Denon DL 103 Tweak

The venerable DL103 moving coil cartridge has been around for a very long while and it still garners a lot of attention.

Mainly because
it’s damn good and very affordable!

Over the years a few third party companies have made some very good upgrades to this cartridge like
  • “nuding” i.e. removing the outer plastic casing
  • Replacing the outer shell with an machined aluminum casing
  • Re tipping the cartridge with a finer styli and better cantilever for improved details
  • Replacing the outer shell with a wood casing and brass mounting plate

Trouble is, all of these mods starts to get a little expensive for a cartridge that costs only $229.

I started reading up on the modifications available from a company called
Soundsmith and one of their modifications included mounting the “nude” cadrtridge on a brass plate and then putting a wooden shell over it.

So I thought,
what about if I just mounted the existing cartridge onto a brass plate?

Would this prove to be beneficial?

  1. I fashioned a plate 21mm x 22.5 mm out of a piece of brass that is 1.3 mm thick. This allowed me to drill 2 mounting holes without breaking through the side of the plate
  2. Next, I fastened the two mounting screws to the plate with two knurled mounting nuts that happened to fit into the space provided in the cartridge casing - this allowed for a preliminary alignment of the cartridge before fixing in place with epoxy.
  3. Then I applied a thin coat of epoxy resin to the plate, ensuring the knurled nuts also had a small amount of epoxy touching them (but not the threads)
  4. Finally, I coated the top of cartridge with epoxy and placed it on top of the plate, over the mounting screws, aligned the cartridge and left to set.


Screen shot 2013-03-28 at 6.32.38 PMDL103

You have about 5 minutes before the epoxy sets, to align the cartridge on the plate.

After about 15 minutes I gently loosened the screws one at a time to ensure the epoxy had not touched the threads.

Leave the cartridge for 24 hours for the epoxy to really harden up before mounting the cartridge back on the arm.

Warning:
  • the net effect of doing this will change the weight of the cartridge and consequently the effective mass of the arm, which in turn effects the resonant frequency.
  • So before proceeding, ensure all of these factors are within the limits of the arm/cartridge compatibility you are using.

The outcome of these modifications in combination with my arm ( a Rega RB250) was stunning.

The cartridge was transformed to a whole new level of performance, with a very detailed and well rounded sound. The bass may be a little too lean for some tastes. Personally, I like to hear the details in a bass line rather than that low plodding muffled beat. The biggest improvement was in the dynamics that this cartridge now conveys.

Adjusting the cartridge VTA to track a little
tail-down will recover some of the bass, but that’s to your taste and depends on the angle you choose - I have read some people run this cartridge at 15 degrees instead of the recommended 20 degrees - as I said - to your taste Happy

Orchestral is one genre where this cartridge shines with impeccable details conveyed for all instruments.

Voice is another, with sibilance control that is smooth and detailed without being shrill.

Unfortunately, precise cartridge alignment now requires you to be somewhat of a perfectionist but rewards you with a very deep image.

For me, it is by far the best $12.50 I’ve ever spent + a little of my time.




Two Thumbs-up

Turntable Mod's

Not so much a "tweak" - more a complete rebuild Happy

NEF_0833

My turntable started life 30 years ago as a Rega Planar II

Rega's approach back then was to utilize a simple plinth design that was low in density with a bonded aluminum top that would shed vibrations before they reached the arm and platter. Alas, this design was prone to larger "floor vibrations" and required a substantial stand to effectively isolate it.

Rega's solution was to bolt a metal frame to the wall, which worked well with "brick walls", but with timber-frame construction it failed to provide a complete solution.

Since that design, Rega and other manufacturers have adopted the original simplistic Rega design format, but using materials like MDF to build plinths that are acoustically inert.

Taking a queue from these designs I decided to build a new plinth made of 3 sheets of bonded MDF giving it considerably more mass and superior isolation qualities. The design point of increasing the mass is that any vibrations in the component shelf will not be able to move a high mass plinth, especially when combined with an isolation foot with extremely good absorption properties like Sorbothane, as detailed in the section Component Isolation Foot in this blog

The plinth is supported by three of these feet with a modification to imbed them into the underside of the plinth. The feet have been located such that the points at which the arm and platter bearing are attached to the plinth sits in the "null point" of any residual vibrations.

The Arm
The original "S shaped" arm was originally replaced by a Rega RB250 tonearm with the addition of a Cardas Incognito one piece loom, but the latest addition is an Audiomods Series 3 tonearm pictured here (also see Audiomods "Classic" Tonearm Review). This arm uses the RB250 arm tube and that’s where all similarity to the Rega arm ends!

This shows the micrometer VTA adjustment which allows for repeatable adjustments and more importantly, resetting back to the original state.

The counterweight is “drilled out: to lower it’s centre of gravity and has an additional fine tuning adjustment weight for very accurate setup.

STRATFORD_007_NEF_0837



Setting VTA

VTA is “generally” correct if the top of the cartridge is parallel to the playing surface

If your arm has VTA adjustment the process is relative easy, otherwise shims need to be applied

Getting the top of the head-shell parallel requires a device something like this one

VTA Gizmo

You can make one very cheaply

  • a couple of washers,
  • a screw and a couple of nuts,
  • a felt pad for the bottom
  • a piece of foam
  • and a dressmaking pin

Place an album on the turntable (do not start the motor)
Lower the cartridge onto the album
Set the pin touching the front of the front of the cartridge.
Fine adjustment can be accomplished by turning the screw running through the grey foam
Move the device to the rear of the cartridge and adjust the VTA so the pin touches the top of the cartridge at the rear
You may need to re-check the front again after the adjustment and repeat the process

Voila - the cartridge is pretty darn close to parallel - better than eyeballing Happy

You can then adjust VTA so the cartridge is in either a tail-up or tail-down position - as desired


The Sub-Platter
The original Sub-platter has been replaced by the
ISOsub GT 2 S UPGRADE SUB PLATTER and ceramic bearing from Isokinetic. Note: the three brass spacers in the photo are required to elevate the platter above the central spigot so the platter can be used without a turntable mat.


NEF_0834
The original glass platter has been replaced with an SRM/TECH Deluxe Acrylic Platter for the Rega

To round out the tweaks the motor has been replaced with the
Rega II Motor Upgrade kit

Installed on the arm is an all time classic - the
Denon DL-103 Phono MC Cartridge (with brass mounting plate)

The only original parts left from the Rega Planar II is the switch and the cover!

These "tweaks" have elevated this turntable to a performance level that rivals many higher-end models.

I could have purchased a new turntable for the price I have paid out on these upgrades Laugh - but the outcome of this exercise has been very enlightening and increased my knowledge pertaining to the important elements of good turntable design and I feel the turntable performance exceeds any turntable of that price by a considerable margin.

So, what improvements did each tweak make?

  • Plinth re-build - provided a much improved soundstage, lower background noise and better details in instruments, together with the near elimination of vibrations to the arm and platter
  • Audiomods Series 3 tonearm - huge improvements in fine details of recording venue such as concert hall reverberations and soundstage
  • ISOKINETIK Sub Platter - significant improvements in the hi-frequency details and silent bearing operation
  • SRM/TECH Deluxe Acrylic Platter - in combination with the Sub-platter the Acrylic Platter has made huge improvements to the details and 3D image to a level I had only heard on turntables costing substantially more.
  • Rega II Motor Upgrade kit - near elimination of wow and flutter and much quieter operation

Isolation Plinth


Isolation Plinth

UPDATE: in place of the 3/4” MDF isolation plinth I now use an 3/8” granite tile. It provides superior isolation when used with the Component Isolation Foot


PHOTO OF NON_SLIP DRAWER LINER USED
ProGripShelfLinerBlack_x

Component Isolation Foot

Here is a very effective way of isolating components from vibrations that are present in the component rack and shelves

I currently have this implemented on my turntable using a 1.25" ball and under my amplifier using a 1/2" ball.
The washer should be slightly larger than the component foot

Only a single layer of 1/8" or 1/10" thick sorbothane is required

I found any thicker than this actually made my turntable sound a little "muddy" - i.e. not as crisp and dynamic

NOTE: you can remove the component foot altogether and apply the sorbothane directly to the chassis, provided it is flat

ISOLATION FOOT

NOTE: This design is very similar to very successful methods employed in Japan, where they use huge rubber blocks or springs to isolate buildings from the surrounding terrain in the event of earthquakes - it's just on a very much smaller scaleHappy