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Can someone explain the benefits of an outboard tape preamp?
Thanks.
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In most machines the preamps were compromized in that they had to accommodate several functions and equalization schems. When you change the speed of the tape everything changes; output level, EQ, ETC. When you change function-everything changes. Also some machines used the same preamp for mic input in Record mode that the playback head used in playback mode. Electronics is a compromise. It's just a matter of how much one is willing to compromise. A commercial product also has input from the marketing department that takes president over the engineering department. Most pro machnines have seperate record and playback amplifiers. Also head geometry is very dependent of tape speed. A 30 ips playback head has to have a much longer pole piece because of wavelength in order to reproduce flat bass frequencies. Slower speeds require shorter pole pieces. So the preamp has to be mated to the speed and the heads (inductance). The highest signal to noise ratio results when the resonance of the head is within the audio passband which correspnds to a head of 400=600mh. For good record penetration the record head needs to have a low inductance to accommodate a high freq bias without burning up the tape and this corresponds to a head of around 4mh or less. So a lot of compromise! Solid state circuitry has benefitted from more modern transistors with less impurities and sophisticated topologies. In fact it's taken about 60 years to learn how to design good sounding solid state gear for high definition audio. There are discreet opamps like the Jensen 990 and a newer FET990 that can be adpated to tape. M.B.
"...the fool doth think he is wise but the wise man knows himself to be nothing but a fool." Will Shakespeare
Thanks for this excellent overview.
At this point I would consider going upscale with my decks and looking at outboard electronics. The one that I have heard about, but is prohibitively expensive is the Doshi gear.
If you don't have an outboard tape head preamp, you're probably stuck with listening through the 1970/1980s-era solid state one built into the tape deck. These can vary from pretty awful to pretty good. My Otari definitely falls into the pretty good category compared with the (then) top-line Teac deck it replaced.But the deHavilland 222 tubed tape head preamp I now use is in a whole different category, sonically. I know this because when I had the Otari wired to acommodate the deHavilland I had it done so as to be reversible, making the comparison easy, if not exactly lightning fast.
Given the pigmy tape renaissance we tape fans are currently enjoying and the newfound availability of really great-sounding tapes, I think an outboard preamp is just about mandatory. If you're really into the medium, that is.
Edits: 09/25/14
Mandatory? Wow. My interest is peaked.
FYI, I have a Revox A77 and a B77, and a few other machines in storage.
My concern is that an outboard preamp is not an insignificant dollar outlay, from the prices I have seen.
How do you bypass the internal preamp circuitry in your machine?
Even back in the early 80's and late 70's Mark Levinson designed the LNP-2 preamp for recording purposes. It came with two big VU meters and Levinson, the man, designed because he was not happy with the electronics in his revox.
Older Units Like the Mac C20/C-22 and the Marantz preamps also sported a tape head input. Back then you could actually buy Tape decks without electronics ( I once had a Tandberg built in such a fashion).
Very interesting.
I still think for the most part, outboard preamps for that time were for the more serious diehards.
But for sure I now see the the benefits.
Good question, to which I don't have the answer. I'm in the midst of a hotbed of DIYers (me, I'm a tech illiterate) and just turned over the project to one of them, told him what I wanted, and voila.
I'm sure the answer would be different re your Revoxes anyway, although I gather it's not a hard problem to solve. I had a pristine-looking A77 Mk IV I bought on eBay, but after its caps started exploding (my tech calls them "firecracker caps") and it caught on fire, I gave up on it :-)
It's true that a good outboard preamp costs real money (my deHavilland was $2300), but be wary of the cheap ones. A friend who has one says his is pretty marginal, gain-wise, which means the S/N ratio isn't something to write home about.
I hear you. If technical illiteracy was a country I would be the President.
My A77 is is pristine condition. Almost NOS.
Yes, I would think that a "budget" tape preamp would be a lateral move. The prices I have seen for well reviewed models are really eyebrow raising.
I have a friend who scored a Tekefunken tubed reel deck from the 50's...a real beauty.
The A77 is a great "starter deck".
Replacing the (potentially) exploding caps Dave mentions and upgrading the capacitors on the playback boards brings it up (quite) a notch.
Must be someone "around" you that can do this work.
Charles
Ouch!! I heard that! My pristine A77 Mk IV is a killer deck. When I was doing a lot of concert recording back in the day, those meters could pin and still deliver excellent sound to the Agfa/Ampex/BASF/Maxell/TDK tape.About 8 years ago, I sent it up to Steve Smith in Nashville to bring it up to snuff, and that puppy is still cranking out great sound 35 years after I bought it.
But I still want an A80 anyway. Or an Sp7. Or an ATR-101.
Edit: I'm not sure why you would call it a "starter" deck, 'cause it'll beat the pants off any of those Akai/Pioneer/Sony/Teac/Otari decks, but I think it has to do with the paucity of buttons, knobs, switches, and screwdriver pots to twiddle with. This isn't new in the audiophilia world, which is largely populated with people who are obsessed/impressed by such features which they are often clueless about. ;)
:)
Edits: 09/26/14
I tell folks thinking of getting into tape and NOT having a machine that the A77 and it's variants can't be beat for reasonable starting price, reliability and good sound - for both recording AND playback.
If you then like the "hobby", you can take off from there; sell the Revox - and maybe even get your money back!
Charles
Whatever the merits of the Revox A77 (they sure managed to elude me and mine, not to mention my very able tech) I'd recommend a Teac of the 2300 series WAY before that one. Those particular Teacs really are bulletproof and sound quite good, IMHO. 'Course you might end up with one that makes my exploding, fire-prone A77 look good. Stranger things have happened :-)
I owned a Teac X-1000R and a Revox A77. Both were brand new at the time and I personally biased and equalized both for Scotch 207, which was one of the best tapes available in those days. There was no comparison between the Teac and the Revox; the Revox kicked the Teac's ass.
I don't know what the problems was with your A77, but I owned two of them and they were perhaps the best consumer tape deck every made. I think you just had to know how to adjust them properly. I was a PMEL tech at the time and I had access to fully equipped electronic laboratory. The Revox A77 was a class act.
Best regards,
John Elison
I owned an X-1000R too. My tech at that time, who also worked on the older Teac A2300SD, said the X-1000R was not as well built as the older Teac. It certainly didn't sound any better, or as good. My Revox was a comedy of errors. Three trips to my current tech who keeps the Otari and older Teac in shape, first for the exploding caps, then for the fire it had, then to see if he couldn't, somehow, make it sound at least as good as that Teac.
The whole idea had been to replace the older Teac with the Revox, and the more he and I tried to make that happen, the less it seemed likely until I finally bit the bullet and gave up on it after spending real close to $1K on it. When I did give up, it had pristine heads, a new pinch roller, new lights (without which its end-of-tape stop doesn't work). It never equalled the Teac A2300SD sonically (both were Dolby decks, by the way) and never came within light years of sounding as good as my Otari. I've never been so frustrated with a piece of gear in my life.
"I did like the way you linked Studer and Revox with that slash thingie, like they were in the same league."
Living here in the States, that's how the company was generally referred to, although, I do concede that Willi Studer didn't include the "slash" character in the company's marketing. It was just a "space". Sorry about the slash.
Still, an Otari will never touch it, sound-wise.
Sorry to read about your unfortunate experience with your tech.
:)
Beats the pants off an Otari, huh?
I know you love your Revox, but come on.
LOL!I know there are some Otari 5050 owners here, so I'll try to be tactful. ;)
I've worked with both the Studer pro machines and the Otari pro machines. There's no comparison. Studer/ReVox is hands-down a higher quality piece of audio engineering.
Having said that, I wouldn't mind having a 5050 as a semi-pro deck - it's a very nice machine, and very cool-looking, with lots of knobs and switches.
Tactful enough, I hope?!
:)
Edits: 09/26/14
At the studio where I assist, we've got a 1/4" R67 and a 1/2" A80 Mk-III, both half-track. (Yes I miss the 24-track 2" A800, and the great and different smells two-inch tapes give off.) Both machines get regular use and are meticulously maintained. For a recent transfer project we rented an Otari 5050 1/2" 8-track, and were pretty surprised at how good it sounded. It was certainly in the ballpark, and surprisingly quiet for that format.
Yes, if I could I'd swap my MX5050B2-II for any 1/4" Studer. But the audio performance of the Otaris can be pretty good, even though the transports aren't as gentle.
My own experience with Revox-branded decks is not so good. Had two A77's, one a Mk-3 and the other a half-track Mk-4. Never got either one sounding like they should, thought I didn't know how to do a full alignment then so that could be the issue. A definite dud was a Studer B710 Mk-II cassette deck. So pretty, so beautifully made, but the Nak Dragon ate it for lunch.
WW
"A man need merely light the filaments of his receiving set and the world's greatest artists will perform for him." Alfred N. Goldsmith, RCA, 1922
"Never got either one sounding like they should, thought I didn't know how to do a full alignment then so that could be the issue."
It's good that you admitted that.
It's quite true that not every tape deck tech knows how to work on an A77. Heck, even something as seemingly simple as adjusting the brakes is a challenge to most techs.
I am excited to say My Otari 5050 is on the way. After reading this thread I am already wondering what the preamp upgrade would sound like. Does anyone know a good tech in the Maryland/DC area that is competent to work on these decks since I am not? It would be good to know if it ever or when it needs servicing.
Lance
...no way. I owned (past tense) a Revox. The A77 MKIV version at that.
I did like the way you linked Studer and Revox with that slash thingie, like they were in the same league.
I won't be dissing my A77, though -- as Mr. Stellavox did its rehab (Starting with two organ donors that I supplied and adding a third of his own provenance to come up with one good one)...
My little trove of foundling MX5050s has a way to go before coming world-class... but at least the price was right.
all the best,
mrh
As a "starter deck", I tell folks thinking of getting into tape and NOT having a machine - the A77 and it's variants can't be beat for reasonable starting price, reliability and good sound - for both recording AND playback.
If you then like the "hobby", you can take off from there; sell the Revox - and maybe even get your money back!
Charles
"My" foundling Otaris have - as they say - been 'rode hard and put away wet' by their erstwhile owners (a local radio station)... but the price was right...
or, is it of Otaris as is said of a certain European automobile?
"The most expensive [used] car you'll ever own is a cheap Mercedes!"
all the best,
mrh
There is a "sonic bottleneck" in most stock commercial and many professional tape transports - and it is in the playback preamplifier stage. The reasons include the switching devices necessary to implement various equalization networks. I'd also state that because the the last tape decks were designed 30 years ago, the electronics (good as a lot of them were) have not "kept pace" with circuit and component improvements since then.
Mark Levinson noticed this in the late (19)90's and offered an "audiophile" tape (head input) module for his Audio Suite that was adopted by a number of recording studios.
I opine that everyone today who has actually A/B'ed an outboard pre versus stock tape electronics will agree that there is a large improvement in the sound. Tape heads can sound different also. Interestingly, I (and others) have found that a lot of decks also make much better recordings than they play back.
Charles
Interesting observations. Thanks.
The only theoretical argument against an outboard preamp would be that your are creating a longer, more complex signal path, with extra cables.
But if the end result is superior, then no matter.
In the early days of (consumer) tape recorders, the tape deck was typically just the transport and heads; no electronics. A tape recorder had the electronics (bias oscillator, preamplifier and equalization) onboard. Nowadays, we expect tape decks to include electronics.
One can easily imagine a carefully designed and built outboard preamp bettering the one built in to, say, a modest consumer-grade TEAC or AKAI tape "deck" of the 1970s.
The attached JPG, from the 1961 Allied Radio catalog (site link below) shows an example.
all the best,
mrh
Thanks for you response. Makes sense.
Great catalog! Those were the days. I am sure my dad would have thumbed through this. He always had several decks in the house.
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