Dolby NR processor not worth it for R2R.

P

powervinyl

Member
I recently received a Concord DBA-10 Dolby NR unit from a seller on eBay. The unit works as advertised but the amount of noise reduction just isn't worth it.

The unit came with a calibration tape and a calibration reel. Calibrating the unit wasn't too bad. I used a sealed NOS reel of Ampex 631 tape for my recording tests and I recorded "nothing" because I wanted to see what the background noise of the tape was. At 3-3/4 IPS, there was not a whole lot of noise on the tape to begin with. In order for the noise to be annoying, I would have to jack the volume up higher than I would ever listen to. The Dolby circuitry worked and took some hiss but it wasn't dead silent. Dolby NR seemed pretty worthless at 7-1/2 IPS. Again, it wasn't dead silent but the volume would have to be waaay up.

It was getting late in the evening so I recorded a few tracks pop music tracks from a LP. The signal didn't have the dynamic range of classical music so any noise would have been drowned out. I'll do some more tests tonight.

The lesson I learned here is that there is no substitute for quality tape. Good tape = good recordings. Keep the Dolby for the 1-7/8 IPS cassette decks.

-- Boris
 
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I found this as well- the operating noise generated by the Dolby unit was more than the tape noise that was removed by the Dolby. So I ended up with MORE noise. What kind of reel deck do you have? I was using an Akai 4000DS
 
If you want silent, I would recommend DBX, then again, if you can stand the slight hiss, I would just leave it. I am not a fan of those old dolby units as they seem to do more harm than good IMO.
 
I bet that GX-280 sounds even better than my 4000DS, so we're in the same boat. vincei has a good point about dbx; those are usually newer and better built (quieter) units. Or, if you want to go really old school AND have spend $$$, you could find a Dolby A processor. Or a newer Dolby S / SR. Either one would be a pro unit, so the operating noise should be lower.
 
Well, Decca London relied on some professional form of Dolby from circa 1966 until
the advent of digital recording, so there may be some value to that technology.
At least that's what you find in the liner notes of their 'The Classic Sound' series
of CD reissues. Any thoughts?
 
Dolby-S works wonders on cassettes (and I'm sick of saying it). Dolby-B, which I presume your external unit uses, was never up to much in the first place in my opinion, even on cassette. I am currently using Emtec SM-468 tape on my R2R and I can hear no hiss unless, like you, I "jack the volume up higher than I would ever listen to." No need for any NR there, in my opinion.
 
I was kidding, mostly. I'm not actually denying the importance Dolby has had across the music industry. My experience with all sorts of Dolby for playback and for amateur recording is that it removes too much desired content and/or not enough noise until it breaks completely. I know there are a whole bunch of reasons for this that aren't Mr. Dolby's fault.
 
I never had any truck with Dolby-X (let's call it) until I moved up from the ranks of attempting to play encoded cassettes that were recorded on other decks (basically meaning commercial recordings but also including home recordings from other people) on cheap and probably misaligned decks that I owned. I really was using cheap decks then too -- I never even experienced a high quality deck until long after they were all gone out of fashion and so I could pick them up for buttons. I think most people were in the same boat when cassette was in its heyday except most of them just moved on when the opportunity came and therefore still don't know the difference. However, if you make your own recordings on a decent and, of course, properly aligned deck, you'll get back 'more or less' exactly what you put in (or, to be more precise, the lack of treble you currently experience will completely disappear because you will have a deck that boosts on record and reduces on playback by precisely the same amount). However, if the external unit you use generates more noise in itself than can be cancelled by Dolby-B, then that's obviously the end of that!
 
When all that equipment was new , it probably was more effective. I've learned on this site that capacitors start to go bad after 20 years. Open reel decks have an extended high end, which seems to cover up the hiss, anyway, although I just used my DBX NR on my X-700R, @ 3 3/4 i.p.s. Sounded pretty good.
 
I just got a beater akai yesterday with Dolby. My quick tests told me it could be very useful. Useful enough for quiet classical, and also, instrument parts I like to record before I make it a computer song track.
 
I didn't mention this in my original post but I have always been a fan of Dolby NR in general. Maybe it's just my nostalgia of being a kid in the 80s and 90s and ogling at cassette decks which had Dolby B. I loved recording from the radio, records, and eventually CDs. Every cassette I ever bought always had the double D symbol on it. Dolby became my buzz word. When I finally got a cassette deck with Dolby B and C, I noticed a huge difference between no Dolby, Dolby B, and Dolby C. The difference was less apparent with type II and type IV cassettes.

The Concord DBA-10 is surprisingly quiet. I don't know what the S/N ratio but I know when something generates hiss. It will be a fun toy to play with but I think I won't be using it seriously very much. If I am gunning for high quality reel recording then I will stick with the 7-1/2 IPS max speed my R2R can do. Oh, and use good tape. :)

I can understand why Dolby may have been passed over before it became integrated into cassette decks. The calibration process is fine for those enthusiasts with a technical slant but the average Joe may think it's a bit much and be discouraged. If you used a R2R then the effect is so minimal that average Joe may think that it wasn't worth it. Once the cassette deck came along, Dolby offered noise reduction to those who had the right equipment. Otherwise, the user got a compressed sound that was "louder" and brighter. It's perfect for car audio or portable audio where the highs tended to roll off anyways. So again, if you had it then it was great but if you didn't have it then it was great too.

-- Boris
 
garww makes an interesting point... units with BUILT-IN Dolby are quite effective and a whole different situation. No extra operating noise to contend with; I'd use the Dolby in a second in that case.
 
Ya, my first cassette was a "Technics made my Panasonic". NR was a filter, so I didn't use it much. My first Dolby cassette decks did not track very well. I also had DBX on a Luxman k118, but it didn't really sound better that the new VCRs I was also using at the time. Generally, I always preferred to record without NR (Uriah Heap, etc.).

I also had that stand-alone Aiwa HR consumer product that actually did OK on my LUX k8.

I got back into cassette with a sony cassette 555 and I get good tracking with B and C. I don't plan to record Dolby on R2R, unless there is a reason for it.
 
I purchased a Revox B77 LS (1 7/8, 3 3/4ips) deck that came with a a HicomII NR system. Now that may sound off topic but I'm focusing on NR here.

On the low speed, tape hiss is really audible and frequency response doesn't extend well beyond 10kHz at high levels. So, in this case, NR does have a real benefit and function.

OTOH, R2R is all about 7,5ips at least and with a good deck and proper adjustments, tape hiss is practically a non-issue at this speed and above.

Same applies to my two speed cassette deck and TDK SA cassettes.
 
Nakamichi. In the process I obtained a second one - to be able to monitor while recording.

BTW, the system delivers excellent results. Only slightly worse than dbx.
 
I use the Teac AN180 and AN80 units and have found very little sound degradation in these units...I did rebuild each one's power supply with Schottky diodes and Black Gate capacitors, though, so that may have some bearing on my results...the setup with tape deck > Dolby Unit > dbx Program Route Switchbox > tape monitor on my Audible Illusions is also sensitive to cable effects and high capacitance cables, like Goertz Tourmaline, can cause a bit of high frequency change, so cables have to be audiotioned in each spot to see which gives the sound that I want....

I also have one of the old Advent Dolby units that I tried once about a decade ago and it, too, was a good sounding unit, I just need to go through it and do a bit of recapping, etc., to bring it up to snuff...

dbX xs. Dolby? I think the dbx built into my X-700R may be a little better sonically than the older Dolby units, but I don't really use my deck to record stuff, mostly just for playback of Barclay-Crocker R2R tapes that came factory encoded with Dolby noise reduction.

Barclay-Crocker was like the MoFi of the day, they used slow speed mastering techniques and took extreme care along the way to produce audiophile quality R2R tapes for consumers...and, each and every one is Dolby encoded and 7-1/2 IPS...the quality of them is beyond reproach...they actually rival, and sometimes exceed, the best I have heard from my Linn or any SACD player I have ever had in my system...

Just my experiences....
 
SaSi said:
Nakamichi. In the process I obtained a second one - to be able to monitor while recording.

BTW, the system delivers excellent results. Only slightly worse than dbx.
Click to expand...

My experience too - did test Telefunken's HighCom modules in a setup where we could substitute the tapedeck with a switch

You should be really good to spot the pumping effect , as long as levels where under 0dB VU - Dbx or HighCom ... well - used correct, it is two sides of the same thing in my opinion

both are pretty sensitive to frequency response, and level imperfections
 
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