Tonearm/Cart Resonance frequency...

Looking for thoughts on resonance frequency. General consensus seems to be to try and take it somewhere in the 8-12hz range (ideally 10hz)... since this is adjustable by changing the tonearm or cartridge mass, I'd enjoy hearing some thoughts.

Since I will be setting up the DL-103R on my Pro-Ject 9cc arm which weighs 8.5g, I've been digging around for opinions and resources, so I thought I'd link up some things here, for others...

So the Denon is spec'd for a compliance of 5 compliance units at 100hz. The 100hz spec seems to be a typical for Japanese carts, but doesn't work for directly for the equation. General consensus is to multiply 100hz compliance specs by 1.5 to 2 times, which would give us 7.5 to 10cu for our formula. This was also in line with measurements made and posted elsewhere for various carts. (@shaizada also let me know that it is probably somewhere around 11cu.)

Plugging a compliance unit of 10 into the resonance frequency formula, this is what I would get using the stock 9cc tonearm:

Rf = 1000 / (6.28 * sqrt( tonearm+cartridge mass * compliance))
Rf = 1000 / (6.28 * sqrt( 8.5g+8.5g * 10))
Rf = 12.2hz

Seems a bit high, but maybe not bad. Most sources seem to indicate that things would sound best having the Rf around 10hz... including this write-up with the a handy little graph from Ortofon as well.

So I can also use the online calculator to determine just how much mass I'd need to add to the cartridge (or tonearm) to bring the Rf down to 10hz. Using the third calculator down, it tells me that 25.33g of mass would be needed (still using the 10cu). The tonearm and cart weigh 17g, so we're left adding 8.33g to the cartridge. (Weights and/or screws could be used to do this...)

The trouble with this is that the largest counterweight Pro-Ject has is rated for carts weighing 11-15g. So I would be limited to adding 6.5g to the cart (which weighs 8.5g) to get 15g. If I did go this route, where would the Rf be? Using the calculator again, the result is 10.382hz - not bad.

I have read others who added two counterweights to their tonearms, or just added weight using tape. Honestly, I'm not too concerned, but I was wondering about others experiences with Rf. There is a paper from 1977 which seems to suggest a higher Rf could be beneficial... anyone have thoughts or experience with this?

I plan on picking up the larger counterweight, as well as some weights for the cartridge that I may or may not end up using (thanks to @shaizada again for his suggestions). I'll listen and see what sounds best to my ears...

 

Pick up weights that allow you to experiment and get the cartridge balanced. You have the correct idea so looking at your diligence with this, I am not worried for you at all. Remember, specs is one thing. Use them to get in the ball park. Then tune by ear! Nothing is better than training a good listening ear...I learnt that over years of listening. If it sounds good....IT IS GOOD!