MOX in parallell with a 1 mH inductor for the B200

scorpion · « **Reply #80 on:** 16 Oct 2006, 12:17 pm »

markC, ChuckT and all,

How exciting to get a really good simulation tool !
I have now bypassed my 1 mH - 8 ohm with a 3.3 uF capacitor this at least to me brings back the highs a little bit better.
Audibly smoother high frequency response. As good a capacitor as you can afford, no bipolar electrolytic. I also tested 4.7 uF but found 3.3 uF to please me better. No Zobel is used just the inductor, the resistor and the capacitor, all parallel in the signal lead. Yes, hurdy_gurdyman - Dave, SOME notch-filter !

The response-table for the new circuit is:

Freq    Effect

100    - 0.1 dB
200    - 0.4
500    - 2.1
1000    - 4.8
2000    - 7.0
4000    - 5.7
6000    - 4.1
8000    - 2.9
10000    - 1.8
15000    - 0.9
20000    - 0.5

Edit: If you compare the above table with my tables below you can see that from 6000 Hz and upwards response is some 2-3 dbs higher than acceptable from a linear response view. This was enough to produce the effects that Vinnie R in the following post direct rightly identified as troublesome.

/Erling

Vinnie R. · « **Reply #81 on:** 16 Oct 2006, 01:01 pm »

I tried 3.3uF caps (Auricaps) and used a mini toggle switch to quickly switch them in and out of the circuit while listening.

While putting the caps in the circuit did give a more detail, I found them to decrease the naturalness of the sound. Cymbals moved too close to the front of the stage instead of being pushed back where they belong... behind the singer. I really love how well balanced the sound is with the 1mH || 10-ohm BSC circuit in place, but with the 3.3uF's installed, the emphasis in the top end sounded less natural and that balance was thrown off. Also, with the caps in place you can also hear more recording flaws (e.g. hiss, noise).

Defintely worth trying because it is so easy and some might prefer the caps in place. How your baffles interact with your room and other equipment, AND your tastes will determine if the caps are right for you.

-Vinnie

scorpion · « **Reply #82 on:** 16 Oct 2006, 06:50 pm »

Vinnie,

You are dead right about the cymbals. I was a little to quick to post. The balance was not quite right, I listened to vocals, strings, white noise and FM-noise when judging the sound. Some jazz-records proved your point. I put my Zobels (5.6 ohm + 8 uF) back and this did the trick.

I have compiled a table to illustrate what we are up against. The B200 is compared against 93 dB average sensitivity for 2.83 volts/1m over the fundamental frequency range. Also is illustrated my simulation with 1mH||8 ohm||3.3 µF + Zobel (5.6 ohm + 8 µF):

Visaton LRC+Zobel

100 0 dB -0.1 dB
200 0 -0.5
500 -2 -2.3
1000 3 -5.0
2000 7 -7.4
4000 6 -7.3
6000 7 -6.1
8000 7 -4.9
10000 7 -3.9
15000 1.8 -2.4
20000 -12 -1.5

/Erling

JohninCR · « **Reply #83 on:** 16 Oct 2006, 11:01 pm »

Now we just need a stock vs with phase plug comparison. Then, if they really do give
wider and smoother dispersion of the HF, you get to start the whole process over again. aa

scorpion · « **Reply #84 on:** 16 Oct 2006, 11:45 pm »

Guess I have to stick to the stock version.

There is another German fullranger 'Omnes Audio L8' ( http://www.omnesaudio.de/ ) which reminds of B200. It has a phaseplug.
Response is much more linear than B200 but it starts to fall off rapidly after 10 kHz. Dispersion is no better. But you would do without frequency correction. It is tempting to try that one too.

I have wondered a bit what would have resulted if Visaton had tried a Fostex type dustcap with a small hole in the middle to get rid of
dustcap-cavity resonances ?

/Erling

markC · « **Reply #85 on:** 17 Oct 2006, 01:56 am »

Funny thing is, I kinda liked the sound better with a .47 cap in place after I cut the second one out. Can't explain that one.. perhaps mood, grid variation...I don't know.

I don't have a command of the P-spice software-that is my friends expertise. But from running several different variations on the fully purchased software, our findings are a little different. This is with a .68 mH inductor and an 8 ohm resistor + .94 mf cap.
100 -.1
200 -.5
500 -2.25
1k -4.2
2k -4.9
3k -4
4k -3
6k -1.5
8k -.5
10k -.2
15k +.5
20k +.5
I think that the main objective is to tame the "Sting" between around 1khz and 3 khz. How much you want to attenuate it is personal preference. I still am enjoying a slightly aggressive mid range. The values above are achieved by plugging in the dcr of the inductor and the re & le of the driver. Without these values the outcome is quite different.

markC · « **Reply #86 on:** 17 Oct 2006, 02:29 am »

Quote from: scorpion on 16 Oct 2006, 11:45 pm

Guess I have to stick to the stock version.

There is another German fullranger 'Omnes Audio L8' ( http://www.omnesaudio.de/ ) which reminds of B200. It has a phaseplug.
Response is much more linear than B200 but it starts to fall off rapidly after 10 kHz. Dispersion is no better. But you would do without frequency correction. It is tempting to try that one too.

I have wondered a bit what would have resulted if Visaton had tried a Fostex type dustcap with a small hole in the middle to get rid of
dustcap-cavity resonances ?

/Erling

This driver looks very interesting. If I had more money to squander, I'd certainly buy a pair to check out. Perhaps in the near future.. Higher qts and lower power handling than the B200 leads to bass reinforcement but that's o.k with me. Perhaps I can persuade my friend to buy a pair to see if it will get him over his "audio envy".

scorpion · « **Reply #87 on:** 17 Oct 2006, 08:54 am »

In the end it boils down to personal preferences. But differences between various component variations are not that great once you have
the fundamental balance in place. I could live happily both with my last circuit and the simple 1 mH||8 ohm thing.

But in the light of my recent simulations I think I would recommend 1 mH in combination with a 6 - 10 ohms resistor. The 1||6 combination
I think would be something to try for those with T-amps and SETs. Efficiency in the affected frequencyrange would not go under 94 dB and
it is my firm conviction that it definitely merits a try.

/Erling

markC · « **Reply #88 on:** 21 Oct 2006, 04:56 pm »

Well, my inductors and resistors arrived yesterday, and I slapped 'em together and tried them out. The parts for the filter consist of a 12 awg Alfacore .68 mH inductor and a Mills 6.8 ohm 12W resistor. I also got 6.2 ohm and 8 ohm resistors to experiment with. The difference in these quality parts is nothing less than incredable! I had a couple of friends over last night for a listening session and we were absolutely amazed at what the B200's were delivering. The bass is so much improved that for the most part we listened without my subs. It was the first time one of the guys had seen/heard open baffles and he was well..baffled.

If your using a notch filter, you owe it to yourself to order up some Alphacores and Mills.

mcgsxr · « **Reply #89 on:** 21 Oct 2006, 06:04 pm »

Roughly, what did these parts cost Mark?

Partsconnexion?

Thanks for the insight,

markC · « **Reply #90 on:** 21 Oct 2006, 06:10 pm »

Yep, Partsconnexion. C$ 82.15 all in. Thats including 6 resistors, not just 2.

scorpion · « **Reply #91 on:** 21 Oct 2006, 07:03 pm »

I say, you have some great parts over there ! Result is no surprise.

/Erling

fergs1 · « **Reply #92 on:** 25 Oct 2006, 05:58 am »

greeting ladies and gentlemen, just mondering if having very low dcr coils lessons the sensitivity knockoff of the filter circuit, and could someone explain how the different coil and resistance values affect the sound. ie 8ohm resistor with varying coil between .68 and 1mH and like wise with adjusting the resisotor.I guess the resistor affects the level of attenuation?But I still don't quite understand the relationship between coil value aand response. Go easy on a newbie cheers fergs

scorpion · « **Reply #93 on:** 25 Oct 2006, 08:44 pm »

Fergs and others interested,

I put together some of my simulations. The B200's response is calculated against an average sensitivity of 92 dB (2.83 volt/1 m), a figure given by a recent independent measurement in the German Hobby HiFi magazine (Aug-Sept nr 5/2006). I have averaged response also a bit around the given frequencies. But it will give a very good picture of the actual response of the B200.

The other tables are my simulations of different component combinations:

Freq    Visaton 1mH||10 ohm   1mH||8 ohm   1mH||6 ohm .68mH||6.8 ohm .68mH||6.8||.47µF 1mH||8ohm||3.3µF + Zobel 5.6ohm+8µF

100 +1 dB -0.1    -0.1 -0.1 -0.1    -0.06 -0.1
200 +1    -0.4    -0.4 -0.5 -0.2    -0.2 -0.5
500 - 1    -1.9    -2.0 -2.2 -1.2    -1.2 -2.3
1000 +4    -4.4    -4.3 -4.1 -3.0    -3.1 -5.0
2000 +8    -6.8    -6.2 -5.4 -5.0    -5.1 -7.4
4000 +7    -6.5    -5.7 -4.7 -4.9    -5.0 -7.3
6000 +8    -6.3    -5.5 -4.4 -4.7    -4.8 -6.1
8000 +8    -5.9    -5.0 -4.0 -4.4    -4.5 -4.9
10000 +8    -5.2    -4.1 -3.5 -3.8    -3.9 -3.9
15000 +2.8 -4.6    -3.9 -3.1 -3.4    -3.3 -2.4
20000 -12 -4.2    -3.9 -2.7 -3.1    -2.9 -1.5

I hope this will give a resonable picture of different combinations.

markC has bought very high quality parts for his network. I can only support his recommendation.

WindChaser,

I finally got to tweak my simple T-amp. Just substituted the input capacitors for Auricaps. Incredible improvement.
Very good with the B200 (including LR + Zobel) (sic!) and probably as good with any other decent loudspeaker.

/Erling

markC · « **Reply #94 on:** 26 Oct 2006, 03:08 am »

These components made a very noticable improvement, but I'm not saying that the values of them are written in stone. Experimenting is the best way. I'm quite sure that room acoustics will be a factor.
I listened with the different value R's and my findings are as follows in MY room....

6.2 ohm a little much in the top end of vocals especially female-a bit fatiguing after a long session. Bottom end lacking.

8 ohm very smooth and non abrasive but lacking a little in the lower mids such as male voice sounded a bit thin.

6.8 ohm Goldilox would like this one. Ever so slightly hot in the upper mids, (such as harmonics of female voice), but that helps bring the overall sound alive. Bottom end is for sure the best of the 3.

I'll be building my final, (yea right), version with the .68 coil and the 6.8 R.

I'll go out on a limb here and say that this is the best sound that I've experienced in my home with my current set up. The only variable in the last year or so is the speakers; including subs and plate amp.

Acudoc · « **Reply #95 on:** 26 Oct 2006, 03:22 am »

Mark,

Can you provide some more info on your room and baffle dimensions and any interactions between the two that you have noticed?

I am trying to figure out what type of baffles to build for my b200's

I have a relatively large room, 14' wide and 29' deep, sitting position is approx 10' from the wall.

Thanks for sharing your findings

John

markC · « **Reply #96 on:** 26 Oct 2006, 03:38 am »

Baffle dimensions are 40" H x 30" W. Room is 21.5' L x 12" W x 7.5' H. 4 Quick & Dirty Jon Risch bass traps, 2" acoustic foam on front , ( attempt at live end dead end set-up), carpet, heavy curtains on the 2 windows, basement rec-room type area. Infinite baffle sub woofers.

In a room as large as yours, it is my opinion that you will need sub woofer reinforcement.

Russell Dawkins · « **Reply #97 on:** 26 Oct 2006, 06:45 am »

markC,
what is the distance from centre of the B200 to bottom of the baffle and are they centred on the baffle? Are the baffles without wings?
Sorry if I'm making you repeat yourself.

markC · « **Reply #98 on:** 26 Oct 2006, 09:51 pm »

Russell,
23" from the bottom of the baffle to centre of the driver. Yes, the baffles have wings with 10* angles cut between them and the centre baffle. They are always wide open which means that the wings are angled back only 10*. The outside wing is 12" wide and the inside wing is 8" wide, which puts the driver off centre of the entire baffle. There is a crappy picture of them somewhere on the forum, I'll try and locate and post it for you.

Check the "Open Baffle" subject for the pic.

Russell Dawkins · « **Reply #99 on:** 26 Oct 2006, 10:33 pm »

found the pic, thanks mark.
It seems the dimensions you gave - 40" H X 30" W are the overall dimensions, including the wings. Sort of a miniature PHY-type baffle.