Ortofon A90

ack · Jun 6, 2011

Thanks. I'll post impressions asap. The trade-in price really made me pull the trigger in the end; basically I got 70% of what I paid for the XX-2 new! This speaks volumes about their quality; I'll miss that bugger - it played everything with so much ease, including big organ symphonies like Saint Saens #3 (Boston/Munch); very impressive cartridge - blows the same piece on XRCD transfer out of the water.

ack · Jun 6, 2011

So from reading the various threads on a'gon and especially the responses by Ortofon/USA, it's quite clear that this cartridge requires perfect SRA adjustment to sound its best, which is exactly what mullard88 ended up with (when he says the rear of the arm is higher than the headshell, or when Valin says he set his at 90.6 degrees - he really means +0.6 off vertical). I need to understand the Replicant 100's geometry a little better before settling on the optimal SRA, but it's probably going to be +0.6 to 2.0 degrees.

JackD201 · Jun 7, 2011

Wouldn't it be cool if there was a list of A90 owners? It seems there are quite a few of us right here at WBF. Congratulations Ack!

ack · Jun 7, 2011

Thanks Jack. The more I think about it the more I like its eventual VTF tolerance that you guys claim - it let's you adjust SRA for every record if need be - and certainly experiment easily during initial set up - w/o having to worry about the inevitable concurrent shift in VTF; but the ultimate shift in null-point alignment with such adjustments is still a concern, though. It feels like with this cartridge you eventually settle in the middle of the recommended VTF range, then simply play with VTA/SRA for the best results - which is a far easier adjustment to make on the fly than VTF or any other, with a good arm.

ack · Jun 7, 2011

So the mysteries are unraveling one by one

Looking at Ortofon's web site, the stylus is unlike any other, in that it has very sharp edges (corners) and wants to make as much contact with the groove as possible - for all intents and purposes, this is an attempt to be an exact replica of a cutting head (hence, I assume, its name). This obviously requires perfect SRA for it to line up with the groove's modulations, and this posting corroborates all this:

[Ortofon] agreed with the notion that SRA has a profound effect on the performance of the cartridge, as the Replicant diamond’s size and shape requires careful stylus rake adjustment to get the sharp edges perfectly within the groove.

Unfortunately, that will of course be different from record to record, and micro adjustments are required during set-up - good luck to me!

Mike, your input here from your 12+ month experience will enlighten everyone.

ack · Jun 7, 2011

Don't you just love math... So here's the approach I will use to set up this cartridge:

Set VTF to the recommended mean 2.3g
Use MintLP at first to position the cartridge roughly where it should be
Set VTA so that SRA is dead on 0 degrees from vertical
My VPI JMW 10.5i arm has the following characteristics:
1. Pivot to spindle (OC) 262mm
2. First null at 55mm
3. Second null at 155.5mm
This results in an effective length of 277mm (= (OC^2 + NP1*NP2)^0.5)
To get an offset SRA angle of 2 degrees, the resulting triangle calculations tell me that I need to raise the arm exactly 9.67mm. Since the effective length will be affected very very slightly, I may settle for something like 9.5mm
Re-adjust VTF to 2.3g; hopefully VTA will now be very close to the prescribed 23 degrees
Use MintLP again to exactly position the cartridge
Adjust Azimuth

I may play with the arm height range (0-9.67mm) with listening tests, but I doubt I will diverge a lot; basically, if the math is sound, there will be no reason to.

MylesBAstor · Jun 7, 2011

ack said:
Don't you just love math... So here's the approach I will use to set up this cartridge:

Set VTF to the recommended mean 2.3g

Use MintLP at first to position the cartridge roughly where it should be

Set VTA so that SRA is dead on 0 degrees from vertical

My VPI JMW 10.5i arm has the following characteristics:

Pivot to spindle (OC) 262mm

First null at 55mm

Second null at 155.5mm

This results in an effective length of 277mm (= (OC^2 + NP1*NP2)^0.5)

To get an offset SRA angle of 2 degrees, the resulting triangle calculations tell me that I need to raise the arm exactly 9.67mm. Since the effective length will be affected very very slightly, I may settle for something like 9.5mm

Re-adjust VTF to 2.3g; hopefully VTA will now be very close to the prescribed 23 degrees

Use MintLP again to exactly position the cartridge

Adjust Azimuth

I may play with the arm height range (0-9.67mm) with listening tests, but I doubt I will diverge a lot; basically, if the math is sound, there will be no reason to.

1. How are you going to check SRA?
2. How are you going to check azimuth?
3. You may need a different counterweight for the arm since the cartridge at 8 gms is a little on the light side.
4. You may want to ask HW if the effective mass of the arm is optimal since it's a pretty high compliance cartridge. You may need if I remember correctly, a slight decrease in the arm's effective mass.

ack · Jun 8, 2011

MylesBAstor said:
1. How are you going to check SRA?
2. How are you going to check azimuth?
3. You may need a different counterweight for the arm since the cartridge at 8 gms is a little on the light side.
4. You may want to ask HW if the effective mass of the arm is optimal since it's a pretty high compliance cartridge. You may need if I remember correctly, a slight decrease in the arm's effective mass.

#2 is easy - have the test record and will use the Revox again. #1 is an art, to find the 0 degree point, using a loupe; but it's no more an art than using MintLP to align it. The cart is actually exactly as light or heavy as the XX-2, so it's not a problem. WRT compliance, you'll see above that I calculated the resonance at 9.38Hz which should be fine, but I can check with VPI and see if a I need a smaller counter-weight - thanks.

MylesBAstor · Jun 8, 2011

ack said:
#2 is easy - have the test record and will use the Revox again. #1 is an art, to find the 0 degree point, using a loupe; but it's no more an art than using MintLP to align it. The cart is actually exactly as light or heavy as the XX-2, so it's not a problem. WRT compliance, you'll see above that I calculated the resonance at 9.38Hz which should be fine, but I can check with VPI and see if a I need a smaller counter-weight - thanks.

You might want to check into those inexpensive digital microscopes for checking SRA. Makes it a lot easier. Think we've discussed it here a while back! Seems to take a lot of the guesswork out dialing the cartridge in.

Have you tried the Soundsmith Counter Intuitive on your VPI arm? That makes dialing everything in world's easier-you won't disturb azimuth while dialing in VTF and vice versa. Can also just use it to tune the sound by ear also. Find that can adjust VTF in increments of 0.001 gms and that will make a different too.

ack · Jun 8, 2011

MylesBAstor said:
Have you tried the Soundsmith Counter Intuitive on your VPI arm?

To make me look smart the answer is, Yes I have one.

shhh, the reality is I just ordered it, so technically I'll have it when the cart arrives - thanks

ack · Jun 8, 2011

So I researched the inexpensive digital microscopes and they won't really do; one really needs to get the higher end ones like MF's, which enable you to take measurements - w/o measurements, it's still a crap shoot. I don't feel like spending $250 right now for this, would be nice if I can borrow one from someone local...

ack · Jun 8, 2011

On the compliance, VPI said

9.38 is nearly perfect, don't change anything

MylesBAstor · Jun 8, 2011

ack said:
To make me look smart the answer is, Yes I have one.

shhh, the reality is I just ordered it, so technically I'll have it when the cart arrives - thanks

Shhhhh....that's OK, I bought three of them, one for each wand

You won't be sorry. I have always hated designs beginning with the Wilson Benesch arm where both azimuth and VTF were coupled

MylesBAstor · Jun 8, 2011

ack said:
So I researched the inexpensive digital microscopes and they won't really do; one really needs to get the higher end ones like MF's, which enable you to take measurements - w/o measurements, it's still a crap shoot. I don't feel like spending $250 right now for this, would be nice if I can borrow one from someone local...

I'll defer to your research. Just know some people who swear by the $60 but I tend to agree with you. The more expensive scope seems a lot more user friendly. I also think that if you go back to the thread where we talked about setting SRA, someone actually used a telephoto lens and then made a grid on the computer? Maybe it was George who we rarely see here anymore?

ack · Jun 8, 2011

I, at least, had done that - I had posted pictures of my arm with the XX-2, with a superimposed grid using a computer to show the slightly raised back and downward incline - if that's what you are referring to. This was my attempt at easily showing a 2 degree difference, but that's because I couldn't take a close-up picture of the stylus itself, although I did verify back then the 2 degree SRA with the same 10X loupe I will use now.

Basically, neither the picture/grid nor the loupe approach will be as good as a microscope with measurements, and to me, no measurements simply means more pretty pictures.

MylesBAstor · Jun 8, 2011

ack said:
I, at least, had done that - I had posted pictures of my arm with the XX-2, with a superimposed grid using a computer to show the slightly raised back and downward incline - if that's what you are referring to. This was my attempt at easily showing a 2 degree difference, but that's because I couldn't take a close-up picture of the stylus itself, although I did verify back then the 2 degree SRA with the same 10X loupe I will use now.

Basically, neither the picture/grid nor the loupe approach will be as good as a microscope with measurements, and to me, no measurements simply means more pretty pictures.

OK thanks!

Maybe it's just my age but those loupes drive me loopy nowadays

One of these days, sooner than later hopefully, going to get me one of those better digital scopes!

ack · Jun 8, 2011

It's probably worth it buying one... But the good thing about the human eye in this case is that it's fairly easy to tell a dead vertical stylus through a loupe, as opposed to trying to figure out if the angle you are looking at is 2 degrees or not - that's where the math comes in to set the expected SRA afterward, w/o straining your eyes. I think it's going to work well. What's unfortunate is that I will probably have to do it all over again after about 100 hours or so of use, as the cartridge sets in.

ack · Jun 9, 2011

The A90 is mounted, aligned, and with the proper SRA as best as I can tell (yes, the rear of the arm is raised significantly). With one hour on it... the results are utterly impressive and realistic. Herb Albert's trumpets are right here on Casino Royal, as is Diana Krall on Live in Paris (which blows the CD away, BTW), and finally Heifetz's violin. Bass is extremely tight - the Telarc bass drum is very impressive and realistic. Impressive dynamics, 3D layering. I am equally amazed at the Ayre P-5xe... VTF is at 1.968g and unfortunately it can't go any higher, therefore I need a lighter counterweight... Let's see how it plays out over the next 100 hours. This is the cartridge that HP didn't care for?

MylesBAstor · Jun 11, 2011

ack said:
It's probably worth it buying one... But the good thing about the human eye in this case is that it's fairly easy to tell a dead vertical stylus through a loupe, as opposed to trying to figure out if the angle you are looking at is 2 degrees or not - that's where the math comes in to set the expected SRA afterward, w/o straining your eyes. I think it's going to work well. What's unfortunate is that I will probably have to do it all over again after about 100 hours or so of use, as the cartridge sets in.

What do you think about this?

http://cgi.ebay.com/USB-Digital-Microscope-500-Times-Measurement-software-/260783726455?pt=LH_DefaultDomain_0&hash=item3cb7ebdf77

ack · Jun 11, 2011

I can't tell the brand, so no idea. I would really seek a Dino-Lite, as they are the leaders; see the link I posted above for Fremer's (newer) version; costs $249. I might get one too eventually, just not now - the math is all I need at the moment.

Ortofon A90

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