Perhaps I should mention that some of the preference for the sound of 30 ips over 15 ips has to do with the choice of EQ standard.
15 ips NAB is the EQ standard that gives 15 ips a bad name, IMO. Designed by Ampex for the tapes and machines of its time (1953), it requires a big record bass boost that modern machines using modern tapes don't need. This is a problem, since it significantly reduces low-end headroom on the total system. The end result, on organ or other bass-heavy music, is a tendency for low-frequency intermodulation distortion. Also, the NAB curve on the high end leaves more headroom than is needed for modern machines and modern tapes, resulting in reduced S/N and more noticeable hiss.
15 ips IEC1 has no record bass boost, less intermodulation distortion, better high end S/N and less prominent hiss. Those features, combined with the low end advantages of 15 ips and lower tape cost than 30 ips make it an appealling choice. Jay McKnight (MRL) even offers his Studio Master or "SM" EQ for 15 ips that boosts the high frequency flux another 3 dB above the levels of the IEC1 standard, but I have not used that standard.
Since the fall of 1970, there is only one EQ standard for 30 ips and it is known as either AES or IEC2.** It is wavelength identical to 15 ips IEC1 and the same calibration tape can be used for either speed without level compensation at any frequency, but merely by recognizing that frequencies are doubled at 30 ips. 30 ips AES also lacks the shortcomings of 15 ips NAB (bass distortion and greater hiss) and so may also be an appealling choice compared to NAB. However, the bass roll off will be raised an octave compared to 15 ips and that may be a nuisance recording music with strong low end parts.
Cheers,
Otto
** The IEC standard does include an IEC1 standard at 30 ips which is never used for new recordings and is only used for 30 ips 1/4" mono recordings made in Europe prior to 1955. Oddly enough, I've been listening to such recordings a lot lately, albeit on CD, since I've been listening to recordings of Debussy piano work recorded in Europe by Walter Gieseking in the early 1950s.
No argument there. I used to do mostly: DASH, Pro Digi and ADAT transfers. And of course plenty of analog transfers. We had to turn down a client once because our studio did not have a Stephens 2 inch 40 track. I believe that is the 811D. I think.
We had: 2 Otari MX-80s with the 32 track head stack, the 2 inch head stack with the 1 inch 12 track playback head for playing back tapes made on the Scully 284-12; a Tascam 1 inch 16 track recorder, a half inch 8 track, a Studer A800 Mark 2, 1 inch 8 track, 3 Studer 827s, 3 JDF Magnetics 2 inch 8 track head stacks (we usually mounted those on the 827s), an restored Ampex 300 -4 half inch 4 track, 2 Sony 3348HR, 2 Mistubusihi X-850s, a dozen ADATS......but, no 2 inch 40.
Fun! I am retired now at 62 because of my poor vision.
Your discussion reminds me of a talk I had with my Uncle Jack awhile back. He used to be an audio engineer as far back as 1967. He is still going at 73! We were arguing over the merits of 15 and 30 ips. Apparently it used to be the thing to run your 2 inch 16 track at 30 ips. Back in 1973 that would get you 69 db 'A' weighted signal to noise ratio. I asked, "What about Dolby A?"
I myself have transfered lots of 1 inch 8, 2 inch 16/24/32 track tapes encoded with Dolby A. A few with DBX Type 1. Mostly between 1970 - 1986. I assumed Dolby A was standard by the early seventies. Certainly in big Pro studios. By 1971, 20 studios in London, England were using 2 inch 16 track with Dolby A. Uncle told me, "Not every engineer liked NR. I never liked the way Dolby A sounded on 2 inch."
Question. Wouldn't running your tape at 30 ips castrate your bottom end with the 2 inch 24 track machines of old? for example the Otari MTR90
@ 15 ips.....30 - 20 000 +-2db
@ 30 ips.....50 - 25 000 +-2db
Record / reproduce.
I have transfered a few 2 inch 24 track tapes made at 30 ips and the low end is just not the same. Still sounds good.. Is it worth spending double the price in tape just to get another 2 db of signal to noise ratio? The MTR90 like other 2 inch 24 tracks of the the period could pull 66 db unweighted (69 db 'A' weighted) without a problem at 15 ips. This is extremely quiet already. Distortion is lower of course and smoother top endnat 30 ips, but the MTR90 is
60 - 18 000 hz +- 1db at 15 ips Record/reproduce.
This is a pretty linear top end already.