know-how to experiment in that direction. A notch
filter just adds a capacitor along with an inductor and resistor, so the high end is passed through. Here are
a couple of notch filter calculators for anyone interested.

http://www.mhsoft.nl/ParallelNotchFilter.asp
http://www.lalena.com/audio/calculator/parallelNotch/

scorpion · « **Reply #29 on:** 22 Sep 2006, 08:59 am »

Hi,

Nice to be the guru for once..

JohninCR,
I do not think that a Notchfilter will do the job here. You have to have an effect all the way from 1 kHz to 10 kHz. I tried to calculate my filter with that in mind. The alternative is proper equalization as Dmason said before.

I have experimented a bit with different values and also with a Zobel as complement. My impression is that an inductor value of 1 mH paired with resistor values 8 - 12 ohm give the best compromise. If you don't use a Zobel effects are lessened in the higher frequency range. If you would like to experiment I suggest that you start without a Zobel-filter, just with the RL-circuit. I have measured the same output at 12500 Hz with the RL-circuit as I had without it. To my ears, at least, as soon as I had hooked up the RL-circuit I knew that I liked the resulting balance far better than the unfiltered speaker. I have used airwound and foiltype inductors and metal oxide resistors for my filters.

JohninCR,
I don't really like your links for the Notch-filters. It will give persons the impression that these are easily calculated devices. They are not.
To be able to construct a good Notch you should also be able to measure your speakers response during the constructing phase.

/Erling

Danny Richie · « **Reply #30 on:** 22 Sep 2006, 12:31 pm »

Just by-pass your LR circuit with about a 1uF to 1.5uF cap value. This will allow the top octave to come back up some.

hurdy_gurdyman · « **Reply #31 on:** 22 Sep 2006, 02:42 pm »

Quote from: scorpion on 22 Sep 2006, 08:59 am

JohninCR,
I don't really like your links for the Notch-filters. It will give persons the impression that these are easily calculated devices. They are not.
To be able to construct a good Notch you should also be able to measure your speakers response during the constructing phase.

/Erling

I consider online calculators for notch, zobel and crossovers as a good starting place only. Unless your speaker is a perfect resistor, one will need to measure, listen (always a good idea) then modify accordingly.

Dave

hurdy_gurdyman · « **Reply #32 on:** 22 Sep 2006, 02:44 pm »

Quote from: Danny on 22 Sep 2006, 12:31 pm

Just by-pass your LR circuit with about a 1uF to 1.5uF cap value. This will allow the top octave to come back up some.

I was wondering why this wasn't included in the circuit. it make sense to bring the highs back up. In effect, the circuit becomes a sort of wide notch filter. I've used this same type of filter on other drivers with good results.

Dave

scorpion · « **Reply #33 on:** 22 Sep 2006, 06:59 pm »

Danny, hurdy_gurdyman,

Infact, I think this to be an open question. With my experiment with Zobels 5.6 ohm and 9 Microfarads and the LR-filter I do think that comining back with high frequencies is not at all a bad idea, your capacitor values are certainly in the right direction. Considering the all over effect if you just put in 1mH and 8- 12 ohm resistors you won't be losing so much in in the high frequencies, as you perhaps think.

/Erling

JeffB · « **Reply #34 on:** 22 Sep 2006, 08:30 pm »

scorpion · « **Reply #35 on:** 22 Sep 2006, 08:36 pm »

JeffB,

The picture is all right. But just start with 1 mH inductor and 10 ohm resistor. And enjoy it all the way !

/Erling

markC · « **Reply #36 on:** 23 Sep 2006, 12:06 am »

I believe that if you run the b200's by themselves, then, yes a bsc network is definitely necessary. But, if you add low end re-reinforcement, (which I could not do without with these drivers), then, the bsc is already accounted for. By adding db's to the lower freq's, you are in essence creating bsc without chopping the higher end efficiency. Read - adding to the lower freq's to even out responce rather than chopping upper freq's to even out response while maintaining the efficiency.

Danny Richie · « **Reply #37 on:** 23 Sep 2006, 01:00 am »

Whether you EQ out the loss with gain or not your amp will see the same power demand to get it to the same level. If you want to hit 90db levels in the sub 900Hz range then it will take the same amount of amp output whether there is a passive BSC network on it or if it is boosted.

opnly bafld · « **Reply #38 on:** 23 Sep 2006, 01:29 am »

I think what MarkC meant was,
let the B200 do what it does best unrestricted and add a self powered bass system.

Lin

Danny Richie · « **Reply #39 on:** 23 Sep 2006, 01:42 am »

That's too high to be playing a self powered bass system if you plan of compensating for the baffle step loss with it.