What's the sound quality differences between 3.5" and 7" per second?

[smurfer77]

As others have mentioned, make sure the peak of the program/music runs your meters hot.

Also, for the RT-707 make sure your mic input volume is at zero (assuming you are using the line input). Additionally, and this will make a big different with RT-707 recordings, is to do whatever you can to keep the line input volume at half or below - this is achieved by having a loud enough source. At this setting of about 4-5 line input you will not clip the input, and you will keep down noise from the amplifier circuit in the RT-707. Above 5 or 6 and you can hear the hiss from the RT-707s amplifier.

 

[safebet]

once I incorporated two dbx 400 units, which makes switching between components a piece of cake.

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Yes, some folks may not know that as well as the patented noise reduction system dbx offered a number of consumer based tape support products like the 400 (and other model) tape switching units.

The caution I would offer to anyone thinking of adding multiple decks and potentially even multiple switches to their rig is to pay attention to cable length and routing. The 400 is a "passive" switcher which, for better or worse, means there is no active buffering between tape decks. Accumulation of capacitance will occur when placing multiple cables together on the same signal source and can cause a roll off of high frequencies.

For example, if I am recording a source to only tape deck #2, I will configure input source for deck #1 and deck #3 elsewhere so as not to further load the primary circuit delivering signal to the target deck. The effect is not always noticeable but important to understand if seeking optimum performance as most of us are.

To the OP question, I find 7.5 ips operation to be optimum if seeking quality without use of excessive tape. Tapes I recorded at 3.75 ips 40 years ago have not retained high frequency detail as well as those I had recorded at 7.5 ips. Further, wow and flutter tend to be less significant if audible at all and clarity is improved.

 

[KentTeffeteller]

No need to over-complicate things....if you create a dbx-encoded tape, then you will have to have the dbx unit connected to DE-code it on playback. If you have more than one deck, it is a simple matter to swap the dbx between them....just unplug the RCA cable from one deck, and plug it right into a different one. Maybe a 10 second job, certainly not a BFD.

As I said earlier, the results are quite dramatic, you can basically record at 3 3/4, while getting results pretty much like 7 1/2. A good way to double your recording time, while maintaining the integrity of the sound quality.

DBX also demands strict level practices as well. You have to be conservative with levels to keep pumping and breathing down, and your machine needs to be in top mechanical and electrical order.

 

[Onebean]

As others have mentioned, make sure the peak of the program/music runs your meters hot.

Also, for the RT-707 make sure your mic input volume is at zero (assuming you are using the line input). Additionally, and this will make a big different with RT-707 recordings, is to do whatever you can to keep the line input volume at half or below - this is achieved by having a loud enough source. At this setting of about 4-5 line input you will not clip the input, and you will keep down noise from the amplifier circuit in the RT-707. Above 5 or 6 and you can hear the hiss from the RT-707s amplifier.

Smurfer77, I assume you are referring to the input level pots on the back of the machine next to the input / output RCA jacks. I am currently running these in the detent at the middle position. With those set in the middle, I typically set the input levels on the front of the machine to around 6-7. I'll check the level position on the mic input, and make sure it's at zero.

Thanks to everyone who responded. I'm feeling much better about my approach to recording.

 

[Blue Shadow]

Did you look over the White Paper? Lots of info in that to give you a great background to build on and get the most from your machine.

 

[Onebean]

I haven't yet, but I will. Thank you for the link.

 

[oldvinyldude]

Wow-lots of feedback. Not up to the level of the "Best way to clean records", but.....

I have experienced the small loss of high end on tapes recorded many years ago, at 3 3/4. I don't really notice, unless I have heard the original recently. Fortunately, the Maxell XL and similar tapes allowed enough signal on the tape, that a modest bump in treble does not give me a hiss problem. I don't use headphones, where hiss is easily discernable.

 

[Onebean]

Best way to clean records typically turns into an online fist fight. This has been good clean informative fun.

 

[smurfer77]

Smurfer77, I assume you are referring to the input level pots on the back of the machine next to the input / output RCA jacks. I am currently running these in the detent at the middle position. With those set in the middle, I typically set the input levels on the front of the machine to around 6-7. I'll check the level position on the mic input, and make sure it's at zero.

Thanks to everyone who responded. I'm feeling much better about my approach to recording.

Hi again. The pots on the back knock down the signal before the line ("FLAT") amp. And the one of the front knocks it down after the FLAT amp. The amp just makes a certain amount of noise, and as you turn up the knobs on the front (mic especially, but also line) you can hear that. You want to ensure that your audio signal is as large as possible compared to that noise, without clipping the input (or saturating your tape or pegging the meters). The knob on the back can usually be left at middle detent if you have a source with variable volume (although I have found need to turn it up when using a Dolby B unit...). Basically set your line volume knob on the front to 5 (or lower) and turn up your source volume (at the source, of failing that try the rear input pots). This will keep your audio signal well above the noise of the FLAT amp. For an experiment, try the opposite.... turn your source down (of off) and the line volume on the front panel up... with headphones you will easily hear the hiss go up.

 

[Onebean]

So the line level input pots on the back should at max, and the front level adjustments down low?

 

[Onebean]

Never mind that last question. I reread your post and it makes perfect sense. Thanks

 

[JH Magnecord]

I find it depends more on the dynamic range of the music itself: "electronic music" (Rock) has a far narrower dynamic range than, for example, Classical or "acoustic music". 3.75 for Classical sounds like the speakers covered in wool...no top-treble brilliance or lifelike timbre to it AT ALL. However, with Rock (where the top end is really not much beyond the 9000Hz range) the slower speed doesn't degrade it so drastically as to find it fatiguing.
Then, again, one also has to take into account how equalization circuits affect the process as well; by: applying "pre-emphasis" -treble boost- at lower frequencies in tandem with bias to clamp down saturation distortion the slower the tape travels. Funny experiment: get an old "Scotch 111" tape from the early '60s (preferably: the red boxcover with the Brylcreme-looking jazz band on it) and --- make a test recording at 3.75 of FM tuner interstation static, then: make the same recording test with any MAXELL "UD" or "XL"-type tape 1975 or newer (at 3.75). You'll notice the Scotch will sound so dull that, it would have to be recorded at 15 to try to even sound like it has the response of the Maxell at only 3.75.