Oscilloscope vs. Analogmajik

[Tom C]

I’d like to get a higher degree of precision in my cartridge alignment, and am wondering if anyone has experience using a ‘scope versus software like Analogmajik or Feickert.

 

[amirm]

I just watched a few of their videos. You can replicate the same with a test LP, a sound card (NOT scope), and measurement software. You are in for a lot of learning though to get there. So as much as $750 is huge amount of money for a one-time use tool, it will get you there much faster and with less error. Perhaps you can get together with a few other LP users around your area and share in the cost.

 

[Tom C]

What type of measurement software, do you mean something other than Analogmajik?
Thank you Amir. BTW, this is such an awesome site. There has never been anything else like it.

 

[scott wurcer]

What type of measurement software, do you mean something other than Analogmajik?

The signal processing involved is actually fairly simple and can be done in any number of open source math packages, but as stated you need to understand the process and have some familiarity with the algorithms. Any test LP with left/right/vertical/lateral 1KHz reference tones should work. I like to think of the cart having roll, pitch, and yaw as well as possible misalignment of stylus to motor. One can certainly obsess this no end.

 

[amirm]

What type of measurement software, do you mean something other than Analogmajik?
Thank you Amir. BTW, this is such an awesome site. There has never been anything else like it.

Thanks. As Scott mentioned, there are many choices. ARTA is a good starting choice (I think they have a free trial but otherwise costs 79 Euros) and easier to learn some of the others. http://www.artalabs.hr/

If you have a laptop, you can use it with the internal sound interface and use the microphone input to make some measurements to learn the ins and outs. There is little intelligence or case specific measurement in Aanalogmajik so you should be able to replicate their measurements using ARTA and just buy their LP. Their special sauce is pairing a specific test tone with a generic audio measurement, taking out the guesswork.

 

[DonH56]

I’d like to get a higher degree of precision in my cartridge alignment, and am wondering if anyone has experience using a ‘scope versus software like Analogmajik or Feickert.

What is your technical background? As Scott said you could use an open-source math package like Python + Octave or whatever but need a fairly high knowledge base.

 

[scott wurcer]

Dr. Feikert uses a phase measurement of the crosstalk IIRC, there is nothing going on but measuring the phase and amplitude of the crosstalk and finding the optimum. I would find taking the data with a headshell that has no azimuth adjustment rather tedious, measuring the relative amplitude and phase of the 1KHz reference signal in each channel is rather trivial.

I have a copy of the Adjust+ LP but have not walked through the exercise with Python, BTW the best test LP we found was the 45 rpm one by the Swiss outfit CH for their $$$ pre-amp.

 

[Tom C]

What is your technical background? As Scott said you could use an open-source math package like Python + Octave or whatever but need a fairly high knowledge base.

I have a two-year degree in electronics, worked as a tech for a while repairing guitar amps and PA’s, then in a factory that made machine tools. Later, I studied medicine (I’m now a radiologist), so I had to learn some physics, MRI, ultrasound and about X-ray tubes and power supplies.
Had some calculus, stats and finite math.
I’m not an engineer, so it would be a learning curve, but I like to think I’m teachable.

 

[scott wurcer]

I’m not an engineer, so it would be a learning curve, but I like to think I’m teachable.

Dr Feikert's site is down for maintenance but there is a link to a Youtube that shows the process nothing there that could not be duplicated easily. Mostly high school geometry involved in the stylus/groove wall/motor assembly. Don't know where the little spirit level came from but you could DIY one sacrificing a cheap level.

 

[Wombat]

Makes me wonder how cutting-lathe heads were aligned and to what specs?

 

[scott wurcer]

Makes me wonder how cutting-lathe heads were aligned and to what specs?

We all wonder that. Buried in some threads at diyaudio are a lot of test LP measurements that were part of an effort to do a group buy of a new test LP. The bottom line is that there are probably no recording engineers that are going to tinker with or tweek their equipment to our specifications.

 

[restorer-john]

Dr Feikert's site is down for maintenance but there is a link to a Youtube that shows the process nothing there that could not be duplicated easily. Mostly high school geometry involved in the stylus/groove wall/motor assembly. Don't know where the little spirit level came from but you could DIY one sacrificing a cheap level.

If the spirit levels were as bad as the test records they were selling, I feel sorry for all those poor audiophiles trying to align their gear.

Those little levels you can find anywhere, but they are terrible due to the internal fluid cavity rarely being horizontal to the sides. Every side is gives a different reading.

The cylindrical bubble levels are better. You can roll them on a flat surface to test them and the bubble will stay in the correct place.

 

[DubbyMcDubs]

If all you want to do is get the channel balance and phase correct, I can't see why you couldn't use a scope if you have one. You will need a test record like the Analog Productions Test LP which has tracks with isolated left and right test tones, as well as the mono in phase track. https://store.acousticsounds.com/d/...imate_Analogue_Test_LP-Turntable_Set_Up_Tools

You can buy the inexpensive RCA to BNC adapters and plug the output of your phono preamp into two separate channels. These are usually about $3 each.

Take care as the ground on the scope inputs is usually mains earth referenced. Should be OK, but just check. If you want to know more about that watch this: https://www.youtube.com/watch?v=xaELqAo4kkQ

I have not done this myself, but I recently purchased a turntable and was going to give it a go using the same test LP.

 

[scott wurcer]

If all you want to do is get the channel balance and phase correct, I can't see why you couldn't use a scope if you have one. You will need a test record like the Analog Productions Test LP which has tracks with isolated left and right test tones, as well as the mono in phase track. https://store.acousticsounds.com/d/...imate_Analogue_Test_LP-Turntable_Set_Up_Tools

The problem there is that you want to differentiate between the real channel imbalance due to the L/R gain of the motor and the imbalance due to the alignment (crosstalk).

 

[DubbyMcDubs]

The problem there is that you want to differentiate between the real channel imbalance due to the L/R gain of the motor and the imbalance due to the alignment (crosstalk).

OK, cool. Can you please expand on that a little?

 

[scott wurcer]

OK, cool. Can you please expand on that a little?

If you can find a description of Dr. Fiekert's technique he claims a better result using measurements that would be hard with a scope. I'm not sure how much a difference if any it makes.

I suspect that with a little care the scope or fozgometer technique is good enough for most people.

 

[DubbyMcDubs]

If you can find a description of Dr. Fiekert's technique he claims a better result using measurements that would be hard with a scope. I'm not sure how much a difference if any it makes.

I suspect that with a little care the scope or fozgometer technique is good enough for most people.

I agree. How far do you go with these things? Diminishing returns.

 

[ajawamnet]

Wombat said:


Makes me wonder how cutting-lathe heads were aligned and to what specs?

We all wonder that. Buried in some threads at diyaudio are a lot of test LP measurements that were part of an effort to do a group buy of a new test LP. The bottom line is that there are probably no recording engineers that are going to tinker with or tweek their equipment to our specifications.

At opus one, we used a scope with a lissajous pattern and a test record with mono sweep tones...

Similar to what we used in mastering:
https://archive.org/download/BasicDiscMasteringLarryBoden600dpi/Basic Disc Mastering Larry Boden(600dpi).pdf

The lathe also has a tonearm

- you can check to see if the lacquer is being cut matches the tonearm as long as it's calibrated with a test record... Once you calibrate the tonearm you can then cut a test of tones and see how well it matches the ref disc.

As he mentions here you can ... "listen as you cut - do, de do do do do dooo":

Yea, the do de do was a bit much...


As to tracking a good distortion meter with a known good test tone record can help.

 

[Tom C]

Diminishing returns, for sure. No matter what you do, even if you get the setup perfect, it’ll only be right for that particular copy of the test record. A different copy, even of the same record, will have different imperfections, and won’t play exactly the same.
My thinking when asking the question was that if you get the branded software, it will be purpose built and therefore easier to use and maybe better functionality, whereas the oscilloscope would be more versatile, and could be used for testing other things. The oscilloscope could be had used for less money. The test records aren’t all that expensive (I’ve got the Hi Fi News). And you have to buy the ADC sound card separately, if you go with Analogmajik.
When I get around to it, I thought I might try something like this
http://www.sillanumsoft.org/prod01.htm
used with a sound card, just to get started and see what I’m able to figure out. I imagine the hardest part of any method is making the fine adjustments in stylus placement. Then adjust for minimum distortion, maximum signal and near equal channel levels.

 

[scott wurcer]

I've been working on a Python script to display the azimuth tuning information directly from a soundcard. One thing that came up was that setting or calibrating the L/R channel gain for each device in the chain is important. The problem with the average external sound card is that they usually have a cheap log scale pot on each input so I would say you at least need to apply the same input to each and set the gains equal before you start.

If you are simply using 1kHz reference tones RIAA is not necessary and you can use the mic pre-amps on the soundcard directly. It goes without saying DO NOT ever apply the 48V phantom power to your cartridge.