A good rumble filter will attenuate differential signal, which is vertical groove modulation, without affecting horizontal modulation. If you have a single subwoofer (or two) driven in mono (mixed Left and Right) this will solve your problem. I bet you could Google "rumble filter" and find a diy kit.
By the way, the pumping of your woofer cones does affect the sound although you may be used to it and not notice. |
I have KAB's rumble filter ($170) and it completely solved my problem. At first I didn't understand why my woofers were going nuts, then once I finally learned what the problem was, I was able to get a separate rumble filter and life is good.
Michael |
Dear 240zracer: The Eldartford suggestion: run the subwoofer in mono way is really the best one because you don't have to add any other " stage " ( rumble filter ) to the signal.
Like Eldartford already posted the pumping in your woofer cones are adding intermodulation distortion and certainly makes a degradation to the signal reproduction.
Regards and enjoy the music.
Raul. |
Couple of things guys. This is a three-way stereo speaker, not a subwoofer. I just looked at the KAB. It turns everything below 180Hz to a mono signal. Seems like a rumble filter should only operate from about 18Hz down like the ones on my old integrated amps used to do. |
Some phono preamps have them built in. I am running a Sim Audio LP 5.3. The filter is engaged with a jumper. |
I was going to add a high-pass filter at 18Hz to my woofer crossovers, but that passive method requires some very large caps and inductors. Might have to revisit that. Also noticed the Bellari phono preamp has a rumble filter. Pretty nice feature on an inexpensive unit. |
Actually, if the phono preamp is where this circuit would be, if it existed, I don't see why it isn't a feature on all phono preamps. |
240zracer...The 18 Hz rumble filter attenuated everything. The mix-to-mono approach can use a much higher frequency, although 180 Hz does sound a bit too high. If you don't use a subwoofer you will need to buy a line level device. But you don't need to buy a whole new preamp. |
Hello, I use a 20hz filter which I believe is necessary for any LP playback system. Since my system is very capable of reproducing low bass I also use a rumble filter which monos the signal at 38hz. 180 hz is too high to sum to mono. Try the 20hz filter first then if you still have a problem you may need a rumble filter. The two types of filters are for two different problems and 20hz is the first one to address.
This all depends on your system and its bass reproduction abilities ie: tonearm/cartridge and table interaction and its bass reproduction and your speakers ability to reproduce low bass. I think stereo reproduction is important to at least down to 50 hz and lower if possible.
My 20hz filter and the rumble filter are in the Marchand Bassis.
Bob |
bryston preamps with phono has this. |
Thanks Bob. I just talked to Marchand. They do indeed have solutions, the Bassis being one of them. They also can supply the very large inductors needed to add a passive high pass circuit to the woofer crossover itself. I don't think I have rumble, just a bit of subsonic woofer cone movement. Looked at your system. Very impressive! |
My feeling is that the KAB is a state of the art device having used it. I am not technically very knowledgeable but the KAB website would lead me to believe that the rumble it is attacking at 140 hz. is strictly related to vertical modulation caused by warps, whereas other subsonic crap which is actually recorded right onto the record is eliminated at much lower levels. Kevin at KAB would be able to shed more light on this if you contacted him. I can only tell you that my experience is that the KAB essentially did the same job in my system (in terms of eliminating woofer pumping due to subsonic issues) as my new (and much more expensive) phono preamp with a very sophisticated subsonic filter (-9db @ 10 hz, -18db @5 hz and -48db @ 2 hz) does.
And don't confuse what's in the Bellari or some of the cheaper phono stages with a top notch high quality subsonic/rumble filter like the KAB if your system really deserves it. I recently had David Hadaway (at DB Systems) install a very basic subsonic filter in a MM phono stage of his that I purchased used for my son's system. He was going to charge me all of $10 to do it, but I told him to bill me $20 (great guy, great products, great service). It was simply a matter of soldering in a capacitor and that phono preamp is now -3db at 27 hz. which is certainly fine for that system and has eliminated all woofer pumping.
As it stands, FWIW, I have the KAB unit now sitting here doing nothing, which I would sell for a reasonable price if you are interested. It will involve buying another set of interconnects as well, but I can assure you it will solve your problem in a high quality way.
I would wager that your speakers (as mine) are ported. |
Hi Hdm. Yes they are ported. And I'm no expert either. Maybe I should contact Kevin as I did Marchand. I still believe that I do not want to attenuate, or mono, any frequencies above 18Hz. And I'm sure you are correct when you say there are high quality and low quality solutions for subsonic crap. I actually have a small problem with my speakers reacting on only certain LPs. They are not flapping all over the place. They are Eton 11 inch woofers, btw, and the cones move very, very easily. That might be compounding my problem.....if indeed it is a problem worth solving! Know what I mean? Injecting additional electronics and ICs to solve something that is more of an irritation than an audible rumble. I'm a little confused, but that's normal in my world:) |
240: I think that you will find that when you eliminate this problem from your system that it will indeed sound considerably better. That is certainly my experience. My limited understanding of the problem is that, apart from having your speakers making movements which they are not supposed to (which can't help but effect sound quality if you think about it), the subsonic issue has pretty substantial detrimental effects in terms of amplifier performance and possibly longevity as the amp works its guts out reproducing these ultra low frequencies.
A high quality filter like the KAB or the one David Hadaway sells separately for around $200 will, I think, get the job done in a "high quality way", whereas the cheaper, simple capacitor solution will obviously involve some compromises.
The other alternative, of course is to upgrade your phono stage. I was actually kind of shocked in the past few years when I got back into vinyl that many of the quality phono stages do not include a subsonic filter (alas, that's how I ended up with the KAB), but the designers of these products are looking at things from a purist standpoint and a desire to produce ruler flat frequency response. In the real world, though, particularly with ported speakers, there are many systems that are going to have subsonic issues, which was why, in the end, when I upgraded my phono stage recently I focused only on phono preamps with a high quality subsonic built in. |
Hello again, I think the Marchand Bassis is a great unit. Mine is set up after the Marchand XM126 crossover so only the low freq go through it. It has a 20hz filter and a rumble filter of which I find both to be necessary. Also the Bassis eq is very subtle and I believe would be a wonderful addition to your system. It only extends the bass response where your system starts to fall off and you can correct the Q and the bass extension. It works with ported and non ported speakers but is most effective with non-ported. As far as additional equipment and interconnects remember as Einstin said to make things "simple but not too simple". Well here is your solution for several problems, of which, for the most part you are unaware of untill you hear it. You do have rumble and subsonic problems, and they do need to be eliminated. Musical reproduction is like the universe, you always know there is something more out there....
Bob
PS thanks for the compliment on my system. I consider my system minimalist as it only has what is necessary for reproduction of vinyl music. That includes the Bassis which, if you understand it, is a great piece of equipment and is quite reasonably priced. I recommend that you buy it with the stepped attenuators rather than the pots if you do indeed buy one. |
240zracer...Take Hdm's advice, and get the rumble filter.
Your concern about maintaining stereo separation down to 18 Hz is not reasonable.
1. LP cutting practice (usually) is to mix to mono at low frequency.
2. Many people don't think that LF sound can be localized, hence the popularity of single subwoofers.
3. Although the cut-in frequency of the filter may seem a bit high, remember that its action is gradual, and considerable separation will be maintained well below the stated frequency. Thr filter designers were free to pick any frequency, and they built what worked best.
4. If you don't like it you can easily unplug it. |
OK, guys, and thank you! I now believe I need to solve this rather than ignore it. Going to re-read this thread, visit the websites again, and make couple of phone calls. The one thing my gut tells me not to do, is attenuate above the 20Hz. I just listened to an orchestra recording. In the jacket is a picture. There are no less than five string basses on the far right. There is substancial bass in the far right of the soundstage when I play this LP, and my right amp meter bears this out by showing how hard that channel is working. So I guess I don't believe bass is non-directional. It also sounds like bass will improve overall, by solving the problem and my amp will perform better. Everyone who posted seems to agree on that. That's some really good incentive. Off to the websites......again! And thanks, again. |
I haven't read all of the responses to your question. Forgive me if I'm totally off base.
While you are rethinking your underlying problem consider whether or not you might have a mis-match between the mass of your TT's arm and the stylus' compliance. That can cause minor or major subsonic problems. Some times these are severe enuf not to be curable by just using a subsonic filter. Some more anal folks would find this type of fix undesirable in any event. They would want to fix the underlying problem, not just use a band aid. If you've already eliminated this possibility march onward............:-) |
Hi Newbee. You might be reading my mind. I have been revisiting compliance this morning, looking for errors and ideas. Here's the poop. Scoutmaster, JMW-9 (7.7gm effective mass), ZYX FUJI with silver base for added mass(5gm cartridge + 4gm silver base + .5gm screws) Cartridge compliance of 15 horizontal and 12 vertical gives me resonance at 10 or 11Hz. My thought is to try a bit more mass at the cartridge. I'm also going to pay a lot more attention to the woofer movement on various LPs. I see 3 ways to improvement. Compliance, add high-pass filter to the woofer crossover, or electronic filter. If the high-pass filter at 18Hz didn't require a 700mH inductor, it would be a very good solution, IMO. It seems like everything I do is a collossal struggle, but I intend to win. |
240zracer...Did you price that 700mH inductor as an air core unit? And you need two. That ought to make your decision easy! |
Eldartford.....no but I figure about the price of a Corvette. I am with out a cartridge for the moment, so woofer problems have to wait till I solve that issue. |
don't need one because the Bugle RIAA response is 30Hz to 60kHz with a Bandwidth of 15Hz to >150kHz which is gives enough headroom for the sound to stretch out but prevents any woofer pumping.
The Cornet does the same thing: RIAA response is 25Hz to 25kHz. Bandwidth = 15Hz to 30kHz. |
The old Audiocontrol C-101 equalizer has a Rumble reducer button(Low frequency summing) and a subsonic filter. They regularly show up on ebay and sometimes here. |
