[Wayner]

Shape isn't an issue.........it's a function of distance. The shape can and does affect amplitude. Taper affects fundamental tone.

Hmmmm, Are you sure? Why are lots of tonearm manufacturers now making tapered tone arms? Like  my lighting pole example, all of those that are tall poles are tapered. I think first for structural reasons, then I think for harmonic reasons. Didn't the original Golden Gate bridge vibrate itself to death and they had to rebuild it, or am I thinking of some other bridge?

Wayner

[bastlnut]

hallo,

tapering the tonearm does help a little.
the resonances will decay and will not stay at the given amplitude or even be amplified!
it does not mean that they will be reduced enough to not be heard.

regards,
bas

[Wayner]

Agreed. That is perhaps why this portion of the topic is elusive. There apparently are several factors at work together, that are hard to separate and work on individually. Like fixing one thing, screws up another.

Back to the old saying "diagnosis is 99% of the cure".

Wayner

[neobop]

David,
If you have an oscilloscope and test records you'd know better than I, how to check transient response. I'd think square wave response would tell you everything you need to know. You'd be able to see overshoot (underdamped) and rise time. Is this the JVC? I can't recall if it's a dial or goo up top. It might be easier to clean it out and start from there, if it's goo.

Check the low frequency resonance amplitude at the same time. It should be interesting. I'm curious about the relationship between optimal cart damping vs low frequency resonance.
neo

[Wayner]

On top of all of this good stuff is the inclusion of the possibilities of:

Internal tone arm wire rattling.
Screw shell head wires rattling.
Tonearm lock vibrating when not in the "locked position".
The stylus guard on the cartridge rattling.
Cueing lever vibrating.
Dial on counterweight vibrating.
Counterweight vibrating, sometimes in sync with the dial.
Linkages under the tonearm (for auto and semi-automatic TTs).
Any small springs, linkages, pinnings or what ever, under the TT.
Motors vibrating, humming.
Capacitor(s) humming, vibrating (starting capacitor, switch capacitor).
Transformer (direct drives, crystal controlled belt drives).

What else?

Wayner

[BaMorin]

On top of all of this good stuff is the inclusion of the possibilities of:

Internal tone arm wire rattling.
Screw shell head wires rattling.
Tonearm lock vibrating when not in the "locked position".
The stylus guard on the cartridge rattling.
Cueing lever vibrating.
Dial on counterweight vibrating.
Counterweight vibrating, sometimes in sync with the dial.
Linkages under the tonearm (for auto and semi-automatic TTs).
Any small springs, linkages, pinnings or what ever, under the TT.
Motors vibrating, humming.
Capacitor(s) humming, vibrating (starting capacitor, switch capacitor).
Transformer (direct drives, crystal controlled belt drives).

What else?

Wayner

Yep, that covers more ground.

FTR, I use as light and floppy perferably "silk" wrapped headshell leads, as stiff ones make a lot of noise.
Again, it's one of those noises you may not hear until it's gone.

My Grado's can't be played with a stylus guard 

When re-wiring an XA/XB arm, the wires run through the foam inserts. counter twisted pairs.

Not much under my ARs to vibrate......the motor's 1st fundamental is 12.5 hz which is employed into the top plate, I drain roughly 9db of that through the terminator plate I designed that attaches to the studs.

the motor wires are wrapped and secured.

[dlaloum]

Presenting ... Wayner performing "Dem Bones" (backing tune by Mills Brothers...)

Internal tone arm wire rattling.
Screw shell head wires rattling.
Tonearm lock vibrating when not in the "locked position".
The stylus guard on the cartridge rattling.
Cueing lever vibrating.
Dial on counterweight vibrating.
Counterweight vibrating, sometimes in sync with the dial.
Linkages under the tonearm (for auto and semi-automatic TTs).
Any small springs, linkages, pinnings or what ever, under the TT.
Motors vibrating, humming.
Capacitor(s) humming, vibrating (starting capacitor, switch capacitor).
Transformer (direct drives, crystal controlled belt drives).

[dlaloum]

David,
If you have an oscilloscope and test records you'd know better than I, how to check transient response. I'd think square wave response would tell you everything you need to know. You'd be able to see overshoot (underdamped) and rise time. Is this the JVC? I can't recall if it's a dial or goo up top. It might be easier to clean it out and start from there, if it's goo.

Check the low frequency resonance amplitude at the same time. It should be interesting. I'm curious about the relationship between optimal cart damping vs low frequency resonance.
neo

Hi Neo,

Don't assume - I'm learning as I go...!!

Yes it is the JVC... with "dial-a-damping" electronic damping - but the electronic damping is limited to LF. (below 300Hz from memory)

Plasticine tends to work best between 300Hz and 3000Hz - so might provide a good combo with the servo damping.

Planning on measuring resonances soon (still working on the cartridge loading stuff).
The Square wave measurement is very visual.... but depends a lot on gut feel/experience, and doesn't provide a real "Quantified" method.

Also thinking of used some LF sweeps combined with Waterfall plots - might expose various harmonics more clearly.

Picked up the measurement software a couple of months back - it includes a (so far unused except for a brief glance at my square wave track) oscilloscope feature among many others...
I am still trying to work out how best to use it and what each measurement might actually mean sonically.

So, really I have a toolbox, but I have never used these types of tools, and am learning as I go.
I have some understanding / Experience with the RTA/ FFT analysis tool that I have used for Frequency Response plots... Being economical downloaded software, it makes enormous assumptions about the technical knowledge and experience of the user.... (ie little or no manual) - which is frustrating!

Hence questions like mine.... about how best to measure the different parameters, how to achieve a quantitative rather than qualitative analysis.

bye for now

David

[neobop]

David,
I'm not a tech or an EE or anything like that. Maybe Wayner can chime in and straighten us out, cause I'm sure we'll be floundering. My ex partner in the electronics biz was a wiz with this stuff and he showed me the output of my amp on a scope. First off you need a signal fed into the amp. In this case it came from a signal generator. Then the output of the amp is observed. So I assume you need test records to observe the output of your record player.

Old test reports of phono carts sometimes had square wave response so there has gotta be a way to do this. In general when you look at the form of a square wave, the closer it is to looking like a perfect square, the better. The vertical line on the left side of the square is initial response. Ideally, it should be a straight vertical line. It will actually angle up a little to the right though, and that amount of angle shows the rise time. I guess it is the distance, calibrated on the horizontal time constant, from the beginning of impulse to when the signal is reproduced. The line across the top of the square is the reproduced signal. You'll see overshoot as that line on the left going past the top of the square and coming back down. I think overdamped will be seen as rounding of the top left corner of the square. I bet if you search the web you can find much more authoritative instructions.

I got a test record a while ago now, but I still haven't used it, LOL. It's Analogue Productions one. It's really designed to set up and calibrate mastering equipment and playback. It has some cool stuff on it if you have the equipment. You can adjust your VTA with an IEC, IMD test signal. But you need an intermodulation distortion tester.     I'm looking at the back cover now and track 5 on side 2 is a 1K to 10Hz sweep at -20db below reference level, vertical. "Resonance anomalies in the tonearm/cartridge interface will show up as amplitude peaks and dips as the frequency sweeps down." Wow, you can do this by ear and it's easier in mono. I think maybe I should clean this bad boy.
neo

[Wayner]

A square wave on a test record is something I've seen from time to time, but it always makes me ponder. So the groove on the test record has to look like the square wave on the scope, so that means the stylus will hit a brick wall, so to speak. We have a moving mechanical device (the platter) which we have some how put a digital signal on (a square wave). Most un-natural for a stylus or music for that matter.

The square wave is a digital signal. It is either on or off. It has instant on and off values and is basically pulsating DC. How much distance does a record groove cover in a millisecond?

I need to go have some tea.

Wayner

[dlaloum]

A trapezoid track doesn't quite have the same ring to it....

My cursory look showed a trapezoid on the oscilloscope - which is what you would expect given the constraints of the medium....

I may need to take some screenshots of the scope....

[BaMorin]

A square wave on a test record is something I've seen from time to time, but it always makes me ponder. So the groove on the test record has to look like the square wave on the scope, so that means the stylus will hit a brick wall, so to speak. We have a moving mechanical device (the platter) which we have some how put a digital signal on (a square wave). Most un-natural for a stylus or music for that matter.

The square wave is a digital signal. It is either on or off. It has instant on and off values and is basically pulsating DC. How much distance does a record groove cover in a millisecond?

I need to go have some tea.

Wayner

Funny you should mention that Wayner.........As if one looks at the grooves in an album, and then hears that groove played, It's hard to believe the system even works in the first place. Considering the different wave forms needed to produce the same note from different instruments. The wave form, not the pitch is what determines the instrument we hear.  So, if you have a guitar, a cello, and an Oboe all playing a perfect A-440
at the same time, the groove should have a triangle wave, a sawtooth wave, and a square wave all cut together. Hmmmmmmmmmmm?  what instrument plays a perfect sine wave?  I mean other than my unshielded turntable motor?

[dlaloum]

what instrument plays a perfect sine wave?

Pipe Organ!

And a great way to test your speakers, amps, and window mountings / fittings.....

[BaMorin]

Pipe Organ!

And a great way to test your speakers, amps, and window mountings / fittings.....

sound exiting a pipe will be square wave.......sound eminating from the surface of the pipe will be "sine"

[Wayner]

OK you guys, is a test record a necessary tool? I've gone 40 years without one, tho I did have a real cool record that had earthquakes and Ionic disturbances on it. I think I threw it out. Once in a while, I eye up the Acoustic Sounds Test record, but at $50, is it going to be worthwhile or not.

I guess it's related to the topic, and maybe I'd feel different if I had one. I certainly don't have all the answers, in fact very few and those answers are suspect. I do know lots of questions.

The one thing I know for sure is that the AudioCircles has never had a larger, smarter brain bin then it does right now, so newbies, you better start asking some questions before we all get bored with the topic and move on.

While I didn't expect any definitive answers to this topic, I knew that there would be some great ideas, concepts, concerns and opinions thrown in. If anything, we all can look at our own rigs and wonder where some trouble makers are and hopefully put a hex on them and do a positive fix.

I think the greatest thing a guy can do is experiment. They did it in the sixties (poor Timothy Leary) and look where that got him. Oops, sorry, flashback. I mean, if you think you have some issues with the tonearm/cartridge/appendages, try some things you think will fix your particular problem. Nothing can start you more in the right direction then having a flat, level, secure and massive bass for your table to perch on. Unlevel, unstable tables can unleash all kinds of demons from the get-go and things get worse from there. Get the basics right and the rest seems to fall into place.

A properly set up table with a nice quiet record will blow you away, especially if your system has dynamic and holographic capabilities.

Wayner

[DaveyW]

OK you guys, is a test record a necessary tool? I've gone 40 years without one

I've got one, but it rarely makes it out of the cover.
I much prefer to use standard test tracks that I've become very familiar with, looking for certain preferred traits and characteristics.
At the end of the day it's all about the music.

A properly set up table with a nice quiet record will blow you away

Absolutely - Despite spending a fair sum on a CD player with extensive auditioning, it very, very rarely gets used.
Vinyl all the way for me. 

Cheers
Dave

[BaMorin]

OK you guys, is a test record a necessary tool? I've gone 40 years without one

I have a Shure ERA lV test album that only gets the test bands used to check arm resonance.

I have a few favorite well known tracks that i use to dial in VTF and bias on various albums.

My son did find some very interesting albums for me that have no lead-in grooves from track to track.
(locked tracks)  It comes in a kind of a suit case made just for the albums. It appears to be a teaching collection. 16 albums total.........mostly classical works. some of the albums have music on one channel, and vocals on the other channel. The instructions are to move the balance knob right or left to isolate the parts.
Seems like a nice way to check azimuth. All of the albums are un played.......heavy vinyl that looks exceptionally clean. He found it for $4.00  Produced by Columbia Special Products

I used to have (many moons ago) a pink noise album for setting up graphic equalizers along with a ratshack DB meter.........I still have the meter.......don't know what happened to the album.

[dlaloum]

Test record...... depends....

I started some months back by comparing tracks with different cartridges.... curiosity, and a hint of dissatisfaction with my old cartridge, .....I started looking around.... got a couple of cartridges to try out.

When I compared the tracks the differences were clear....
I recorded the tracks using CoolEdit, aligned their starting points, and pulled them into multitrack mode.

This allowed me to switch from track to track instantly at the click of the mouse and do direct a/b/c/d comparisons.

Differences were clear.

Then (curiosity again!) - I used CoolEdit's statistics function to do a brief analysis of the tracks...

There were differences in average (RMS) levels as well as peak levels...

So I pulled the statistics into a spreadsheet, worked out what level would allow me to match all the average levels without clipping any peaks, and then adjusted all the tracks.

So now all the average levels were within 0.01db of each other.
There were still differences in the peaks (interesting!)

And then I redid the listening test..... lo and behold the tracks all sounded alike! -or did they?

The next step took a long time, some hours of listening, and coming back fresh a couple of times.

The differences I had identified before were mostly still there - but had reduced by an order of magnitude. It took A LOT more work to identify differences.

Then I did further reading.... in forums like this one (all the usual places....) - and realised that there are frequency related level differences - ie I had matched the average level - but the differences in frequency response were still present - and these are the thing that determine the overall "tone" of the cartridge.

So if I wanted to do the same thing I had done with the levels, but now in the frequency domain, I would need to equalise....
This led to another round of research, some experiments with equalisation software, and a realisation that the first step is to get the cartridge loading right, as this has a huge impact on the "tone" of a cartridge.

Given 5 or 6 (now more like 20-30!) cartridges, doing it all "by ear" was becoming more and more difficult, and taking huge amounts of time - so I was needing to move from qualitative analysis to quantitative analysis....

This is where I purchased some RTA/FFT software, and went hunting for test records. I ended up picking up about 6 different test records.

Initially, my first one was the HFN test record - which is good for aligning, tracking capability, and has a Pink Noise track - unfortunately the Pink Noise track is flawed above 16kHz (I was getting strange results with susbtantial rise in the 16-20kHz range.... Werner Ogier put me out of my misery by warning me that it was the record....)
The CBS test records are probably the most trusted out there, as they actually verified their records using microscope analysis....

The 20-20kHz sweep on that seems very good - although it does have strange little peak around 350Hz.
 
Also if using a test record, you need to find one that has the tones you need to match the test you want to do, and the tools/measuring instrument you are using.

I am still down the rabbit hole of instrumentation, graphs, charts and measurements - although I am starting to understand more about cartridge behaviour and how to adjust loading.
Also the possibility of canceling out some of the anomalies by using a 2nd cartridge in a cancelling circuit (basically used as an inductor) -further analysis on this is ongoing.

Along the way I discovered that mass market cartridges have substantial variations in inductance and resistance between the two channels.... and top of the line cartridges of the same design from the same manufacturer are much much closer to being identical.
examples : AT20 - almost perfect match, AT440-not bad not great, DR250/AT3472 series (12 examples measured) mostly not so good with some good examples.

Also with each systems total capacitance and cartridge inductance varying (I have supposedly identical cartridges of the same model varying by 50mH...), it requires measurement (of total capacitance), and then some modelling of cartridge F/R to determine where and how to adjust the loading.
An RTA (real time analyser) along with both Pink Noise track, and frequency sweeps allows the type of measurements I've done.

To do this effectively also requires:
A phono stage with no capacitance load (so you can add C load externally using loading plugs)
A phono stage with a very high (500k ohm ++) impedance - you can easily lower it with loading plugs, but you cannot raise it!
A multimeter that can measure both inductance and capacitance, within the required range for cartridges and cables.

If the software is also capable of "waterfall plots" (3d layout of frequency response adding a time based axis) - then you can use frequency sweeps with waterfall plots to identify system resonances relatively quickly...

The resonances could be caused by anything - arm/compliance interaction, plinth vibration, motor- who knows!!.... but you can identify them - which is step one.

So there you go - there is the Rabbit Hole.... if you wander down there you will meet the Mad Hatter, Cheshire cat, the hookah smoking caterpillar, and their friends the vinyl measuring technology geeks.

Can you handle it?
Do you dare?

bye for now

David