Help me work out these measurements I dont understand

[The Vinyl Adventure]

I'm intrigued to know if my current tonearm/headshell/cart combo is a better combo than the last set up ...

I think I need to know effective mass of the tonearm which will somehow help me work out this resonant frequency that I learnt(ish) about here

http://theartofsound.net/forum/showthread.php?t=10476&page=2

But how do I work of this effective mass .. In fact, more ideally if I provide details of the tonearm can someone else work it out for me... ? :)
(You can tell me how you did it, but I'm not sure I will get it)

[The Vinyl Adventure]

Where's that Barry when you need him ;)

[Reid Malenfant]

Where's that Barry when you need him ;)
Barry is a wonder, he knows his stuff :)

I think he's on holiday :scratch: :eyebrows:

[The Vinyl Adventure]

Poo...
There must be another smarty pants here somewhere!

Check this out for a coincidink
My two Philips carts on two different headshells with different mounting screws weigh exactly the same

412mkiii
http://i728.photobucket.com/albums/ww282/hamish_gill/9b5e054f.jpg

412mkii
http://i728.photobucket.com/albums/ww282/hamish_gill/4f6b7ca6.jpg

Don't know how useful these weights are but I'm posting them anyway...
They are so light the counterweight is about a mm from the pivot bit...
Is that good for a low effective mass?
I don't know what I'm talking about at all here ...

This is the TT http: //www. vinylengine.com/ library/pioneer/ pl-600.shtml

(You will need to take out the spaces in the link)

[NRG]

If you know the resonance, cartridge+fixings mass and compliance you can work out the arms effective mass.

There is a neat calculator over on VE: http://www.vinylengine.com/cartridge_database_tools.php#ResonanceCalculator

You will need a test record to workout the resonance frequency.

With regard to your scales are you sure they are not magnetic?

[Reffc]

Send me he details Hamish and I'll work it out for you.

Basically there's several things to remember when selecting a new cart and setting up.

As you've rightly identified, you need firstly the tonearm mass and the cartridge mass. Add these together to get the effective mass.

Next, you need to know what the dynamic compliance figure is for the cart. Compliance is simply how "springy" the cantilever and suspension are, or by how much they deflect for a given load applied.

Once you have these, you can use a graph to calculate from effective mass and compliance where your resonant frequency lies. It should be in the range 8 to 14Hz.

Following the selection of an appropriate match, I can take you through the steps of set up. You'll need the arm's effective length (pivot to stylus) and recommended null points. Easiest way after this is to use an arc protractor.

Without going into detail, just PM me and I'll sort it out for you

Cheers

Paul

[The Vinyl Adventure]

Cheers Paul and Neal

I think I'm going to come unstuck here to be honest ...
The only info I have on the tone arm is in the info on it on vinyl engine
See the bottom of post #4
The is no mention of tonearm mass ... ?

As for the carts ...
This is the mk ii http ://www .vinylengine.com/library/philips/super-m-mark-ii.shtml
This is the mk iii http ://www .vinylengine.com/library/philips/super-m-mark-iii.shtml
(take out the spaces in the link (who makes a site that can't be linked to??? Bloody crazy!!!))

I'm guessing my intrigue is a non starter...
I'm not so bothered as it sounds ace, just interested in getting to the point I got to in the thread about this cart on my rega (see the link in the first post)

[The Vinyl Adventure]

... Oh and as for the scales ... Other cart/headshell combos weigh differently ... They are perhaps not the best scales, but they arent too bad ... Known weights read as expected ...

[Reffc]

Hi Hamish

the tonearm is a medium mass arm (safe to assume from 9 to 15g) with an effective length of 237mm. That estimate of tonearm mass (minus headshell) won't be a million miles out.

From that, a good approximation for your set-up can be made.

Cart compliance is 12.5 cu;

Headshell plus cart mass is 14.55g (heavy!)

Total effective mass is about 24g.

Looking at the compliance charts, this will bring the resonant frequency to about 9Hz, which is a little on the low side but still ok, and syll within the "ideal" range.

This assumes that the quoted compliance figure is at 10Hz (some Japanese manufacturers quote compliance at 100Hz for which you need to multiply the original figure by about 1.8).

Looking at your tonearm effective length, it's stated as 237mm.

This is the distance between the pivot centre on the tonearm to the STYLUS. You need to set the arm/stylus up to this length (either adjust the arm or cartridge in the headshell).

The easy way to do this is to use an arc protractor. The good news is that your tonearm shares the same geometry as the Rega RB300 so you can use the protractor suited for that:

ie

Baerwald protractor, null points at 66 and 121mm

arc protractor: (http://www.google.co.uk/imgres?hl=en&sa=X&rlz=1C1FDUM_enGB473GB473&biw=1920&bih=971&tbm=isch&prmd=imvnsfd&tbnid=CTN1-CiR5RywRM:&imgrefurl=http://www.audioasylum.com/cgi/t.mpl%3Ff%3Dvinyl%26m%3D827785&docid=xuiZBHxL2qH4BM&imgurl=http://gall)

Or:

Lofgren "A" protractor: (http://www.google.co.uk/imgres?hl=en&sa=X&rlz=1C1FDUM_enGB473GB473&biw=1920&bih=971&tbm=isch&prmd=imvnsfd&tbnid=lwBYZ_WCdwtM7M:&imgrefurl=http://www.audioasylum.com/audio/vinyl/messages/95/954175.html&docid=5srFbcgpQfyrcM&imgurl=http://gallery.audioasylum.com/cgi/gi.mpl%253Fu%253D3771%2526f%253DArc_Protractor0002 .jpg&w=1000&h=768&ei=PaSST9LIEKqs0QXdy9HwAQ&zoom=1&iact=rc&dur=211&sig=107373716343725465709&page=2&tbnh=134&tbnw=175&start=45&ndsp=54&ved=1t:429,r:4,s:45,i:176&tx=70&ty=105)

Print these out and alter printer settings to achieve correct scale (there's a scale shown on each).

Use a pin to pierce the null points and cut a hole for the spindle point (7.5mm diameter)

Place over TT and align the tonearm (with bias set to ZERO and balance to recommended VTF) lower the stylus onto the outer null point and check alignment. Move to inner null point and check that stylus follows the arc. If it doesn't, move the arm or cartridge in or out until it does. Once it follows this arc it means that at the two null points the stylus is exactly parallel to the grooves and distortion will be minimised for the chosen protractor.

Not as fiddly as it sounds and you need to be careful not to damage the cantilever.

Once done, pinch up the bolts just beyond finger tight (pliers would do), re-check VTF and that the arm is level when the stylus is on the record surface (adjust tonearm height if not).

Don't forget to check Azimuth. You do this by glancing along the cantilever when the stylus is resting on one of the null points (outer easiest) and the line that the cantilever makes with the null point line should appear straight and true as if one line. If there's a kink, your headshell needs twisting gently one way other the other to correct the Azimuth.

Finally, re-check VTF and set bias to equal VTF, then use a test LP (or any you're familiar with) to check for distortion (sibilance, fizzing or brreak-up). If it tracks ok without break-up, then all is fine.

Hope this helps


Cheers

Paul

[The Vinyl Adventure]

Cheers for all that Paul!
Based on you estimate I have a "better" resonant frequency than with the rega ... That was really what inwas interested in finding out!

I had actualy used the rega protractor before it went off to micke ... I was not aware that it might actually be quite an appropriate choice...
Thanks for the links, I'll get them printed monday! I'm quite comfortable setting up a cart as it goes ... It was the resonant frequency that I was intrigued to find out about ...

You say that 14.5 grams is heavy ... Yet I thought these carts were considered quite light at 6-7 odd grams, and same for the headshells ... The magnesium headshell I just sold was more than 10g alone ...
I even chose te slightest mounting bolts I could find assuming that keeping the mass down was the best thing to do for a high compliance cartridge??

The counterweight is also butted up against the pivot thingy (what's that part of the tonearm called??) http://i728.photobucket.com/albums/ww282/hamish_gill/78d391ec.jpg
based on that it strikes me that this must be a lightweight combo for this tonearm??

[Reffc]

Hi Hamish

I guess that 14g isn't out of the way for a cart plus headshell, but it takes the tonearm effective mass to a "light-heavyweight" from a medium mass one. Rega are about average for a medium mass arm (11-12g?) and as they don't have a detachable headshell, it's only the cart adding to the effective mass.

You're right RE keeping the mass down for a high compliance cart (I'd consider high compliance as 20 or over). More importantly though, medium mass tonearms allow a greater variety of cartridges to be used than light or heavy mass arms. There is a "however" and that's where a light mass tonearm is used. you can add weight to the headshell to bring up effective mass, allowing a variety of carts to be used (within reason to avoid increasing bearing friction). This works especially well with sme type II improved arms (6.5g). I'm using a Denon DL110 cart on my 3009 at the moment, and had to add a few grammes weight to bring the effective mass in line with ideal resonance range. The combo works very well. You can't do that with heavier arms, so light or medium allow best flexibility.

[The Vinyl Adventure]

You say you concider high compliance as 20 or over ... So is mine not nessasarily that high?

I guess none of this really matters in the grand scheme of things .. I'm overjoyed at how good it now sounds especially concidering the tt and mkii (my fave of the two) cost me a total of £70 ... I'm just trying to get a slightly better grasp of what I'm dealing with!

The fact that I was on the right lines trying to keep the mass of the cart/shell down was I suppose what I was really trying to find out with this thread ...
I got outbid today on a ADC LMG-1 headshell which sounds like it might be a bit lighter than what I currently have (and maybe a little better too) so I shall continue to keep an eye out for one of them I think ...

[kcc123]

Your Philips 412 mk2 is indeed a high compliance cartridge. It has a compliance of at least 30 cu. According to Hi FI Choice, the compliance was measured as high as 42 cu so a low mass arm is needed.

[The Vinyl Adventure]

Your Philips 412 mk2 is indeed a high compliance cartridge. It has a compliance of at least 30 cu. According to Hi FI Choice, the compliance was measured as high as 42 cu so a low mass arm is needed.

define "needed" when it sounds wonderful on what i have it on now...
I have kinda been down this road before ... when I was finding out about it on the rega ...
but im interested to know peoples thoughts on this

[kcc123]

May I ask : What arm are you using for the 412 cartridge?

[The Vinyl Adventure]

The arm that is on the Pioneer PL600x

http://i728.photobucket.com/albums/ww282/hamish_gill/_DSC9636.jpg

[kcc123]

The Pioneer arm has an effective mass of about 16 grams and the cartridge weighs 6 grams. So the total mass is about 23 grams with screws and nuts. The resonance frequency will be 6 Hz if the cartridge compliance is 30 cu. If the arm mass is 6 grams , then the resonance frequency will become ideal at about 8 Hz.

[The Vinyl Adventure]

... I fear I may go over old territory here ...
My less than ideal 6hz sounds really good ... So what's the issue?

Also, how do you know the mass of the arm? Where did you that 16g figure from?

[Reffc]

16g would be about right for the arm plus headshell. Add the cart weight to this to get total effective mass. I plucked the 12.5 compliance from another resource but it sounds like this might be way out according to the 30 figure quoted above and this would indeed lower resonant frequency to around 6Hz (record warp and foot-fall territory). At worst, the sound will be a little duller than it could be and you will be more prone to picking up resonance and distortion from warped LPs. If however it sounds good, then don't worry too much. Its a guide. If your ears tell you it sounds great, then just enjoy it.

[The Vinyl Adventure]

Cheers for that ...
I don't seem to have any issues with footfall ... So I shall remain happy I think :)

[keiths]

Hamish, do you leave the lid on when playing records as in the photo? With the turntable so close to that speaker, I'm sure it'd sound better with it removed.

Cheers,
Keith.

[The Vinyl Adventure]

It may well do, but with a 9 month old baby who is learning to walk and grabbing everything to help support her ... It's just not practical at the mo!
I will give it a go one evening though!

[Spectral Morn]

It may well do, but with a 9 month old baby who is learning to walk and grabbing everything to help support her ... It's just not practical at the mo!
I will give it a go one evening though!

Where does the time go....

Regards D S D L

[The Vinyl Adventure]

Tell me about it!!!

http://i728.photobucket.com/albums/ww282/hamish_gill/87f67aca.jpg