There are no dumb questions

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Steve E.
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There are no dumb questions

Post: # 24536Unread post Steve E.
Thu Apr 04, 2013 9:21 am

Some here may disagree with me, but I feel there are no dumb questions. I want to reset the tone around here on this issue. Too many people are feeling shut down, prematurely. Some of them are wandering away, or merely lurking out of fear of being perceived as idiotic. I fear we are missing out because of this. This board could be more dynamic.

I don't even really mind questions being re-asked endlessly. I don't see such a problem.

Sometimes, yes, there is laziness. It is definitely true that the search engine, both internal and Google, is your friend. It's a great idea to plug in some key words before asking things on the board. And I do think the "Gee, I want to start a pressing plant with $2000! How do I do it??" repeated pattern gets old. OK, that one is really, really dumb.

But I suspect that, usually, when people ask a question around here, it is because:

1) there is a nuance to their query that has not been addressed before, or
2) the amount of info available here is daunting and overwhelming
3) they don't know the correct terms that could make a search easier for them

So be kind and patient when people ask questions. If you know of the best prior thread(s) dealing with the issue, be a peach and post them. Suggest search terms. If the question bores you, don't answer it.

On behalf of all potential idiots and potential future genius experts.....thank you!

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lucien
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Re: There are no dumb questions

Post: # 24559Unread post lucien
Fri Apr 05, 2013 8:37 am

Hello everybody,

First post here :wink:
On many boards there's often a section for beginners or newbies. What about creating one?
For instance people like me could ask dumb questions without feeling ashamed. Experienced members who are bored of reading and answering basic questions would just not watch this section.

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Steve E.
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Re: There are no dumb questions

Post: # 24592Unread post Steve E.
Sat Apr 06, 2013 2:13 pm

That's a good idea and one I will consider. Thank you!

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dave friday
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Re: There are no dumb questions

Post: # 33144Unread post dave friday
Wed Jan 14, 2015 2:27 pm

Hi all, I grew up thinking that record were/are cut with high frequency premphasis and bass cut.The bass cut was/is to help with groove spacing?
Mixed in with the above is riaa nab and so on.
Ta.

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opcode66
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Re: There are no dumb questions

Post: # 33146Unread post opcode66
Wed Jan 14, 2015 5:40 pm

Electrically cut records have implemented the Orthophonic EQ curve. Then around 1949 when 7" came out, there was the New Orthophonic EQ curve. When cutting a pre-emphasis is on the highs and a de-emphasis is on the lows. The zero point is 1Khz. This is referred to as the Inverse RIAA or IRIAA EQ curve.

On playback there is a de-emphasis on the highs and an emphasis on the lows. The zero point remains at 1Khz. This is referred to as the RIAA EQ curve. Every phone pre-amp has one.

When the IRIAA and then the RIAA are combined, they should cancel each other out. As long as the two were implemented correctly. In my experience, this is rarely the case. There is usually some non flat response due to either the phono pre not having an exacting curve, or the cutting amp that was used to make the record. But, under perfect conditions, the resulting signal should be flat when run through IRIAA and then RIAA.

This in no way speaks to the why. Why do this EQ'ing only to have it cancel itself out on playback? Well, you said groove spacing. Others say it is because you are trying to override surface noise on the disc. Neither is true. As explained to me by Al Grundy and in books. The standard was employed because of the restrictions of recording technology back in years past. And, because of the material they were recording. A lot of music was driven by a vocalist or vocalists. And, when recording, they maybe had one or two microphones in a room to record an entire band or orchestra lead by a singer. Unless you wanted things like the percussionist to drown out the vocalist, you had to do some EQ'ing. That way, the higher vocal range would have precedence on the recording and not the drummer or bass. So, on recording, you pump things past 1K, up to 20+db at 20K. And, bring down the lows. Cut the disc. And, on playback, do the reverse, and everything sounds balanced.
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jjgolden
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Re: There are no dumb questions

Post: # 33150Unread post jjgolden
Thu Jan 15, 2015 12:02 am

" Hi all, I grew up thinking that record were/are cut with high frequency premphasis and bass cut.The bass cut was/is to help with groove spacing?
Mixed in with the above is riaa nab and so on.
Ta."


You're right.
Cutting with the RIAA (bass cut) is directly related to groove spacing. i.e. to allow standard album lengths to fit on a disc. 18-20 minutes.
Without it there would be huge low end excursions which use up tons of space and in some cases could become violent enough to damage the moving mechanics of the recording head/coil/piston rods etc.

The treble boost/cut of the RIAA curve is beneficial on playback to reduce surface noise of the vinyl pressing.

JJG

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opcode66
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Re: There are no dumb questions

Post: # 33157Unread post opcode66
Thu Jan 15, 2015 7:22 pm

So I guess that makes me and Al wrong then JJ????

Skip ahead to 5:08 in this video for the explanation direct from the horses mouth.

Skip to 9:30 where Al jokes about getting rid of RIAA entirely.
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jjgolden
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Re: There are no dumb questions

Post: # 33159Unread post jjgolden
Thu Jan 15, 2015 8:06 pm

Hey Todd,

I was directly answering the question that dave friday asked.
Al refers to it, (Groove spacing) in your video at 10:20 - 10:42.

Do you really feel my response to dave fridays question is not true?


JJG

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opcode66
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Re: There are no dumb questions

Post: # 33161Unread post opcode66
Thu Jan 15, 2015 11:47 pm

Your response is a happy byproduct of the RIAA EQ curve. It is not the reason for it. Neither is surface noise.

I believe I am also directly answering the question.

Al mentions the bass reduction increasing recording time. But, it is not explained as the reason for the RIAA bass reduction. Al quite clearly explains in detail the reason why in the video. In fact, Al takes about 5 minutes to explain this. What you are citing is a happy coincidence of the RIAA EQ that Al mentions biefly in passing. Clearly not the why. Which, unless I'm misunderstanding the question here, is exactly what was being asked.
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EmAtChapterV
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Re: There are no dumb questions

Post: # 33163Unread post EmAtChapterV
Fri Jan 16, 2015 5:02 am

That was a very informative video, but I need to ask what on earth happened starting at 3:17? Al's record cutting knowledge was so powerful that it apparently ripped a hole in the fabric of reality. :shock:

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jjgolden
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Re: There are no dumb questions

Post: # 33170Unread post jjgolden
Fri Jan 16, 2015 9:55 am

Whatever, I guess we both answered from different perspectives.
You were answering the "were", and I was answering the "Are" part of the question.
You're awesome, I'm awesome, everybody is awesome.

JJG

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dave friday
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Re: There are no dumb questions

Post: # 33186Unread post dave friday
Sat Jan 17, 2015 7:37 am

Thanks all,the information helps but why does the cutter head output increase with the lowering of the Audio frequency (with the same audio level).
Ta.

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markrob
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Re: There are no dumb questions

Post: # 33188Unread post markrob
Sat Jan 17, 2015 9:27 am

Hi,

When you say cutter head output, I assume you are referring to its excursion (stylus movement). If so, then if the head has flat velocity response and the RIAA EQ is turned off, then excursion increases 6db (double) for each octave lower in frequency. This is due to the mathematical relationship relationship between velocity and excursion (it must be so). Imagine the stylus moving back and forth 1000 times per second with a peak to peak movement of +/-.001". The velocity of the stylus changes over the course of that cycle ranges from 0 at the peaks of excursion to its maximum at the zero crossing (its neutral position). If you cut the frequency in half, but keep the peak velocity constant, the stylus will need to move twice as far.

With the above in mind, the RIAA curve makes the cutter head move with a constant excursion in the range of frequencies from 50 Hz to 500 Hz. This is the reason space is saved on the recording. Below 50 Hz, the head response reverts to constant velocity . This was done to mitigate against rumble in the playback chain. From 500 Hz to 2122 Hz, the head is in constant velocity mode. If you did not have space issues, it would make sense to just record across the entire audio spectrum in this mode. Above 2122 Hz, high frequency pre-empahsis is employed. This is a simple noise reduction technique used in many audio systems. If you did not do this, given the decrease in excursion of the stylus at high frequencies, you would fall below the noise floor of the medium. This is a good solution to the recording problems associated with cutting records. In the electrical recording era before the RIAA curve was standardized, there were several EQ curves in existence that had similar shapes. They differed in the location and number of turnover points. Way back, playback systems often had selectors for the various curves that were used. Standardization eliminated this mess. The selection of these turnover points is somewhat arbitrary (within some limits). What Al is alluding to is that at the time the RIAA turnover points (50,500, 2122 Hz) were selected by RCA, music did not have as much high frequency information as is the case with much modern music (think synth's, close miking, super bright mixes). At issue, is the fact that the amount of high frequency boost provided for in the RIAA curve can require extreme amounts of peak power to be applied to the cutter head and in some cases, require the used of limiters and other processing to make sure that the head doesn't fry or cause recordings that cannot be tracked by playback devices. So the reasoning behind the curve is both scientific and intuitive. What Al is saying is if you were starting from scratch (no pun intended) today, the choices might be different given modern recording techniques and improvements in the recording chain.

I hope all of this makes sense and gives you some insight into the questions.

Mark

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opcode66
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Re: There are no dumb questions

Post: # 33193Unread post opcode66
Sat Jan 17, 2015 4:04 pm

markrob wrote:What Al is saying is if you were starting from scratch (no pun intended) today, the choices might be different given modern recording techniques and improvements in the recording chain.
Exactly. Ideally, I would prefer a far less severe curve on both sides of 1K. It would be cool to implement RIAA V. 3. Make a box that can plug into the output of a phono pre to resolve the differences between the current RIAA and V. 3. Then cut all new records with the new curve and implement the new curve in all newly made phono pre-amps. But, sadly, the days where standard changes like that could be implemented are over. I've been toying with the idea of implementing something like this for personal use however.
EmAtChapterV wrote:That was a very informative video, but I need to ask what on earth happened starting at 3:17? Al's record cutting knowledge was so powerful that it apparently ripped a hole in the fabric of reality. :shock:
Compression Codecs and editing software. That splice didn't render nicely and caused disruption for a little bit.
jjgolden wrote:You're awesome, I'm awesome, everybody is awesome.
Confirmation of an already known fact. :wink:
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dave friday
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Re: There are no dumb questions

Post: # 33208Unread post dave friday
Sun Jan 18, 2015 2:39 pm

Thanks all,so as the frequency goes down there is more time that the cutter is powered for?
I Have been struggling with this!

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markrob
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Re: There are no dumb questions

Post: # 33209Unread post markrob
Sun Jan 18, 2015 3:43 pm

Hi,

Maybe this will help:

In the first image there are 2 sine waves of the same amplitude but one is twice the frequency of the other. There are two cycles of the higher frequency sine wave in the space of one of the lower frquency.

You can see that the higher frequency sine wave has a larger slope (rises faster) at the start as compared to the lower frequency wave. Its velocity is greater.

In the second image, the lower frequency sine wave's amplitude has been doubled as compared with the higher frequency sine wave. Now they both have the same slope (or velocity).

Mark
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dave friday
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Re: There are no dumb questions

Post: # 33216Unread post dave friday
Mon Jan 19, 2015 5:41 am

Thanks again,I re read some words by Gilbert Briggs ( on cutter heads ).
So..as the recording frequency is lowered the cutter is powered ( on both half cycles) for a longer time,and so the stylus is moved further ( on both half cycles)
Ta.

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oldskoolhead
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Re: There are no dumb questions

Post: # 34824Unread post oldskoolhead
Mon May 04, 2015 9:45 am

maybe an FAQ as a sticky in the newbie section would be an idea, mitigating the need to answer the same questions over and over and negate the need to know the required search terms to find such info, once a question becomes a nusiance it can be added to the thread lol

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thades
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Re: There are no dumb questions

Post: # 38561Unread post thades
Wed Nov 18, 2015 12:14 pm

Hello!

This is my first post in the group. I've got a Presto 6-n, with a Presto 1-D cutter head (that was rewound to operate at 8 ohm). I recently purchased an iRIAA preamp filter from Max Gorbman at MXTRNX Custom Audio Devices. So I'm getting VERY close to finally having a working system! My questions are these: If I'm powering my cutterhead with a modern solid state 8 ohm amp, what type of wattage should I be looking at. Also, I've lead that an inline fuse should be placed between the cutter amp and the cutter head. What should that fuse be rated?

Best,

Ted

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mossboss
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Re: There are no dumb questions

Post: # 38563Unread post mossboss
Wed Nov 18, 2015 12:45 pm

Do a search here There are schematics as well as all the information you are asking
Best
Chris

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