Revox A700 tape machine.

I'd start with http://www.reeltoreel.de/worldwide/A700.htm.

Its a scam site. I have hunted down all the Revox sites and too many only deal with the A77. There is a British site but they want $140 for a service manual another site took my money and ran. I know the IS has more tape machines than most so I thought may be an honest person might just help me out, or are there no such people out there any more?

http://cgi.ebay.com/Revox-A700-Service-Manual_W0QQitemZ290114015082QQihZ019QQcategoryZ67812QQssPageNameZWDVWQQrdZ1QQcmdZViewItem http://stores.ebay.de/BEERSOFT-High-End-Audio_W0QQsspagenameZL2QQtZkm

Hi! I have A700 Service Manual in pdf file. I have Revox A700 myself and found this manual very useful. I can email it to you if you give your address.

Im interested in it as well. pls send me one.

many many years ago, I dealed with A80 wide tape table recorder. its 8 tracks. and can be expend to 16 tracks.

Thank you can you go to my CR4 mail box I will post it there.

Hello, I have just read your entry in CR4. I would be very much appreciate it if you could send me the pdf manual for the Revox A700. My email address is: pedyson@aapt.net.au Thanks in advance. Pedro

I would appreciate a copy please.

Thanks in anticipation,

Peter049@hotmail.com

I would like a copy please.

Peter049@hotmail.com

I'll also be happy to get a copy of the manual

Sir,

I am interested in the purchase of an A-700 recorder. Can you give me some info on this machine. I presently have an Otari 5050B, Technic RS-1506, Ampex A7300 and Tascam 32B. I am looking for a recorder that has micro-processors that make a lot of what happens to the tape automatic. I would love to have a recorder that slows down near the end of the tape in fast rewind or fast forward. I want a machine with a dump feature and one with a repeat feature. Does the Revox A700 have these abilities? Thank you very much. My email addresses are

bob@business800voicemail.com

Bob

Hello Lexx66,

I just own a A700. A service manual would be great. My e-mail address is:

jbhuisman@chello.nl

thank you for this service.

hello. I have just joined the forum and found your post/offer from last year to send a service manual to another member. Would you be willing to do this for me? I'd be happy to compensate. I have two A700's.

Thank you.

Tom

Hi! I have A700 Service Manual in pdf file. I have Revox A700 myself and found this manual very useful. I can email it to you if you give your address.

could you please send me this pdf manual, it would be great! I have a A700 still working fine, but needing some retuning..

I'll be happy to share with you specific tests with some old and new tapes.

Thank you in advance

Hi there, I have a Revox A700 and it has some problems. Could you please send me all the electronic doc that you have? Thanks very much. marc.corbeel@gmail.com

Hello, I have just read your entry in CR4. I would be very much appreciate it if you could send me the pdf manual for the Revox A700. My email address is: marcello.salerno@tin.it Thanks in advance

Hello Lexx66,

I saw your message here, and I am looking for a manual for the revox a700. Could you be so kind and send it to me as email?

jugu730@web.de

hi gerry here i would like a copy of revox a700 manual to see what it takes to service it thanks my e five-4-five@outlook .com. im in bc canada wheres a good source for parts?

This set seems very old one else. and not as good as the A80.?

its desk type? still in using? wonderful.

A700 is semiprofessional ("prosumer" as they now say) machine, not big console-type one like A80. It still works well, after some minor repairs and adjustment. I use it at home to listen to my tapes and record some rare LPs.

See your CR4 mail box for my email address.

I know this type of recorder, it can be doulbe tracks, 4tracks. But I hvent ever use them. most products from Studer are well use.

I know they were widely used in the field of broadcast and studio. and music lovers like it very much for their music recording and enjoy favourite music at home.

matching it there was a 8 chennals console, it was also produced by studer.

the control system and audio parts is well use, only the recording head needs to replace and make a little modify of its curve. I thnk.

digital recorder put into use, we forget it almost.

good old days.

May I enquire as to your intended use of this antique?

Today's digital audio is about a million times better on all counts, including price, mobility, signal to noise ratio, dynamic range, THD and post-production control.

Is it for sale to a museum or an eager collector?

Because if so, I happen to have a Bruel & Kjaer 7001, including it's original reference manual, and extra tape wheels.

Mind you, it weighs some 50 Kg, and shipment is on you.

wow, its really an antique for us.

I know this B&K company, a good sound and vibration measuring specialists. I hve ever used their many instruments, very good and advance at the time.

I saw a pic of recorder in lst 30's not long before. very heavy, its not tape recorder , but a disc recorder.

I hve a new disc player in somewhere in my little store room. which is made in cina.

in spite of lots of digital recorder on market, good quality, lower price and much advantage, but it seems not to take displace the old analogy mode recorder.

audio specialist loves its btter sound quality than todays digital recorder. we , ordinary people, of cause cannt distinguish their difference, but specialist can hear this tiny diffence. out.

do you remember vaccume tube amplifier? today there are lots of music fans still love it very much,

they prefer to listen this amplifier rather than listen to morder compact recorder.

to be true, I cannt distinguish this difference, but fans insist on that beeter than this one etc. so do some speakers etc.

th e old recorder equipments are still theri favourite.

"...its not tape recorder , but a disc recorder..."

No, no. It is a tape recorder. It's other reel is behind the front one, they are rotating in opposite directions, and the tape is inversed 180 degrees from the feeder-reel at the bottom, to the takeup-reel on top. The inversion allows the top reel to spread like a book-page to the right, revealing the bottom reel underneath, for service, splice, or spool-up.

On top speed, it has a frequency response of DC to 20 Khz. Lousy by today's standards, but fantastic in 1969.

The front enlarged:

This is an instrumentation recorder, i.e. the machine for recording signals from measuring devices, measurements, constant monitoring of some values, etc. It was used in different scientific or technical areas, but not for sound recording! Bruel&Kjaer is very well known for their measuring and scientific equipment. Such instrumentation recorders usually use frequency modulation when recording signals (like FM radio). You can tell it from the frequency responce of the device which spreads from the DC. You cannot record DC on tape directly.

you are quite right, Lexx66!

B&K is a famous measure instruent company in Danmark. I familiar its traditional panel.

this tape recorder, as their other products, is use for measure record. not for art music record and enjoy.

no tape recorder can record DC signal. its impossible. from electromagnetic induct principle, yoiu will know it.

their specification may has anther meanning.

This is not the whole story, however, with this monster:

This particular one, happened to be used for both. It's audio recorder use, was for fine tuning enclosure cabinets for High-end PA speaker systems, and for frequency response curves of Disco dance rooms, and admittedly, even for fine music reproduction, capturing Moving-Coil Turntable albums to 1/4 inch tapes, for later hi-fi disco playback.

Was even used to record hi-fi narration for a soundtrack, taking advantage of the tape width. Shameful vandal abomination!

"...Bruel&Kjaer is very well known for their measuring and scientific equipment..." - Please don't tell them.

Microphone and line pre-amps to accommodate for 20k? (to 100 pf) impedance, with load impedance of about 2k?.

All that besides it's "serious" lab use as a measurement instrument.

"...You cannot record DC on tape directly..." - Yes you can, and on any tape. Up to its 1.4 volt peak, on this particular one. The only snag being to recognise an calibrate for your DC bias-point, to later measure or reproduce.

Here some pics taken a few minutes ago:
.ClosedPartedOpened180 deg tape-twistHeads and capstan Transport controlSpeed dialControl panel

youi can record DC by modulator way! then demodulator.

Right, right. Both modulator and demodulator actually part of the recording system.

Cnpower, let me ask you this, just to confirm what I was told:

This system was designed to transcribe from DC to 20 khz. It means it can roughly record a sinus, of say, one to five hz. You can see it on oscilloscope, not hear it, of course.

But if you record a spike, not sinus, you can even record at 0.0001 hz if you want. A spike is a one event, as complete.

But this is because audio recording is really like AC current recorded of flat potential media - the magnetic tape.

To reproduce it you have to modulate the audio-"AC" with a carrier frequency, because otherwise you can only capture small part of the audio frequency-spectrum, on the magnetic layer of the tape.

If you have a digital code, or pulse-train recorded on magnetic media, like on floppy for instance, and some of the code is the same sign for long repetition, can be considered as a short burst of DC, right?

Then you have to find the bias, or DC-offset point, relative to the noise-floor of the media to identify the voltage-level of what you recorded of DC.

This is how you calibrate the sensitivity of a digital-reading magnetic head.

Did I make a big mistake here?

Please correct me if I'm wrong, this is what I was told.

Hi, Yuval,

I can give you some little suggestion. dont complain me if it would be wrong.

normally audio frequency will be 16 -- 20KHz. you are right, you cannt hearing lower than 16hz and higher than 20khz.

therea re many ways to recorder supper lower frequency, modulator and demodulator is a ususal method.

that means you can use a serious of swithcher signal to on/off chop the pre- recorder signal. so that the lower signal was changed into sample signal, the signal has a very wide spectrum, you have to filter, before recorder. then yoou can use a socalled phase sense demodulator to recover it. just like some DC amplifier.

if you would recorder a spike signal, its another things, not 0.1, 0.11, 0.001 etc.

the signal has a very very wide spectrum, the narrow the signal has the wide spectrum it will be , just like white light has all color visual light. (through Furior transform) then you can recorder its ac part then recover.

its belong to vibrecation and ananylsis theory.

In mordern tv instrument, the spike capature ccan be use a little capacitor, charge and dischaege to complete the process.

In the tape recorder there is a dc bias or ac bias, mostly is ac bias, especially professional tape recorders are all ac bias,

its principle is keeping a hi fi record for a audoi siganl. due to magnetic feature, at its original point, there is no linear part, we have to avoid the part to get more linear record. the dc or ac bias can reach the target.

soft disc is recording a pulse signal and use MFM or other type encode, it neednt use bias.

but erease head must has a stronger current to get a dc or as megnetic field.

generally the head is ac to get more higher erease megnetic effect.

in that disc redorder, there is also a special eread head, which erease two side signal remain middle, in order that can be easy replay.

DC balance panel, behind the transport remote-control.

carefullly adjust the bias is to get more better linear record. an d more wide record range. ie, dynamic range.

you are right.

calibrate is another meaning. it can get a standard output to compatible other equipment.

they are different adjustors.

I thnk Lexx07 can give more detail expression, he still deal with the recorder.

modern vedio recorder has less such adjustor, i forget almost all the procedure.

most of the people in room seems to deal with large power motor transport system. less analogy engineers are interested in the topic, so if my answer is wrong , dont mind.

No, no. You helped me to understand this beast.

It is still working, only the last time I used it was in 1994, for trying to tune room-acoustics for narration recording booth in a studio, using spectrum analyser, pressure-zone microphone (PZM) with linear pre-amp, and noise generator with pink and white noise signals.

Thank you for the explanation. Now I understand it better.

aha, Yuval, you cheat me. you are now a archetcture acoustic engineer!

look you use such special tool!

pink noise generator, pzm and spectrum analysiser! wonderful for a listennign room measuring. and then you can say, select absorb material for the room, cancel stand wave and compensate frequency response etc. and then select amplifier and delay amplifier etc,for 5 +1 channels dolby room ...

but why dont you use a burst signal to measure repidly.?

change your smoking appearance. I m sorry, I dont like smoke.

dont mind.

No, no. I'm Not an acoustic engineer. It was part of movie making. I'm not telling what my profession is. This is better for mystery here, on CR4. Don't you think?

Also,I don't smoke. I only like the picture. No smoking for me thank you. I stopped smoking couple years ago.

Burst signal is full-spectrum, and needs a fast computer analyser. It's like one question - one answer, for the whole spectrum.

With noise and microphone analyser, you calibrate for each frequency at a time, and get a good, slow, accurate reading.

It's like many questions - each with it's own answer. You have time to see a freak frequencies, which is very good to pause, and look for feedback or standing wave problems.

What do you think?

yes, burst has wider spectrum and get less stand wave at measuring. mordern RAM can store and calculate with fast Fueriour analasis. fft

at low frequency is not too good effect at htat time, when I used it.

pink noise is another tradition tech. a 3db descent of white noise to get more effect of measure speaker. and room frequency response.

I cannt reply you profoundly. its out of my depth nowl.

I have a collection of precious old tapes that I am trying to restore. I found them in a junk yard in Musselburgh, Scotland. They are off air copies of many great classical concerts of the last 50 years and the BBC seems to have lost most of them. They include the only extant copies (to my knoweldge) of two of Havergal Brians Symphonies. The were recorded and maticulously catalogued by a Dr Wallace before his death. The BBC are refusing to restore these and aquire them for their archive so I am trying to lay my hands on a Revow 77 and or a Revox 700 (those were the machines used for recording) so I can remaster them myself and give copies to the National Museum of Scotland. Can anyone help

"...those were the machines used for recording) so I can remaster them myself..."

This is a great idea, and was actually applied in old-days photography: I used my camera lens for the print-enlarger to ensure the minimum of distortion in the image transfer.

Admittedly, I never thought of it in the context of audio reproduction.

Nothing escapes your keen eye.

Hi Yuval

I began this thread in 2007. I had found an archive of taped classical music, dating back to 1957, I was trying to find a machine to digitise the tapes as they are very rare- copies of many classical concerts recorded off air from the Edinburgh International Festival. I still have the tapes, do you still have the Bruel and Kjaer? I'd cover the cost of delivery if it's still available.

best wishes

Croc

A nice man from Turkey bought it from me about a year ago, and since it sat idle in my sister's garage for a few years, rotting away into oblivion, I decided to let go

Did any collectors ever show any interest in your B&K 7001 - I have one too with all manuals and the beautifull NAB hub convertors. It is so well made I can't bring myself to scrap it - although I have to admit that I cannibalised the continuous loop attachment as the basis of some advanced industrial automation! (Its in the UK and yes it is 50Kg)..............

Greetings, I don't suppose you have a schematic for the 7001? I have one of these machines and I need to debug it ( no record on 15 IPS ) It is in perfect cosmetic condition and I need to keep it alive :)

Yuval,

Do you still have Bruel & Kjaer 7001 for sale?

If so, please let me know.

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Yes - I hope my sister didn't throw it away. It's probably there including it's spools and it's original user-manual - but it weighs some 50 kilograms or more - how would you ship it abroad ?

Dear Yuval,

I also have a Bruel & Kjaer 7001, it has some problems, please share for me the manual.My email is nghihn@gmail.com, thanks.

I no longer have the manual, but I'm positive a user and service manual can be retrieved, by approaching the firm in Naerum, Denmark, or at : https://www.bksv.com/en/

Make sure you specify your machine's serial-number, and year of production.

I doubt very much, such an old machine's user or service manuals are to be found on one of the web's many user-manual archives - but who knows ? - you might just get lucky

Hi, Yuvel,

you can go to your school library for some old book of audio when you are free.

then you will find they may be very interesting. you can even build a vaccum amplifier to remember your old time in university and play with friends.

youi may find its difficult to seek a vaccum tube in your country.

a word added, at the time the bk recorder use 4 section record to get 0--20kc flate response. but today only one section. and the frequency response can get to less than +-2db

Some enthusiasts are all about tube amps like the British "Quad" flat-amp, but I personally like best, the good Japanese audio transistor integrated amps from the seventies, like Superscope, Onkyo, Technics, Pioneer and many others.

Hi again! Now it's time for me to ask for help. It happened so that I got myself another tape machine - Technics RS1500. All attempts to find a service manual had no success. Maybe someone can help me with the manual and/or cirquit diagram for this machine?

What's with you people, and all-that zeal for magnetic audio recording?

At best, it's lower than 60 db (mostly around 45), when you can have modern sampling rated at 98 to 115 db, not to mention THD levels of 0.001% compared to magnetic at around 1.0%? Not to mention WOW and Flutter, noise-floor, and God knows what, virtually non-existent in digital sampling.

Is this for some museum related paraphernalia?

Many of the Studer / Revox manuals (including A700 service manual) are now available as a free download from Studer ftp site at: ftp://ftp.studer.ch/Public/Products/

useful link, thanks.

http://www.hifiengine.com/manuals/Revox/A700.shtml

I just registered and downloaded the ftp manual from there. no problems.