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Review: Custom LP Outer CLAMP (long)

Posted by banpuku (A) on October 7, 2009 at 07:45:32

While not without drawbacks, LP outer rings can increase LP playback enjoyment and sonic appeal. Proper implementation is key and like anything else in audio, “one size does not fit all.”


A few primary benefits of using an LP outer ring are identified below:
1. Improved turntable platter speed stability due to increased mass added by the outer ring. This results in beneficial increased inertia, helping to keep speed stability maximized.
2. Improving record-to-platter coupling minimizes LP vibration.
3. Record flatness is maximized which improves SRA/VTA consistency during playback and also minimize woofer excursion caused by warped vinyl.

Some of the potential drawbacks of using an LP outer ring have been noted in Vinyl Asylum, including:
1. Sound deadness caused by overdamping
2. increased bearing wear due to increased weight added by the outer ring


During the past decade, two turntables have graced my audio system, namely the Rockport Capella II and my current reference, Brinkmann Balanced (note: both tables are of state-of-the-art build and sonic quality). Custom LP outer rings were manufactured for each of these turntables. The review/comments below are specific to the Brinkmann Balanced outer ring.



Design (outer ring vs. outer clamp)

Originally, the design called for brass as the material of choice. However, the material cost differential between brass ($900) vs. aluminum (about $150) led the design toward the later.
The Brinkmann Balanced platter has an outer diameter of roughly 12 ½” with a chamfered outer rim, allowing lipped LPs to hang over the outer edge. This is one of the positive benefits of the Brinkmann Balanced platter design.

Based upon experience with the prior custom outer ring (made for the Rockport Capella II), the current design needed to correct prior design errors. The new design needs to self-center, be easy install/remove and prevent any damage to the platter potentially caused by contact with the outer ring.

To allow easy on/off placement and avoid metal contact between the outer ring and platter, the outer ring has a chamfer on the inside of the lower lip.

The current design is a self centering design, thus avoiding adverse lateral wear on the platter bearing. While the platter OD is 12 ½”, the ID of the ring’s lower section is 12 5/8”. The additional 1/8” gives 1/16” play on either side. Tape is placed on the inside edge of the ring’s lower section. This fills the 1/8” platter-to-ring gap, which allows for a press fit solution. The press fit tightness can be adjusted by using more or less tape (including different tape thicknesses). As the fit is adjusted to be somewhat tight, the press fit design eliminates horizontal and vertical play/movement of the ring. Most importantly, the press fit allows the ring to clamp the LP’s outer edge to the platter. Thus, what was originally an LP outer ring is now an LP outer clamp.

The clamping nature of the device has the following benefits:

1. Eliminates the need for a heavy outer ring which might adversely wear on the bearing
2. Eliminates horizontal and vertical movement of the outer ring
3. Securely clamps the outer portions of LP to the platter
4. In conjunction with the Brinkmann Balanced inner LP clamp, the outer ring/clamp maximizes LP-to-platter surface contact (likely only surpassed by vacuum technology)
5. Flattens highly warped LPs
6. Damps ringing in the outer ring/clamp

The Brinkmann Balanced turntable has an excellent inner record clamp. The screw design allows the user to adjust clamping force. Additionally, the Brinkmann uses a ¾” spacer washer that sits on the platter and below the LP. When clamped, the LP’s inner portion is forced down over the spacer onto the platter. This also forces the LP’s outer portion to make contact with the platter. However, some LPs have dishing, and thus the spacer can either increase or decrease LP-to-platter surface area at the LP’s outer portion depending upon if the LP dishes up or down. When dishing up occurs, the LP-to-platter surface area is decreased and thus, the outer rim of the LP does not make any contact with the platter. While extreme (and if one examines the LP/platter carefully), as much as 50% of the LP’s outer portion may not make contact with the platter. This is the case for almost any turntable designs and is a function of the vinyl flatness (or lack there of).

To remediate the LP dishing issues, the LP outer clamp simply clamps the LP’s outer lip to the platter via the press fit. When properly adjusted, the LP inner clamp and LP outer clamp can create a dramatically improved coupling of the LP and platter. A vast majority of LP warps and dishing can be remediated.


Cost

A local machine shop manufactured the outer ring/clamp. The outer ring for the Brinkmann Balanced cost $450, including aluminum material.


The Sound

Typically, when a tweak or new component is introduced into a system, subtle changes occur. If we are lucky, the changes are easily identifiable (hopefully for the positive) and consistent heard. However, sometimes several listening sessions are needed to identify a perceived change in sonic character. With the LP outer clamp, the sonic changes were dramatic, easily and repeatedly identifiable and consistent. Yes, dramatic is an appropriate word to describe the magnitude of sonic change introduced by the outer ring. Within seconds, not minutes/hours/days, but seconds, the sonic change of the outer clamp was quit evident.
To begin, the outer clamp provided material improvements to imaging and sound staging. More specifically, the sound stage became deeper. An estimated 20-30% increase in sound stage depth was achieved. How and why? One explanation might be that micro dynamics were more readily and accurately rendered due to eliminated/minimized LP vibration. Without the outer clamp, an LP’s outer rim could often make no or minimal contact with the platter surface. At a microscopic level, vibration in the arm/cartridge or platter could be amplified by the LP outer rim, which acted like trampoline. With the outer clamp, the trampoline effect is minimized, if not eliminated.

SRA/VTA is critical to optimized LP playback performance. If an LP has a warp and without an outer ring/clamp, the SRA/VTA will change as the warp increases or decreases the distance of the LP surface from the platter surface. With the LP outer clamp, the LP surface was flattened and thus, the SRA/VTA was more consistent across the entire revolution of the LP, as well as the entire radial surface of the LP (inner diameter vs. outer diameter). A more consist SRA/VTA, when optimized, should result in better sonics including imaging, sound staging, dynamics (micro and macro) and tonal balance. The later, tonal balance, being the most dramatically and positively impacted sonic characteristic. With the outer clamp, the prior perceived solid-state tizz/grunge/edge had been completely eliminated. No longer does the listener get fatigued nor disinterested. Rather, the midrange and upper frequencies have complete extension without the prior annoyances of tizz/grunge/edge. The result was a more involved, musically satisfying sound that better recreated the music event. This could be attributed to the outer clamp’s elimination of micro vibration and consistent SRA/VTA across the entire LP surface. To quote the manufacturer of the TTOuter Ring:

“reducing high frequency noise caused by microscopic vibration that causes the stylus to “hear” sounds that are not there, this causes listening fatigue. The true high frequencies can be extracted from the vinyl essentially cleaning up the distortion caused by a vibrating the record groove. Play only what is there in the groove. Also, “provides smooth and accurate sound across the listening spectrum. The quiet passages are beautiful, less background noise, less tracking and VTA errors”.

Dynamics (both micro and macro) are utmost importance to create a lifelike sound. Some users of LP outer rings have reported reduced dynamics and lifeless sound. As such, this area was critically examined to determine if the custom made LP outer clamp was beneficial or not. Upon initial installment of the LP outer clamp, micro dynamics appears to be reduced. There was a perceived loss of “air” around the venue and instruments. However, upon further careful listening, micro dynamics actually increased. The perceived loss of micro dynamics and perceived loss of “air” was actually the elimination of micro-vibrations that caused distortion. Using well-recorded jazz or classical music, the hall/venue is easily discernable as the micro dynamics were fully realized using the LP outer clamp. Also, background noise / distortion is minimized and thus, a more quiet background is available as well.
Improvements in macro dynamics, especially in the bass region, were easily identified. Tighter, more tuneful, robust bass notes were produced using the LP outer clamp.

Concerning two of the potential drawbacks of an LP outer ring. The sound was not at all “deadened” by the addition of the outer ring. Actually, the opposite occurred, as the sound became more rhythmic (PRAT improved), with great drive and pace. The incremental weight added by the LP outer ring could be a concern, but there is no objective means to prove or disprove this concern. Given the extremely high mass of the Brinkmann platter, the small proportional increase in mass added by the LP outer ring is unlikely to adversely impact the bearing.


For reference purposed, my audio system is comprised of the following equipment:

Transfiguration Orpheus cartridge
Schroeder Reference tonearm
Brinkmann Balanced turntable
HRS turntable platform
Vitus SL-010 preamp with phono stage
Vitus SM-101 mono block power amplifiers
Marten Design Coltrane loudspeakers
JPS Aluminate interconnect and speaker cable

This post is made possible by the generous support of people like you and our sponsors:

Atma-Sphere Music Systems, Inc.

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