[konut]

Hi Vinnie,
          Thought I'd start a new thread (thanks Erling) about this promising addition to anyone who might be using a Visaton B200 driver in either an OB or cabinet. Have you been able to put this together to hear it yet? I thought that it might be a usefull accessory, to anyone using the B200, to add to your line of excellent products. Seeing as its not that complicated, it would be a welcome addition to those without the DIY skills to impliment a smoother response. Waddya think?    

PS. You have a PM.

[mcgsxr]

Can I ask what this does?  Is it designed to smooth the rising response of the driver etc?  Does it affect impedance etc?

NOOB...!

[Vinnie R.]

Hi Konut,

I moved this topic to the Open Baffle Speakers forum because it really applies to the B200 in an OB and hopefully there will be more replies there.

Yes, I have tried this last night (thanks to Scorpion's post on the Darkstar thread) and I will be posting my impressions when I get more time to listen. 

It is an inductor wired in parallel with a resistor.  That combo is inserted in series with the positive lead of the B200 driver.  That is all there is to it. 

One thing is for sure... it does rob efficiency, but with the Sig 30 that is not a problem
 

[jeffreybehr]

"...this promising addition...", "...this..." WHAT?  What is 'it'?  What the hell is a MOX?

Come on guys, don't be so cryptic.  Not all of us came out of the womb knowing this stuff.

[Danny Richie]

They're making a baffle step compensation filter with it. It compensates for the baffle step loss.

[mcgsxr]

Windchaser shared this in the Gravity of a Darkstar Thread over in Vinnie's circle, this would seem appropriate to include here, to help flesh out what it actually is/looks like etc.

Is this the idea...

                                                                                  8 Ohm MOX
+ + + + + + + + + + + + + + + + + + + + + +                      + B200  Positive Terminal
                                                                                        1 mH   



- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - B200  Negative Terminal


John

[Danny Richie]

Eeeeek, Looking at the response curve on this driver it appears that such a filter is clearly needed.



I wonder if this curve was taken on a large baffle (as per the norm). If so then compounding this with the typical baffle step loss of about a 10" wide baffle would leave it pretty thin in the bottom end.

For you head scratchers, the filter allows the lows to past through the inductor with little to no change in output but adding resistance as frequency increases. As frequency increases the path of least resistance becomes the resistor. It takes all that slop from above 1kHz and brings it down to an output level even with what is below 1kHz.

It looks like it would leave an overall sensitivity of about 88db once it is balance out.

It looks like the top octave will be left pretty choppy and will be down about 20db by 20kHz.

[mcgsxr]

Yes Danny, everyone who sees that response curve has the same initial response...

But, I have played around with this driver, on 36 inch wide baffles, some flat and some folded, and have found remarkable sound.

For me, and as a designer, and strong technical guy this may not resonate with you, I find that this driver REALLY loves certain amps, and with others sounds exactly as it appears it would...

Amps in my 1.5 years of experimentation that did not synergize - JVC ES-1, Teac AL-700P (stock, lightly Vinnie modded, and fully Bolder modded), dual mono gainclone, Panny SAXR-25, Panny SAXR-55 (though both Panny's with use of the onboard EQ could be made to sound decent).

Amps that did synergize - JVC EX A1 (my favourite until recently), and an old Magnavox single ended EL84 class A tube amp

With the right amp, these drivers will amaze on an OB.

With the wrong amp, these drivers will underwhelm...

Great stuff, thanks for the insight Danny!  Good luck with your OB project!

Doesn't look like something I can use, since I need the 96dB efficiency with my 3-4wpc tube amp...

[Danny Richie]

It sounds like a tough task to find an amp that mirror images the response problems.

It looks like it would be a good open baffle driver, but I believe I wouldn't run it past 2kHz. From there I'd let a real tweeter take over.

Good luck with your OB project!

Thanks, both models are selling quite well.

Doesn't look like something I can use, since I need the 96dB efficiency with my 3-4wpc tube amp...

Looking at the manufacturers measured response curve it appears that if you put it on a large baffle and had no other baffle step loss, then you compensate for the drivers rising response, you'll end up with only about 88db sensitivity with the B200 driver. So it looks like the 96db rating is pretty misleading.

Then you're still left with it 20db down by 20kHz and a little rough getting there.

I don't believe I could live with those problems.

[foniton]

Mr. Manufacturer...
I don't believe I could live with your speakers, Danny.
The fact they are selling well, if they are, don´t distract me of their absolute ugliness (in form and function).
Many people can make preamps (even double processor computers) with half the components you use for your OB-7´s crossover. If they are open baffle, then any bass-reflex box could be considered open baffle.

This reply is just to show how easy is to judge things you didn´t heard or you don´t really know well (like I do with your speakers).

Best Regards.

[mcgsxr]

Yikes, fonotron, while I think I get the gist of what you were attempting to convey, I fear that it might be misinterpreted as a little caustic for our little area around here...

I have a great measure of respect for Danny, and his ability to research, design, and build speakers that please a great many people.  He is evidently a very accomplished guy, quite scientific in his approach, and successful in his venture.  He is also a valued member of this board, who takes the time to share his opinions, and I for one value that.

Now, I happen to disagree with his position on the b200, but as I am a happy owner of them, and he is a happy builder of competitive products, it is simply that - a disagreement with his position.

In any case, I hope that you both stick around AudioCircles, and have more fun with all of us.

It is critical to remember that it is hard to hear the tone of a post - with the spoken word, you have the benefit of that, and it is much simply to interpret intended meaning.

That said, fonotron, if you were being in any way lighthearted, drop us an emoticon, to be sure we know.  If not, that seems like a strong first post, in a place where some of us seek to get along etc.

Please don't misunderstand me - I value all opinions, dissenting ones included, but I want to make sure (as a volunteer moderator) that we keep it friendly, even when opposing opinions are being expressed.

Thanks,

[Danny Richie]

I don't mind his post.

His comments, even if said jokingly, regard subjective impressions. Looks do not a speaker make.

What I commented on was not subjective or degrading. What I commented on was the measured response curve of a driver. It simply has a response curve that requires a baffle step compensation circuit to balance. Once balanced it should have a sensitivity of close to 88db. There are no ifs, ands, or buts, about it. That's just the way it is.

Now in an open baffle and with the compensation circuit it might sound great. I would expect it to sound great from what I have seen and heard about it. But, the top end is ragged and rolls off heavily.

Just because I couldn't live with that top end doesn't mean others can't and it won't take away from how good it might sound in other ranges.

I'd still couple it with a good tweeter not only for the top end extension but to get back some of the limited off axis response of the large driver.

[jeffreybehr]

In spite of Mark's drawing skills, I still don't quite know what's going on.  I THINK we have a 1mH inductor in series with the driver (creating a low-pass filter).  I THINK a shelving network will have a resistor in parallel with the inductor to reduce its effect in the higher frequencies.  Is that what this is? 

And I still don't know what a MOX is.

[Vinnie R.]

In spite of Mark's drawing skills, I still don't quite know what's going on.  I THINK we have a 1mH inductor in series with the driver (creating a low-pass filter).  I THINK a shelving network will have a resistor in parallel with the inductor to reduce its effect in the higher frequencies.  Is that what this is? 

And I still don't know what a MOX is.

Hi jeffreybehr,

I posted earlier on in this thread in response to Konut:

It is an inductor wired in parallel with a resistor.  That combo is inserted in series with the positive lead of the B200 driver.  That is all there is to it. 

++++++++++ Inductor/Resistor in Parallel +++++++++ B200 +

---------------------------------------------------------------------- B200 -

I think MOX = Metal Oxide (resistor).

I'm just using a 10W wirewound resistor (partsexpress).  Seems to work fine...

Best regards,

Vinnie

[mcgsxr]

What I commented on was not subjective or degrading. What I commented on was the measured response curve of a driver. It simply has a response curve that requires a baffle step compensation circuit to balance. Once balanced it should have a sensitivity of close to 88db. There are no ifs, ands, or buts, about it. That's just the way it is.

Now in an open baffle and with the compensation circuit it might sound great. I would expect it to sound great from what I have seen and heard about it. But, the top end is ragged and rolls off heavily.

Just because I couldn't live with that top end doesn't mean others can't and it won't take away from how good it might sound in other ranges.

Agreed - what you commented on was absolutely objective, based on viewing the measured response curve, and postulating on what it might sound like, when mated to a given amplifier.  No issues with that, nor the rest of what you suggest, especially about the section related to others couldn't live with it etc.

I did not mean to suggest either, that the DIY nasty looking BS I build in my basement is competitive with what you design and build, since I am the only market for what I build, and your speakers have a market indeed.

What I will say, is that I can and do live with this, run full range on a 42x36 winged baffle, and have for over 1.5 years.  I will also mention that 3 other AC members have heard this speaker system in my house.  One of those guys immediately bought b200's.  Another borrowed my baffles, and took them to his place for a while, and really liked them too.  There are scores of folks on that giant thread in Vinnie's circle, who also are attracted to the series of compromises that these represent (and I chose my words carefully) compared to the other series of compromises made in other designs.

Perfect?  Nope, never heard one of those yet.

Enjoyable?  You bet, with the right amplifier, in my room.

But, you also allowed for that too, so I guess I am just another wacko, who thinks he stumbled on something amazing, that in the end has been explored, and abandoned by many before!

Thanks for the insight into measurements, how to design around them etc Danny.

[Danny Richie]

You're absolutely right. Everything has some compromises. One can't live with one set while another can't live with the other.

You mentioned something else that really caught my attention, a huge baffle.

A large baffle can do away with the baffle step loss problem and keep sensitivity high. But I have found that the larger the baffle, the more the music sounds like it is playing from the baffle forward. I do all that I can to keep the baffle as small as possible to minimize surface reflections and increase three dimensional sound staging.

My experience with speakers in a large baffle is that they sound like an in wall speaker.

But then again you have no off axis response from 2kHz and up anyway. Any wavelength shorter than the width of the diaphragm will begin to beam.  8" (the size of the woofer) is about 1,700Hz. So while a lot of other speakers will have adverse effects of surface reflections from the large baffle, your 8" woofer won't have those because of its size, at least in the higher ranges. You will still have those effects from there down.

[Danny Richie]

Hey Vinnie,

Are you bringing any of this stuff to the RMAF next month?

[jeffreybehr]

Vinnie, TYVM for your simple explanation.

[mcgsxr]

Valid points all Danny, especially about baffle width, and how that can, if not addressed, mar the rear wave.  There are plenty in each camp, around wings or not, and how folded baffles lose the true dipole effect etc, but for me, I find that mildly folded wings (and by this I would say less than 45 degrees) are a good compromise.

As for beaming, yes, the highs are best on axis, but again, amp dependant, this can also differ.  With the best synergistic matches, I have found, and demonstrated (I guess proving there are other crazy people, more than my own sanity!) that one interesting thing with the b200, is that it can throw a centred image, when you are WAY off axis - I have mystified folks, by having them literally stand in front of the L speaker, at the normal listening distance (ie not right in front of the speaker) and by surprised by the still centred image.  One "conventional" speaker that I have heard pull that particular stunt (though not in my room...) is the Dynaudio Temptation.

So, careful experimentation, both with baffle size, configuration, and placement in the room can optimize the reproduction of good music, from a single driver - cannot overcome the laws of physics, but a surprising amount can be done, within the limits, to create a great reproductive system, quite affordably.

Of course, the same can be said for conventional speakers, so it is absolutely "dealer's choice", when it comes to what pleases different folks.

I guess I am the kind of guy who can hear the best in a system, in spite of what it may or may not do, against the best of other systems - case in point - 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!

For me, the b200 is a really nice way to affordably (though admittedly unattractively in my system - you have to turn to Louis at Omega if you want beauty with OB!) create a satisfying sound.

Hey, with 2 young kids and a mortgage, this OB thing, and vintage amps, is a revelation!

[markC]

The most effective baffle step for this driver that I have found is to add base in the area that is required. In My room with My open baffles, (with wings-30" wide total), adding sub drivers and a plate amp cut off around 120hz is near the best I and a couple of friends have heard. It has it's problems, which in my opinion are a hot spot around 250k-300k and a rolled off high end if not on axis. But, for me in the sweet spot, my modded Soliloquy 5.3's with Sonicap's sit quietly.

I'm working on a notch filter for the hot spot and hope to implement it soon. Oh, and I think I have synergy with my amps.