Revox B77 Reel-to-Reel
- Thread starter ToTo Man
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Werner
pfm Member
It almost tempts me into hunting for a B77.
Alan, can you run frequency sweeps at several levels (like I have on my site), and a noise measurement, or are you not equipped for that?
https://audiochrome.blogspot.com/2019/12/cassette-tape-comparative-measurements.html
Alan, can you run frequency sweeps at several levels (like I have on my site), and a noise measurement, or are you not equipped for that?
https://audiochrome.blogspot.com/2019/12/cassette-tape-comparative-measurements.html
337alant
Negatively Biased
Hi Werner,
The B77 has been returned to Richard today so cant do any more testing on that one
Thanks for the link to your web site, thats some interesting and thorough testing you have done there
.
I have a Nak BX150E, is that model any good?
I do have the Audio tester software on my laptop and a Tascam144 USB interface but I haven't mastered using it yet so I will have to spend some more time on it.
I also have a ferrograph RTS2 & ATU1 which can measure distortion @1k
IMG_2967 by Alan Towell, on Flickr
Alan
The B77 has been returned to Richard today so cant do any more testing on that one
Thanks for the link to your web site, thats some interesting and thorough testing you have done there
. I have a Nak BX150E, is that model any good?
I do have the Audio tester software on my laptop and a Tascam144 USB interface but I haven't mastered using it yet so I will have to spend some more time on it.
I also have a ferrograph RTS2 & ATU1 which can measure distortion @1k
IMG_2967 by Alan Towell, on FlickrAlan
Werner
pfm Member
Just about any Nak is good, most are very good.
I once restored a totally wrecked BX-125, pretty much the same as a 150. It came out wonderfully, with exceptionally low wow&flutter and ruler-straight frequency responses to beyond 20kHz.
I have also done a BX-2 and a BX-150 that fared less well. Still OK, but not stunning. The condition of the heads matters here.
BTW, Alex Nikitin has an interesting page where he uses Audiotester to plot 315Hz distortion versus level for a number of cassettes. If you repeat this for 4 frequencies or so you could get a pretty accurate fingerprint of any tape+head combination. With very little effort.
http://www.ant-audio.co.uk/Tape_Recording/Measurements/HD3_v_Level/album/index.html
chartz
If it’s broke fix it!
Don’t underestimate an A77, which is equally good, but just more clunky.
337alant
Negatively Biased
The A77 has the potential to sound good if the heads are still OK but in operation its very clunky as you say, the meter's are a joke and my A77 Mk3 HS seems to have a new problem every time I try it.
The B77 mk2 HS is the best of the A77 & B77s IMHO.
I also own a PR99 MK1, Mk2, Mk3 which are also very good with the Mk2&3 have the digital counter / auto locater, the Balanced XLR inn/out on the PR99 could be a disadvantage (depending on your point of view) as it puts transformers in the signal path, but you can convert the monitor out to a pair of RCAs or just make an adapter lead for a direct 0dB out.
Alan
337alant
Negatively Biased
Thanks for that I may have a go at my Nak when I get a moment, I have to say though at the moment my stock Tascam 122 mk2 shows it a clean pair of heels, this is a very good cassette deck. I have just picked up a Tascam 122 mk3 which needs fixing but I know Alex Nikitin rates this machine very highly as well.
I do respect ANT audio writings he is very good at what he does, he made me some Call tapes for my cassette decks which were great.
Alan
337alant
Negatively Biased
Thanks Jonathan.
I bought my Tentelometer and a full set of spring balance scales from Ebay.
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2060353.m570.l1313&_nkw=tentelometer&_sacat=0
https://www.ebay.co.uk/sch/i.html?_...RVFM+-+Plastic+Spring+Balance+Scales&_sacat=0
Alan
This site contains affiliate links for which pink fish media may be compensated.
ToTo Man
the band not the dog
The timely arrival of a new bench for my R2Rs allowed me to listen to my refurbished B77 for the first time this evening. Even running at 7.5 ips it sounds fantastic. Thank you for the tape, Alan, I'm thoroughly enjoying it!
https://flic.kr/p/2jVFQBx
Please excuse the mess and clutter, the video was impromptu.
https://flic.kr/p/2jVFQBx
Please excuse the mess and clutter, the video was impromptu.
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337alant
Negatively Biased
ToTo Man
the band not the dog
I was discussing with Alan how to set recording levels with the B77 as I haven't really worked with VU meters all that much.
During my main 'recording phase' in the 90s I was using a Technics cassette deck which had LED/flourescent peak reading meters, and then I moved onto a Pioneer CD Recorder and Minidisk Recorder where the aim was to simply to avoid transients exceeding the 0dBFS clipping point.
Analogue tape of course plays by different rules. It's also apparent to me that not all VU meters are created equal. The needles on my B77 are more 'agile' than those on my Teac A3440. i.e. when I set both decks to display 0dB with a 1kHz sine wave tone, the B77 needles have greater swing with music and go into the 'red zone' more often than the A3440's meters with the same music.
Alan suggested a good rule of thumb on the B77 is to let the VU meters spend most of their time around -5dB with occasional flicks up to 0dB. He also suggests keeping an eye on the +6dB clipping LEDs and not to let these flash too often.
As an experiment I monitored the B77's VU needles and peak LEDs with the following music replayed from my computer:
1) A track with high dynamic range, RMS levels of -18dBFS and occasional peak levels of 0dBFS.
I set the B77's input levels so that the needles were hitting -5dB for the most part and flicking to as high as 0dB in a couple of places. Even when the needles were only hitting -5dB, the LED clipping lights were still flashing to the beat of the music in many places.
2) A track with low dynamic range, RMS levels of -10dB and frequent peak levels of 0dBFS.
I found I could nudge the input level up to have the needles frequently hitting -2dB to 0dB before the LEDs would flash. However this may be a false sense of security since high frequency saturation apparently increases when peaks are sustained.
I found the result also varied depending on the content of the music. E.g. music with low dynamic range but strong low frequency content needed the VU needles to be set lower to avoid the LEDs flashing.
I'm curious to learn what other folks techniques are for setting recording levels on R2R decks. Do you focus on average or peak levels? And are you anal enough to optimise it track by track or do you take the "life's too short" approach and record a whole album, or even compilations, without adjusting the level?
During my main 'recording phase' in the 90s I was using a Technics cassette deck which had LED/flourescent peak reading meters, and then I moved onto a Pioneer CD Recorder and Minidisk Recorder where the aim was to simply to avoid transients exceeding the 0dBFS clipping point.
Analogue tape of course plays by different rules. It's also apparent to me that not all VU meters are created equal. The needles on my B77 are more 'agile' than those on my Teac A3440. i.e. when I set both decks to display 0dB with a 1kHz sine wave tone, the B77 needles have greater swing with music and go into the 'red zone' more often than the A3440's meters with the same music.
Alan suggested a good rule of thumb on the B77 is to let the VU meters spend most of their time around -5dB with occasional flicks up to 0dB. He also suggests keeping an eye on the +6dB clipping LEDs and not to let these flash too often.
As an experiment I monitored the B77's VU needles and peak LEDs with the following music replayed from my computer:
1) A track with high dynamic range, RMS levels of -18dBFS and occasional peak levels of 0dBFS.
I set the B77's input levels so that the needles were hitting -5dB for the most part and flicking to as high as 0dB in a couple of places. Even when the needles were only hitting -5dB, the LED clipping lights were still flashing to the beat of the music in many places.
2) A track with low dynamic range, RMS levels of -10dB and frequent peak levels of 0dBFS.
I found I could nudge the input level up to have the needles frequently hitting -2dB to 0dB before the LEDs would flash. However this may be a false sense of security since high frequency saturation apparently increases when peaks are sustained.
I found the result also varied depending on the content of the music. E.g. music with low dynamic range but strong low frequency content needed the VU needles to be set lower to avoid the LEDs flashing.
I'm curious to learn what other folks techniques are for setting recording levels on R2R decks. Do you focus on average or peak levels? And are you anal enough to optimise it track by track or do you take the "life's too short" approach and record a whole album, or even compilations, without adjusting the level?
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337alant
Negatively Biased
Richard
On the compilation tape I gave you I only set the levels on a couple of tracks so some may be a little high and some low.
You can do it track by track and get them all right like your first example (maybe could be a touch higher ).
Your second example looks to me to be too high and clipping, the higher you go the higher the distortion so just be thoughtful of that
Anyway experiment and see which you like
Alan
On the compilation tape I gave you I only set the levels on a couple of tracks so some may be a little high and some low.
You can do it track by track and get them all right like your first example (maybe could be a touch higher ).
Your second example looks to me to be too high and clipping, the higher you go the higher the distortion so just be thoughtful of that
Anyway experiment and see which you like
Alan
ToTo Man
the band not the dog
Sorry for the confusion Alan, I should have made it clearer that the above waveforms are of the digital source before I recorded it to tape. I haven't yet dubbed the tape recordings back onto the computer, but I'll be trying this soon.Richard
On the compilation tape I gave you I only set the levels on a couple of tracks so some may be a little high and some low.
You can do it track by track and get them all right like your first example (maybe could be a touch higher ).
Your second example looks to me to be too high and clipping, the higher you go the higher the distortion so just be thoughtful of that
Anyway experiment and see which you like
Alan
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ToTo Man
the band not the dog
This is a superb deck. Admittedly I only have experience with this B77 and my A3440, but one of the things that impresses me most about this B77 is the noise floor of the electronics. When in tape monitor mode my ADC is registering just -90dBFS(!). I'm sure a large part of this is Alan's meticulous restoration work.
I'm still experimenting with recording levels and speeds to find the sweet spots, but it sounds fantastic, especially using the LPR90 tape formulation Alan calibrated it for. However, even basic Maxell UD tape still sounds surprisingly good and true to source.
The only minor gripe I have with the deck is the sensitivity of the input level knobs, - they aren't damped at all and turn freely, which makes fine tuning the recording levels very difficult for someone who has the touch of a klutz! I remember the volume control of my dad's Technics SU-V707 amplifier being like this, - he used to put a strip of scotch tape over it to prevent it being accidentally knocked clockwise!
I'm still experimenting with recording levels and speeds to find the sweet spots, but it sounds fantastic, especially using the LPR90 tape formulation Alan calibrated it for. However, even basic Maxell UD tape still sounds surprisingly good and true to source.
The only minor gripe I have with the deck is the sensitivity of the input level knobs, - they aren't damped at all and turn freely, which makes fine tuning the recording levels very difficult for someone who has the touch of a klutz! I remember the volume control of my dad's Technics SU-V707 amplifier being like this, - he used to put a strip of scotch tape over it to prevent it being accidentally knocked clockwise!
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337alant
Negatively Biased
Hi Richard
Actually those knobs are normally slightly damped, I may have overdone it with the deoxit and flushed the grease out of the shaft
Get some spray grease, pull off the knob and you will see a small gap between the shaft and the sleeve, try a couple of sqirts in there, protecting everywhere else with a cloth.
Don't spray the grease in the wiper part of the pot
See if that stiffens it up a bit
https://www.screwfix.com/p/wd-40-gr...MypPqTbmMx38sZuB4nAaAoI1EALw_wcB&gclsrc=aw.ds
Alan
Actually those knobs are normally slightly damped, I may have overdone it with the deoxit and flushed the grease out of the shaft
Get some spray grease, pull off the knob and you will see a small gap between the shaft and the sleeve, try a couple of sqirts in there, protecting everywhere else with a cloth.
Don't spray the grease in the wiper part of the pot
See if that stiffens it up a bit
https://www.screwfix.com/p/wd-40-gr...MypPqTbmMx38sZuB4nAaAoI1EALw_wcB&gclsrc=aw.ds
Alan
ToTo Man
the band not the dog
To demonstrate Alan's fine work on this machine, I've uploaded a couple of snippets of recording at 15ips and 7.5ips using LPR90 tape so you can hear how they compare to the digital master. Even the 7.5ips version sounds great to my ears with just a slight loss of openness/air compared to the 15ips. It makes me wonder if it's worth rolling through twice the footage of tape for that last few % in sound quality that 15ips brings?
15ips vs 7.5ips comparison:
[removed]
I've also been experimenting with recording levels and find the B77's peak LEDs very helpful with setting levels as they show dynamics that the VU meters miss, even though the B77's VU meters are faster than most other meters. I recorded the same segment of music 6 times, increasing the source output by +1dB each time, but the differences in sound quality were so subtle I decided just to upload two of them to demonstrate the extremes.
Recording levels comparison:
[removed]
The first file was recorded with levels set just high enough to avoid the +6dB peak LEDs lighting up, - this had the VU meters peaking at -3dB on that particular piece of music. (I checked by increasing the source output by 1 more dB and I got a split second LED illumination in a couple of places).
The second was recorded with levels cranked +6dB higher so that the VU meters were frequently bouncing into the red but stopping just short of the +3dB endstop (the peak LEDs were blinking a lot during this recording!).
Even by saturating the tape like in the +6dB example, the sound quality remains surprisingly good; not as clean/crisp as keeping peak levels below the LED threshold but still very listenable. Being an audiophile I’ll probably stick to keeping levels low enough to avoid the LEDs blinking, but at least I know I won’t have to lose sleep if they flash occasionally, just like Alan said really, - the man knows his stuff!
15ips vs 7.5ips comparison:
[removed]
I've also been experimenting with recording levels and find the B77's peak LEDs very helpful with setting levels as they show dynamics that the VU meters miss, even though the B77's VU meters are faster than most other meters. I recorded the same segment of music 6 times, increasing the source output by +1dB each time, but the differences in sound quality were so subtle I decided just to upload two of them to demonstrate the extremes.
Recording levels comparison:
[removed]
The first file was recorded with levels set just high enough to avoid the +6dB peak LEDs lighting up, - this had the VU meters peaking at -3dB on that particular piece of music. (I checked by increasing the source output by 1 more dB and I got a split second LED illumination in a couple of places).
The second was recorded with levels cranked +6dB higher so that the VU meters were frequently bouncing into the red but stopping just short of the +3dB endstop (the peak LEDs were blinking a lot during this recording!).
Even by saturating the tape like in the +6dB example, the sound quality remains surprisingly good; not as clean/crisp as keeping peak levels below the LED threshold but still very listenable. Being an audiophile I’ll probably stick to keeping levels low enough to avoid the LEDs blinking, but at least I know I won’t have to lose sleep if they flash occasionally, just like Alan said really, - the man knows his stuff!
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