| Geoff H |
Hi all. Joe has had a few issues with his B200s. None of the published solutions worked for him. He has given the attached line level passive network a try, and he has left the ribbons off.
No attempt has been made to correct the bass roll-off on his OBs, the bass helper does that. This circuit could be used on other baffle arrangements.
Over to you Joe, when you get away from Miss Jones.
Geoff. |
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| v-bro |
I used this to tame the shout of my Monacor SPH-30X quite successfully:
http://www.audioasylum.com/forums/h...ges/120394.html
only I placed a potmeter on R3 to adjust the effect, it functions more or less like a midrange eq. fader...but once adjusted I never feel the need to change it again... |
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| planet10 |
Step 1 -- phase plugs...
dave
planet10/ of course i have a bias |
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| v-bro |
| Here's what worked well on the Monacor: |
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| v-bro |
| Hi Dave, thanks for your great input!:cool: :cool: :cool: |
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| Geoff H |
| Hi Dave, one thing at a time. The ribbons are off. He must still be with Norah. |
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| MisterTwister |
it's a bit off topic, but how does one design a phase plug?
is there a software simulator for it, or is it just trying out all kinds of plugs shapes until response curve looks better? |
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| johninCR |
Though I reserve the term "shout" for whizzer coned drivers, the B200's do beam and have that long gradually rising response. Below is my solution to both. I call them Constant Directivity Dipole WaveGuides (CDDWG's). The narrower dispersion helps match the lower end response with the HF beaming to sound flatter overall. HornResp tells me there's even a few db gain from some slight horn loading below 1khz, which also helps out. When the waveguide runs out of steam, the dipole directivity takes over. I use them with dipole bass augmentation, but they work surprizingly well run full range with a little bass boost.
BTW, Dave I picked up a used pair of 167's that have your phase plugs. Will those fit a B200, since it has the same VC diameter?
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| Corloc |
| I like my phase plugs from Dave for the B200. The sure help the beaming. The rising response can be help with toeing in or out, a notch filter, or hopefully the new toy John is showing. |
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| Geoff H |
| Nice CDDWG's John. I'll never finish my OBs with all these new ideas. Another to consider. Have you posted details? |
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| JandG |
| Had to let miss Jones take a break......running the B200's with Geoff's circuit thru a Mac MR-74 in FM mono & it is delightfull..mixture of silver mica & polystyrene.. I got all SM coming & AB carbon comps for the circuit.. I will try all polystyrene also.. finally the meat of the guitars is correct.. that has been a major problem for me with a few shouty FR's..Dave's plugs do work well, I used them in a pair of fe167e's..But the surgery was a little concerning.. I am not ready yet to carve on the B200's, but with Daves plugs & a PLL circuit to flatten this unit out might be the big ticket.. it now sounds like my FR in OB that I run in a bedroom system.. it is good..great on guitars..absolutely..amplified guitars are crazy hard to get correct..you wouldn't think so ,,but they are. Back on Nora,, she can become very shouty on all 3 of her albums..That is gone.I have tried analog 31 band EQ's.. & WAY to many dang filters after the amp, & all kinds of stuff with these drivers. This is the 1st hope I have had to run the B200 alone..I can handle it fullrange now. Circuit doesn't have the life robbing effect that passive after amp parts seem to have..there is insurtion loss,.but nothing major. I am running passive TVC into 300B PP amp. I have a 27 pre on bench I am building & it should be nice with this filter. My DAC is also output stage by-passed, so not alot of voltage to work with, still it gets with it..But ran from the MR-74 it flat rocks.. & the guitars are meaty & very natural, with the overtones & harmonics actually bieng heard.. I do not think that is the case with the B200 on it's own..Once I get the nerve,, I will try daves plugs & this filter together..that should be a nice combo,..The ribbon B200 combo is getting on my nerve....ribbons are touchy creature..the magic my single 12" alnico in OB does set me on path to return to B200 FR..I also added some bottom end boost to my BASH plates this mourning w/ resistor changes ...NICE..Thanks Geoff.. |
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| johninCR |
| quote: | Originally posted by Geoff H
Nice CDDWG's John. I'll never finish my OBs with all these new ideas. Another to consider. Have you posted details? |
Thanks. Want to do measurements first, and have to learn how to do them properly. I got picked on for no graphs by telling too much of what my ears tell me. Plus I want to try some other drivers in them first. The driver mounting baffle is changeable, so any 8" or smaller will work. Before the foam and material lining the 108Esigma's were better, but the lining helps alot with the undersized "throat" for waveguide only action. Just got some F120A's in that deserve a turn too. I listened to them for 3 days without augmentation as pictured, and probably only the B200, higher Q hemp, or Supravox can get away with that, since I like bass.
BTW, I owe thanks to GM for some initial guidance during my planning phase. The idea was to copy Dr. Geddes' Summa concept, but in a dipole layout instead of going omni in the bass and monopole WG on top. I got some side benefits I didn't expect. |
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| Vix |
Hi!
Geoff, can you please post again the PLL circuit, a bit bigger? I have troubles reading the component values.
I also have B200's and I love/hate them. Tried passive EQ, but was not happy. Sounded a bit dull. Without ant filters, b200's sound lively, but painful.
Dave's phase plugs are a very good idea, but I am still a bit reluctant to cut through the speakers.
Somewhere I read that treating the dustcap with dammar could improve things... Maybe I'll try that. If it doesn't work, I'll cut it altogether and install plugs...
Vix |
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| Geoff H |
Hi Vix, see what you mean. from left to right, 150pF (or 220pF sot)
0.0027uF, 220 pF. 2 x 100K res. from memory. I'll post another pic when I'm back home. Also an explanation of values.
It will be good to get more feedback. Joe's happy now. Bit of a fluke to get it right first up. Haven't had the joy of being near a B200, yet. Geoff. |
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| JandG |
I'm going to cut the B200's..& use the PLL circuit together,, plugs to kill some beam & the rest in taken care of.
John ,,,Those are crazy nice unit's you built ..impressive stuff.
Geoff, what the heck is ( sot )..?
The values I am running with parts on hand are
+.........51k .....................................................................+ B200
[....200pf.....].......| |
| 1
1 0
0 0
0 k
k |
| 200pf
2700pf |
| .
_.........................................................................................- B200
I am sure this could be tweeked one way or another..but it is definately taken the rise out of the problem area's & is doing positive work to the driver. Well at least as to how I hear it. I am not capable of proper measure ments yet. In do time though I will.
I have 220pf & 2700pf in SM on the way & also some AB CC's for the resistors also coming.. Parts running now are from junk box..alll meausred, but old,, like 40 years old..*s*well cf resistors are new..
My tube amp is 100k input impendance.. |
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| JandG |
| Pay no attention to my feebal attempt @ a thrown together schematic, when posted, it all went every which way,,it is NOT correct..just use what Geoff post's if you try it....damn!!!!!!!!!! |
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| Geoff H |
This diagram should be better. Silly me. Rule 768, don't post pics without previewing them.
The circuit is designed to run into a 100K load, and should be fed from a low z source. There is nothing special or magic about it.
The 51K in conjunction with the two 100K sets the attenuation at higher fs. Going up in freq, the 0.0027uF sets the first knee at 600Hz, where the output of the B200 starts to rise. The 220pF sets another knee at 7Khz, where there is a peak. The 180pf levels the response at 16Khz. The design value was 194. Going to 220pF will brighten the top end a little. Also, this cap will correct, to a degree, the phase shift at high freqs.
http://www.visaton.com/bilder/frequ...s/b200_6_fs.gif
This is not a substitute for phase plugs or any other worthy mod to the driver. It is an alternative to cutting. We should always endeavour to solve these sorts of issues where the problem starts.
"I got picked on for no graphs by telling too much of what my ears tell me"
That's a shame. It's the ears that count the most. Why do many not trust them? I look forward to seeing Johns double sided horns, with or without graphs.
Geoff.
edit: Double checked the pic. |
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| Geoff H |
| SOT = old school electronics, Select On Test. |
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| planet10 |
| quote: | Originally posted by johninCR
BTW, Dave I picked up a used pair of 167's that have your phase plugs. Will those fit a B200, since it has the same VC diameter? |
Not really. A 1" VC with whizzer requires a smaller diameter plug than if no whizzer. The B200 plugs are also longer.
dave |
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| Ricky |
I have used the B200 myself in a commercial design. I cured the top end by putting a 0.3mH coil in series with the driver and an R-C network in parallel before the coil to bring the impedance down again.
Ricky. |
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| scottw |
Geoff H wrote| quote: | | The circuit is designed to run into a 100K load |
Hey,
Doing the correction at the line level is an interesting solution. Is there a way to make the filter suitable to a 50k (or 20k) input? (There is too much I still don't understand about LL circuits.)
Thanks,
Scott |
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| johninCR |
This is not a substitute for phase plugs or any other worthy mod to the driver. It is an alternative to cutting. We should always endeavour to solve these sorts of issues where the problem starts.
That's why I don't try delving into the electronics side. I leave that to you experts, and stick to exploring the mechanical side. With OB's there's plenty of room to explore, which is quite rewarding.
"I got picked on for no graphs by telling too much of what my ears tell me"
That's a shame. It's the ears that count the most. Why do many not trust them? I look forward to seeing Johns double sided horns, with or without graphs.
Listening to music, moving around in the room, and sweeping through tones with 1hz increments around problem areas may not tell the whole story, but I think it paints a better picture than any other method. Sure our ears/brain can be fooled, but they are incredibly sensitive with highly evolved and flexible data processing. I'm anxious to measure only as a test of my tuning by ear, and to generate FRD's to import into my active EQ/XO software to eliminate the guesswork. Plus there are some instances where measurements will prove helpful. |
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| ultrakaz |
Hi JohninCR,
I've mounted my B200 in a front horn (200Hz cutoff or so). The throat was around 4.5". I got a boost (2-6db) between 200 to 900Hz and attenuation (1-4db) from 1000-6000Hz and flat after that. Spacing between driver and mouth changes the balance. This is not an exact science. If I knew how to balance the boost/attenuation I'd really be happy.
I'm not surprised you are getting great results with your waveguide. It almost looks like the front loading section of the Tannoy Autograph.
I'd like to construct those waveguides. If you don't mind, I'd appreciate it if you could post details on the construction of the waveguides (dims, process, and caveats). Thanks. |
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| johninCR |
Ultrakaz,
I'll be sure to share everything, probably more than some want, because I tend to fully explain things. I need to get them to finished form, and once I get something I can listen to my work pace typically slows to a crawl.
These are different since I need to get to finished form before filling voids with sand, which I believe will have a marked improvement. Despite using doubled up real 2"x4" solid laurel to construct the terminus roundovers, the roundovers vibrate a lot, but the relatively thin plywood panels forming the waveguide are quite dead. I may not fully understand the cause of vibration, but I do know 40-50kg of sand per speaker will cure it. I've always wanted some really massive OB's anyway, so this is my chance.
Also, I want to include enough of the science, so others understand it in hopes of furthering the design through technical or aesthetic (esp size) improvements. |
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| Geoff H |
Impedance scaling. For a 50 K ohm input amp, halve the Rs, and double the Cs. 20K, 1/5 the Rs, 5x Cs.
There are several advantages in LL eq. The amp, be it tube or SS is in direct connection with the VC. There is less chance of ringing and other issues. Reactive components reflect back through transformers, placing strange load conditions on the plates.
Another advantage, the slew rate requirements of the amp are reduced if we are shelving the top end. That may not be a problem with a good amp, but why amplify something and then attenuate it? For too many years, I ran my Wharfedales in a 100w pc system, with 10db l-pads to pull them back to 93dB/W. EL84s would have been a better solution.
Slew rate is a measure of how fast an amp can respond to a signals rise time, usually in Volts per Millisecond. Exceed that, then the feedback circuit can't keep up, resulting in transient intermod distortion.
John wrote "With OB's there's plenty of room to explore, which is quite rewarding"
You bet. I trust you are watching Beyond the Ariel I am currently extracting as much as possible from a pair of 6" F/Rs on OBs only 460mm high. Chasing down panel vibes.
Geoff |
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| scottw |
Thanks Geoff,
I thought it was that simple, the main requirement being a correspondingly low source impedance.
If I were to use this ciruit, housed with the amp, and also have a CR to roll off the low frequency (around 100 Hz or so) it would go something like: 1M to terminate the interconnect, your LL eq. filter, then the appropriate CR to roll off the lows(this R is also setting the input impedance for the amp)? Just wondering if the CR would be interacting with the eq. filter.
Scott |
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| Geoff H |
Hi Scott. I would have the bass roll off first. Use lower values, so that the following network doesn't load it too much. ie the shunt R = 10K, Xc=10K, and I would try to stick with 6dB/oct.
I had a look at some of the other links provided. Most seem to be similar with that on the Visaton site. Ricky's situ is a bit different, as it was a commercial design. (Interesting reading about R-A, will the real Richard Allen / Allan stand up?) Trying to ship a LL Filter with a speaker system could give the impression of an afterthought. Magazines would have a field day with it.
However, in the DIY world we can be more flexible, design for performance, not just convenience, and benefit from the effort.
Just a word on capacitors. I think good quality polystyrene are as good as any. Silver Mica were normally used at RF. I don't know of any advantage at AF. S/Ms offer greater temperature stability, not one of our requirements.
Geoff. |
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| Geoff H |
Speaking of afterthoughts: My network has an input Z of 84K at low freqs. A series C with XL of 84K at the desired freq and your done at 6dB/oct. ie 0.018uf for 100 Hz.
Now for a bonus. An additional pot with a series R shunting after the input C, will give you an adjustable bass roll off freq. 80 to 240 Hz could be very useful in setting it up.
Cheers,
Geoff. |
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| scottw |
Thanks for the information Geoff,
I've read what I could find on PLLXO's in general to get a feel for impedance and insertion loss, etc. Heck, I have enough trouble figuring the impedance of an L-pad.
The "afterthought" is an interesting idea I may try. Just trying to scale it to the caps I have on hand. Have one set of teflons that would be nice to use in series and an assortment of Relcap polystyrenes(I like 'em too). One challenge is that the pre is a TVC that may get fussy if the impedance gets too low. I may put something together out of regular cheap parts first and see how it goes.
Scott |
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| JandG |
| Geoff, could you give a example on a schematic on how to implement a 6db HP with this circuit..I am bieng slow as ususal..I usually use TUBECAD for the math on 6db HP when I use them, but don't have a clue how to use it with this circuit..I might not need it now, but would like to try it..since I am active 4th plate's @ 150hz anyway. |
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| JandG |
| scottw, I also am using a TVC with this circuit & also want to try a 6db HP with it. The posted circuit works fine w/TVC on any source I have tried, but I am going active 27/26's pre shortly. My PLL circuit is cobbled together w/Styrene's from old Saba radio & SM's from who knows where. it is very nice.. |
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| Geoff H |
Hi Guys,
This includes the low cut filter. 6dB /octave, -3dB at 100 Hz. This points out another advantage of doing things at line level. Low pass at 8ohm requires a huge cap, which wouldn't work due to the rising Z at resonance. It could have a reverse effect.
Any preamp worthy of the name should be capable of driving this, otherwise interconnect cables would swallow all the treble.
Cheers,
Geoff.
edit: I can read it. |
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| Vix |
| quote: | Originally posted by Geoff H
edit: I can read it. |
I can read it too!
;) :cool:
Thanks!! |
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| JeffB1 |
Geoff,
When you explained how to adjust the Rs and Cs for a different amp impedance did the adjustment apply to the 51K resistor and 180pF cap or only to the two parallel legs with the 100K resistors?
Thanks.
Jeff B. |
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| Geoff H |
Hi JeffB1,
Everything. All resistors in proportion, all capacitors inversely proportional, to the change in load Z, or input resistance of the following amp.
It should be fine to stay with preferred values in the 5% tolerance range.
Regards,
Geoff. |
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| JandG |
| Anyone else put this circuit together..? |
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| earsandeyes |
yes,
I will test it over the weekend and compare it with the MOX based and DEQ2496 based
regards
E&E |
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| Geoff H |
MisterTwister asked "it's a bit off topic, but how does one design a phase plug?"
I don't think so. We are talking about improvements, not methods.
I don't know how to design phase plugs yet, but working on it. Of the ones I have shaped so far, the shorter ones appear to be better, so I need to try even shorter ones.
I am using the classic bullet shape. I think in the "design", too many factors come into it, ie the shape and angle of the apex, and the rate of curve if curvilinear. I want to devise a better way of shaping too. Did the first lot on a grinding wheel, then sandpaper.
I do know that I will shape dowel before fitting tweeters and/or eq. Somehow they bring out a lot of clarity and spread the beam . No filter will do that.
Geoff |
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| Vix |
I've just finished this circuit! Wow! I didn't expect such a huge effect!
Even on-axis, B200 doesn't shout. In fact, for the first two minutes, it sounded dull:scratch: Now my ears have adjusted and it sounds more normal, though I miss a bit of "tizzzz".
I am using it between a tube buffer and a Pass Zen variation 9 amp -without feedback, and input impedance adjusted to about 100k.
I'll do more listening and see it I prefer this sound over longer periods. It sounds much easier, somehow "lighter". Sound floats in the air. As I listen, I hear a peak in the bass that I didn't notice before....
Anyway, this circuit is well worth trying. Maybe I will have to play with some values until I get exactly the sound I want.
Thanks a lot,
Vix |
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| Geoff H |
Hi Vix, You're welcome. The "tizzz" will probably come back, hopefully in a more natural way. At present you are hearing things the tizzz was masking, and your attention is focused on the new sounds, like the peak in the bass.
If you change values to suit your taste, change only one at a time, and wait till you have adjusted to the sound before judging the change.
I guess you'll have to hunt down the bass peak. That can be fun. Try disconnecting the bass helpers, it could be as simple as too much overlap on the bass roll-off.
Thanks for the feedback. It will be interesting to see what others have to say, and then fine tune the circuit.
Regards,
Geoff. |
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| Vix |
Hi,
Geoff, thank you for providing such a nice circuit. While I know that cutting the dustcap and installing a phase plug would be the best option, I was a bit reluctant to do it and was looking for some reversible mods.
After a bit more listening, I am much happier with B200’s than before applying a PLL.
Overall, it sounds “quieter” and less aggressive. Bass peak was solved by lowering the gain on a bass amp. (it is biamped-second amp driving a pair of 12”) I had upped the bass to match a screamy midrange. It was sounding more like a PA, less hi-fi. Sometimes I enjoyed it, but couldn’t listen for very long. Now that there are no nasty peaks, they are much easier to listen, fatigue-free.
On the negative side, they sound a bit soft and just occasionally I miss that shout.
Still, I am going to leave them as they are, and just enjoy for a while.
Regards,
Vix |
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| JandG |
| I installed a 27 tube pre ahead of Geoff's circuit & also have a 150HZ .01uf HP in the circuit also, cleans the mids up. I also bi-amp. With a good pre, this circuit is outstanding. If you think you are missing anything on top, just install a rear fire tweeter. I installed a ribbon in rear fire mode only @ 10k 1st order. Far superior to front fire in my system. My circuit did burn in,, only took a couple hrs. & I really hope others try the LL circuit out. For the money it is definatelly worth soldering it together. I have'n't even installed mine in a proper box, it is all hanging on input of amp. I am using the 180pf- .0027uf -220pf combo w/ SM's & rat shack carbon films. I have Bradley CC's but have not felt the need to even use them. It is nice when something works as this. I do not think Phase plugs can do what this circuit does, I have installed them before on FR's, the would help with beam, but the circuit address's something entirely differant. Not saying phase plugs wouldn't be a good bet, but I dought results would be the same. Both plugs & this circuit together I imagine would be very nice, but cap surgery in not for every one. |
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| Geoff H |
Thanks for the praise Joe. You're probably right in saying plugs won't do what the circuit does. The circuit wont do what plugs will either.
If you were to put on plugs, (and I suggest you do) the circuit may not be needed. It would at least need adjustment.
I have been experimenting with plugs on some little 61/2" w/r to the point I have a feel for shapes etc.
Anyone that has put up with my ranting and raving about my Wharfies will know I wouldn't cut them without being confident.
They are now sporting plugs. And I'm not sorry I cut the dome! There is no electronic trick up my sleeves that will do what the plugs do.
Geoff. |
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| Zen Mod |
| quote: | Originally posted by Geoff H
..........................
They are now sporting plugs. And I'm not sorry I cut the dome! There is no electronic trick up my sleeves that will do what the plugs do.
Geoff. |
ugly!
:clown: |
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| Geoff H |
Zen, your jealous again, just coz my whizzers are bigger than yours.
100 mm, and the motor's big enough to shake it.
I need to trim the ridge left from the dome, and replace the foam damper, it's a bit brittle.
Besides that, beauty 'round here is in the ear of the beholder. |
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| JandG |
| Oh I'm getting the courage to try Dust cap surgery again..at least on maybe my Calrads,, but until I feel the need , the B200's stay as is..going back to active triode pre with this set up has me tickled. I love vintage driver's How did you muster the .........to cut those Wharfdales.....? Maybe I will try my Calrads..mmmmmmm scary... |
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| Ricky |
| quote: | Originally posted by Geoff H
I had a look at some of the other links provided. Most seem to be similar with that on the Visaton site. Ricky's situ is a bit different, as it was a commercial design. (Interesting reading about R-A, will the real Richard Allen / Allan stand up?) Trying to ship a LL Filter with a speaker system could give the impression of an afterthought. Magazines would have a field day with it. |
I am standin up!!! U've bin peepin!:D
Seriously tho Geoff. With the sensitivity of the B200, your LL filter and a bit of encouragement, the tweaky boys with their 10watt tri-paths would kill for this down on the Class D pages.
Without knowing it, you've probably made their day (and another thread starts! Aaaahhh!):smash: |
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| Geoff H |
Hi Joe, on hearing what I got out of the little 6n a halfers, with cone treatment to get the top end up (they were x-oed over to 2" tweeters originally) and then hearing the difference with the plugs, it was pretty easy. Mind you, these Wharfedales are far from stock. So it wasn't a case of destroying history (we did that 30 years ago!)
I was going to have some more practise on lesser gear, but thought what the heck. Cutting the large dome was easier than the little caps.
As it was, the Wharfies had a long cavity in the voice coil that needed filling. About 1.25" from the apex back to the pole piece. That's like a 1/4 wave trap at 2.7 Khz.
Regards,
Geoff. |
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| Geoff H |
Hi Ricky, at risk of been called "old school", I still think class d and full range belong in different rooms. But it's cool if they want to peek through a window. I might have a snoop.
Regards
Geoff. |
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| Zen Mod |
| quote: | Originally posted by Geoff H
Zen, your jealous again,........................
Besides that, beauty 'round here is in the ear of the beholder. |
:D ,yes.......I'm glad for ya.......so you have something on what I can be jealous :clown:
look this-another pair........besides dirt and messed flexies,they're in perfect shape.......
little dammar,PVA and Mamboni+BudP............heaven is near ;)
btw-I agree with ya that only toobz are good enough for this type of spks..........talkin' of SS - mebbe just xconductance amps |
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| Ricky |
Trying to ship a LL Filter with a speaker system could give the impression of an afterthought. Magazines would have a field day with it.
Geoff.
Bose did it with their 301's. Without the EQ box, they sounded naff!!:idea: |
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| planet10 |
| quote: | Originally posted by Geoff H
There is no electronic trick up my sleeves that will do what the plugs do.
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:) |
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| Vix |
| quote: | Originally posted by Geoff H
And I'm not sorry I cut the dome! There is no electronic trick up my sleeves that will do what the plugs do.
Geoff. |
Ok, ok...
(you guess what I have in mind)
:D :devilr: |
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| Zen Mod |
| quote: | Originally posted by Vix
Ok, ok...
(you guess what I have in mind)
:D :devilr: |
if ya need plugs (for free ;) ) and you don't have someone with lathe shoot me with PM
Belgrade is not so far for envelope....... |
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| Geoff H |
The plugs aren't that hard to make. If you have a variable speed drill, a drill press and vice, vernier callipers, and a Philips bit, and dowel stock, you can DIY.
If you have never cut a dome, I suggest you get hold of some old drivers to play with. Smokehouse Bob said he had more control with a saftey razor than a scalpel type knife. That works for me to. Also, if you haven't checked out Dave's site,(Planet10) head there now.
On the Panasonics, the cap was glued to the VC former. I don't know if that's the case with the B200. Do not cut the former. I left a small ridge of the cap. Painted it with PVA, to harden it, then used sandpaper to smooth it down, then sealed it again. Be very careful not to let any dust into the gap.
Cut a length of dowel taking into account the distance from the apex to the centre pole, and the length you want protruding, square up one end, drill a pilot hole as close to the centre as you can. I used a washer as a guide. Fit a Philips head counter sunk screw.
Now we can turn the dowel with a screw driver, or the power drill with a bit. But first get the the diameter of the plug down to size. What we want is as small a clearance between the VC former and plug. I achieved 1/2 a mm. Then shape the plug on a sanding wheel, and finish by spinning the plug on the drill, cupping sandpaper around the plug end.
Dave uses 2 screws to hold the plug. My single screw hasn't moved on the Wharfedales (Oh! I've tried, the duelling percussionists on Sacred Fire) By countersinking the screw just below the surface, the base of the plug will have more grip than just the screw head.
This is what I started with. |
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| Geoff H |
| Then ended up with this, built from scrap and leftovers. I found myself listening to these more than the Wharfies, despite the thin bass. |
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| v-bro |
Hi all, I measured the notchfilter I previously posted.
As I mentioned it is adjustable so here's the filter in full effect: |
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| v-bro |
| Here's what happens when the adjustment potmeter is shifted in the other direction: |
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| v-bro |
Obviously the value for the capacitor should be chosen smaller to adapt the B200 better maybe even a smaller coil value (like 100nF and 80mH instead of the 150nF and 100mH that I use right now...), as a matter of fact I tweaked the filter today to adapt better to my Monacor SPH-30X 3" fullrange drivers.
Here's a measurement with the old filter: |
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| v-bro |
I know it looks kinda bad, but in real life this configuration sounds very good. The drivers would measure a lot better in a proper enclosure. But I made a very small (1 liter) enclosure to produce stereo sound for portable use (so no hifi quality was aimed at)... With the filter installed the midrange area was very nice and the bass and higher frequencies much better, the latter even better audible from a larger distance.
After the tweaked filter is finished I can show the difference...
Here's how it measures without filter: |
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| Geoff H |
Hey v-bro, it don't look to bad for a mini system. What would be interesting to see is a transient test at the null freq. There may be enough R there to damp it, but then that increases time delay.
One thing I like to avoid is LC combinations, and stick to C only, ie a twin T filter. No tuned circuits to excite.
Also, I don't place too much weight on FR graphs. OK for before and after comparisons, but unless you compensate for room effects and calibrate the entire kit regularly who knows what your results will / should be. In the case of the B200, I only had the published data and Joes ears to go by.
If I notice a problem, I'll take measurements to identify the problem, make changes, and listen. Taking measurements at that time only proves (or disproves!) you know your stuff. Doesn't mean you have cured the problem. That's why I haven't asked anyone to do FR graphs. It's THEIR ears that must be happy.
I'll might have a look at your driver later, see what I can come up with, just for fun. As they say, 2 heads are thicker than 1.
Geoff. |
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| v-bro |
Hi Geoff,
I also like to avoid LC speakerfilters, that's why the line level RC filters caught my eye. I only follow my ears in this game and measure afterwards, sometimes discovering my ears didn't analize very well, sometimes they do. But basically I go for the sound my ears most like to hear.
It would be nice if you could come up with another approach, other ideas have been very revealing before. So thanks in advance! |
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| Geoff H |
| Hi V-bro, see my post in your 3" thread. |
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| Geoff H |
OK, lets get back to the B200. Who hijacked that any way. Whoops, I did it again.
Going on some of the comments made, I suspect something is happening as a bonus.
The cap that provides the high freq boost will give a phase shift as it comes into effect. The current through a capacitor leads the voltage.
It could be compensating the phase as the HF leaves the apex of the cone, bringing it into line with the midrange.
That falls into line with some of the comments.
If anyone is interested in doing a FR graph with the phase plugs and minus the filter, we can optimise the filter to use with the plugs.
Cheers,
Geoff |
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| JandG |
| My filter is still going strong,, ran direct to compare & ran for the haywire mess of my circuit & put in back in. Time for me to put in in some small project boxes.What I got going on looks down right scary... |
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| Geoff H |
Why not mount the components on a tag strip, and mount inside the amp. Less plugs and sockets, less cables.
Good idea reverting back to the pre filter days. How long did run without the filter?
Regards,
Geoff. |
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| JandG |
I ran it for just one song,all I needed to hear..With a good pre as my 27 is, this filter is a dream with it.I lack nothing & the mids are just a delight & can listen till I drop..No fatigue & no percieved lack of life or dulling which is quite strange because that is what happened with every passive after amp filter I used. Good idea about the tag strip, I run the circuit as this.
.01uf Vitamin Q leading the pack for 150hz 6db HP & then the circuit as 180pf-.0027uf-220pf & resistors set for a 100k amp. Then a ribbon in rear fire mode only @ 10k 1st order w/ no padding. results are best I have had to date sonicaly with B200. Amp is a 300B PP for 22w. BASH active plates set @ 150hz 4th , driving the Vifa M26wr-09-08's. all on same baffle. Can I install the circuit in my 27 preamp..? 
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| Geoff H |
"Can I install the circuit in my 27 preamp..?"
Yep. In terms of cable capacitance, may be better in the main amp.
Depends where you have room. Anywhere other than the birds nest on the table has to better.
Geoff. |
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| JandG |
| quote: | | Anywhere other than the birds nest on the table has to better. |
That is exactly what I have to....*s* Not insulated or nuttin...living dangerous or just plain stupid I would say, I'll go with stupid.!!!!!!!!!!!!!!!!1 |
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| v-bro |
And on top of that it's noisy, the circuit functions as an antenna for all kinds of static that's on the air....
Even if your ears can't hear it, your components might still get stressed by it.... |
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| v-bro |
Have to admit I also experiment that way first (to determine the neccessary components and their size) , but in a shielded perimeter my ears most of the times can even tell the difference.
Most low component count circuits I place in a separate box first (to experiment with) and if they're a good add-on to another circuit and providing it fits in the enclosure of that circuit I build it inside....
It gives the advantage of:
-Being able to modify the original circuit at a later date without having to open the amp up all the time.
-Compare to the original in the amp again after modification.
-Using it as a temporary add-on to other systems.
I just like to experiment....:D |
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| Geoff H |
"your components might still get stressed by it...."
Ah.., he's using valves, not 3 legged fuses.
And long may they glow into the night. |
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| v-bro |
| Well not anymore for some time now...:) |
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| Estes |
| quote: | Originally posted by Geoff H
[B]Hi Guys,
This includes the low cut filter. 6dB /octave, -3dB at 100 Hz. This points out another advantage of doing things at line level. Low pass at 8ohm requires a huge cap, which wouldn't work due to the rising Z at resonance. It could have a reverse effect.
Any preamp worthy of the name should be capable of driving this, otherwise interconnect cables would swallow all the treble.
Cheers,
Geoff. |
Geoff,
I have been most of the information on this post regarding the B200 but this filter is confusing me. Is it possible to implement this circuit/filter if one only has an integrated amp? I'm trying to cut off my B200 at 100hz and add either the Alpha 15 or Beta 15.
John |
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| Geoff H |
Hi John, if you have pre out - main in links, that's where it can go. Failing that, build it into the amp, infront of the vol control. That's an issue if you have different speakers on A-B out. May need to be able to switch it out.
If you have a circuit diagram of the amp, I'll have a look. I don't think your one your own there.
Regards,
Geoff. |
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| planet10 |
| quote: | Originally posted by Geoff H
if you have pre out - main in links, |
If you have a tape loop it should work there as well.
dave |
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| Estes |
| quote: | Originally posted by Geoff H
Hi John, if you have pre out - main in links, that's where it can go. Failing that, build it into the amp, infront of the vol control. That's an issue if you have different speakers on A-B out. May need to be able to switch it out.
If you have a circuit diagram of the amp, I'll have a look. I don't think your one your own there.
Regards,
Geoff. |
Geoff,
I ok with the woodworking part but still trying to learn the electronics end. Just to clarify exactly how to install the circuit -
On the line in side - common is negative
- the leg at 0.018uf - positive
Input R of amp- top + and bottom - (does this go into the input of the amp? on just the right channel?
Sorry if these questions sound dumb - just trying to picture (in my mind) either end of the circuit and what they connect to.
John
ps: I will be testing it on an older Adcom preamp/amp system before I use it on something better. |
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| Geoff H |
Hi John, no apologies needed, I shouldn't assume you can read my mind.
"On the line in side - common is negative
- the leg at 0.018uf - positive"
That is correct.
"Input R of amp- top + and bottom - (does this go into the input of the amp? on just the right channel?"
Should read "Input resistance of amp" And yes, the top is +, the lower, common, ground, or -.
A filter is required for each channel.
HTH
Geoff |
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| JandG |
Geoff,
I feel better now.....rat nest is gone.!!!!!!!! went w/ AB CC's for resistors this round.....*s*
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| Geoff H |
Very neat. Improved WAF! No problems with hum pickup??
Geoff |
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| JandG |
| No, not from this circuit at least,.now my 27 pre is a differant story..it is my first scratch DIY build & almost got it quiet, . My layout was not the best on tube placement, as is no body told me you can't put a rectifier inbetween Vr-75 glow tubes & the 27's..lol .........I am building a 26 now..so hum will be apart of my life for awhile while I learn to conquer it. I didn't even have percievable niose issue from the correction circuit even when rat nested, at least I couldn't hear it. Just looked scarier than sh....But I do really feel better now, about not shorting my amp out & such...Sure appreciate you takeing the time to put this circuit together for everybody. If I were someone thinking of putting this curciut together, I would just use cheap Stryrenes & Rat Shack film resisors & be done. |
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| Geoff H |
Good mistakes are the ones we learn from. Bad ones cost you $ and happen that quick you can't tell what happened first.
I have seen commercially built tube amps with hum balancing circuits to fix a layout problem. Not the right way to go about it.
Good luck with the 26s. |
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| gilbodavid |
| Anyone compared geoff's circuit to the MOX at audiocircle yet? I've run my b200's solo moxed at 0.68mH and 6.8ohms, and its still to sharp for me, so about to go with 1mH and 8 or 10ohms. this circuit is totally different! I am a slow to enact but excited by the final result yet to come |
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| JandG |
| Yes, I have compared the MOX circuit to this. I prefer this circuit for many reasons, I also HP @150 & run the circuit as stated my last couple posts, still unchanged. What amp , pre & speaker style...do you have running.?I have not been eyeballing differant drivers since I did a final install of this circuit, just building tube gear now & haveing fun...... |
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| hm |
Hello,
no one thought over a sat HORN |
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| Geoff H |
Hi HM, no I didn't think of a horn. Brings up the bass though, but adds delay. Did you use a RS level meter? Good top end if you did.
I don't think Joe would adopt a horn. He's OB.
Regards,
Geoff |
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| hm |
the measurement is made by Visaton,
no XO, pur direct 0° 1 m,
you didn´t notice the construction,
which delay, do you know the HAAS effect,
first wave ... look my site ABOUT WHAT,
every OB has more delay,
you kiding me or don´t understand. |
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| Geoff H |
Hi HM, I was thinking more of stored energy in the baffle / cabinet. We agree on one thing, less is more. I couldn't see any waterfall plots on your site.
On an OB, the delayed rear wave attenuates much more than that from a BLH.
The attached is the result of an OB under development. The SPL meter has a 18 dB/oct slope above 10K. |
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| Geoff H |
And the CSD.
Cheers,
Geoff. |
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| planet10 |
| quote: | Originally posted by Geoff H
And the CSD.
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Geoff
Does the sw you are using allow you to set the time axis in periods?
dave |
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| hm |
Hello,
"On an OB, the delayed rear wave attenuates much more than that from a BLH."
sorry this is wrong!!
change the time of your csd, this doesn´t help.
Your fre. response is what: 1 W 1m 0° ?? XO ? B200??
Do you can change something of waterfall by a FR? No!!
so look the producer data.
Until 1994 i didn´t measure, I let measure by the
driver producer or the DIY journals where i publish,
and my joiner take measurements, sorry I listen only ;-) |
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| Geoff H |
Hi Dave, you mean like this. Arta comes with good documentation, if you read it. Note to self, ****.
HM, if the rear wave is not enhanced by the BLH, I dont see the point in it, yet the design has a strong following. Some of us like the sound of a full ranger on an OB.
The waterfall will be changed by cabinet materials and type. That is audible. And yes, I do understand about the first wave. So much so my other full rangers are undergoing surgery. That's another story.
The FR is at 1 metre, about one watt. No xo. No, it's not a B200, and there is no producer data - I'm working on it. Yet to fix the dip at 1K now that I have extended the top to 18K. Then attack the stored energy.
I too use my ears more than meters. In Joe's case, I used his ears and interpretation, and Visaton's published data to arrive at something he's happy with.
Regards,
Geoff. |
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| hm |
Hello,
this threat is about the B200, what helps another driver
fre. response??
Show us the B200 OB fre. response, nothing else,
compair it with my solution, specially the SPL.
no dought about listening to OB´s, that not the point.
Yes of cause a bad box is listenable.
Your CSD shows more than 40 ms at 2 kHz,
that is worse as can be.
I didn´t say that my solution is the only way,
it is only a puristic solution, without XO and a never realised
soundstage with ~96 dB 1 W with one of the best sat
8" FR the B200. |
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| hm |
Here is an example of a good Waterfall
the Basstuba with Manger, unbelievable the high´s,
show us something with the B200, please. |
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| Geoff H |
HM you are correct. This thread is about the 200B. My CSD and FR was to prove the point there is a lot more than just FR.
So have you a CSD for the SAT Horn? (which I think is a nice solution) so it can be compared to one on an OB with 200B.
Regards,
Geoff. |
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| hm |
sorry no,
may be Visaton,
or my joiner.
the key of this solution is first:
the horn works only up to~600 hz with a warm roll of !!
2.
koaxial horn throat and mouth.
3.
extrem small wall distance the last 45 cm of the horn.
if you listen in 4-8 m distance and take enough sub´s,
its one of my best, in normal distances 2,5-4m the smaller one´s
better, specially WAF ;-)
regards Horst |
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| Geoff H |
This is from the Visaton site. I can only assume the driver was mounted on a standard baffle.
www.visaton.com/bilder/ausschwing/gross/b200_zd.gif
Joe's system retains the 96dB/w, as the filter is placed in front of the amp.
The CSD I posted was measured when placing the baffle on a upturned plastic tub. The time at 2K is about 20ms when on the floor.
Perhaps some one else has a CSD of the B200 in a cab.
Regards,
Geoff. |
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