Tape Frequency response comparisons between several tape brands

Disclaimer: This is by no means a definitive test between tape brands and models, however it does show some of the basic differences between the various formulations.

Our test setup is a good working Otari 5050 Mk 1 with good heads, and a Soundtech 1510A tape deck analyzer. The tape deck is running at 7 ½ and 15 IPS, and is a ½ track machine, using the full width of the tape in one direction. We set the recording and playback to be as flat as possible at both speeds with ATR MasterTape, tweaking the bias and eq controls as required. We then ran frequency response tests of the more popular brands of tape that we had on our test bench. All frequency response measurements were made at -20db.

Otari 5050 tape deck  How to read the frequency charts

As a refresher, the picture to the right shows how to read our Soundtech 1510A tape analyzer. Each vertical division is 10db, with the frequency plot going from 20Hz at the far left to 20Khz at the far right. While 10db per vertical division seems to be a very coarse scale, keep in mind that typical tape deck measurements are done 20-20Khz at +/-3db, for a total allowable variation of 6db between the lowest amplitude frequency and the highest amplitude frequency. The scale used for our images below show clearly what each frequency response is.

The ATR MasterTape shows a flat frequency response +/- 2db from about 60Hz to 20Khz at 7 ½ IPS, and about 40Hz to 22Khz at 15 IPS. That is pretty typical for an Otari 5050 deck with a high quality tape.                                                                                                                                                                                 

7½ IPS 15 IPS
ATR MasterTape ATR MasterTape

Next up, we have the ATR MDS-36 tape. This is 1 mil tape, with 1800’ on a 7” reel, or 3600’ on a 10.5” reel. Since you can record a typical record album of 45 minutes on one side of an 1800’ tape at 7 ½ IPS, this was the preferred tape length back in the 60s to 90s for consumer machines.

The ATR MDS-36 tape is similar in frequency response to the MasterTape, so no bias or eq tweaking is required between the two tape types in order to get a very similar response.

7½ IPS 15 IPS

Then I ran the RTM 911 tape through the Otari. The RTM911 is the equivalent to the ATR Mastertape. Both are +6db tapes before saturation, and the frequency responses between it and the ATR Mastertape are very close to one another, meaning that if you want to swap between tape brands, you don’t need to change the bias and eq settings to get the same results from your deck.

7½ IPS 15 IPS
RTM 911 RTM 911

Next up we have a new old stock pancake of Quantegy 499 tape that we inherited from a recording studio that shut down a few years ago.  The tape is still in good shape, although the roll on our bench is just starting to shed a bit due to the 100s of passes we’ve put on it testing decks. Compared to the MasterTape, it has a bit of a boost around 2Khz to 22Khz at 15 IPS, which means the tape playback will be a bit brighter sounding than  the source. (this could be made more flat with adjustment of the bias and eq settings). Without changing the bias and eq, at 7 ½ IPS the 499 tape has a bit more boost around 5Khz, then dropping off around 18Khz. Again, with some bias and eq tweaking, the high frequency response could be flattened and extended a bit.

7½ IPS 15 IPS
  Quantegy 499 Quantegy 499

The next tape I tested was the Capture 930 tape. Capture tape is less money than either the ATR or RTM tape, but with a poorer frequency response, as the tape is not back coated. Note that the high frequency response isn’t bad at 15 IPS, but starts dropping off at 10Khz at 7 ½ IPS. The tape copy with this bias and eq setting will sound a little dull compared to the source. If we were to tweak the bias and eq to bring up the high frequency response with the Capture tape, then you’d have other back coated tapes sound far brighter than the source. For general purpose testing, or for old tube mono or low end portable recorders, the Capture tape is fine. For more critical recordings and a better frequency response, we recommend the better back coated tapes.

7½ IPS  15 IPS
Capture 930 Capture 930

I also tested a lightly used roll of late model Maxell UDXL tape. While the Maxell tape is a bit brighter at both  7 ½ and 15 IPS, it stands up to the test of time. We estimate that this Maxell tape came out the late 1980s, as it was an 8th generation box. (an exhaustive Maxell tape history is here on AudioKarma) :


Again, the Maxell tape could be made flatter by tweaking the bias and eq on the Otari.

7½ IPS 15 IPS
Maxell UDXL   Maxell UDXL

Last, I tested a generation 4 tape of Maxell UD non back coated tape. As expected, the results were similar to that of the Capture 930, less high frequency response than those of the various back coated tapes tested.

7½ IPS  15 IPS
Maxell UD Maxell UD