turntable styus feedback

[ironlake]

I have a ar 77xb turntable with a shure v15 type V HE cartridge and find the following test to be the best I can devise for checking acoustic feedback.

I have the table on a custom made shelf that screws to the wall. The table sits on that and on the table is a like original turntable mat made by a fellow in litchfield, mn. I can take the tonearm and put the stylus on the record with out the table turning, turn the table on and off to be sure the stylus is in a lp groove and the platter is not moving.

Now carefully start to turn the volume up and listen to your speakers. I can get up to 100 watts perchannel with no howl etc.

How many of these 15,000 dollar turntables can equal that. I doubt any of them.

If you havent looked, go to acousticsounds.com and click on audio stuff and look at the prices. You will see that 15,000 is not out of the question for almost anything yet absolute sound put the 100.00 shure in the recommended category.

Have any of you guys got into this area of sound yet.????????

[dynaco_dan]

I have a ar 77xb turntable with a shure v15 type V HE cartridge and find the following test to be the best I can devise for checking acoustic feedback.

I have the table on a custom made shelf that screws to the wall. The table sits on that and on the table is a like original turntable mat made by a fellow in litchfield, mn. I can take the tonearm and put the stylus on the record with out the table turning, turn the table on and off to be sure the stylus is in a lp groove and the platter is not moving.

Now carefully start to turn the volume up and listen to your speakers. I can get up to 100 watts perchannel with no howl etc.

How many of these 15,000 dollar turntables can equal that. I doubt any of them.

If you havent looked, go to acousticsounds.com and click on audio stuff and look at the prices. You will see that 15,000 is not out of the question for almost anything yet absolute sound put the 100.00 shure in the recommended category.

Have any of you guys got into this area of sound yet.????????

Hi there

If the turntable is mounted on a wall, concrete or brick, or slab then that is maximum isolation from feedback.

[ironlake]

It sure did not work on a direct drive sony table I had mounted the same way. I could not turn it up very loud as the sound waves in the air still bothered the feedback of the table. The ar has to be the best table out there.

[bonejob]

I have a ar 77xb turntable with a shure v15 type V HE cartridge and find the following test to be the best I can devise for checking acoustic feedback.

I have the table on a custom made shelf that screws to the wall. The table sits on that and on the table is a like original turntable mat made by a fellow in litchfield, mn. I can take the tonearm and put the stylus on the record with out the table turning, turn the table on and off to be sure the stylus is in a lp groove and the platter is not moving.

Now carefully start to turn the volume up and listen to your speakers. I can get up to 100 watts perchannel with no howl etc.

How many of these 15,000 dollar turntables can equal that. I doubt any of them.

If you havent looked, go to acousticsounds.com and click on audio stuff and look at the prices. You will see that 15,000 is not out of the question for almost anything yet absolute sound put the 100.00 shure in the recommended category.

Have any of you guys got into this area of sound yet.????????

Hi there

If the turntable is mounted on a wall, concrete or brick, or slab then that is maximum isolation from feedback.

It sure did not work on a direct drive sony table I had mounted the same way. I could not turn it up very loud as the sound waves in the air still bothered the feedback of the table. The ar has to be the best table out there.

With any turntable, acoustic feedback can occur by means of either of two possible pathways: vibrations from the speaker can pass through the turntable base/plinth to the platter and record surface, the circuit completed by the tonearm/cartridge. Or, the sound from the speaker can be transmitted through the air directly to the pickup, which acts like a microphone, completing the feedback loop. By your methodology, you have shown that the latter is apparently not a problem in your system.

As for the former, I invite you to get your hands on a Shure test record or something similar that includes bands of test tones. Start up from the bass. I doubt you will have any problem in the 20-30 Hz area because few speakers produce substantial output in that range. But somewhere between 40-80 Hz, your speakers will likely find a frequency that is a harmonic of some fundamental resonance of your room, vibrating the furniture upon which your turntable rests. Very few turntables are isolated well enough to prevent closure of this kind of feedback loop. The resulting feedback can literally cause your tonearm to jump off the record surface and into the air! It will do this even at relatively low volume!

With real music material, subsonic feedback traveling up through the plinth to the tonearm will be unlikely to cause the arm to actually mistrack, let alone jump up out of the groove, but it can and does adversely affect the reproduction, veiling and muddying the sound. Isolation from direct through-the-air feedback is MUCH easier to accomplish than taming feedback through the plinth caused by subsonic room resonances. Much of the money going into a turntable that costs the price of loaded E-class Benz is spent addressing this more difficult problem. Extremely heavy mounting racks, coupled through the floor substructure, your building's foundation and the ground underneath it and screwing directly into the North American tectonic plate, extremely thick and heavy platters carved from lead crystal doped with unobtainium trioxide and rotating in thin air suspended upon a bearing created by the interaction of super-conducting magnets chilled with liquid helium... etc. etc.... This is all for the purpose of disrupting any and all possible feedback pathways for subsonic resonances and their low-order harmonics.

Is this going overboard just to address that last nth of audio perfection? Only you and your credit limit know the answer to that, but isn't that what high-end audio is about - chasing perfection to the very limits of technology and Bill Gates's net worth? Certainly, a point of dimishing returns can be found in some remarkably inexpensive but well-engineered turntable/cartridge combos. The classic AR turntable happens to match well with Shure cartridges and does well enough in most people's homes. Well enough to satisfy moderately discriminating people with normally shallow pockets. But it's more than a mere stone's throw from perfect. This fact has inspired many DIY'ers with better ears than finances to come up with remarkably creative, yet low-tech and affordable ways of improving subsonic isolation, noticeably improving the performance and sound quality of the AR turntable as well as other good modestly-priced turntables from Pro-ject, Music Hall, Thorens, etc.

[ironlake]

THE DYNAMIC STABILIZER ON THE V15 TYPE V DOES A SUPER JOB OF ISOLATING TONE ARM RESONANCE. tHE SURE TEST RECORD FOR THE 5 HAS A SPECIAL TRACK FOR WATCHING THE STYLUS VIBRATE AT AROUND 10hz , THEN YOU PUT THE STABILIZER DOWN AND THE VIBRATION IS GONE. I USED A FLASHLIGHT TO SHINE ON THE STYLUS FOR BOTH TESTS SO I COULD SEE THE MOTION.