@audioquest4life , you tossed the old hinge hardware? Sota uses some really nice hinges with adjustable friction. I'm sure Donna would sell you a pair. You can mention my name if you like. Having to lift the cover off al the time is a recipe for disaster.
@lewm , Thanks Lew. I'm not sure about "dogged determination." Setting up the jig is the hardest part. It takes a lot of test cutting to get the tolerances right, but once that is done you can knock these out all day long with minimal effort. Now hand cut dovetails is dogged determination. But, this is not a $10,000 coffee table and I'm not exactly getting paid for it. After all, it is just a turntable:)
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Nice finger joints. Dogged determination, for sure.
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@mijosyn,
LOL, they sure do.
This excerpt from your statement is so true ""But, experience is always the best teacher." Excellent point.
Speaking of dust covers, after our last move, my Denon dust cover ended up shattered, in pieces, and missing hinges. How that happened is just weird. I had to order a replacement dust cover from that company on e-bay who makes replacements for a variety of turntables, but, it did not have the mounting hardware to connect to the turntable hinges. It is a perfect match and has the hinge slots, just no hinge mounting hardware. So, now I have to lift the dust cover and set it down when changing out records in our living room system. I keep the dust cover on otherwise to control dust from settling and keeping the cleaning lady from polishing the wood veneer on the Denon. I have found the tonearm a few times moved to the center from its resting place.
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@audioquest4life , Glue always makes that claim:)
Yes, what I did when I was young is quite comical looking back on it. Learning in the school of hard knocks. But, experience is always the best teacher and after 55 years of it you usually gain enough to have some idea what you are doing. The big leap was when I started out with DSP in 1995. Seeing is believing and when you start measuring the lights come on.
Rock On, Mike
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@mijostyn ,
Glad you have things started out and now you are able to "rock out" again and play your music at listening levels that only a few appreciate...I get it. I also like to play loud every once in a while. Well, perhaps, more lately;). The work you did to your system and room to ensure that you can enjoy playing music loudly without problems is what makes this hobby fun. Your subwoofer builds are intriguing to me because customized them to take advantage of using DSP, which you already use for your system. I use SVS (4 each) with the limited DSP they have, but it works.
Like you, I have lots of mass for my turntable. It is already 120 plus pounds, sitting on top of a 275 pound Clearaudio MontBlanc stand, on top of bamboo floor with anti-vibration and sound absorbing adhesive (that's what the special glue container says (275 per 5 gallon), on top of concrete. No resonance issues in this system even with 100db plus levels, which is not part of my loud norm. only once in a while.
Back to the main topic. Of course, you realized this symptom was some form of resonance emanating from the dust cover based on increasing the loudness of your music. I experienced that once with my old (still is use for living room) Denon DP62L sitting between a pair of Polk Audio SDA2's being driven by Carver M1.5Ts.
This was in the early 80's when I first joined the military and lived in the barracks, so no thought of treating room acoustics. Whenever I played Def Leppard or AC/DC really loud, I would hear that resonant feedback that you mentioned. My trick to eliminate this resonant feedback was to prop the dust cover up so that it was not entirely touching the turntable base, about a 45 to 55 degree lift. I forgot what I used, but I am sure it was some crude and rudimentary fix that only Soldiers would figure out when you wanted to make things 'happen" or accomplish the mission.
Back then I was a novice and knew virtually little about tweaking, only, plug and playing and treating issues if they were gross, bass to boomy,.move speakers away from walls, too little bass, move back to walls, not loud enough, get bigger amps, and bigger speakers, and so on and on it went for years. I have learned a lot since then...hence, my moniker, which has philosophical meaning to me, the journey will never end. We will always learn something new as we grow older or experience new things, in this hobby, other hobbies, or in life.
Hmm, now I want to dig out some Rush 2112, Three Blind Mice, and Miles Davis, talk about eclectic tastes in music, LOL. Low level listening sometimes, in the room live feeling most of the time. It is all enjoyable.
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@mijostyn
Thats great news - perhaps you could play Reference Recordings RR12 "Gates of Dafos" at 120db and post it on youtube.
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Dear @mijostyn : Good ! !
Now is time to enjoy it: just do it !
R.
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@lewm , @rauliruegas @atmasphere The skirt is finished and installed. It is lined with felt which makes a good seal. It works perfectly. I can no longer induce any feedback with the dust cover closed. I can sleep at night now:)
I
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Dover, The next arm I get will be a Schroder LT. I am already looking into mounting it on a modified Sota base since I plan on making a new one. As long as the suspension can handle the greater weight I should be able to make it fit.
I am in total agreement on the Linn having owned two many years ago. They do seem to have everyone hooked on the upgrade mania. Good business.
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@dover , I believe you are analyzing the problem incorrectly dover. Increasing the effective mass would make things worse by giving the the tonearm more inertia. The bass gets the suspension bouncing at 24 Hz. Life not being perfect, the tonearm has more inertia at the cartridge end and it is bouncing also enough to generate a 24 Hz signal that keeps things going. If the suspension does not bounce there is no problem regardless of volume. I can peg it no problem. I'm quite sure this would happen with any tonearm mounted as it is just along for the ride.
The bass response is pretty much the same across the shelf. It does not increase appreciably in the corner because the side wall is only 1 foot deep. It is not much of a corner from an acoustic standpoint, not at all like the corner of a room. This was one of the first things I measured.
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@mijostyn
@dover , Are you saying the Schroder is causing my feedback problem? If so that would fly in the face of the obvious. If I lift the dust cover or close off the bottom the feedback stops. I did nothing to the arm.
The feedback is being amplified by the cartridge, which is mounted on the arm, which is mounted on the TT subchassis.
The closed lid changes the environment, but the arm/cartridge is what is getting excited at a particular frequency.
I would have tried a couple of things -
Bypass the suspension and see if any changes occur.
Increase the arm effective mass by 2g
You might find the problem disappears.
Also I agree with @atmasphere - locating the TT in a corner or niche is the worst possible location for the sort of issues you have.
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@mijostyn
I was just about to buy one of those Oswald Mills Audio K3’s. Actually, it is the only way you can get one of those arms.
Actually you can build it yourself, it’s an old audio amateur design, here is an example
Its all a parody - I call the arm "a bridge to nowhere", nowhere being the TT - its a con.
Its similar to the Linn Sondek - comes from the land that gave us haggis, well the Linn like the Haggis is a bag of bits that nobody wants.
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@lewm , and I was just about to buy one of those Oswald Mills Audio K3's. Actually, it is the only way you can get one of those arms. I plan on tossing the turntable and sticking that arm on an AR XA just for spite.
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Like you, Mike, I was joking. I wouldn’t have a chance trying to change your point of view.
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@rauliruegas , I hope you realize Raul that I was joking. That's what the smiles were supposed to convey.
I am here because I still play records just like everyone here. We all enjoy music in our own way. You have no idea what my listening capabilities are and I yours. I have no idea what you are listening too and you I. It make more sense on these forums to talk about the way things work, much more concrete. We both dislike unipivot arms for the exact same reason. They do not function the way the ideal tonearm should. We both have probably used and listened to examples we did not like.
@dover , Are you saying the Schroder is causing my feedback problem? If so that would fly in the face of the obvious. If I lift the dust cover or close off the bottom the feedback stops. I did nothing to the arm. It is perfectly capable of playing at outrageous volumes without any difficulty at all. It is tuned right where I like it. If you are saying it is just a bad arm I and many others will disagree with you. Thanks for your input.
@lewm , I think that is an argument for a different day.
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@mijostyn
I'll let you in to a little dirty little secret - its the arm.
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Dear @mijostyn " has no idea what he is listening too "
That is all my knowledge level I'm and my friends totally sure.
To my quality level standards your phono stage is totally out of question even with your Voice..
At this time all your statements in this thread tells me that your overall quality MUSIC level targets are way lower that what you showed in other threads. If this is your reality then you are not a gentleman that really want to help analog lovers in this forum through your posts.
Your technical knowledge level is way superior to.
R.
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Hold on Guys! I have not bought one yet. I'm just going to listen. I am equally enthralled by low impedance MCs and transimpedance phono stages. Unfortunately, the price of admission is going up in leaps and bounds.
I see what the problem is with strain gauges unequalized. Most rooms create more error but that should not be an excuse.
On the other hand I am still greatly enjoying The Voice on my ARC PH3 SE. They match up well and SS guys would never know it was a tube phono stage except maybe rauliruegas who is just claire voyant and really has no idea what he is listening too:)))
I bought a large piece of Macassar Ebony which should be big enough to do the whole plinth. Should I do dovetails or finger joints? What do you think would sound better?
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That statement was probably incorrect. Apologies to Mijo. But I still don’t think he should attempt it before acquiring a thorough understanding of RIAA.
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I don’t know whether the SS SG phono stages account for this but I’d be surprised if they don’t incorporate some corrective filtering in the 500 to 2000Hz region.
@lewm The last time I heard one, it had no eq. The claim was that it didn't need it- which is misleading. And sure enough, the LP I used for reference (which I recorded) didn't sound right. I heard months later that EQ was being offered, but apparently that is incorrect??
The thing is, a strain gauge has really high output; some of them I've seen can drive an auxiliary level input. The parts needed to execute the EQ are inexpensive and small, and could be installed in a very small box that is part of the interconnect cable, since it can be done entirely with passive components. So it puzzles me why this isn't done.
It has to happen in conjunction with transduction of the cartridge signal.
Why is that?
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Dust cover is a kind of ''self explaining'' expression. Dust is everywhere but
we don't wan't them on our records. So even a kid can grasp the
''connection''.
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Interesting experience you have. I don’t like my dust cover to be next to my system at all when I listen, I even keep it in different room when it’s long listening. Maybe it’s too much, but I think my cover is very reflective as it pretty big put on-of style and covering whole tt.
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Whatever you decide, my advice would be not to try to introduce the filtering externally with your digital filter device. It has to happen in conjunction with transduction of the cartridge signal.
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Dear @mijostyn : You need to go for the one that match your way of thinking. No one of both phono stages you named are my cup of tea but this is me and that's all.
Look, when I want to listen analog everything that's below my system control must be analog and does not be digital manipulated in any way.
Again, that's me and I'm way different to you with different targets and MUSIC priorities.
R.
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@lewm , It is a good question I plan to ask Mr Ledermann. I have not seen him mention this. I can do it digitally although replicating the phase shift Ralph talks about won't be easy.
@rauliruegas , I viewed Channel D's web site last night. The Lino C 3.0 is now out and it has both MM and Voltage Mode MC capabilities among circuit improvements. It is also up to $6000 if you option it up. It has also lost the simplicity I like. Makes the Loco look better to me.
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Thanks, Ralph. All Atma is saying is that a strain gauge needs a little EQ in order to correct for the RIAA pre-emphasis standard used to cut all LPs. I don’t know whether the SS SG phono stages account for this but I’d be surprised if they don’t incorporate some corrective filtering in the 500 to 2000Hz region.
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Lots of smart EE with ears have tackled the SG equalizer equation and sonics, Iverson comes to mind…
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So what we have here is a perfect example of knowledge and facts (compliments of atmasphere) vs. ignorance and alternative "facts" (untruths).
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RIAA EQ is +20dB at the bottom, -20dB at the top. SG does not require this so the statement is true.
@millercarbon
Not really... The problem is that by the time you get to 20KHz you're not going to be 20dB down. Please look at the actual RIAA de-emphasis curve:
See that flattening out part in the middle? That's what I'm talking about. A strain gauge simply bypasses the flattened out part and continues rolling off the output following the 6dB slope as seen on the left side of the curve- so the highs simply won't be right. Imagine that red line just continuing down at 500Hz instead of flattening. You can see the error that is introduced. In reality it won't be as far off as the red line would be as I just suggested since were talking about a curve using analog filter theory.
To properly EQ a strain gauge, a pole (seen at 500Hz) has to be introduced (a rising response) and then a zero (seen at 2100Hz) going back to flat, so the strain gauge can do its thing.
So imagine an EQ curve that is flat from the bass up to 500Hz, then rises for 2 octaves at 6dB/octave and then goes back to flat. That's the math of it; the actual curve won't do that- it would be smoother of course in a way that is similar to the smoothness of the de-emphasis curve you see above. If this is not done the EQ won't be right.
@mijostyn Have you heard the cartridge? Theoretically it should out track any other cartridge but his MI cartridges track anything I can throw at them. I can correct frequency response problems but I won't get involved if there are not significant advantages in the design.
I don't know if its the same one but I have heard Soundsmith SG cartridges before. Tracking isn't what I'm talking about- I'm sure it tracks fine as the one I heard did. I'm talking about equalization. I provided the information you need to set the EQ right above. Can you dial that sort of thing in? If you do it in the digital domain, be sure to include an algorithm that includes the phase shift and frequency bump of analog filters.
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@atmasphere , Have you heard the cartridge? Theoretically it should out track any other cartridge but his MI cartridges track anything I can throw at them. I can correct frequency response problems but I won't get involved if there are not significant advantages in the design.
@rauliruegas , I have no experience with the Lino C. I have an ARC PH3 SE which I really like for high output cartridges. It is a simple unit with just one switch in the signal path. It is a hybrid tube unit with a FET front end. It really does not have enough gain for cartridges with output < 0.5 mv. It is 30 some odd years old and still in perfect working order but it is time to move up. I do not like complex phono stages. It is too easy to damage the low level signal coming from a LOMC. The Lino C is a minimalist unit which is balanced throughout which I really like. Loading adjustments are not required and it is battery operated, another big advantage. I can use the ARC for high output cartridges which I prefer to MCs with certain music. The other candidate is the Sutherland Phono Loco.
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RIAA EQ is +20dB at the bottom, -20dB at the top. SG does not require this so the statement is true.
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Because of the way this works it requires no RIAA equalization. One of its many advantages over the conventional approach.
@mijostyn @millercarbon This statement is false. While it is true that the cartridge has an output that seems to complement the RIAA de-emphasis curve, from 500Hz to just above 2KHz (75uS) in the RIAA curve there is a bit where it flattens out. This causes an unequalized strain gauge device to be a little off. So they do need equalization to be correct but not nearly as much as a regular constant velocity device.
Its correct to say that it roughly approximates the needed de-emphasis.
Take a look at the RIAA curves- you'll see a 'zero' at 500Hz (318uS) (where the math says 'flat'- that's why its a 'zero' instead of a pole) and a pole above 2KHz (75uS) which re-introduces the slope. A strain gauge doesn't have that zero so what happens is it has the same slope across the band. This causes the highs to be and sound wrong. Its not glaring but if you know the recording its easy to hear.
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Dear @mijostyn : Years ago I listened the SS SG mounted in a Schroeder tonearm and in first rate room/system and there I had the opportunity to compare it against the Lyra Olympos and at least for me no contest against that Olympos set up.
Years ago too in the SS site was a link and the SG real curve and unfortunatelly SS decided to take out/off the site.
" The Italian article did a very good job of explaining to a general audience the difference between "velocity" devices and "displacement" devices.."
In a very hot dialogue where I posted PL him self posted:
" I have measured the SG in many arms, and recently in my Schroder Reference SQ, the new SG design (which you did not hear) it was +/- 1dB from 50 Hz to 12K in conformation with RIAA. ..."
That measure tell us a swing of 2db where our ears are more sensitive but the deviation from the RIAA below 50hz and over 12khz are even higher.
No problem with if what you listen like it.
Now, I understand you owned or listen to the Lino that could be better performer that your today phono stage.
I know very well the overall design of the Lino and other current mode phono stages and for personal reasons I'm not with the kind of overall designs/parts used to build those phono stages.
But that " preference "/captivated you have with and that you "" exaggerated highs supposedly a hangover from the RIAA curve. Several reviews have noticed this. I can correct for it "" in the digital domain precludes my recomendation to you to really arrive nearer to the recording and live MUSIC event.
My path/road is totally different from yours.
R.
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@millercarbon , Correct MC, when the gauge is stressed it changes resistance which modulates the supplied voltage which is subtracted afterwards leaving only the signal. Messing with the power supply might not be a good thing. If the voltage subtracted is not exactly equal to the voltage added you will get a dc offset. If your amps go down to DC you could have fried woofer for dinner. If run through a preamp this might filter the DC out.
I do not think it is weak bass but rather exaggerated highs supposedly a hangover from the RIAA curve. Several reviews have noticed this. I can correct for it so it is no worry for me. Weak bass I won't tolerate. If I can't feel the bass drum beat that would kill it for me.
@rauliruegas , you did not make a suggestion for a phono stage or comment on the Lino C. I'll be taking 5 records I know very well down with me. I should be able to pick up any major problem depending on the system Mr Ledermann is using. I won't spend that kind of money if I am not completely comfortable with it. I am also very captivated by the transimpedance approach to amplifying a moving coil cartridge. The only problem is that it limits you to very low impedance cartridges. I have no problem with this as there are many excellent low impedance cartridges. I read uniformly good things about the MySonicLab cartridges then there is Lyra and Ortofon. The new Verismo looks very interesting. The My Sonic Ultra Eminant Ex with an impedance of 0.6 ohms is perfect for a transimpedance stage.
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I have the Soundsmith Strain Gauge, got one used about a month ago. SG does not use RIAA or any kind of normal phono stage because it is not any kind of normal cartridge.
MM and MC both are generators that generate a voltage by moving. The faster they move the greater the voltage. SG does not work that way at all. What it does, the cantilever is connected to strain sensors that detect deflection. These are used to modulate a voltage coming in from the SG preamp. So the preamp generates the voltage, the cartridge modulates it (similar to the way a tube acts as a valve) and the resulting signal comes back into the preamp where it is amplified.
Because of the way this works it requires no RIAA equalization. One of its many advantages over the conventional approach.
Overall it is a nice step up from Koetsu Black Goldline/Herron VTPH2A. With one exception, the low end is a bit weak in comparison. In terms of tracking though it is darn near seamless. Recordings that seemed to have hopelessly large amounts of sibilance now sound like the normal level of sibilance you would expect from a real live person. Percussion in particular is tracked exceptionally well. Listening to SG confirms Koetsu has a real talent for tailoring resonance. The Black Goldline may be entry level Koetsu but it truly is a wonderful cartridge. The SG on the other hand gives the distinct impression of listening to the master tape.
SG also has some nice features like auto-mute and a built-in 12Hz filter. Its main weakness would seem to be the power supply, which can be upgraded with SBooster, Farad, etc.
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Dear @mijostyn : I hope you don't pull the trigger on that kind of SG cartridge because make no sense to play LP recorded with the RIAA eq. curve through a dedicated phono stage with no inverse RIAA eq...
Just saying,
R.
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@rauliruegas , what would you suggest?
On December 3rd I am traveling to New York City and on the way we are stopping at Soundsmith to audition the strain gauge cartridge. If I decide to go with that it comes with a dedicated phono stage. For a moving coil phonostage I was looking at the Channel D Lino C, the transimpedance unit. I would probably try a My Sonic Lab cartridge to go with it.
@lewm , Actually, right now I am using 48 dB/oct slopes with a cut off of 100 Hz. Yes, smaller drivers are capable of higher freuquencies. The "speed" of a woofer is indicted by it's frequency response as I said before. Otherwise a subwoofer's sound is not dictated by speed as long as you stay away from it's limits. 12" woofers generally are good to 1000 Hz and we go nowhere near that. With the right crossover and time correction you can match subwoofers to any loudspeaker.
I can get you over your digital phobia in a heart beat. Who knows. Maybe next time you wander towards Vermont :-)
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Dear Raul, That’s a very interesting article. The author makes a good point that using the term "fast" when describing a woofer is specious, because the "speed" required to reproduce very low frequencies accurately is within reach of any well designed woofer. But then he goes on to say: "There are reasons to use lighter, lower-mass woofer cones. They just happen to be different reasons than the ones you’ve read in print. Smaller woofers don’t make faster bass, but they do reproduce higher frequencies than larger woofers can reproduce, and this is all important when it comes to speaker design. You want the midrange driver and the woofer to integrate with sublime symmetry, with perfection and with nary a single problematic interaction throughout their overlap zone. This is why you want smaller, lighter, "faster" woofer cones -- not because they lead to faster bass. That overlap zone is so amazingly critical to your perception of bass speed that there is little or no tolerance for error." Note also that your expert does allow for the idea that some woofers are "faster" than others; he has only re-defined the term in a sense with which I do not disagree. By the way, no one "told me" anything about this. My conclusions are based on real world experiences that I had maybe 35-40 years ago when I was playing around with woofers to supplement ESLs that I then owned. So, I am expressing my personal independently arrived at opinion.
So perhaps I can be faulted for my choice of the word "fast", but what your authority wrote above is what I had in mind. Now if Mijostyn is using an 80db/octave crossover, on both high and low pass filters, then perhaps the capacity of his woofers in his system to produce higher frequencies is moot. On the other hand, all of his audio is passing through the digital domain afforded by his digital filter. That does not appeal to me.
Mijostyn, Along the same line of reasoning, you wrote, "Lastly, there is no such thing as a "fast subwoofer" when a woofer is not fast enough it’s high frequencies roll off." I hope you see the internal contradiction there. If there is no such thing as a fast woofer, then there is no such thing as a woofer that is not fast enough. But to both you and Raul, I would concede that I was guilty of sloppy semantics. When I say "fast woofer", I am thinking of the woofer and its enclosure as a whole. And I did not make that clear. You could put a small, i.e, "fast", woofer in an enclosure that limited its speed by virtue of what happens to the back wave, and it wouldn’t sound so fast, which we can define here as able to integrate well with an ESL panel. Like I responded to Raul, perhaps with an 80db/octave slope you need not worry about the capacity of your woofer enclosures to deal with frequencies above your crossover chosen point.
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Dear @mijostyn : Good, I applaud your attitude to achieve the best sound that puts you nearer to the recording and nearer to the live MUSIC.
I'm sure that your new subs will be an improvement as the new plinth however anything you do can't carry to full success till you change the item that proccess the cartridge signal and that's is the Phonolinepreamp.
No matters what the unit you own rigth now is way inferior of what you are looking for..
Yes, it's up to you.
R.
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@rauliruegas , I know exactly what is going on. The two chambers above the subchassis are resonating at 24 Hz. This causes the subchassis to bounce at 24 Hz. This is picked up by the cartridge completing the feedback loop. The sub chassis is a solid 1" thick aluminum plate that extends to within 3/32" of all sides of the plinth. Your middle ear has a vent tube to release pressure. It is called the Eustacean Tube. When it gets block your hearing gets damped by up to 10 dB at some frequencies because pressure in the middle ear will not allow the ear drum to move as well. On a hunch I decided to block my turntable's Eustacean Slot with the skirt you see on my system page effectively giving it a hearing problem. It was very easy to test. The first track on Soundgarden's Badmotorfinger gets the feedback going throughout the entire song. With the skirt in place there is none. It is a bit hard to miss. When a 24 Hz feedback loop gets going the entire house shakes.
Right now the skirt works perfectly I just have to dress it up a bit. Yes, I can and will build a new plinth that won't do this when I run across that special plank of wood. If I am going to put in all that effort it has to be very special.
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@lewm , It can work either way. I think the majority of people building subwoofers come up with a design concept, then choose an appropriate driver and finally given the parameters of the specific driver tweak the dimensions of the enclosure to suit.
If you look at the picture of my system on the floor you will see a woofer to the outside of each panel then in the center those two boxes on the floor are subwoofers. They are pointed at eachother. These woofers have 200 lb sealed enclosures with a Q of 7.6.
The new design is a decagon cylinder with 1.5 to 2" side walls (they vary). There will be a 12" driver mounted in each end. They will also be sealed. There is no reason to resort to ports when you have advanced "room control" which is really speaker control. With enough power you can make a subwoofer do just about anything. I would have liked to use larger drivers but space will not allow.
The tonality of a system is debatable and we all have our own preferences. What is not is image and detail. DSP allows you the adjust the frequency response of the channels individually so that they are exactly the same. This gives the best image and with it detail. Every audiophile that has heard it goes out and gets a processor and I am not kidding, every single one.
Lastly, there is no such thing as a "fast subwoofer" when a woofer is not fast enough it's high frequencies roll off. Usually, the cone breaks up first. Even 18" drivers can make it to 500 Hz. I think what people really mean by this is muddy vs well defined. Mud is coming primarily from the enclosure. Then there is the amp's ability to control the driver. Some amps are good at it, others not so hot. You need a powerful amp with a very low impedance output stage. Transmission lines are a way of effectively doubling the size of the driver at certain frequencies. They are very difficult to make and require a lot of trial and error tuning. It is much easier to use large drivers or a multitude of small ones.
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Dear @lewm : "" I don't care much about frequencies below 30Hz. I much prefer a "fast" woofer that can mate well with an ESL around the crossover point. A seamless blend is hard to come by..""
Who told you all that including that no sense " fast " woofer or your statement came from your first hand experiences and I said " first hand experiences " because you are totally sure about. Could you explain it?
Btw, please read this link:
http://www.soundstagenetwork.com/maxdb/maxdb061999.htm
R.
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Dear @mijostyn : Thia is what I posted:
""
Now, I think that you are not measuring what you need to measure ( I don't know what you need to measure. ) or you are doing not in the rigth way.
In theory everything can be measured " problem " is what to measure and you have to " figure " out about in ""
You posted: " sealing off the space under the turntable with a skirt. "
You with all your measure tools still does not know what happened down there with out the skirt.
" The final solution is a new plinth... ", yes that's the easy road to go that not necessary warranty success: maybe yes or maybe not.
R.
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Mike, You sure get up early in the morning. More important or at least as important in conceiving a supplementary woofer or subwoofer is the cabinet design. The choice of cabinet type would affect the choice of woofer, I would think. So what are you going to build, acoustic suspension, bass reflex or other ported design, open baffle, or what? (I can't be sure from your photos what type of cabinet you are presently using, either, and I don't see 4 woofers. Where are the other 3?) For me, I don't care much about frequencies below 30Hz. I much prefer a "fast" woofer that can mate well with an ESL around the crossover point. A seamless blend is hard to come by, even if using an 80db/octave slope, or especially so if using such a very steep slope. I have no dog in this fight; I'm just curious to learn. I long ago decided on a fast, smallish woofer in a Transmission Line enclosure as my ideal for mating with a full-range ESL or an ESL that needs help at low frequencies. If I wanted more oomph (as in SPLs) I would use two or more of such agile woofers per channel.
By the way, I agree with you, everything can be measured. But sadly, once you've done that and technically perfected the frequency response in room, I have yet to hear a system that was obviously benefited by such contouring. (On the other hand, in the past several years, I have not auditioned that many systems other than my own.)
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@wyoboy , several issues. The first is that the cabinet is built into an alcove so it is definitely not moving. The second is that I designed the room so that it has no back wall. It is broken up between the kitchen and dinning room, the nearest solid wall being about 75 feet away. I also use line arrays which limit dispersion so as to minimize room effects. There is some modal behavior but it is very weak in comparison to the usual situation. The bass at both side walls is very much determined by the boundry effect. In order to get the turntable to a balanced frequency response environment I would have to put it out in the middle of the room.
@rauliruegas , I owned Velodynes for perhaps a decade in the 90's and I got them working tolerably well but I was using an outboard crossover. IMHO the major problem with subwoofers is not the cone material but the enclosure and positioning of the drivers. Any good subwoofer driver 12" and up is capable of beating 0.5% distortion it not over driven. Everything else comes down to enclosure resonance and shaking. For commercial subs Your Velodynes are not bad but (and I really mean this politely) they are not near as good as what I am using now never mind. what I have in store. I aim to build the most accurate subwoofers possible with current drivers and I will do it. (or go broke trying) As for measuring. How do you know what and how I am measuring except the tools I have mentioned in these threads? The only part of a HiFi system that is not measurable is the human mind. Everything else is easily measured with the right tools. The bane of speaker design has for decades been the room they are placed in and even that is measurable. Any problem you identify can be fixed. If you can't identify it it becomes a mystery and something you "can't measure."
As for my dustcover problem. That has been fixed by sealing off the space under the turntable with a skirt. I can now bury the volume with the dustciver down and it will not feed back. I put a picture of the solution up on my system page. The final solution is a new plinth which I will get around to when I find that special plank.
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Mike--you say the bass frequency response is pretty much the same all along the TT shelf--is the bass response pretty much the same all along the left wall? or could you possibly slide the entire cabinet one way or the other to find a bass null at 20-30 Hz---or would that be a real PITA?
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Dear @mijostyn : If you are using paper cone I think that you have to stay that way ( btw, I cross too at around 100hz. My Velodyne HGS are heavy modified by me because its electronics design: input and crossover are very poor but great all other design/build. ). Stay away of other cone material on subs.
Now, I think that you are not measuring what you need to measure ( I don't know what you need to measure. ) or you are doing not in the rigth way.
In theory everything can be measured " problem " is what to measure and you have to " figure " out about instead to use your time in this thread.
R.
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