How far is your speakers to the TT? Your rack, floor if suspended, is moving. Have you tried moving the sub further away from the shelf supporting the tt?
I had the Trumpet. What you described was one of the main reason why I sold it since I have a suspended floor, and acoustic feedback or rumble seems louder on it compared to other preamps I have including the Cornet 2. To be honest, one of the thing that I really hate on this hobby is rumble/acoustic feedback, another one is hum.
You said your isolation is good, maybe it is not good enough. Please check my TTs on my system page. With plinths more than 60 lbs each not counting the TT on top of them, I thought I have a good isolation by mass loading from feedback or rumble (assuming it is not coming from the tt). Even with the 50 hz cut off filter on my orions ASP, the feedback is still there. My solution was to reconfigure the speaker placement making sure that it is further away from the TT. I moved the speakers 2 feet away from the rack (increasing the separation between the two speakers) and solved the problem.
My bass horns roll off pretty fast down in that subsonic region. They are down 6dB at 20Hz and drop pretty fast after that. Once you get down below 16Hz or so I would think that the system would begin to pick up resonances from the arm/cart. Who wants to listen to that? :-)
Well, I took the subsonic filter option. I built this excellent subsonic filter, and if anything the quality of vinyl playback has improved with additional clarity and increased apparent available power. I highly recommend this subsonic filter.
http://sound.westhost.com/project99.htm Regards, Fap.
Thanks for your suggestions, but I still think the problem is more inherent to the medium than my setup.
My racks are about 200 lbs each. Each shelf is it's own seismic sink with 50 lbs of sand in them. They are spiked to a cement floor. My TT itself weighs about 30 lbs (plus the motor which is about another 30 lbs). I am also using a Mark Kelly designed motor controller (think SDS), which makes the motor dead quiet. That's not the source of any vibrations either.
See here: http://cgim.audiogon.com/i/vs/i/f/1155818474.jpg
and here: http://cgim.audiogon.com/i/vs/i/f/1155818602.jpg
(note: bubble wrap is replaced by squash balls which proved much better at isolation from the shelf)
The subsonics are definitely not due to speaker interaction, since it happens on the lead in groove right away, before anything is playing. It is visible on the regular speakers too, when the sub is on or off. This is not an isolation problem due to standing waves in the room, but a rumble problem due to low signal vinyl interaction with the cartridge and phono stage.
Therefore: standard subsonic issues with vinyl. I even tried damping the tonearm, with no affect on the subsonics but a lack of air and life to the music - so that's been reversed now.
I spoke with Jim Hagerman about this and he said he purposely did not limit any extension at either end, making the Trumpet very wide bandwidth. He suggested changing out the .22uF inter-stage coupling caps to .1uF as a possible partial solution. I did this with no obvious change (however they are now upgraded to RTX's).
Please keep the ideas coming. At this point I think the answer is going to be electrical (e.g. a rumble filter), but I'm open to trying other suggestions first.
Is the Corian material a great option to use for plinth? I only ask because I have a DIY Corian arm-board on my SOTA and question its immunity from feedback.
Thanks for the link Fap. Is this filter available in a kit form, or just the schematic as provided? Where does it plug in, between the cartridge and phono stage or after the phono?
I assume the whole signal rides through it ... if so then I assume the op-amps affect the entire signal. So I would expect that different op-amps might affect the overall sound in different ways - no?
You mentioned an increase in apparent available power, so maybe it adds a bit of gain also?
What phono stage are you using with it? Did you notice any affect on transparency or soundstaging or the top end?
When I built it I was told that Corian is dense and fairly inert. It certainly is heavy (and pretty to look at), but I often question the same thing as you. I have toyed with the idea of applying a heavy piece of aluminum or some such to its bottom as an additional damping solution. But I have trouble trying to figure out how to attach it sufficiently and whether I should put some EAR Isodamp or some such between it and the Corian (e.g. constrained layer damping of sorts).
Hi Bob, yes circuit boards are available for the circuit, but all components need to be sourced by the constructor. All parts are easily available from the usual parts shops.
The filter input is connected to the output of the phono stage. I also use the Elliott Sound Products P06 phono stage which actually has an extended low frequency end. The P99 filter cleans up all unwanted cone movement due to warps etc completely. 18 Hz is where my filter starts operating.
As the amp is no longer trying to reproduce all the unwanted subsonic rubbish, there is more power available for the real music! Regards, Fap.
Bob, oh I forgot to mention I've noticed no audio degradation to any aspect of the audio quality with the use of the subsonic filter.
I was worried about that possibility, but it hasn't happened. I'm happy! Also there no no gain through the filter. The filter circuit is set for 'unity' gain. Regards, Fap.
I suspect you are not able to 'dampen' the vibrations from the wood block or corion table. Squash balls was the right idea. Spikes are a bad idea. Personally I'd try memory foam next or a different sized wood block and platter - to me they both look too thin and both would necessarily tend to vibrate/flex in the vertical plane over their surface.
Of course you guys know that you could also do the filtering between the pre and the amp. I'm beginning to think about trying this sometime for exactly the reason Fap pointed out. If you cut those unwanted frequencies out so that the amp and driver doesn't have to work on trying to reach those lowest regions, it should clean up the bass. Hey, it works on the other drivers up the spectrum.
Most rumble is from vertical groove modulation. Horizontal modulation, which is a mono signal is much cleaner. A good rumble filter will blend the LF signal to mono, which many people do anyway when they connect a single subwoofer. Also, when records are cut the LF is often blended to mono right on the LP so that less-than-audiophile cartridges can stay in the groove. If the LP has been made this way all the LF you are getting off it in stereo is rumble.
Many LPs have rumble cut into the grooves and no amount of vibration isolation will help. Particularly in older recordings the air conditioning systems of recording halls were a big cause of rumble. It went unnoticed until newer playback systems with extended LF response came into being.
In his paper on resonances in turntables,Paoul Ladegaard of the air bearing tonearm fame,theorises that cartridge/tonearm resonance is by far the most important issue to be addressed here.Therefore matching your cartridge to the effective mass of your arm,so that you have a cartridge resonance of 11-12HZ is the most optimal adjustment you can make,coupled of course with good isolation.Ladegaard was sure rumble does not exist and you corrected this parameter.
As I understand it, in the ESP P99 design the idea of summing the two stereo channels to mono was originally considered but later discarded because of possible frequency response anomaly considerations.
My own experience with the P99 filter is that its design is superb and it works perfectly in practice as intended. Regards, Fap.
I wasn't that happy with the summing solution. Stereo subs have proven much better in my room. The bass is no longer boomy, LF details and directional clues are much better.
36 dB roll-off! That'll get the job done.
I'm curious about the phase issues mentioned on the page that Fab linked and wondered what some of you guys think. I was thinking of such a subsonic filter at the input of the sub's plate amp. My question regarding the low frequency phase variations with such a filter is this. If the mid-bass driver is feed by the line out of the sub's plate amp, would that alleviate any/most concerns about phasing?
Dan_ed and Fap...I am a strong proponent of multiple subs, but when playing LPs I have found summing of LF to be essential. Of course you can make a rumble filter which simply attenuates all LF, but why throw away the mono component which is relatively rumble-free?
Hello, I was the original poster in Alberts thread asking him about this. I had planned for a thread but PTMCONSULTING beat me to it:)!
I told Albert that I need a 20hz (subsonic) filter and a rumble filter at 40hz. I have stereo subs, they are stereo down to 40hz, below 40hz is mono and then the 20hz filter kicks in. This eliminats most of the unwanted noise.
My system consists of a Shelter 901 on a VPI TNT 3 with a Eminent Technology ET2 arm. A pair of Bent Audio step up transformers into a Hagerman Trumpet then into my electronics/speakers. The two filters are built into my Marchand Bassis.
A simple question for everyone reading this for an informal poll. Do you or do you not need or use a 20hz filter or a rumble filter?
Myself I use (obviously, need) a 20hz filter and a rumble filter at 40hz.
Bob (Acoustat6) - it seems that we both use a Hagerman Trumpet. This is a great phonostage but we both seem to suffer from a subsonic problem using this unit.
According to Jim H, he didn't limit bandwidth in any way, instead relying on the TT itself to provide the isolation.
- are there additional isolation solutions to eliminate this that can be implemented on the TT, like a constrained layer damped heavy sub-structure under the plinth, aka 1/4" Aluminum/lead/etc?
- is the problem inherently in the grooves where only an electronic solution would address it completely?
Oh, great! Two Bob's. ;-)
Ptmconsulting, I think that at some point all you are left with is the groove thang and resonance from the table so there could be a need for an electronic solution for subsonics. I have my table sitting on two 1/4" aluminum plates that are bolted together. This plate sandwich is sitting on 3 Stillpoints. All of this is sitting on a 4" deep sandbox with granite shelf. Other than warped records I don't notice any problems.
But, as I said before, I am probably benefiting from the natural roll-off of my sub/bass horns. So maybe that answer's the other Bob's poll question. I don't think I need a sub filter at this point. Less is most always better, IMO.
However, I am open to trying it to see if I could benefit from using one. I'd probably shoot for a 16Hz cut-off.
Hello, Bob and Dan, I believe we are of course looking at several different problems rolled into one. Turntable isolation, the turntable, system freq response, the recording/pressing, cartridge/arm compatibility etc.
Bob, most definatly it is not a "problem" with the Hagerman.
One of the things I see (and which Dan mentioned), in comparison with Dans system is that my system is 8db UP at 20hz as opposed to Dans which is down 6db at 20 hz. That is a 14db difference at 20 hz. This means my system is 4-5 times louder than Dans at 20hz! And my freq response is still climbing till 16hz (ie: 10db up at 16 hz, therefore perhaps a 20+db difference with Dans at 16hz). This is a huge difference and can certainly explain a need for a filter or for that matter not needing one.
Of course this does not address the question where does this "noise" come from. Though it may explain why some need a filter and others don't.
The other Bob,
Bob #2 (I like that! :-)), that is the measured natural roll-off of the horns. To further complicate things there is a +6dB gain with having two subs, or so I am told. But your reasoning is still valid and does explain how different systems may need different solutions.
Acoustat6...What you describe is ideal. All we could quibble about is the frequencies.
So I think I'm hearing what I kind of feared - that, given very good isolation, the final solution to subsonics lies in the signal path via a filter of some kind. I fear this because I would prefer to keep things as clean as possible. I fear this because I just know I will hear something missing in the top end, or the soundstage, or something like that that bothers me more than a little subsonic rumble once in a while.
I guess the only way to know is to try it myself. Well, I'm a DIY kind of guy, and the filter can probably be built for about $50 and a little time. I've got a few questions out to Elliott Sound Products about their filter and how I can implement it. I will share those on this thread when they reply.
The First Bob (#1 I guess, since I started the thread :-)
I received a reply from Rod Elliott on my questions about his filter (see below):
My question about using a lead acid battery or a laptop power supply: "The circuit is specifically designed to operate from a split (+/-) supply. While a single 12V supply could be used, I don't recommend it."
Op-amp related questions: "All the signal runs though the opamp all the time - there's no other way to do it. You can use any dual opamp that you like - despite its age, the NE5532 is a good choice, as is the OPA2134."
Gain related question: "The circuit is unity gain."
Thanks Rod. I will have to reassess after the holidays are over. I may try a few other things in the meantime. Maybe an experiment with resonance damping in the headshell just to make sure it's not a mechanical issue I'm having.
Thanks for everyone's replies,
Hi Bob#1, Keep us informed. Many times, people report a increased clarity to the music, as a result of removing unwanted cone movement (equals noise, wasted power from you amp and loss of control of the driver). And your amp will be happier.
You appear to have only one sub, so you are in mono at your crossover point. That would be your "rumble filter".
You now need to try a 20hz filter for the subsonics.
Albert had kindly offered to speak to me over the phone regarding this issue, but I think we should keep it in this thread so everyone can benefit. Albert if you have any suggestions or comments please post them here.
Bob#1, you are probably limiting your system if this is a problem in your system. It needs to be eliminated for your system to shine (if it is disturbing/loud enough). How you do it is up to you. Whether you can find a mechanical solution, adding a filter or roll off of your speakers low freq extension. All of these have benefit in not hearing rumble or subsonics. If you can live with a little "rumble" that is an option that is up to you.
My guess is it is not rumble (since you have a mono sub, OR it may be rumble that is above your crossover point!) so it is probably subsonics ie: below 20hz. And filters work very well for this.
You never did mention when you have this problem, is it at certain volume levels, LPs with low bass, certain records that otherwise appear quiet?
Of course there is one other problem that is not system related which I mentiond above, which is rumble pressed into the record. Some of this rumble can even be above 100hz. This you just have to live with, knowing that it is in the lp and not your system. But even this can be eliminated, with a filter. The problem with this is that you want to keep it stereo down to as low as you can. I think this means stereo down to at least 50hz or better yet 40hz. And these freq will do a very good job of elimininating most rumble.
We are not men , we are Devo
Hey Buddy-Bob 2,
I can say with some certainty that the woofer pumping is there on most LP's to one extent of the other. But my ears feel like they are popping on some, but not all, LP's. If I turn the sub off on these I don't get that annoyance (my regular speakers probably drop down to about 30hZ). It is most noticeable on the lead-in groove and 1st song or two, and less at the end of the record, but still there.
You are correct about the amp - less low frequency need means a more efficient presentation overall, helping both speakers and amp.
I don't have time for a new project right now, but I will probably get itchy after New Years and look at this possibility again. It also means adding another interconnect into the mix, since there's no room to incorporate this into an existing box.
I've seen or been able to feel (to the touch) unwanted low end woofer excursions in smaller bookshelf/monitor speaks I've owned in the past during record playback that on paper could not produce subsonic frequencies.
This tells me that the unwanted signal was not subsonic, yet still undesirable in terms of reproducing unwanted low frequency noise often associated with record playback that one would ideally prefer to not exist.
Despite having access to low in addition to subsonic filters available, my choice was most always to not apply low (high pass) filters that would also negatively impact the real music signal in that range of the audio spectrum.
Effective isolation, clamps, etc. are probably more effective ways of dealing with low end noise introduced during playback of warped records, etc. without impacting the music.
If your record is warped or cut too poorly to deliver satisfactory sound, even with filters, clamps, etc., then you have two practical options:
1) get a better pressing of the record
2) buy the CD or digital equivalent if possible.
Unless the tt is not operating properly, that is seldom the cause IMHO.
Low end noise, audible or not, is one of the inherent banes of vinyl.
That's just the way it is.
Bob#1 said, "I can say with some certainty that the woofer pumping is there on most LP's to one extent of the other."
I say, you are correct on your assesment.
Bob#1 said, "But my ears feel like they are popping on some, but not all, LP's."
Yep, no doubt some are worse than others and some have almost zero rumble, or less subsonic noise.
Bob#1 said, "If I turn the sub off on these I don't get that annoyance (my regular speakers probably drop down to about 30hZ).
Sure you are not reproducing it! But its still there!
Mapman said, "I've seen or been able to feel (to the touch) unwanted low end woofer excursions in smaller bookshelf/monitor speaks I've owned in the past during record playback that on paper could not produce subsonic frequencies."
I say, yes, that's true but we are dealing with two different entities, though they may have the same mother. Subsonics is a different ball of wax from rumble.
Mapman said, "Despite having access to low in addition to subsonic filters available, my choice was most always to not apply low (high pass) filters that would also negatively impact the real music signal in that range of the audio spectrum.
Effective isolation, clamps, etc. are probably more effective ways of dealing with low end noise introduced during playback of warped records, etc. without impacting the music."
I say,I am so happy that that works for you, but it does not seem to be working for me or Bob#1. It seems to me that the more effective way is the two filters, for me. Without impacting the music.
Mapman said,"Low end noise, audible or not, is one of the inherent banes of vinyl.
That's just the way it is."
I say, why not put the filter in, if it is a problem. If you don't hear it, don't worry about it.
"I say, why not put the filter in, if it is a problem. If you don't hear it, don't worry about it."
Agree. It's not illegal. If it works for the better for you, then you should do it.
BTW the other common negative effect I've seen with rumble and other types of low frequency noise, is that even if it is not audibly disturbing to someone , the fact is it uses up significant amplifier power to produce noise. This can result in the amp clipping and damaging the speaker. Ironically, the low frequency noise usually ends up damaging the tweeter first, at least in most cases that I have observed over the years.
Rumble, due to turntable vibration or recorded in the vinyl has always been my second gripe about LPs, the first being HF surface noise. CDs have taken care of this problem.
Imagine my surprise to get a CD of theatre organ music (from Organ Stop Pizza, in Mesa AZ) which has what seems to be lots of LF noise. It took me a few plays to realize that this sound is exactly what you hear in the hall as you eat your pizza and drink your beer. It's the organ's air generation machinery. Once you realize that it is not a recording deficiency it ceases to be an annoyance.
In a similar vein, surface noise does not bother me when I play my LPs of Benny Goodman's 1938 broadcast recordings. Somehow it becomes part of that particular musical experience.
I am in agreement with your perspective on these things.
Two good things (relatively) about low frequency noise playing records:
1) I find it less offensive during listening than high frequency noise
2) If you can see the woofs on speakers, you can be sure when it exists because you can see and/or feel it perhaps even easier than you might hear it.
I tend to agree with you Mapman. The less I have to put in the signal path the better I feel about it and the better the transparency/musicality. I would far prefer to find a mechanical solution that doesn't alter the rest of the sound, if possible.
If not, I could still be happy with my rig the way it is. This is not a burning issue, but just an investigation into options and potential solutions.
And in this economy I am less likely to get itchy fingers and spend $ on a trial and error kit that has zero resale value (unless, of course, I DO get itchy fingers after the holidays and need a project to keep me busy).
It hasn't been a burning issue for me either. It is what it is. You either live with it or there are ways to deal with it both physical (clamps, new records, CDs instead) or via signal processing (filters, etc.).
On the signal processing front, when it comes to dealing with complex signal processing issues like this, technically, a lot more can be done in the digital domain than in the analog, but it is a complex undertaking and not one I would recommend for the uninspired.
And why, in God's name, would one ever run a beautiful analogue signal from a turntable through anything digital, unless they were forced to upon pain of being drawn and quartered? :-)
I think I'll open a bottle of wine tonight and listen to something nice on the old-TT.
Not me, but I just thought it ironic that technically the most practical way to clean up a messy analog signal off a turntable were one so inclined might be to convert it to digital first before doing the processing.
The horror! The horror!
Still, DCS and other companies do some truly magical things in the digital domain!
Ptmconsulting... Your "beautiful analogue signal" has probably been generated out of a digital mixing consile :-(
Hi Bob, you could try these;
They are only $30 and would give you an idea of what would happen if you implemented a subsonic filter. I dont know the quality of the units or how they would sound. But it would give you a feel for a subsonic filter and an indication of what one would do for your system.
Please feel free to experiment with you tt/arm/cartridge and let me know if you come up with something that you think I should try.
Hey, those little RCA "Sub Sonic Filter pairs" looks cool, and may well be worth trying out for only $29.
There are 2 values: 20Hz and 30Hz. Both have a 12db slope to them - not very steep. So if I was looking for 3db down at 17Hz then the best choice would be the 30hZ ones, right? I mean, down that low on the scale a 12db per octave slope goes very slowly down.
I found a chart with note values on it, but it only goes to 27hZ: http://www.phys.unsw.edu.au/jw/notes.html
Well, late for the discussion, as always.
It looks I'm having the same problem with my TT- woofers and even midrange driver pumping, start. with the lead in groove.
Subsonic filter aside for now, where do I start?
Cartridge?, TT support?, mat? subwoofer?
Hi Bob, I would most definatly go with the 20 hz filter, and I do believe 12db/octave cut is enough for you. Though my 20hz filter in the Marchand Basis is 18db/octave.
You do not want to start eliminating freq at 30hz. It is not necessary with todays great turntables and we DO want extension down to 20hz. Just not below it.
If the noise you are hearing is rumble, not subsonic, then a rumble filter is necessary. This is only necessary if you have stereo subs. Then you need to go to mono at a freq that eliminates most rumble which I believe (at least in my system) at 40hz. Some lps will still exhibit rumble above that freq, but they are far and few between and most is eliminated by the rumble filter at 40hz. A little higher is OK (up to 50hz, perhaps a tad higher). The Kab rumble filter which I believe was mentionend in this thread is set at 140hz. WAAAY to high, that is stereo there and includes voices instruments that would be mono'ed at 140hz and below, NO good.
With a 12db/octave 20hz filter you would be;
-12db at 0hz,
and -6db at 10hz,
and -3db at 15hz,
and -1.5db at 17.5hz.
With a 18db/octave 20hz filter (such as the one I employ) you would be;
-18db at 0hz
and -9db at 10hz,
and -4.5 at 15hz,
and -2.25 at 17hz.
A 30hz filter would get you -12db at 15hz and -6db at 22.5hz. You dont want that.
I'd start with the production quality of the record being played especially if the problem does not occur with the table running and no record playing or it is obviously variable from record to record.
If it is the table (is that a direct drive model?), maybe try a mat with better isolation.
Thanks for your response. Yes, it is DD table, and I use Isoplat mat with cork backing. Driver pumping seems to happen only with the record playing, and with all types of record. As soon, as I lift up the tonearm, it stops.
Could that be an issue with the cartrige compliance mismatch with the arm? I have Shelter 501 MK II on silicone damped Technics arm.
Also stock Technics feet are replaced with Audiopoints.
There's been a lot of talk about rumble and subsonics. How does one differ from the other?
Another question about these little RCA filters - anyone guess what's inside them? They are sooo small there can't be much. The rest of the signal runs through them too, so I am concerned a bit.
BTW - I tried something a little different today. I think by now you've all heard of the Cartridge Man's isolator:
I never liked the idea that it was squichy and compliant. Some time ago I tried putting a thin piece of EAR Isodamp between my cartridge and headshell and thought I noticed a difference. But I pulled it out again. Well this morning I put it back in and I can say that I think this makes a nice improvement in soundstage and smoothness of sound (Yes, I adjusted the balance and VTA afterwards).
Unfortunately it didn't cure any low frequency aberrations, but I do think it is going to stay. The good news (and you didn't hear it from me) is that you can contact EAR and they will send you free samples of Isodamp. It also works well under your motor as a vibration damping aid, or under any transformer in a power supply.
I notice in your pic that the table sits close in from of on of the speakers. That may be a challenging location unless the floor in your listening room is extremely rigid, like a concrete foundation or such and same true for your stand.
If you can as a test , you might try locating the table behind the speakers for better isolation.
Unfiltered, on most good systems, most records will produce some movement in the woof and possibly the mid-range as well depending because few if any records are cut perfectly or are perfectly flat resulting in low frequency noise.
Relocating the table better and using a record clamp might be two easy things to try to reduce the effect.
Visible driver movement is often associated with the specific record itself. In this case, the patterns and magnitude of movement will vary from record to record.
If the problem is due to vibrations from the table motor system being picked up, I would expect little variability in pattern and magnitude from record to record.
If motor vibration is the source, it would probably persist the same regardless of tt location and specific record playing and this may require servicing of some sort for the table to fix if possible.
Bob#1 said, "There's been a lot of talk about rumble and subsonics. How does one differ from the other?"
Subsonics is below 20hz and rumble is out of phase info above 20hz that is usually diminished by 40-50hz, though some lps have rumble up to a much higher freq., perhaps up to 100hz and even higher? And some have very little.
I don't know what is in the little filters. There cannot be much. Perhaps you would like them better if the came in a 20 pound one foot square box with a ton of wires and capacitors and resitors and tubes and...:)
I think the point here though would be to try them just to see if it affects your problem in a posative manner. Perhaps knowing that the little filters are not the best in terms of sonics. But if they do the job as intended a higher quality filter would be in order.
On the other front I spoke with my brother last night on this subject and his suggestion was to look into cartridge/tonearm compliance. I will work on this and post my findings. He suggested, after doing some research and calculations, that I add weight to my tonearm to lower the current calculated resonance of 14hz to 11hz.
I have a Dynavector 20X-H cartridge on a Moerch DP6 red dot tonearm. Supposedly the correct tonearm for this cartridge (gotta love a Moerch, since you can buy and change armwands to match the compliance of the cartridge).
I was listening yesterday and, although there was some cone movement in the sub and woofer drivers, it didn't interfere with the music at all. I think I'm leaning more toward living with it than putting something else into the signal path that might negatively impact the rest of the sonic spectrum. Getting rid of this last little annoyance would not be worth compromizing any other part of the music.
"Perhaps you would like them better if the came in a 20 pound one foot square box with a ton of wires and capacitors and resitors and tubes and...:)"
Isn't that necessary to qualify as high end?