Akai GX-620 Reel to Reel Tape Deck Measurements

[staticV3]

What are you talking about??

IVX wants to use blank tape as test signal to calibrate an R2R deck in the absence of a proper reference reel.

All that's needed is for someone with a calibrated deck to upload a recording of blank tape, then everyone else can compare it to their deck playing a blank tape and EQ to match.
(That's the idea)

 

[restorer-john]

l think if the FFT of Apex 456 tape's noise played with two different R2R is identical, then these 2 R2Rs have the same frequency response. If so, hence you can show me your FFT result with Apex 456 digitized in Australia, let's believe that your R2R has a perfect frequency response. Mine has bad freq.resp and I'm in China, and around me no reliable source for a nice test-tape, but I also have original 456. Is that still funky or can I EQ my R2R with your noise as the reference?

Ampex 456 is a disaster of a tape. It sheds before you even look at it. So the sticky shed oxide sticks to everything and even if it were totally blank, baked, the FFT of noise would be inconsistent even on perfectly aligned and set up decks.

The frequency response is rec head to playback head and you've got to have a reference tape. Otherwise you are aligning to something that is most likely wrong in the first place.

 

[restorer-john]

IVX wants to use blank tape as test signal to calibrate an R2R deck in the absence of a proper reference reel.

All that's needed is for someone with a calibrated deck to upload a recording of blank tape, then everyone else can compare it to their deck playing a blank tape and EQ to match.

That makes no sense. It's the ultimate circle of confusion.

Have you ever aligned and set up a cassette deck/RTR with a reference calibration tape?

 

[staticV3]

That makes no sense. It's the ultimate circle of confusion.

Have you ever aligned and set up a cassette deck/RTR with a reference calibration tape?

I'm just trying to explain @IVX's idea to help the discourse. I'm not advocating for it.

I have no experience whatsoever with R2R.

 

[restorer-john]

You cannot use an FFT of a "reference" blank tape. The deck you are playing back on is not new- we know that- it's likely 30-50 years old. The head/s will be worn and the HF response will be variable. So what is right and what isn't?

Do you boost the HF in REC to achieve a flat FR in PB? Or do you boost HF in PB to be flat from a worn REC or PB head? Assuming all your heads are fully aligned in azimuth and zenith to a "reference" tape in the first place, why mess around with blank tape at all?

Three head RTR or even cassette deck alignment in 2024 is a nightmare. The original "calibrated" factory tapes are long gone, worn out, or are copies of copies that are worth nothing.

I have Philips and BASF alignment cassettes and one 1/4" reference tape that has sticky shed itself- lol. Much as I love old formats, I don't miss them. I have several beautiful RTRs but rarely fire them up unless someone asks me "what is that thing?".

 

[restorer-john]

Here's a big Akai GX-625 10.5" NAB reel unit sitting in my loungeroom pretty much as an ornament.

 

[IVX]

just an idea, I don't need R2R too. However, I don't believe if my idea doesn't work

 

[restorer-john]

I don't need R2R too.

It just looks good. People love the visual and the sound is really nice. Warm and fat.

You really don't want to get into RTR. Too expensive in 2024. I have heaps of NOS BASF blank tapes on 10.5" NAB reels but what am I going to record on it? CDs I already own?

Makes no sense, but I love RTR anyway. Just don't use any of the decks I own anymore. Too much restoration time and not enough enjoyment time. LOL.

 

[mhardy6647]

It is too expensive. I've even de-acquired some tape things here in the past year or so, including my RT-909 (which had reached the point of needing rehab that I was unwilling to tackle myself or to pay for someone who knows what they're doing to tackle for me).


N.B. that "Ampex 407" reel is strictly for take-up use.

It's in a much better place now.