NAB or IEC (CCIR)

[Rob]

Given a choice what EQ do the tape veterans choose and does one have a sonic advantage over the other?

[Albert Porter]

I have very limited experience but hold the opinion that IEC/CCIR is the more accurate EQ.

I have some AAA tapes from Germany and one is RIAA and the others are CCIR. I prefer the CCIR, my machine is a Studer. Might be different result with another machine?

[astrotoy]

Albert, I think you mean NAB and not RIAA.

My experience with vendors is that almost all of them are doing IEC/CCIR EQ on the 15ips 2 track. The one exception is Ed Pong (UltraAnalogue) who records using NAB. He also records at a higher level, so there is better S/N (without any saturation). You can order his tapes either NAB or IEC/CCIR. I order mine NAB, since that is what he recommends. All I have to do is remember to switch to NAB, since all the rest of my 15ips 2 track tapes are IEC/CCIR. (and then switch back!).

Larry

[Rob]

I noticed UltraAnalogue offered it both ways which spawned the post. Thanks for the insight Larry, my tape pre accommodates both IEC and NAB eq, I'll order Ed's tape in NAB and give it a whirl.

[MylesBAstor]

Just a little background excerpt from Arian Jansen

Several people have asked me if it would be possible to make an external circuit to convert a standard reel to reel recorder with NAB equalization to IEC (CCIR) equalization. It is indeed possible to add a simple passive circuit in between the output of the reel to reel recorder and the amplifier that will achieve that goal, albeit with some small compromises.

Before going into the details of this circuit I will go over the difference between NAB and IEC equalization. Equalization standards are vastly different for different tape speeds. I will therefore limit this article to a tape speed of 15ips only, since that is most likely the only speed for which a NAB to IEC conversion would desirable. IEC equalization at 15ips is better when using modern tape formulas. However for 7.5ips NAB equalization is the better choice in combination with modern tape formulas.

When recording sound on a magnetic tape, the electrical signals that go into the tape recorder are converted into magnetic signals in the recording head that magnetize the magnetic material on the tape. As with all magnetic materials, the tape will have a maximum magnetization level. If that level is exceeded the tape will saturate and the signal will be distorted. That is the reason for the VU meters on your tape recorder. They allow you to maximize the tape magnetization without saturating the tape.

Unfortunately, the saturation level of the tape at higher frequencies is lower than at low frequencies. This is true for every tape, but tapes from the 50’s and 60’s exhibit this problem much more than ‘modern’ tapes from the 70’s and 80’s. In order to compensate for this saturation problem at higher frequencies, the higher frequencies where recorded at a lower level than the lower frequencies. This would then be compensated on the playback side, so that the frequency characteristic would be flat at the output of the tape recorder.

To avoid that everybody would do their own thing and there would be no compatibility between recorded tapes, standard equalization curves were developed in the 50’s and 60’s. Even though there were still many different ‘standards’ in that time, only two remained as true standard equalization curves in the world. In the 1950’s the National Association of Broadcasters (NAB) adopted a standard in which the high frequencies on the recording side where rolled off above 3150Hz. They also decided that the low frequencies needed to be lifted below 50Hz. This measure was a concession to the limitations of the playback electronics from that era. The NAB curve on the recording side looks like this:



In the 1960’s the Comité Consultatif International pour la Radio (CCIR) in Europe developed another standard, later adopted by the International Electrotechnical Commission (IEC). This standard rolled of the high frequencies at 4500Hz and did not change the low frequencies. The CCIR / IEC curve on the recording side looks like this:



There are people far more technically knowledgeable here about tape than me but in nutshell, new tapes experience less saturation at high frequencies and thus IEC. As a result, there's a significant increase in the s/n ratio, less hiss and also greater dynamics using IEC.

[MylesBAstor]

I have very limited experience but hold the opinion that IEC/CCIR is the more accurate EQ.

I have some AAA tapes from Germany and one is RIAA and the others are CCIR. I prefer the CCIR, my machine is a Studer. Might be different result with another machine?

Part also might be whether or not your machine is optimized for NAB or IEC too.

[Ki Choi]

Simply put, NAB alters both HF and LF whereas IEC alters only the HF. Thus, IEC EQ is closer to the original with less EQ or no EQ in LF at all. So I vote for IEC.

[MylesBAstor]

Thanks for simplifying things!

[jcmusic]

Simply put, NAB alters both HF and LF whereas IEC alters only the HF. Thus, IEC EQ is closer to the original with less EQ or no EQ in LF at all. So I vote for IEC.

Agreed!!!

[c1ferrari]

Just a little background excerpt from Arian Jansen

Several people have asked me if it would be possible to make an external circuit to convert a standard reel to reel recorder with NAB equalization to IEC (CCIR) equalization. It is indeed possible to add a simple passive circuit in between the output of the reel to reel recorder and the amplifier that will achieve that goal, albeit with some small compromises.

Before going into the details of this circuit I will go over the difference between NAB and IEC equalization. Equalization standards are vastly different for different tape speeds. I will therefore limit this article to a tape speed of 15ips only, since that is most likely the only speed for which a NAB to IEC conversion would desirable. IEC equalization at 15ips is better when using modern tape formulas. However for 7.5ips NAB equalization is the better choice in combination with modern tape formulas.

When recording sound on a magnetic tape, the electrical signals that go into the tape recorder are converted into magnetic signals in the recording head that magnetize the magnetic material on the tape. As with all magnetic materials, the tape will have a maximum magnetization level. If that level is exceeded the tape will saturate and the signal will be distorted. That is the reason for the VU meters on your tape recorder. They allow you to maximize the tape magnetization without saturating the tape.

Unfortunately, the saturation level of the tape at higher frequencies is lower than at low frequencies. This is true for every tape, but tapes from the 50’s and 60’s exhibit this problem much more than ‘modern’ tapes from the 70’s and 80’s. In order to compensate for this saturation problem at higher frequencies, the higher frequencies where recorded at a lower level than the lower frequencies. This would then be compensated on the playback side, so that the frequency characteristic would be flat at the output of the tape recorder.

To avoid that everybody would do their own thing and there would be no compatibility between recorded tapes, standard equalization curves were developed in the 50’s and 60’s. Even though there were still many different ‘standards’ in that time, only two remained as true standard equalization curves in the world. In the 1950’s the National Association of Broadcasters (NAB) adopted a standard in which the high frequencies on the recording side where rolled off above 3150Hz. They also decided that the low frequencies needed to be lifted below 50Hz. This measure was a concession to the limitations of the playback electronics from that era. The NAB curve on the recording side looks like this: [ATTACH=CONFIG]n9389[/ATTACH]



In the 1960’s the Comité Consultatif International pour la Radio (CCIR) in Europe developed another standard, later adopted by the International Electrotechnical Commission (IEC). This standard rolled of the high frequencies at 4500Hz and did not change the low frequencies. The CCIR / IEC curve on the recording side looks like this: [ATTACH=CONFIG]n9388[/ATTACH]



There are people far more technically knowledgeable here about tape than me but in nutshell, new tapes experience less saturation at high frequencies and thus IEC. As a result, there's a significant increase in the s/n ratio, less hiss and also greater dynamics using IEC.

Very instructive post...thanks Myles and Arian

[Rich Erdey]

I recently acquired an MCI JH110 with a 1/2 and 1/4 inch head stack using the recapped internal electronics for playback. I've quickly learned how to use the test tones to adjust the setting screws on the repro cards before each tape playback. There is a dip switch on each of the 2 repro cards (left and right channel) to select NAB or IEC. I've been recently told by someone who dupes alot of 15IPS tapes that it's generally better to record the dup with the same EQ as the original. for example: "original recorded in NAB, record EQ setting for the dup: NAB". . I've respected this "rule" so far and now have had this source dup several 1/2 in copies, 4 NAB to NAB and 1 IEC to IEC. The NAB tapes have tremendous dynamic range and little hiss. The IEC tape has excellent dynamic range but more "hiss" than the NAB titles. If the hiss should be less with IEC, Is it correct to assume that hiss on this dup might suggest the source tape was more than several generations away from the master? If it were recorded in NAB, instead of IEC, would the hiss be worse?

Now let's assume we're going to make a copy of a 1/2in tape recorded in NAB.
Playback source tape with EQ setting NAB.
Blank tape: new, high performance SM468 1/2inch
Let's also assume there are 1K, 10K, 50K test tones recorded on the dup and these are used to calibrate for playback.
Given the excellent discussion by Myles and the opinion of K Choi above would most who have choice of NAB/ICE playback capability prefer to record all tapes with EQ setting: ICE (CCIR) regardless of the source EQ setting? Can anyone who's done an A:B comparison (NAB to NAB, NAB to ICE) two dups using same source tape comment about any sonic differences with each copy?

[astrotoy]

Rich, what machine are you using for the repro and what machine are you using for record. If you can record in both IEC and NAB, I am assuming your record machine has record settings for both EQs. Also your repro machine should have settings for both EQs also in addition to setting the test tones with the setting screws.

As my signature indicates I have two Ampex ATR-102's both with 1/4" and 1/2" head blocks, so I can record and play any combination of those tape sizes. I dub a lot of tapes, from IEC or NAB (where I go through my Doshi 3.0 tape prepro which has settings for IEC and NAB and AES) and I use my test tapes or the test tones on the master tapes to do the fine adjustments on the Doshi controls, once the EQ switch is set.

However, for record, I only use IEC, even though I could pull my Audio cards out and change the dip switches for NAB. I do, of course, set the bias and frequency adjustments on the audio cards depending on what size and type of tape I am using. So I can't give you any suggestions on whether to stay in NAB or convert to IEC.

Larry

[Rich Erdey]

I only have one tape machine, an MCI JH110 with 1/2 and 1/4 in head stacks that I'm using for repro only. As I indicated, my MCI can play back in NAB or IEC using a switch on the repro card. I'm getting tapes made on other machines. For example, Tape project is using ATR's to make tapes. They, like you, prefer to record in IEC regardless of the source tape's equilization, but they are capable of doing either on request.

[astrotoy]

I only have one tape machine, an MCI JH110 with 1/2 and 1/4 in head stacks that I'm using for repro only. As I indicated, my MCI can play back in NAB or IEC using a switch on the repro card. I'm getting tapes made on other machines. For example, Tape project is using ATR's to make tapes. They, like you, prefer to record in IEC regardless of the source tape's equilization, but they are capable of doing either on request.

Rich, I misunderstood your question. It looked to me that in your second paragraph you were asking about making a dub. You also said on your first post that you adjusted playback by adjusting the setting screws with the test tones, not by a switch on the repro card. With a switch and the setting screws you should have the NAB and IEC correctly set.

AFAIK, the vast majority of prerecorded 15ips 2 track tape that are available for sale commercially are sold as IEC only. One of the few that does offer both is Ed Pong (Ultra Analogue). Ed does all his recordings in NAB and he prefers NAB for playback. However, he will make dubs of his tapes in either IEC or NAB. I happen to buy his tapes (which are very fine BTW) in NAB, since it is extremely easy for me to playback either NAB or IEC. He has released more than 40 albums so far and I have purchased almost all of them. I know many on this list who have purchased his tapes, I think most of them get them in IEC.

There are a couple of tapes that were put out by Groove Note (by the artist Jacintha) that were done in NAB (Myles found this out since the boxes were not marked with the EQ.) I have those also. Since prerecorded tapes are typically pretty expensive, I haven't done any experiments with buying both NAB and IEC versions of the same albums.

What are the tapes you have on 1/2"? Not too many commercial companies release tapes on 1/2". I have 8 of the Tape Project on 1/2", all in IEC. I would be very interested in what else is available out there.

I did read in Dave Denyers "The Reel to Reel Rambler" in his latest column where he interviews Lynn Stanley, that he compared her album in NAB and IEC. IIRC, he said he thought the NAB was much better and the original was done in NAB. However, I don't think he said much about the set up of his playback machine and also how the reproduction chain was done for her tapes.

There may be other companies that will make dubs in either EQ and someone else in the forum may be more knowledgeable than I am. I know that quite a few people have machines that are only set up for IEC.

Larry

[cupboy]

I have an interesting problem. I recently purchased a tape that is CCIR and have only a NAB machine. The tape is 2 track 15 IPS. Any suggestions on how I might play it other than purchasing another machine?

What will happen if I play it on the NAB machine? Would it lack bass or have too much bass, and would it lack high frequencies or have too much treble? I may want to play it just to check that the recording is good. And then later play it back with the proper EQ once I figure that problem out.

[Skylab]

The differences are very subtle. You will get a little bit more treble and bass than intended. It will probably sound great 🤪

[MylesBAstor]

I have an interesting problem. I recently purchased a tape that is CCIR and have only a NAB machine. The tape is 2 track 15 IPS. Any suggestions on how I might play it other than purchasing another machine?

What will happen if I play it on the NAB machine? Would it lack bass or have too much bass, and would it lack high frequencies or have too much treble? I may want to play it just to check that the recording is good. And then later play it back with the proper EQ once I figure that problem out.

If electronically inclined, here is a way to build a unit to convert EQs.

http://nomanlab.com/sale/lim_docs/nab_to_ccir.pdf