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Author Topic: 7 ? VS. 15  (Read 8419 times)

Offline labosh

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7 ? VS. 15
« on: December 02, 2012, 10:15:09 PM »
hello everyone,

once again, might be an easy question for you, and very important for me.

I recently did a comparation recording same music on 7 ? speed and 15 speed using Revox PR99 and Maxell tape.

I used a CD so I had the sound of the source unchanged.

The results were pretty shocking to me regarding my poor knowlegde of tapes, that a recording on 15 speed should be better?

The recording on slower speed 7 ? - came out when transfered back to my DAW apr. 2db louder, with much more low frequencies, while the recording on 15 speed  was nicely superior only in hi frequencies, and definetely poor in bass.

Is that normal, or is something wrong with my Revox?

There's no deformation in sound, neither hiss, and all of these differencies are just slightly noticable, but revealing that the recording on slower speed is louder and much more closer to the original source is not what I heard.

thank you for your comments!
Labosh   

Offline ironbut

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Re: 7 ? VS. 15
« Reply #1 on: December 03, 2012, 01:11:26 AM »
Hey labosh,

I suspect that the issues you're seeing are the results of improper recording bias. I'm certainly no expert on the recording end of recorder adjustments, but I do know that bias should be done for the speed and particular tape that you plan to use.

Of course if your machine has been biased for 15ips and the formula of Maxell tape that you're using, than my guess is off base and the problem is elsewhere.

If you wish to read a bit about biasing, MRL has a nice pdf available.

http://home.comcast.net/~mrltapes/#More_info

If you're not sure how your machine is set up, it would be best to take it to a qualified service tech to have it serviced.
I'm not sure if you have a personal preference for the Maxell tape you're using, but if you wish to get the best out of your machine and plan to do a lot of recording, you need to have it biased for the tape you plan to use at the speed you plan to record at.
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Offline labosh

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Re: 7 ? VS. 15
« Reply #2 on: December 03, 2012, 04:28:29 AM »
Hey Iron!

thank you.. that helps. I'll check the BIAS.
Labosh

Offline niklasthedolphin

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Re: 7 ? VS. 15
« Reply #3 on: December 10, 2012, 04:06:39 PM »
It just might not be any BIAS issue.

http://www.endino.com/graphs/

Commonly known, 15ips lacks bass tones compared to 7?ips as 30ips lacks bass compared to 15ips.

The FR moves one octave for each doubling of speed

http://homerecording.com/bbs/general-discussions/analog-only/30ips-15-ips-mastering-282941/

http://www.electricalaudio.com/phpBB3/viewtopic.php?f=4&t=907
« Last Edit: December 10, 2012, 04:16:45 PM by niklasthedolphin »

Offline docb

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Re: 7 ? VS. 15
« Reply #4 on: December 10, 2012, 05:10:07 PM »
It just might not be any BIAS issue.

http://www.endino.com/graphs/

Commonly known, 15ips lacks bass tones compared to 7?ips as 30ips lacks bass compared to 15ips.

The FR moves one octave for each doubling of speed

http://homerecording.com/bbs/general-discussions/analog-only/30ips-15-ips-mastering-282941/

http://www.electricalaudio.com/phpBB3/viewtopic.php?f=4&t=907

Using a head designed for the desired tape speed ameliorates this issue. The links to which you refer discuss the use of the same head at different speeds. The length of the track on the head determines the lowest frequency response. A head design optimized for 7.5 ips will not sound as good at 15 ips. But a head design optimized for 15 ips can sound better at 15 ips than one designed for 7.5. Note also in those graphs that the head bumps are practically non existent in the better machines.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline niklasthedolphin

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Re: 7 ? VS. 15
« Reply #5 on: December 10, 2012, 06:04:25 PM »
It just might not be any BIAS issue.

http://www.endino.com/graphs/

Commonly known, 15ips lacks bass tones compared to 7?ips as 30ips lacks bass compared to 15ips.

The FR moves one octave for each doubling of speed

http://homerecording.com/bbs/general-discussions/analog-only/30ips-15-ips-mastering-282941/

http://www.electricalaudio.com/phpBB3/viewtopic.php?f=4&t=907

Using a head designed for the desired tape speed ameliorates this issue. The links to which you refer discuss the use of the same head at different speeds. The length of the track on the head determines the lowest frequency response. A head design optimized for 7.5 ips will not sound as good at 15 ips. But a head design optimized for 15 ips can sound better at 15 ips than one designed for 7.5. Note also in those graphs that the head bumps are practically non existent in the better machines.

No change of head stack was mentioned in the Opening Post.

Do you have a head stack with extended frequency heads in mind when you mention "optimized head design"?
Or would it be the heads impedanse being manipulated to dampen the low end bump being the speed optimized heads?

The low end bump, by nature, will be there dictated by the choise of speed; however insigniicant they may seem on more modern decks using IEC (CCIR) rather that NAB curve.
The Bump will always move one octave up with a doubling of speed.
Below the low end bump there will practical be no low end left.

Normaly a change of head stack will be the choise of the amount of tracks.

Many decks, also pro decks from Studer, Lyrec and other decks I know of, have a choise of speeds but no option of specific speed optimized head stacks.

Please enlighten me/us.
« Last Edit: December 10, 2012, 06:10:50 PM by niklasthedolphin »

Offline docb

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Re: 7 ? VS. 15
« Reply #6 on: December 11, 2012, 11:06:14 AM »
Yes I am suggesting that one can have a custom head the size of which is optimized for a given speed. There are sometimes heads that can be substituted from one brand of deck to another that can be more optimal than the stock head as well. Greg Orton is quite flexible about making custom heads to meet a particular need and John French has done quite a few head swaps to optimize the performance of various decks.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline niklasthedolphin

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Re: 7 ? VS. 15
« Reply #7 on: December 11, 2012, 12:50:38 PM »
Yes I am suggesting that one can have a custom head the size of which is optimized for a given speed. There are sometimes heads that can be substituted from one brand of deck to another that can be more optimal than the stock head as well. Greg Orton is quite flexible about making custom heads to meet a particular need and John French has done quite a few head swaps to optimize the performance of various decks.

That's great to know.
Thank you.

However, unless you are certain that Labosh (the person behind the opening post) har some kind of frequency extending heads on his deck, my post/advice to Labosh from December 10, 2012, 04:06:39 PM will stand valid.

Offline docb

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Re: 7 ? VS. 15
« Reply #8 on: December 12, 2012, 06:35:57 PM »
Quote
Commonly known, 15ips lacks bass tones compared to 7?ips as 30ips lacks bass compared to 15ips.
I think that if you include the phrase "when using the same repro head", your comment is indeed quite valid.
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline tandyman

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Re: 7 ? VS. 15
« Reply #9 on: July 29, 2013, 07:03:45 AM »
I think it could be a record level problem,I use a cd that i have recorded with some tones,1K is recommended although i use 400c/s,record this tone at the slower speed with the levels set to 0 (zero) on the meters with the switch set on source.now hit the tape button.if the level is not the same then internal adjustment is needed.do the same at the higher speed.some machines allow adjustment at both speeds but not all.my sony only has one,so i set the slower speed to 0,the higher speed is then 1db higher which is close enough, of course different tapes have different levels so stick to one brand,also if the machine has eq/bias switches check these when testing as one setting may suit the tape without internal adjustments.
« Last Edit: October 15, 2013, 02:31:36 PM by tandyman »
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