TT setup questions...

[risabet]

I'm clueless on TT setup even though I used to own one and planning another analog setup sometime in the near future. For starters, what is cartridge loading?

If you look at the FR response of an MC into a 47kohm load you'll see a rising response at higher frequencies, peaking in the 30 to 50kHz or higher range mostly. In most situations you want to tame and damp this.

Generally speaking LOMCs require a lower input impedance than the standard 47kohms available on a MM phono input. This is the load the cartridge will see. Generally, the lower the loading the more damped the ultrasonic peak in the response and the lower the output of the cartridge.

You can in theory calculate the proper load impedance by knowing the DC resistance of your cartridge and multiplying by 10 as a starting place. You'll have to fine tune by ear as always.

Cartridges running into transformers may need lower loading than those running into active devices.

You can probably find all the info re: any cartridge at the site below.

http://www.cartridgedb.com/

 

[Joey_V]

Woohoo!

Orientation was only 1 hour! I got the rest of the day to work on this blasted TT!

 

[Joey_V]

Still working on it... got the image better down center, then I realized that the VTF was a off (too light)...

Had to do a do-over again... *sigh*....

Keep you guys posted once I get everything set. I got Papa Dave's number on speed dial in case I have trouble.

 

[rhd1953]

Some old tricks for cartridge alignment

First, the suggested soundfountain.com provides an excellent setup procedure/process with diagrams.

-turntable level is critical and as suggested, leaving a round bubble level on the turntable is best...you never know if the turntable was bumped and is now not level. With it always there, you always know it's level or not.

-I have an old magazine (Audio Critic, I think) with a table of overhang adjustment settings, someplace. That is, with "A" arm pivot to stylus distance and "B" arm pivot to turntable platter center distance, use "C" overhang from the table(A-B=C). Adjusting, you add B+C to get what A should measure and move your cartridge. I'll look for it, it's been a long long time since I've used it.

-optimize offset angle for 2 locations on a record. Remember, it will be exactly aligned at those 2 locations and increasingly off as it moves away from them. So, 1/2" in from the lead-in groove and 1/2" out from the typical inner most groove, would be two good locations for adjustment.

-a preamp with 'Left-Right' selector (Apt-Holman pre-amp is one) is very handy cartridge alignment checking tool...I couldn't afford an oscilloscope. Mistracking/alignment error is immediately obvious to your ears.

When everything is set correctly, the cartridge will not jump left or right when dropped (to the record groove, a very small distance, say 1/16 th of an inch) and will ignore a record scratch (follow the groove, not the scratch) or bumps. An extra headshell and old/cheap cartridge would be good for practice.

The phono section of your pre-amp is very important too. Long ago I bought an Apt-Holman preamp (solid state) which was supposed to have a phono pre-amp that was 'overload' proof. I up-graded to a used Audio Research SP-9 pre-amp (tube hybrid) and guess what, some of the least likely records (Neil Diamond's 'Classics The Early Years') were overloading the Apt-Holman phono section! You just never know.

Currently I burn cdr's directly from records (thru my pre-amp), rip 'em on my pc, and listen to pc play lists/audio directed to my main audio system.

 

[Bernard]

-a preamp with 'Left-Right' selector (Apt-Holman pre-amp is one) is very handy cartridge alignment checking tool...I couldn't afford an oscilloscope. Mistracking/alignment error is immediately obvious to your ears.

I'm unclear as to what the selector does. Please elaborate. Does it subtract the right signal from the left ? If so, you can achieve the same thing by reversing the leads of one channel at the cartridge, and using a mono test disc.

 

[risabet]

Not sure about the Apt/Holman but the left/right selector typically allows you to hear each channel individually through both speakers, that is, right through both speakers or left through both speakers.

 

[rhd1953]

Difference mode on selector switch

No, Left-Right is subtracting one channel from the other.

Yes, switching 2 leads, for the same channel, at the cartridge is the same thing...essentially putting one channel out of phase with the other. I minimize touching the cartridge connections though, they're prone to poor connections/hum, ect.

Difference mode on a mono record wouldn't leave much. Never tried it. Any signal distortion should be out of phase, so it would show up.

 

[risabet]

First, the suggested soundfountain.com provides an excellent setup procedure/process with diagrams.

-turntable level is critical and as suggested, leaving a round bubble level on the turntable is best...you never know if the turntable was bumped and is now not level. With it always there, you always know it's level or not.

Assumes the round bubble level is accurate. Use a real framing level for much better accuracy. Obviously you can't leave it on the table.

-optimize offset angle for 2 locations on a record. Remember, it will be exactly aligned at those 2 locations and increasingly off as it moves away from them. So, 1/2" in from the lead-in groove and 1/2" out from the typical inner most groove, would be two good locations for adjustment.

The null points are defined by the mathematics of the chosen alignment formula. The Baerwald null points are at 66mm and 120.9mm from the spindle but there are other alignments that offer different nulls, Lofgren (70.12mm/116.2mm), and different levels of tracing distortion. B tends to have lower distortion outside the outer null point and inside the inner but higher average distortion. L tends to minimize distortion between the null points and has the lower average distortion but the highest peaks.

Of course none of this matters with a linear tracking arm. As overhang is 0

The phono section of your pre-amp is very important too. Long ago I bought an Apt-Holman preamp (solid state) which was supposed to have a phono pre-amp that was 'overload' proof. I up-graded to a used Audio Research SP-9 pre-amp (tube hybrid) and guess what, some of the least likely records (Neil Diamond's 'Classics The Early Years') were overloading the Apt-Holman phono section! You just never know.

Cartridge output is kind of important here as is the phono gain.

 

[Bernard]

Difference mode on a mono record wouldn't leave much. Never tried it. Any signal distortion should be out of phase, so it would show up.

That is used to check the azimuth. When correct you get the lowest output.

 

[Satch]

Did you try taping a few pennies on top of the cartridge?

Sorry, that was bad... Just a flashback.

I like the looks of the VPI Scout and am looking forward to setting up a TT in my system, but jeeze, is this what I'm looking forward to?

Satch

 

[tonepub]

Get a Rega P7 and you won't have to dink around with most of it....

If you want vinyl but DONT want to go through endless tweaks, I can't recommend the Regas highly enough.

 

[Craig]

One of the adjustments on the JMW-9 tonearm is done by adding more or less twist to the wire that connects to the top of the tonearm base. You disconnect the small connector and add turn it 360 then reconnect. It seemed strange to me too but thats one of the adjustments on this arm.

This is the adjustment that increases or decreases tendency for the arm to swing to the inside of the record. That's about the extent of my TT setup knowledge from when I owned a VPI Scout. I wish I kept it.

If it were me I would spend the $ and a have a dealer properly set it up and it would be real nice if he showed me a few things on setup when he did it. If you really want to learn about TT setup then the TT setup DVD should be a good resource.

 

[slowGEEZR]

Did you try taping a few pennies on top of the cartridge?

Sorry, that was bad... Just a flashback.

I like the looks of the VPI Scout and am looking forward to setting up a TT in my system, but jeeze, is this what I'm looking forward to?

Satch

The Scout comes with its own protractor with a single point for setting the cartridge. It is accurate and easy; at least it was accurate when I double checked the alignment with another two point protractor.