Moment Of Truth

Calle_jr · Jul 30, 2015

First sidewall reflections will hit 1.5sqm SMT Wing95 diffusion. These very narrow wing-elements measure 600x600x95mm and, like the other wing-elements, they not only diffuse but also variably delay first reflections.

Matts Odemalm developed the wing-elements to achieve a delay and evenly staggered energy distribution in the reverberation. Like the green curve in this example;

First roof reflections will hit 5.5sqm SMT Golden Horns.

The wall behind the speakers is treated with slot panels on 300mm depth and 50% absorption.
It is a soft LEDE concept with modest absorption in the speaker zone and quite live in the listening zone. I'm planning to see what happens when I increase the amount of absorption in the speaker zone. HH is probably better...

Calle_jr · Aug 2, 2015

Here are some recent room measurements!
They are made with REW and a UMIK-1 microphone from MiniDSP.
REW supports the UMIK-1 and MiniDSP has a calibration text file for it.

ddk · Aug 2, 2015

Calle_jr said:
Hmm.
If I ask kindly, can you please play this for me...

I'll open the door and point you in the right direction to search for it, soon you'll forget what it was you were looking for and find other gems to listen to

.

david

Calle_jr · Aug 2, 2015

ddk said:
I'll open the door and point you in the right direction to search for it, soon you'll forget what it was you were looking for and find other gems to listen to .

Good answer!

I did the measurements shown in the graphs above with both speakers at the same time. I think it may be better to measure left and right speaker separately, and combine the measurements.

Calle_jr · Aug 9, 2015

Results from two separate measurements with REW (left and right channel).
The SPL diagram is filtered with 1/12 smoothing.
Ventilation and dog shut down.

Here's a zoomed diagram of the ETC 0-50ms:

Clickable!

Ron Resnick · Aug 9, 2015

Your room and set-up look great! The Veritys must sound amazing driven by Jadis!

LL21 · Aug 9, 2015

This has been one of the most fun threads to read from the beginning. People say that meticulous setup and choosing components as part of a system are important...i think this thread demonstrates that. It has been particularly fun to see how you have even placed the Helmholz resonator inside the record rack. Very very cool. Congrats. I am sure i will come back to this thread again more than a few times to re-read. Thanks for taking the time to post this thread, and very glad you decided to do so.

Calle_jr · Aug 9, 2015

Thanks everyone!

It's been a long journey. In this house the experiments started 15 years ago.
The room is ok, but I would so much like to have just a little more room width and height.
In Sweden, that means I have to build my own house or buy a very old one, because the room layouts in residential developments have been standardized since the early 50's, and the interest on loans etc was based on the efficiency and so on. They had tally counters and watches to study the moving patterns of housewifes and family members in kitchens, bathrooms, bedrooms etc and presented very extensive rules based on that and the industrialisation of the building sector.
So all architects were trained and forced to use these rules. It means a corridor is always 1.20m, and room widths are rarely more than 3.60m and room heights are 2.40m. This system was omitted quite many years ago, but the results are still very much in use and the whole industry is based on that. Everything is multiples of 0.6m, which also is quite special when studying room modes in Swedish buildings. They always coincide (fundamentals or harmonics), and you can instantly tell if/what problems occur by walking into a Swedish home.

This is actually quite interesting history, and it all started with the visions of Folkhemmet: https://en.wikipedia.org/wiki/Folkhemmet
It involves politics, and some say it's a combination of all good things, some say all bad things.

Some of the ideas went terribly wrong, e.g. when the biggest grocery chain made all the wares in blue-white duotone and explaining the content like "bread", "coffee", "toothpaste"...:

So, we were afraid it was not going to be any Kuzma, AudioNote, Jadis, Verity but instead one blue-white "turntable", one "preamp", one "poweramp" and one "loudspeaker", and that a committee should decide what is "Lagom" (good enough) for the citizen

Anyway, the result after almost a century is that most things in the society is of moderately high standard everywhere. Very little low standard, very little high standard. Lagom...

Next up, I think will be equipment rack.

Calle_jr · Aug 11, 2015

The Hifi rack story

The output signal from a cartridge is based on one thing only - vibrations!
Unfortunately, the cartridge doesn't know if the vibrations come from the record grooves or from some other source. These unwanted vibrations will blend with the wanted ones and will get amplified.

A system performance from a mechanical point of view depends on;

Imposed vibrations from external sources, music, footfall, cd transports, tt motors, trafos etc.
System geometry, stiffness, mass
System damping

The first bullet is rather clear even if it is not so easy to quantify.
The second bullet is very clear and easily computed. Can be troublesome if the substructure (floor slab) has resonant behaviour.
The third point is a tough one, because it probably affects the music quality more than other parameters. I.e. it is easy to eliminate vibrations but it will kill the sound.

One strategy I've been working on for quite some years is to control the eigen frequencies and to limit vibrations to a state of critical damping.

I have strived to create structures with eigen frequencies above the TT eigen frequency and sway and rumble that can occur below 8 Hz.
But also, the tonearm+cartridge system gives resonance at 10Hz (varies, this is for my system).
So, a rack for a turntable should stay safely above 10Hz to avoid resonances in my opinion.

Critical damping is not so easy to control in practise. Here's a simple illustration in case you are not familiar with the quantity;

From left: underdamped, overdamped and critical damped. The brown fluid illustrates something with higher viscosity than the blue

A parameter describing the degree of damping in a system is the so called quality factor Q. Overdamped systems has Q<0.5 and underdamped has Q>0.5. When Q=0.5 the system will go the quickest way to rest, and is called critical damping.
A damped structure with mass M and stiffness k can be expressed;

Where c is the damping constant.

One way to control and limit is to start with a rigid, underdamped rack and take it from there by applying wood, tackit, composites and/or other elastic materials to fine tune, possibly approaching critical damping

Calle_jr · Aug 11, 2015

.
You have already seen the latest "prototype" if you visited the first page of this thread, and here are some setup pictures;

.

audioline · Aug 11, 2015

Hi Calle
Did you hear Big changes after installing the new racks?

//Kim

Calle_jr · Aug 11, 2015

audioline said:
Did you hear Big changes after installing the new racks?

Hello Kim,
My previous rack was very good, so the differences are not BIG.
What I hear is more definition, like solid response.
But I am far from ready with this structure. The frame is extremely good, but the shelves are only temporary.
It's clearly underdamped now. If I play a silent groove and hammer on the floor, I here a distinct "ding" from the speakers.
I tested to put a 5mm Timbertech mat between the oak shelf and a BDR shelf and put the turntable on that. It was clearly a bad tuning, so that was removed.
I'm working on a composite shelf now and will post here as soon as it's ready.

I asked previously in this thread (post #19) if anyone had experience from the Combak Line Enacom RCA, because I would be interested to test them as short cables between stepup and phono input. Still noone?

Calle_jr · Aug 26, 2015

Mmmmmmmmmmmmmmm!

ddk · Aug 27, 2015

Calle_jr said:
Mmmmmmmmmmmmmmm!

New coffee table?
david

Calle_jr · Aug 27, 2015

ddk said:
New coffee table?

Exactly! and a small stool for feet resting.

The table is heavy, and luckily I had a friend to help me move it in the house.

4Point must be demounted, and Stabi Ref lifted away and so I could turn the rack 90 degrees;

adamaley · Jul 5, 2016

You must be enjoying your new mystery device so much so that you have neglected us all.

Calle_jr · Jul 9, 2016

adamaley said:
You must be enjoying your new mystery device so much so that you have neglected us all.

Oh, sorry for that and thanks for reminding me.
I will continue immediately!

Calle_jr · Jul 9, 2016

The outer frame and subchassis is assembled on delivery.
There are three feet on the outer frame of which the two in front are adjustable, making also the outer frame possible to level.
There are four decoupling towers in the outer frame, and three of them coincide with the feet.
The subchassis is assembled on these four towers.
Detailed leveling can be done on the four knobs on top of these towers (similar to Stabi Ref).

The decoupling is very heavy and inert, but should still be classified as floating.
I have to both hands to push to even notice it's moving.

Calle_jr · Jul 9, 2016

When the protecting cap is removed, the shaft with the ruby ball bearing appears in a cup

8-10 drops on the ball, and the rst on the shaft.
Excessive oil gets stored in the reservoir, so there's no risk for overdose.

Calle_jr · Jul 9, 2016

My story with Stabi M is a long one.
I think I made the decision already in June 2009 when Franc Kuzma was working on the prototype, and I got a chance to see it in Germany.
But, a little less than 2 years ago, I started to try to improve my setup of Stabi Ref, rebuilding my rack etc.
I had cross dialogs with Franc Kuzma and several other vibration specialists.
Everyone knows the problems to tune serial springs.
I was quite successful, but all dialogs ended with like "anyway, with Stabi M it's something completely different"

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