# ifi Zen Phono Review (phono stage)

## Rate this phono stage:

• ### 4. Great (golfing panther)

• Total voters
135

#### MaxwellsEq

##### Addicted to Fun and Learning
I think what @Frank Dernie is saying is that, to a first order model, your "bridge" model is not wrong, but when used dynamically, microsecond to microsecond, the results are affected by 2nd and 3rd order artefacts and some of these may be chaotic (mathematically). This is in the nature of dynamic systems. Because the signals are so low, understanding the dynamic model is important.

#### Thorsten Loesch

##### Senior Member
I think what @Frank Dernie is saying is that, to a first order model, your "bridge" model is not wrong, but when used dynamically, microsecond to microsecond, the results are affected by 2nd and 3rd order artefacts and some of these may be chaotic (mathematically). This is in the nature of dynamic systems. Because the signals are so low, understanding the dynamic model is important.

Well, my model focuses on the first (and second) order effects, as they also tend to be most material in the system.

But it seems to me that Frank suggests that everything I write is completely wrong (as opposed to simplified and incomplete).

Thor

#### Bob from Florida

##### Major Contributor
Allow me to enlarge.

Because we have a stiffer spring and a larger mass moving, we ideally apply additional damping to the arm, because the stiffer spring and greater mass will result in MORE movement at the resonance frequency.

Just compare to a car suspension, imagine you put very heavy wheels and tyres onto more stiff suspension. Without an shock absorber the wheel will oscillate more violently. Add a shock damper, voila, the oscillation is damped.

The LF resonance of arm & cartridge are not really that different.

But we are talking about a second set of resonances.

A tonearm is ultimately related to a bridge. It is a bridge between two points, one more or less fixed point (ideally the pivot is fixed 100% dynamically from the view of the cartridge in the audio range) and one that is suspended (by the cartridge cantilever and it's suspension and damper).

We know bridges have bending modes that have their own resonances. The famous "Army unit collapsing a bridge marching over it in lock step" story illustrates this. We are talking about the same resonances.

http://scihi.org/broughton-suspension-bridge-resonance-disaster/

Typical old style tonearm's use constant wall thickness and constant diameter tubing. This obviously makes for a structure with a strong single resonance. Now resonance can be damped using a rubber type damper at the end (or both ends) of the tube. Damping resonances at the end of a structure is known as edge termination and is for example used in speaker drivers where the same problem exists. The rubber surround and the "lip" attached to the code edge perform that damping.

One can also use a rubbery insert in the tube that produces some damping or coat the inside of tube. This is rarely done due to the added complexity. Using a "S-Shaped" tube breaks up resonances into multiple sections that have higher resonance frequencies, with the fundamental resonance reduced.

Given that the pivot needs to be rigid, the point where the tube resonance can be terminated and damped is the headshell end. Moreover, the headshell end is also the point where we vibrate the tube with energy passed from stylus and cantilever.

Having a rigid coupling between Cartridge/Headshell will be most efficient in sending vibration energy into the arm tube and will in turn excite sympathetic resonance, which will in turn vibrate the cartridge, leading to an unwanted input into the cartridge. So it is desirable to defeat or minimise these resonances and isolate the cartridge from them, as well as isolating the arm from the cartridge's vibration energy.

Having a lossy connection between Arm and headshell makes the conduction of vibration energy less effective and can provide edge/end termination of resonances in the Arm structure. It will also reduce the conduction back into the cartridge of any resonant energy of the arm tube resonance.

Even without resonance, vibration energy send into the arm structure will propagate as wave in the metal to the pivot point where it will reflect back to the source. A good illustration is the wave reflection in a water tank. A similar process applies to high frequency cables in electronics:

Having an Arm structure that is not "regular" (varying tube diameter and varying in wall thickness) can reduce resonance, but not reflections. To cancel reflections needs additional damping in such a structure. Rigid coupling between Headshell and Arm Tube will maximally transmit vibration energy back & force. And no, the Arm Pivot and weight of structure attached to it does not "ground" or "drain" vibration energy, the more rigid the pivot etc. the more energy is reflected back towards the cartridge.

The next part in the system is the cartridge. Older cartridges have cases with a very loose coupling between the actual pickup and usually plastic case. Some cartridges (e.g. reportedly the Denon DL-103) are even designed to have deliberate anti-resonance in the cartridge case for resonances in the pickup (Generator, Cantilever & Stylus).

Others, especially modern "High End" cartridges have rigid cases and rigid links between case and pickup. This creates differing conditions for the propagation of vibrational energy from stylus & cantilever into the Arm structure and back.

For the DL-103 the top plate of the case should be allowed to resonate freely. The included soft plastic O-Rings should be placed between headshell and cartridge. They from a first line of damping and lossy coupling. Note this is strictly applicable to DL-103.

For the DL-103, the Arm should not be of a rigid type, to further avoid transmitting vibration energy into the Arm structure and resonant and reflected energy from returning to the cartridge.

Other Cartridge/Arm combinations need to be considered individually.

The HiFi News Test LP should be used to adjust effective arm weight to get the VLF resonance frequency right. Some form of fluid or eddy current damper is desirable to damp the VLF resonance.

Placing led tape at the golden ratio point on the arm tube can be used to adjust effective arm weight AND to provide damping of both resonances and vibration transmission. One can also shift the tape along the length of the arm to find the "best spot".

If a spring based anti-skating mechanism is used, ideally this is removed and replaced with a string/weight Anti-skate.

See here, two arms have lead tape. Only the Ortofon Arm which is designed together with the SPU Cartridge and Headshell as system is left without " tweaking"

View attachment 267582

Thor

When I got my new turntable I moved the Denon 103 from my Graham Robin Arm (Jelco with detachable headshell) to the Clearaudio Satisfy Carbon Fiber arm. The bass response seemed lacking until I installed the "Denon Cap".

Possibly, this does some of the things you refer to in your post. I never tried the washers between the headshell and the 103. Perhaps I will try it if I ever get tired of the Hana SL.

#### HarmonicTHD

##### Major Contributor
Forum Donor
I think what @Frank Dernie is saying is that, to a first order model, your "bridge" model is not wrong, but when used dynamically, microsecond to microsecond, the results are affected by 2nd and 3rd order artefacts and some of these may be chaotic (mathematically). This is in the nature of dynamic systems. Because the signals are so low, understanding the dynamic model is important.
Correct and it is not about @Frank Dernie being unwilling, but it simply can not be explained in a few sentences in an internet forum, when the complexity of the model / math requires at least a graduate degree in ME with specializing in the field of mechan. dynamic systems. Especially, depending on possible non-linearities, the solution might even require a numerical approach.

Not trying to sound dismissive, but maybe an analogy would be to try to explain the details in DAC design, to someone, who just understood ohms law.

#### thewas

##### Master Contributor
Forum Donor
Especially, depending on possible non-linearities, the solution might even require a numerical approach.
Yes, as soon the number of degrees of freedom increases an analytical solution isn't feasible nor sensible, for example while a tripple pendulum shows already chaotic behaviour compared to a single and double one:

Source and more:

#### Bob from Florida

##### Major Contributor
Yes, as soon the number of degrees of freedom increases an analytical solution isn't feasible nor sensible, for example while a tripple pendulum shows already chaotic behaviour compared to a single and double one:

View attachment 267646
Source and more:
Can you describe how your pasted equation from the link provided applies to tonearms?

#### thewas

##### Master Contributor
Forum Donor
Can you describe how your pasted equation from the link provided applies to tonearms?
As I wrote above it is an example to show how increasing the order of a dynamic system increases the complexity exponentially.

#### Thorsten Loesch

##### Senior Member
Correct and it is not about @Frank Dernie being unwilling, but it simply can not be explained in a few sentences in an internet forum, when the complexity of the model / math requires at least a graduate degree in ME with specializing in the field of mechan. dynamic systems. Especially, depending on possible non-linearities, the solution might even require a numerical approach.

We are not talking about precisely quantifying all processes in the system, but about an intuitive understanding of the basics and to be first cognisant of the possible issues, determine which are the largest and consider approaches to mitigate the largest problems. A 70/30 approach so to speak.

That does not need a huge amount of math.

Not trying to sound dismissive, but maybe an analogy would be to try to explain the details in DAC design, to someone, who just understood ohms law.

But we are NOT talking about the small details, but the fundamental principles.

Thor

#### Thorsten Loesch

##### Senior Member
When I got my new turntable I moved the Denon 103 from my Graham Robin Arm (Jelco with detachable headshell) to the Clearaudio Satisfy Carbon Fiber arm. The bass response seemed lacking until I installed the "Denon Cap".

Possibly, this does some of the things you refer to in your post. I never tried the washers between the headshell and the 103. Perhaps I will try it if I ever get tired of the Hana SL.

The link shows interesting measurements. It also shows what happens if mass is added somewhere, so resonances.

Thor

#### AaronJ

##### Active Member

Can I use a DL-103 on a stock Technics arm or not?

#### Thorsten Loesch

##### Senior Member
View attachment 267714

Can I use a DL-103 on a stock Technics arm or not?

SL-1210? Yes.

You must use the washers supplied with the cartridge between cartridge and headshell and you must fit the small extra weight supplied with your turntable to the headshell.

Thor

#### Frank Dernie

##### Master Contributor
Forum Donor
But we are NOT talking about the small details, but the fundamental principles.
It is the fundamental principle most people clearly don’t grasp, and why should they?

Minor details of a small subset of the fundamental, like a higher mass arm maybe better matching a low compliance cartridge are “common knowledge” even if the speculation about the reason for this is usually way off. That is fine, IMO.

It is speculation between these bits of “common knowledge” and the real world what is actually happening in a complex dynamic system that is unhelpful, IMHO, and pointless because it casts zero actual light on the subject and leads to people thinking stuff which isn’t true.

#### AaronJ

##### Active Member
SL-1210? Yes.

You must use the washers supplied with the cartridge between cartridge and headshell and you must fit the small extra weight supplied with your turntable to the headshell.

Thor
Is there something different about the 1210 arm vs the 1200 (presumably the same arm I have on SL-100C)?

#### Thorsten Loesch

##### Senior Member
Is there something different about the 1210 arm vs the 1200 (presumably the same arm I have on SL-100C)?

No, SL1200/1210 just denote different colours.

Visually the Arm looks the same, though it seems the headshell lacks the threaded hole for the extra weight (and I suspect the weight).

Get a Hifi-News Test LP and see what the main arm resonance ends up at. You can use lead tape wrapped around the Arm tube near the headshell to add effective weight to lower the resonance frequency if it ends up too high (likely).

Thor

#### Bob from Florida

##### Major Contributor
As I wrote above it is an example to show how increasing the order of a dynamic system increases the complexity exponentially.
I am unsure as to how looking at a complex equation helps us when it comes to tonearm resonances and matching cartridges to tonearms. I asked how and did not receive an answer. Looking at the link reminded me of a story I heard many years ago. A mathematician and a chemist were given identical vases and asked to determine the internal volume. The mathematician spent many hours making measurements and determining equations describing the curves of the vase so as to determine the volume. The chemist filled the vase with water and then poured the water out of the vase into a graduated cylinder.......
How complicated is really necessary to arrive at the solution?

Last edited:

#### Thorsten Loesch

##### Senior Member
The chemist filled the vase with water and then poured the water out of the vase into a graduated cylinder...

And the practice oriented engineer, lacking lab glass used a 0.25 Liter mineral water bottle and counted how many bottles content would fit and eyeballed the rest and provided an instant, in field first order approximation of the volume, which commonly suffices for practical purposes.

Naturally, all there answers were wrong anyway, as non worked with absolute precision.

Thor

#### thewas

##### Master Contributor
Forum Donor
I am unsure as to how looking at a complex equation helps us when it comes to tonearm resonances and matching cartridges to tonearms. I asked how and did not receive an answer.
Let's make it then more clear for you then. The tripple pendulum is a model of 3 links with masses connected together rotating just around one axis. A non rigid tonearm-cartridge system in reality has to be modelled as an infinite number of masses able to be rotating and bending around all axes, something that obviously cannot be done with simple analytical models but is usually approximated with numerical discretisation approaches like FEM.

A mathematician and a chemist were given identical vases and asked to determine the internal volume. The mathematician spent many hours making measurements and determining equations describing the curves of the vase so as to determine the volume. The chemist filled the vase with water and then poured the water out of the vase into a graduated cylinder.......
How complicated is really necessary to arrive at the solution?
And the practice oriented engineer, lacking lab glass used a 0.25 Liter mineral water bottle and counted how many bottles content would fit and eyeballed the rest and provided an instant, in field first order approximation of the volume, which commonly suffices for practical purposes.
See above, of course the vibrational behaviour of the tonearm system can be measured with modern techniques like laser interferometry but those are neither simple nor give automatically a deeper understanding or model of the system, so above stories aren't good analogies and show the problem that @Frank Dernie correctly described.

Last edited:

#### mike70

##### Addicted to Fun and Learning
Well, yes, it's a very complex problem... now I'm thinking if you can trust the compatibility tables in the internet. Even the counterweight position changes the math.

Worst with the famous Japanese cartridges compliance measurements at 100Hz.

#### JeremyFife

##### Senior Member
Let's make it then more clear for you then. The tripple pendulum is a model of 3 links with masses connected together rotating just around one axis. A non rigid tonearm-cartridge system in reality has to be modelled as an infinite number of masses able to be rotating and bending around all axes, something that obviously cannot be done with simple analytical models but is usually approximated with numerical discretisation approaches like FEM.

See above, of course the vibrational behaviour of the tonearm system can be measured with modern techniques like laser interferometry but those are neither simple nor give automatically a deeper understanding or model of the system, so above stories aren't good analogies and show the problem that @Frank Dernie correctly described.
Follow this thread with interest (and no illusions about actually understanding the complexities). Appreciating the heavyweight contributions.

So... do some due diligence research on trusted sites, buy gear that plays nicely together and then just enjoy the music?

(Genuinely interested in the thread - it's astonishing how complex these systems really are)

#### thewas

##### Master Contributor
Forum Donor
Follow this thread with interest (and no illusions about actually understanding the complexities). Appreciating the heavyweight contributions.

So... do some due diligence research on trusted sites, buy gear that plays nicely together and then just enjoy the music?

(Genuinely interested in the thread - it's astonishing how complex these systems really are)
Thank you and I fully agree, what matters most for consumers like the most here is that they are happy with it, the engineering behind is something for the people who make them but can be an additional hobby for interested enthusiasts.

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