While it may not seem like it, i always encourage "contrasting points of view". That is why i said "let the fireworks begin" : ) If everybody felt the same way or did the same things, there would be no need for forums like this as we could not learn from each other.
To respond directly to Dave's ( Dopogue ) comments, my findings are based on the following observations. By posting these, i hope to clarify why i've made the statements that i did and help some of you better understand why / how i arrived at these conclusions:
1) you MIGHT reduce surface noise on discs using a non-supportive mat due to the fact that the record is not uniformly flat or evenly supported. The stylus is actually riding higher in the groove and is therefore not picking up the "gunk" that is ground down into the groove. While this might seem like an initial benefit, read on.
2) The problem with this is that you now have accelerated side wall wear on the discs and have increased uneven wear on the stylus since it is no longer centered down into the groove.
3) Since the stylus is no longer centered and riding as deeply in the groove as it should be, you now have less distinct left / right imagery. Bass impact is also reduced since the stylus is no longer fully modulated by the entire depth of the groove. If you have a pivoted arm, anti-skating is also affected in a negative manner.
4) The reduction in direct deep groove contact with the stylus reduces dynamic range. Since the stylus is not "pushed" or "modulated" as hard on louder passages since it is riding only the upper surface of the groove, there is less variance from the quiet to loud passages and dynamic range is reduced.
5) Since the stylus is no longer seated firmly and deeply in the groove, tracking ability is reduced. In order to compensate for this, one must increase the downward pressure ( tracking force ) applied to the cartridge. This can be verified if you have test LP's set up to measure the tracking ability of an arm / cartridge combo. In severe situations, the stylus will literally be thrown out of the groove. Needless to say, this is not good and is not only offers audible proof that this type of mat is not beneficial to performance, it offers visible proof.
6) Besides all of the above, a non-supportive platter mat that does not fully support the record and somewhat "floats it on a cushion of air" or "decouples it from the platter" allows the disc to be influenced by air-born vibratrions to a much greater degree. This can lead to increased amounts of acoustic feedback and lower resolution. This is especially true if you like to listen at higher volumes or have speakers that are capable of room shaking bass. The records can actually "micro-vibrate" to the beat of the music being produced at volume by the loudspeakers as they move great amounts of air. This in turn can modulate the stylus within the groove which results in less accurate transfer of information from disc to stylus. As such, all of the isolation or coupling that one has done to minimize TT chassis induced vibration goes out the window as you've increased the problem of "micro-vibration" directly at the record to stylus interface. This results in a greater amount of "haze" and loss of true detail while adding artificial artifacts to what you are hearing. Granted, the artifacts sound "musical" in many aspects as they are directly derived from the beat of the music that is helping to modulatate the stylus within the groove.
As one can probably gather from all of the above, i'm pretty opinionated about this and most any subject that you throw at me : )
Honestly though, i've taken steps to try and miminize all of the above problems and that is why / how i found out what i now know. This knowledge is based on first hand experience with a lot of testing involved. Being a technician by trade, i want to know and understand why something works / doesn't work, so i've tried to do things in a manner that helps me break things down to the point that i can better understand the situation.
As such, i've ended up using a very heavy chassis on the turntable to minimize the impact that external vibration might have on it. The platter and arm are suspended so as to further isolate any vibration that might make it through the already mass loaded TT chassis. The platter is heavy to increase flywheel effect, i.e. minimize speed variations due to taking advantage of having the momentum of high mass already spinning, the platter mat is fully supporting of the disc, the disc is anchored at the spindle via a clamp to increase coupling to the platter and minimize air-borne vibrations, the outer edge is secured in place via a vacuum platter to minimize the effects of warpage while also increasing coupling to the platter and the arms that i use are linear tracking in design to minimize tracking error and keep the stylus as centered within the groove as is possible. These arms also allow adjustable VTA "on the fly" so as to be able to compensate for the slight differences in vinyl thickness.
While i know that there are many different thoughts on the subject, this is what i've found to work best. Obviously, others might have different points of view. As such, i'd love to hear them and why they have those thoughts. I'm never against trying to learn or comparing notes : ) Sean
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To respond directly to Dave's ( Dopogue ) comments, my findings are based on the following observations. By posting these, i hope to clarify why i've made the statements that i did and help some of you better understand why / how i arrived at these conclusions:
1) you MIGHT reduce surface noise on discs using a non-supportive mat due to the fact that the record is not uniformly flat or evenly supported. The stylus is actually riding higher in the groove and is therefore not picking up the "gunk" that is ground down into the groove. While this might seem like an initial benefit, read on.
2) The problem with this is that you now have accelerated side wall wear on the discs and have increased uneven wear on the stylus since it is no longer centered down into the groove.
3) Since the stylus is no longer centered and riding as deeply in the groove as it should be, you now have less distinct left / right imagery. Bass impact is also reduced since the stylus is no longer fully modulated by the entire depth of the groove. If you have a pivoted arm, anti-skating is also affected in a negative manner.
4) The reduction in direct deep groove contact with the stylus reduces dynamic range. Since the stylus is not "pushed" or "modulated" as hard on louder passages since it is riding only the upper surface of the groove, there is less variance from the quiet to loud passages and dynamic range is reduced.
5) Since the stylus is no longer seated firmly and deeply in the groove, tracking ability is reduced. In order to compensate for this, one must increase the downward pressure ( tracking force ) applied to the cartridge. This can be verified if you have test LP's set up to measure the tracking ability of an arm / cartridge combo. In severe situations, the stylus will literally be thrown out of the groove. Needless to say, this is not good and is not only offers audible proof that this type of mat is not beneficial to performance, it offers visible proof.
6) Besides all of the above, a non-supportive platter mat that does not fully support the record and somewhat "floats it on a cushion of air" or "decouples it from the platter" allows the disc to be influenced by air-born vibratrions to a much greater degree. This can lead to increased amounts of acoustic feedback and lower resolution. This is especially true if you like to listen at higher volumes or have speakers that are capable of room shaking bass. The records can actually "micro-vibrate" to the beat of the music being produced at volume by the loudspeakers as they move great amounts of air. This in turn can modulate the stylus within the groove which results in less accurate transfer of information from disc to stylus. As such, all of the isolation or coupling that one has done to minimize TT chassis induced vibration goes out the window as you've increased the problem of "micro-vibration" directly at the record to stylus interface. This results in a greater amount of "haze" and loss of true detail while adding artificial artifacts to what you are hearing. Granted, the artifacts sound "musical" in many aspects as they are directly derived from the beat of the music that is helping to modulatate the stylus within the groove.
As one can probably gather from all of the above, i'm pretty opinionated about this and most any subject that you throw at me : )
Honestly though, i've taken steps to try and miminize all of the above problems and that is why / how i found out what i now know. This knowledge is based on first hand experience with a lot of testing involved. Being a technician by trade, i want to know and understand why something works / doesn't work, so i've tried to do things in a manner that helps me break things down to the point that i can better understand the situation.
As such, i've ended up using a very heavy chassis on the turntable to minimize the impact that external vibration might have on it. The platter and arm are suspended so as to further isolate any vibration that might make it through the already mass loaded TT chassis. The platter is heavy to increase flywheel effect, i.e. minimize speed variations due to taking advantage of having the momentum of high mass already spinning, the platter mat is fully supporting of the disc, the disc is anchored at the spindle via a clamp to increase coupling to the platter and minimize air-borne vibrations, the outer edge is secured in place via a vacuum platter to minimize the effects of warpage while also increasing coupling to the platter and the arms that i use are linear tracking in design to minimize tracking error and keep the stylus as centered within the groove as is possible. These arms also allow adjustable VTA "on the fly" so as to be able to compensate for the slight differences in vinyl thickness.
While i know that there are many different thoughts on the subject, this is what i've found to work best. Obviously, others might have different points of view. As such, i'd love to hear them and why they have those thoughts. I'm never against trying to learn or comparing notes : ) Sean
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