Fozgometer

Dougdeacon,

Can you recommend a currently available test disc that facilitates the listening method? Interestingly enough many years ago I found that the listening method was easier, faster, and better than all the instrumentation just as you suggest. Back then I used a Shure test record that is no longer available. BTW, in those days, while in college, I worked in high end hifi retail and was the go to guy for setting up turntables. So I had a lot of practice.

Thanks,

Bill

In a couple of years of adjusting azimuth on multiple cartridgess using the Wally Analog Shop tool, I don't remember ever seeing much change in output (ie, channel balance), but differences in crosstalk (ie, channel separation) were immense.

About 10 years ago I dropped the instrumentation after realizing that I can adjust by ear just about as accurately and far more quickly. As with the instruments, I've never heard a difference in channel balance when tweaking azimuth within reasonable limits (ie, within a degree or so from vertical), but changes in crosstalk from even the tiniest possible adjustment are readily audible.

YMMV, of course...

Many years ago on Vinyl Asylum, two very knowledgeable guys wrote long treatises on azimuth. At least one of them was an advocate of adjusting for "least crosstalk", rather than "equal crosstalk" (into both channels). Along the way, both stated that one should not attempt to correct for inequality in gain between channels by adjusting azimuth. First of all, even the most extreme differences in azimuth make a very small difference in relative gain between channels. I tried it with my Triplanar and Signet Analyzer; a difference from about +15 degrees to -15 degrees off the 90 degree starting point made barely a 1 db difference in channel balance, and by the way music sounded awful at either extreme. And second, you can't have it both ways; correcting azimuth for crosstalk, as one should do, will not lead also to any significant correction in channel imbalance. So, I guess you're referring to how channel imbalance might contribute to errors in adjusting azimuth for crosstalk. (Yes?) To me, that is no problem if you reference the adjustment to a "0db" point with respect to the channel that is receiving the signal, as I noted above. Don't know about the Foz, but the Signet allows you to do this. You'll still have a channel imbalance, maybe, but crosstalk will be as low as you can get it. The point is that referencing both channels to 0db for the driven channel removes the inequality in gain from the equation, as much as is possible and IMO.

Lew, no, they do not imply that channel imbalances can be fixed by adjusting azimuth. However, the manual would be much more useful if it included information on how to deal with channel imbalances when adjusting azimuth for optimum channel separation (crosstalk). There are discussions on this topic at several forums but no clear answers as how to best handle it.

Regards,
Tom

"The Fozgometer does have a test for channel output balance as well."

It would be nice to be able to compare the outputs of the two channels, but do Fosgate imply that it can be equalized via azimuth adjustment?

Doug, thank you for the clarification regarding channel separation as a surrogate (derivative statistic) for crosstalk. I had used the term crosstalk in the past when describing the Fozgometer but wanted to be consistent with the manual. If you read the manual it does not discuss crosstalk, probably to avoid confusion.

Lew, the test record recommended by Musical Surroundings is produced by Analogue Productions and utilizes a 1kHz tone for the two channels. (They also state that any 1kHz test tone track, one for each channel, can be used.) I have to assume that the two tracks are accurate and equal in output. I have read suggestions to purchase as many as three versions of test LPs to compare tracks and ensure consistency.

I have been curious to use other test tone frequencies to see how the optimum alignment for the 1kHz frequency compares to lower and higher frequencies.

And yes, when I said balanced I was talking about trying to equalize channel separation (crosstalk) between channels. The Fozgometer does have a test for channel output balance as well.

Regards,
Tom

I have to agree with Doug. Moreover, crosstalk, it seems to me as a layman, cannot be discussed without reference to a level of signal. The Signet Cartridge Analyzer guide advises one to use (any of several possible test LPs) with a 1kHz steady state tone on one channel and nothing on the other. Then you set the Analyzer to receive the recorded signal and set that value to "0db" on its meter. You then set the Analyzer to receive the signal on the ideally negative channel, and the meter shows a value on the negative side of its 0db marking. Thus you can say you have negative X db of crosstalk into the channel that is receiving no intentional signal. Then you repeat the process using another band on the test LP that has signal encoded in the opposite channel. Because you have referenced your result to 0db in both cases, you can say that the level of crosstalk in both channels is equal, or not. And you can discuss magnitude in a meaningful way. Also, as Doug inferred, the results will be very different at different test frequencies. It's usually best around 1kHz and worst at the frequency extremes.

So, I don't know what the quoted part of the Foz manual means exactly, except I guess it would be acceptable to not know the reference level, so long as one did not change the level when comparing crosstalk into channel A with crosstalk into channel B. The signal level, whatever it may be, HAS to remain constant it seems to me, when doing that, if you really want to be able to say you have equal amounts of crosstalk in both channels.

TKetcham, The only other thing in your last post that I would mention is the business about "balance". If you are talking about achieving equal amounts of crosstalk in each channel, then I understand, and I do think that's what you meant. But if you are talking about "channel balance", as in equal gain in both channels, adjusting azimuth is not a way to get there.

... the manual states that channel separation is what's being measured.

"Channel separation" is just a derivative statistic. The only way to quantify it is to measure how much information intended to be in channel A is bleeding into channel B, and vice-versa; i.e., crosstalk.

If you measure crosstalk in each direction, average the results and subtract from a notional maximum signal level, the resulting statistic is called "channel separation". The less crosstalk, the greater the channel separation. They're exactly and inversely proportional.

A statement that one is measuring channel separation but not crosstalk would be nonsense. They're two sides of the same coin.

Turns out Peter Ledermann has already used my "fun" method but without disconnecting the distracting active channel first. See last paragraph -

http://db.audioasylum.com/cgi/m.mpl?forum=vinyl&n=840188&highlight=

Cheers,

Stingreen, I may try a uni-pivot tonearm some day. But for now, it's gimbals, man.

Best,
Tom

Tom...actually its very rewarding when you listen to the final results and how each of the parameters effect the overall sound. ...and you really only have to do the whole job once (until the next cartridge comes along..)

Lew, the manual states that channel separation is what's being measured. Also: "The readings are virtually independent of overall signal levels, and can be made with a wide range of input signals without effecting accuracy."

So your comment about what correct azimuth entails is consistent with using the Fozgometer for alignment. Try to get both the best balance between channels and the highest separation in each channel. As you also mention, the two are probably synonymous in a perfect world, but I've found that sometimes it's a compromise between the best separation and the best balance. But which should have priority is not clear to me and I've biased the alignment in favor of trying to get channel separation in better balance while maintaining the best separation value in the lower of the two channels. Does that seem reasonable? (Reasonable or not, it sounds mighty fine. :-)

It would be helpful if Mr. Fosgate and Musical Surroundings were a bit more thorough in describing what the goals are and how to get there.

Regards,
Tom

There are two schools of thought with regard to the endpoint of azimuth adjustment. One says to go for the least amount of crosstalk, in which case I have found over many years (using the Signet Cartridge Analyzer which reads out in "db") that the amount of crosstalk will not be equal in both channels. The other says to go for equal amounts of crosstalk in both channels, even if in doing so you have to sacrifice the absolute best values for crosstalk, which is nearly always the case. There is no right or wrong in choosing either endpoint.

I presume the Foz reads crosstalk at 1kHz. Yes? If so, what do the numbers "17" and "19" mean? If the readout is in db, then it is usually a negative number indicating the level of crosstalk below 0 db, when the channel being measured is set to 0 db. In that case, one typically sees better than -20db at 1kHz (meaning a number more negative than -20).

Ooops, that's "your" description. I had started with a different train of thought and then changed everything but "you're". 8-)

Stringreen, you're description of setting azimuth on a VPI uni-pivot doesn't motivate me to try one out. If VTF is directly coupled with azimuth adjustments and is that fidgety, I think I'll stay with gimbal-pivot tonearms. :-)

So to clarify that there shouldn't be a need to adjust VTA/SRA and VTF when setting azimuth: IF arm length and VTF are stable while adjusting azimuth, having to tilt the cartridge even 1 to 2 degrees will only change height by ~0.05mm to ~0.10mm from a reference vertical stylus setting. I've measured record thickness differences greater than that on a single LP, let alone the differences in thickness between LPs.

Enjoy the music!

Tom

Tom...I'm using a VPI 3D arm, and can tell you that when moving either counterweight or CounterIntuitive around the arm tube..even slightly, I can't prevent it from moving front/back..even a miniscule amount which changes VTF. I must check and check again all the parameters. ...and when adjusting the vtf, I must again check the Foz for its indication. When I'm doing this, it seems endless, but I eventually zero it in. White out indications et al, are way too broad and inexact for me.

Stringreen, you shouldn't have to adjust VTF or VTA/SRA or alignment when adjusting azimuth. All of those parameters should be been set and locked in before you adjust azimuth.

If you have a tonearm that uses a set screw to adjust azimuth then yes, you could be affecting tonearm length if the arm tube is somehow pushed or pulled in or out of the tube sleeve. But all you have to do is put a very small drop of "White Out" on the arm tube right at the edge of the sleeve. That provides a reference marking to make sure you aren't moving the arm tube in/out as you tilt it to adjust for azimuth.

Regards,
Tom

Nansk...make the difference as small as you can do it. Mine is exactly right....needed lots of time.. Every time you change the azimuth, you should check to see if the vtf was disturbed. Any raising or lowering of the back of the arm needs rechecking of all parameters including where the stylus sits on the alignment protractor. I know...very tedious....

Hans, the readings you're getting seem on the low side but perhaps you have a very low output cartridge. The channel separation indicated by the Fozgometer is not bad but I would try to adjust the azimuth so the channels are closer to being balanced (smaller difference).

If this is the first time you have used the Fozgometer I suggest experimenting with azimuth settings to see much stylus tilt affects channel separation. Try tilting the cartridge first one way and then another. Not too much but enough to see a difference in the readings. I check the amount of tilt with a small level. When you get the channel separation to be very close, stop and enjoy some music. :-)

Then, when you have some time, carefully listen to an LP with clean solo vocals and/or acoustic instruments to see if you can hear differences as you make fine adjustments. For example, listen to the LP before you make any adjustments using the Fozgometer and then listen to the same LP after you make adjustments. (Use an LP that you don't mind playing several times without resting it between plays.) Vocals and instruments should come into sharper focus when you're at or near optimum azimuth. As you become familiar with how the readings on the Fozgometer relate to the sound you hear, you'll know when you've got good azimuth alignment by the readings alone.

It's a learning process and takes time so don't be in a hurry and enjoy some music as you go.

Regards,
Tom

Did connect the FOZ to a dedicated 230 V AC to 9 V DC powersupply .Did control the calibration test several times ,stays perfect.
Now test my cart with the proper test LP , saw a difference between L and R of two scale points , I mean reading L is 15 , R is 17 .In both cases the leds did only light for the proper channel.Do you think I have to try to make the difference smaller ? With a LP with pink noise you don't hear the other channel.Hope for some input
Regards Hans

I've had a Foz for maybe four years now. During that time I've installed five cartridges on four tonearms on three turntables. All sounded better after setting azimuth with it--that is, better than eyeballing perpendicularity with a Millennium block. The device is not perfect but it's darned handy and works quite well when calibrated properly.

Onhwy61, it all depends on who you ask as to whether or not the Fozgometer indicates the optimal azimuth. Opinions on the merits of the Fozgometer are all over the map, with a wide gap between camps. Not surprising for a device that's attempting to measure weak signals from a limited frequency range based on an imperfect source. Just do a search on how (im)perfect many of the test LPs are. Compounding that is the level of exactitude that is used during the alignment process.

In my opinion, based on setting azimuth for five different cartridges (4 LOMC and 1 MM) with three different turntables, is that the Fozgometer makes it very easy to set azimuth that is darn close to optimal. Sometimes the azimuth is probably perfect, but I wouldn't know because I don't have a way to test for perfection and I don't spend the extra time necessary to validate perfection by ear.

All I can say is that after setting a Baerwald alignment, getting VTF and SRA adjusted, and then quickly setting azimuth with the Fozgometer, I can put an album on the turntable, queue the tonearm, and sit back and enjoy some of the best sounding music I've ever heard in my home.

Man, that's optimal. :-)

Regards,
Tom

Lew, for about 29 years I used an LP12 with a succession of Linn MC cartridges and enjoyed the success you describe.

Almost total noise suppression (even on dodgy and warped discs) allied to first class tracking, even when the carts were well worn.
Must have been a combination of good bearings, accurate manufacture and the benefit of properly controlling all the parts to minimise error (or I just got lucky :)

At the moment I have what you might call a "Feickert situation" i.e. if we physically measured the cart we'd find that the perfect alignment wasn't exactly 0 degrees (either cantilever axis or diamond azimuth) but still within the limits of cart manufacture in general.

No harm in adjusting alignment to get back to Nirvana. ;^)
All the best,

@Stringreen

Since you wear a hearing aid you "must" use 'tools" for all your arm setup!

Setup by ear is not your option. LOL!

Personally, I bought a Signet Cartridge Analyzer about 25 years ago. All you need is a proper test LP, and it reads out crosstalk. Also has other uses. But I also think setting azimuth is a bit over-rated. Most cartridges sound fine if you set azimuth for 90 degrees. (I hate to say this; I used to argue quite the opposite.)

If minimal crosstalk is your goal and you don't have either a mono switch or special test gear, and you don't want to accidentally break your cartridge tags by trying to invert one channel, try this technique for fun.

Use ONE of the -20db pink noise test tracks from the HFNRR disc (or a 1KHz Xtalk track from the Ultimate Analogue Disc).

Listen only to one of those tracks but first disconnect the I/C for the "active" channel so that you are only listening to the "crosstalk channel".
One of the good things about your ears is that unlike test gear they can easily discriminate between random noise, surface noise & pink noise so gauging the level of the crosstalk signal is not a problem.
Crank up the volume of the silent channel until you can hear the crosstalk clearly then progressively adjust by ear for minimum cross-channel bleed.

One thing you will notice is that surface noise on the 25 second test track will become eerily quiet when you hit the sweet spot. (At least in the case of a line contact stylus)

If you try this method with headphones you may have to crank the volume up quite a bit before you hear any crosstalk at all. It can be done with both channels driven but not quite so easily. A useful side-effect is that you will notice the volume or presence increase on the active channel (yes, even with pink noise) when it hits the sweet spot, coinciding with a minimum in the other.

I believe the Foz is a very worthwile tool, even though it hit the fan recently with negative reviews. The difference when properly done to eyeballing, or setting by ear is quite large.

The Feickert software is hassle free and you can see the relationship between crosstalk and phase and have the choice to align to either.

TKetchum...you evidently got a good one, or mine was made on Friday, just before a holiday. The first week I had the car, the exhaust system fell off....I found a wire hanger and crawled under the car and wired it in until I could get it to the dealer. The hood was designed (or not, but this did always happened) ...when taking it out in the rain, water would splash under the car and be routed into the 4 deep spark plug recesses, which would ground out the electrical system, and the car would stop. I had to carry a turkey baster to suck out the water..would be good for a block or 2....also, my car had brakes made from components from Girling and Bendix which didn't quite fit...it would suck air every time you stepped on the brake. I remember riding to NJ from Lime Rock Connecticut using only the hand brake. I could go on..but you get the idea.

The fozgometer is a PIA to use, and so is setting azimuth by ear.

http://www.whatsbestforum.com/showthread.php?9097-Azimuth-adjustment-the-easy-way

Optimizing Arms are a PITA no matter what approach, but the
end result should be pleasing to YOUR ear!

VTA/SRA and azimuth optimum setup tools only go so far, best to fine tune by ear in the end. IMO YMMV!

Lew, you're right, a new battery is not a panacea in preventing all the potential pitfalls in using a sensitive electronic device like the Fozgometer. And no, I don't put a fresh battery in my Fozgometer each and every time I use it. I made the suggestion because it helps to at least establish a baseline if anyone is unsure about the condition or quality of a battery. Do I recalibrate my Fozgometer every time I use it? No, but I do swap out the battery every year and I recalibrate after doing so. It's not difficult. It doesn't take much time. Not really a burden.

Now, setting azimuth by eye and ear, that's a burden. '-)

Regards,
Tom

Tketcham, As I understood Fremer's review and the comments of others "in the know", it seemed that the absolute voltage produced by the battery makes a difference. Thus installing a new battery is not a panacea; it seems that doing so would require re-calibration of the Foz. Brand new "9V" batteries will vary from about 9.1V to 9.6V in their actual output voltage. (I had to buy several for another project, and I measured about a dozen "new" ones. No two were exactly alike in voltage.) So, if the Foz is sensitive to differences in battery voltage of 0.1V, which I am led to believe is true, then it's not so simple as to say that you need to use a fresh battery every time. Seems it's better to say you should re-calibrate the Foz every time you use it, which is a burden on the user. Probably does not make much difference to change the battery in that case, so long as it is still making 9V or more. I am more in Don's camp on this issue; the Foz should be more dependable, and it could be if Fosgate would make an outboard 9V PS for it. But maybe PS noise, even very low level, is inimical to its function. Hence the battery. But also, I don't doubt that what you said is true; a lot of the reported problems may be due to end-user and/or dealer ignorance of how to use it.

Stringreen, Shame on you for comparing an Alfa Romeo to a Fozgometer. I drove a 1967 Alfa Duetto (with Weber carburetors) for six years as my only car, living in NYC with no garage, and it never ever let me down once, not even in snowstorms. In the end, a dishonest and unskilled mechanic "killed" it. (He later went to jail for fraud and theft in connection with his Ferrari repairs.) The post-1968 Alfas did have a rather unreliable fuel injection system that was necessitated by emissions requirements. That fuel injection system may have contributed to the reputation for unreliability. Many cars were converted back to use Webers in those days. Also, many troglodytes don't know the difference between an Alfa and a Fiat. The 60s and 70s Fiats were indeed problematic.

Does the Fozgometer indicate the optimal azimuth setting or does it just get you very close to that setting?

+1 Don. Could not agree more. We are not building rockets here either. Enjoy the music.

Well, Don, I guess your expectations are far higher than mine when it comes to consumer electronic gear. I suppose that for some things, like MRI, EKG, and X-ray machines I expect perfect manufacturing and they'll last almost indefinitely. Same for car ABS systems and airplane avionics. But for consumer stereo gear and accessories, not so much. I expect that every so often one of the units will have a defect, and that they won't work perfectly forever and will need some maintenance.

If that's total bullsh!t then I guess you're right.

Regards,
Tom

@Tketcham

(And to expect that every single Fozgometer manufactured will work perfectly, forever, is unrealistic.)

TOTAL BS! THAT IS EASY, AND WHAT I WANT!

It is just a meter, and a few parts, is a box, and way overpriced!

Why should it not work forever???

Onhwy61, on the contrary, it points out that you need to pay attention to how you use the Fozgometer and what the signal readings mean. As I said in my recent post, I think some of the difficulties in using the Fozgometer are the result of user error or misunderstanding, or faulty cartridges and/or phono preamps. The owners manual is fairly complete but it could be improved by providing more background information on how the Foz works, what the signal readings mean, and how to troubleshoot (and correct) for odd readings or behavior. That would also help users know when the device is actually deffective or needs to be recalibrated by Musical Surroundings. (And to expect that every single Fozgometer manufactured will work perfectly, forever, is unrealistic.)

The Fozgometer is a very handy device to aid in setting azimuth but it's not a purely "plug-and-play" device; you need to use it properly, use a fresh battery, have good connectors, and normally functioning cartridges and phono preamps. Playing vinyl can be very simple if you want it to be. But if you're wanting to get the highest level of playback that's reasonably possible, you have to take the time and trouble to make that happen. I don't consider it a hassle, it's just part of the enjoyment of a lifelong hobby.

Regards,
Tom

Sdcampbell, thanks for the clarification. I have been wondering about some of the problemss people have posted on using and calibrating the Fozgometer. As Mike Fajin mentioned to you, the unit is sensitive to extraneous signal noise so you have to use good quality connectors and a clean signal. I found this out while using one of my phono preamps and a LOMC cartridge; the preamp had developed some signal noise in one channel that was affecting the Fozgometer and making it difficult to set azimuth. So I used the tonearm cables directly into the Foz. That's the preferred method but when you have a cartridge with low output, the range of signal output is reduced so it reduces the sensitivity of the adjustments in azimuth.

Your mention of the Fozgometer being recalibrated to a 30dB sensitivity got me to thinking that I could do the same in order to have a wider range of sensitivity for LOMC cartridges. I'm assuming that's how it would work. I'll have to experiment to see. Or have you already seen that effect?

I know it would cost more to implement but it would be handy to have two signal level settings on the Fozgometer, one for high output cartridges and one for low output cartridges. But that'd make the Fozgometer more expensive for everyone just to make it more convenient for a limited number of users.

Thanks again for posting the information. Helps to understand how these things work.

Onhwy61: I get your drift... I think I would have contacted Musical Surroundings before posting this thread. However, maybe the reason for this thread was that MS was contacted and no credible response?

If this thread was the only source of information about the Fozgometer, I would conclude that the product isn't functionally reliable.

An additional comment or two to my previous post:
Mike Fajin also asked me about the equipment I used during my
calibration attempts. I had downloaded the test tones to my HP
laptop, and connected the laptop to the Foz using an
inexpensive splitter cable with a mini jack on the computer
end, and RCA jacks on the other two "legs" of the
cable. Fajin said a cheap splitter cable (i.e., from China)
could be a problem, and also that playing the test tones from
the laptop, rather than burning the test tones to a CD and
playing it on a CD player, might also introduce inaccuracies.
His advice was to burn the test tones to a CD and use that to
calibrate the Foz, and to use good quality interconnects from
the CD player to the Foz.

P.S. I got my Foz back from MS and it seems to be working
fine. When MS calibrated the unit, it was set to 30db, rather
than 20db as the unit's instruction manual states.

Yup.....mine was really wrong, and Mike send me a whole new one. He tested and adjusted it and it now works fine. I guess its like an Alfa Romeo. When its working, its wonderful, but you need to keep a repair shop close by. ( I had a Duetta...the red sports car from The Graduate)

Thanks. I had the impression from the other posts that the Foz could be calibrated with the test tones and then still give incorrect readings when used to set azimuth. If that were the case, one would have no way to be sure whether there was error and precisely how much error.

If it can't be calibrated to the test tones, it is out of whack. Nothing subjective about that.

How do you define "whack" and whether your Foz is in or out of it? It's based on a subjective impression, is it not? Unless the azimuth is so askew as to be impossible.

Sdcampbell, that's great information. I used the Musical Surroundings test tones to calibrate my Fozgometer and it went smoothly and the Foz works well for azimuth adjustment. But if the unit ever seems to be "out of whack" and the test tone recalibration method doesn't work I'll know to just send it in for service. It's nice to know that the unit is so easily restored.

Regards,
Tom

I was having problems with the accuracy of my Foz, which was still very new (purchased from LP Gear). I tried to calibrate the unit using the test tones provided on Musical Surroundings web site, but couldn't get it correctly adjusted and sent it to Musical Surroundings for service. The service manager, Mike Fajin, told me that my unit was severely "out of whack", but he was able to accurately calibrate the unit using a special signal generator built for MS by Jim Fosgate. So, if you have a Foz that's not accurate, or you have problems with calibration, you might want to send the unit to MS.

I love my Hagerman Piccolo step up. Just a simple twist of the knob and I can select from 6 different loadings. So much nicer than soldering and de-soldering resistors inside a box, and the sound is transparent and musical too. Thanks for a great design Jim,

I thought I'd enter another installment in my saga. The Foz is back, and I set up the azimuth for my new cartridge. From the beginning, I didn't think much of the new Ortofon Windfield. I came from a Benz LPS and the Windfield was not even in the same league. As it broke in it got better and better, but even after a month or so (waiting for a new Fozgometer) it didn't capture me. I have a VPI 3D arm..and Harry gushed over this cartridge who really made be get it. I reviewed every parameter of setup, but loading....today, I worked on that. Harry told me that 500 ohms is what he uses and recommends, so naturally that is how I set it up. I was uneasy about something, and didn't know what. I called Ayre and spoke to Michael...a guru with this stuff. He told me that he would try 4700 ohms....no resistor in place. Ok, I did that and although it sounded better in many respects, it didn't have the magic I was looking for. OK...opened the Ayre preamp, and got in a 1000 ohm resistor and OMG what a difference. Here is magic in spades. The sound changed with the addition of resistance much like an arm reacts to damping. When you have too much damping, the sound just lays there....too little, and there is too much fuzz...not enough instrument placement...spaces between the notes are filled in. I Suspect that the Ortofon is still waking up, but I encourage you vinyl fanatics, to experiment with loading and not just select a value on a whim. Every system is different and you must experiment to find your prescription.

I just got a brand new replacement Foz from Musical Surroundings. Mike (service) calibrated it personally, and sent me a new battery as well. It took about 10 minutes or so to get the azimuth perfect. Now that the cartridge/arm is set up, I'm going to monkey around with loading. I will return.