As a professional user of an A80 2 track 1/2" machine, I can vouch that the B77 is an elegant, good sounding piece of equipment. Quite a few excellent commercial recordings have been made with a B77. These Revox machines have a very transparent top end and solid bottom which other Japanese machines don't have. Its quite a bit of hassle to convert a 4 track B77 to 2 track. I'd say its much easier and more economical to buy a 2 track machine that needs some work and fix it up.
In a way it’s very true what you say about easier Profiguy, but i don’t think so about economical.
The states used gear market is very different to the eu one.
Especially the very small south eastern one.
An eu citizen can’t buy from the states, asia and the uk cheaply, with the taxes the final price will be about an additional 50% of the paid price (+ shipping - the uk shipping rate is ok).
So a 300 euro-dollar machine would end up, about 450 + shipping (for a tape machine from the uk about 40 euros - us and asia is out of question- more than 100)
Central europe is the only real option and then the postage is quite expensive (about 40 euros).
So for a broken a77 mk2-3-4 or b77 from there, you end up paying around 300. Then add parts to that - around 100 more or less.
With 400 euros I think i can get a great 2 speed headblock, one that i wouldn’t find on a broken machibe without big luck. Of course there is work to be done, but since the decision is to keep the machine, i think inwill start “improvements” on it, unless i’m lucky and something broken come my way very cheaply.
The states used gear market is very different to the eu one.
Especially the very small south eastern one.
An eu citizen can’t buy from the states, asia and the uk cheaply, with the taxes the final price will be about an additional 50% of the paid price (+ shipping - the uk shipping rate is ok).
So a 300 euro-dollar machine would end up, about 450 + shipping (for a tape machine from the uk about 40 euros - us and asia is out of question- more than 100)
Central europe is the only real option and then the postage is quite expensive (about 40 euros).
So for a broken a77 mk2-3-4 or b77 from there, you end up paying around 300. Then add parts to that - around 100 more or less.
With 400 euros I think i can get a great 2 speed headblock, one that i wouldn’t find on a broken machibe without big luck. Of course there is work to be done, but since the decision is to keep the machine, i think inwill start “improvements” on it, unless i’m lucky and something broken come my way very cheaply.
I wonder anatech what the head amp you mention is?
Is it a recording head amp, a reproduce head amp, or an input amp? Which pcb of the b77 is the revox part (or oarts) located and what the Nakamichi part is? Is it an op-amp?
Please give me some more details. I doubt that you’re talking about the headphone-monitor section.
Hi Ted,
Okay, if you will attempt the conversion (I advise against it), take lots of pictures, save all old parts and document everything as you do it. Never do anything you cannot come back from - have a back out plan.
You want the playback circuit from the Nakamichi, the head amp. It is an entirely different circuit, different power supply. Pay close attention to grounding and local regulation. All these things work together to make one of the best head amps I have ever seen. Here is the magic.
You will upgrade the record electronics as well of course. Look to newer Tascam or Revox/Studer machines for inspiration. They would use the same type of power supply the new head amp uses. What you are doing is using an excellent chassis and heads and building new electronics for it. Build on the best that came previously and you'll have a killer machine. YOu will not be using the same plug-in cards, so save them as your back-up plan. Your power buss will be separate and you can plug the playback head wires directly into the new board using the same connectors. That is mounted very close to the head block, may as well use new wires, shorter.
So examine a few Nakamichi schematics. Also pay attention to the PCB layout including local regulation. Look at the main regulators as well.
Okay, if you will attempt the conversion (I advise against it), take lots of pictures, save all old parts and document everything as you do it. Never do anything you cannot come back from - have a back out plan.
You want the playback circuit from the Nakamichi, the head amp. It is an entirely different circuit, different power supply. Pay close attention to grounding and local regulation. All these things work together to make one of the best head amps I have ever seen. Here is the magic.
You will upgrade the record electronics as well of course. Look to newer Tascam or Revox/Studer machines for inspiration. They would use the same type of power supply the new head amp uses. What you are doing is using an excellent chassis and heads and building new electronics for it. Build on the best that came previously and you'll have a killer machine. YOu will not be using the same plug-in cards, so save them as your back-up plan. Your power buss will be separate and you can plug the playback head wires directly into the new board using the same connectors. That is mounted very close to the head block, may as well use new wires, shorter.
So examine a few Nakamichi schematics. Also pay attention to the PCB layout including local regulation. Look at the main regulators as well.
This project and research on improving the audio head path, seems more tempting for the time being.
Has the oscillator-bias and erase head circuit anything to do with it or they stay as they are?
Has the oscillator-bias and erase head circuit anything to do with it or they stay as they are?
The bias oscillator design is fine, as is the erase head (which changes when you go 1/2 track). You will make any modifications to that circuit required by going 1/2 track. You are changing all the heads. The bias oscillator output is tapped down for the record circuits.
The output from the bias oscillator will vary a bit with supply voltage, so you could conceivably improve the voltage regulator for that. Any noise on the bias oscillator output goes to tape.
The output from the bias oscillator will vary a bit with supply voltage, so you could conceivably improve the voltage regulator for that. Any noise on the bias oscillator output goes to tape.
Very good advice - i ll see what i ll do with the heads change and the other parts that gobwith it. Budget and time is something to carefully think about.
Seems that needs quite some research, but i really love researching pro-audio mods and circuits (and if budget, time and technical abilities - tools and understanding - allow it, i attempt building).
Really appreciate your input Anatech (and the other members’ too). Honoured to share a bit of your knowledge.
Seems that needs quite some research, but i really love researching pro-audio mods and circuits (and if budget, time and technical abilities - tools and understanding - allow it, i attempt building).
Really appreciate your input Anatech (and the other members’ too). Honoured to share a bit of your knowledge.
@anatech
I did not remember correctly. I checked and It's a 1000II. The reason I don't use my sound system anymore is because I can barely hear. My hearing has gone bad the last few years, so my equipment just collects dust.
I did not remember correctly. I checked and It's a 1000II. The reason I don't use my sound system anymore is because I can barely hear. My hearing has gone bad the last few years, so my equipment just collects dust.
The head amp is one area on a studer A77 where big improvements can be had. Specifically the record amp where the bias is mixed can benefit from a balanced fet based design using coupling transformers. I remember Bernie Grundman's A80 was very similar to my machine. He had custom record and playback preamps designed for him but those were never discussed due to keeping things under wrap from copy cats. I mostly use my A80 for digital transfers, so its mostly playback I'm concerned about.
The A77 and B77 bias oscillators usually don't have enough amplitude headroom to get the best saturation from type II and IV media. Although most people use type I tape, they still want more saturation when dubing drums and bass. The distortion is relatively high when pushing the low end into the red.
For straight playback purposes, the stock versions of A77s and B77s are more than adequate, discounting the noise floor if the machine is used for classical music. At 15 ips the noise can get a little too much.
The A77 and B77 bias oscillators usually don't have enough amplitude headroom to get the best saturation from type II and IV media. Although most people use type I tape, they still want more saturation when dubing drums and bass. The distortion is relatively high when pushing the low end into the red.
For straight playback purposes, the stock versions of A77s and B77s are more than adequate, discounting the noise floor if the machine is used for classical music. At 15 ips the noise can get a little too much.
Very detailed post and opens up to me new fields for research Profiguy. Things about the tape media types, i know next to nothing. Just that maxell ud (or whatever) is good. In the past i knew that metal, or chrome cassetes were good. But then came the cdr, and the whole cassette thing ended for me. And then digital. Now because of that revox i’m back to reels for doing certain few things. Not playback. Not mastering. Not even trying to dream of working with a proper multichannel recording tape deck. All great.
As i wrote for me recording and playback of that recording is the important part, since i transfer the digital mono (usually) recorded source(track) to analog (for that tape vibe) and back to digital for mixing. I don’t think i would use a lot of stereo sources, since currently i don’t record rooms. And pretending that i can master, would be a joke.
As i wrote for me recording and playback of that recording is the important part, since i transfer the digital mono (usually) recorded source(track) to analog (for that tape vibe) and back to digital for mixing. I don’t think i would use a lot of stereo sources, since currently i don’t record rooms. And pretending that i can master, would be a joke.
Hi Ray,
Yes, that is a solid model. Blows most others away. I'm sorry you can't enjoy music as you used to do. Still, I have clients north of 80 who still can tell good sound from bad, and their hearing isn't as good as it was. Never give up! Maybe get that machine into the hands of someone who will be amazed with cassette quality.
Hi profiguy,
The B-77 is a lot better than the A-77 for electronics! Much nicer transport control as well. I wanted an A-700. 🙂
Studer machines are a different animal. The audio electronics are much better. Tape handling not equalled anywhere. In my area, we normally used studio tape, Ampex and Scotch back coated. I forget the new company that was Scotch, but that is typically what you see. Machines cal to that without difficulty.
These tapes are easier to get, Maxell and consumer brands are harder to get and are old stock, so watch for degraded tape. Binder is your enemy #1. Just buy current, new tape, calibrate to that.
Important
If a machine squeals, you have binder on the heads. Stop immediately and clean the entire tape path with Methyl Hydrate. Discard that tape or you'll have it through your collection. These deposits are not visible to the eye. You can reset binder through a heating process, then you have one shot to transfer it to a new tape.
Yes, that is a solid model. Blows most others away. I'm sorry you can't enjoy music as you used to do. Still, I have clients north of 80 who still can tell good sound from bad, and their hearing isn't as good as it was. Never give up! Maybe get that machine into the hands of someone who will be amazed with cassette quality.
Hi profiguy,
The B-77 is a lot better than the A-77 for electronics! Much nicer transport control as well. I wanted an A-700. 🙂
Studer machines are a different animal. The audio electronics are much better. Tape handling not equalled anywhere. In my area, we normally used studio tape, Ampex and Scotch back coated. I forget the new company that was Scotch, but that is typically what you see. Machines cal to that without difficulty.
These tapes are easier to get, Maxell and consumer brands are harder to get and are old stock, so watch for degraded tape. Binder is your enemy #1. Just buy current, new tape, calibrate to that.
Important
If a machine squeals, you have binder on the heads. Stop immediately and clean the entire tape path with Methyl Hydrate. Discard that tape or you'll have it through your collection. These deposits are not visible to the eye. You can reset binder through a heating process, then you have one shot to transfer it to a new tape.
Scotch i think is (was) 3M. Like the “scotch - brite” sponges.
At least we are covered for tape in the eu. Germany had plenty of tape users and factories, back in the day. So loads of nos snd good used reels. And also one of the few new companies that produces new affordable tape is in France. So luckily good rape can be found without robbing the bank.
Whatever you say on the “important” note of your post, at least i know and take good care. I’ve even came across a reel of basf tape that was needing lubrication to heal and half of the reel was very dangerous for the motors. Off the window. A reel of scotch was nearly burned by overheating from a previous user. Dudn’t stay on more than 1min. But the bottom of the machine was a bit full of backcoating and brown residues. I already had few bad stories with bad tape. Luckily enough nothing too harmful.
Magnifying glasses, cotton buds, isopropyl alcohol and a little bit of naphtha on the pinch roller are my friends.
At least we are covered for tape in the eu. Germany had plenty of tape users and factories, back in the day. So loads of nos snd good used reels. And also one of the few new companies that produces new affordable tape is in France. So luckily good rape can be found without robbing the bank.
Whatever you say on the “important” note of your post, at least i know and take good care. I’ve even came across a reel of basf tape that was needing lubrication to heal and half of the reel was very dangerous for the motors. Off the window. A reel of scotch was nearly burned by overheating from a previous user. Dudn’t stay on more than 1min. But the bottom of the machine was a bit full of backcoating and brown residues. I already had few bad stories with bad tape. Luckily enough nothing too harmful.
Magnifying glasses, cotton buds, isopropyl alcohol and a little bit of naphtha on the pinch roller are my friends.
Yes, Scotch.
Agfa wasn't good, nor was BASF. Avoid any real Chrome tape (that is an industrial abrasive!). Chrome tapes will wear heads very quickly, Cobalt has the same EQ and bias levels. Maxell and TDK are Cobalt formulations.
Early Ampex 456 had binder issues, I'm not sure if Scotch 256 was similar. Later formulations did not have those issues. Tapes earlier than these often had problems. Low cost tape was like Ampex 406 or Scotch 226 and others.
Agfa wasn't good, nor was BASF. Avoid any real Chrome tape (that is an industrial abrasive!). Chrome tapes will wear heads very quickly, Cobalt has the same EQ and bias levels. Maxell and TDK are Cobalt formulations.
Early Ampex 456 had binder issues, I'm not sure if Scotch 256 was similar. Later formulations did not have those issues. Tapes earlier than these often had problems. Low cost tape was like Ampex 406 or Scotch 226 and others.
Just another question for you Anatech (or anyone else who may know).
On the oscillator pcb the obvious difference between the 2 track and the 4 track boards is the transformer.
Another obvious difference is that the b77 2 track pcb is quite rare in europe and ordering from the states it becomes very expensive (150 euros for an untested board).
I wish i knew the windings values of the transformerif something custom could be coiled. But since this is pretty improbable to happen. I thought of a different possibility to save me (in case i do the 2 track conversion) money.
The a77 mk3-mk4 boards can be found quite easily here (much more succesful models in europe than b77).
The 2 track a77 transformers has different pins location to the b77 ones. But i wonder if the windings are similar that i could built an adaptor for the b77 board to fit an a77 transformer. I could even built a whole new oscillator pcb around the pins of the a77 board. Only the coils may be harder to find.
So the main questions are:
Are the windings of the a77 mk3v -b77 mk2 2 track transformers compatible?
If yes, is it crucial in this circuit to have the oscillator tansformer on the pcb (or attached to it) or could i move the transformer elsewhere (nearby the pcb) and use jumper wires?
On the oscillator pcb the obvious difference between the 2 track and the 4 track boards is the transformer.
Another obvious difference is that the b77 2 track pcb is quite rare in europe and ordering from the states it becomes very expensive (150 euros for an untested board).
I wish i knew the windings values of the transformerif something custom could be coiled. But since this is pretty improbable to happen. I thought of a different possibility to save me (in case i do the 2 track conversion) money.
The a77 mk3-mk4 boards can be found quite easily here (much more succesful models in europe than b77).
The 2 track a77 transformers has different pins location to the b77 ones. But i wonder if the windings are similar that i could built an adaptor for the b77 board to fit an a77 transformer. I could even built a whole new oscillator pcb around the pins of the a77 board. Only the coils may be harder to find.
So the main questions are:
Are the windings of the a77 mk3v -b77 mk2 2 track transformers compatible?
If yes, is it crucial in this circuit to have the oscillator tansformer on the pcb (or attached to it) or could i move the transformer elsewhere (nearby the pcb) and use jumper wires?
Hi Ted,
This bias oscillator runs at approximately 105 KHz (from distant memory) and a very high amplitude. I would never mess with it or use jumpers. You risk becoming an AM radio station. Remember too, any noise or distortion on that bias waveform goes directly to tape.
In engineering, you have one option no matter how much you want to do something else. Do it properly. Would it work if you found a way around? Sure, but you'll probably just be opening a long series of issues you do not want.
Since it drives the same heads, they are probably compatible from an output standpoint. They may have different drive circuits, so it isn't just adapting a transformer. Remember when I said it would be expensive, and a real pain? This isn't something we would have studied, probably someone else has. Never once did we attempt to use parts from an A-77 in a B-77 that were not the exact same part number. Revox didn't change part numbers unless they were different.
It would be nice if this were possible. I highly recommend against it.
This bias oscillator runs at approximately 105 KHz (from distant memory) and a very high amplitude. I would never mess with it or use jumpers. You risk becoming an AM radio station. Remember too, any noise or distortion on that bias waveform goes directly to tape.
In engineering, you have one option no matter how much you want to do something else. Do it properly. Would it work if you found a way around? Sure, but you'll probably just be opening a long series of issues you do not want.
Since it drives the same heads, they are probably compatible from an output standpoint. They may have different drive circuits, so it isn't just adapting a transformer. Remember when I said it would be expensive, and a real pain? This isn't something we would have studied, probably someone else has. Never once did we attempt to use parts from an A-77 in a B-77 that were not the exact same part number. Revox didn't change part numbers unless they were different.
It would be nice if this were possible. I highly recommend against it.
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I would like Anatech's opinion. In the 1970.s I bought a box of AMPEX 444 mastering tape. I used a few reals. Does the tape have any value today or is it junk?
Hi Ray,
As long as it was stored properly (cool place) and is still good, it should be saleable. 444 is very old, but tape is so scare you'll have a home user buy it for sure. "Mastering tape" would get their attention.
As long as it was stored properly (cool place) and is still good, it should be saleable. 444 is very old, but tape is so scare you'll have a home user buy it for sure. "Mastering tape" would get their attention.
Anatech,
Thanks. It was kept in the basement for 50 years, not subject to any temperature extremes. I used 3 reels and have 9 unused reels left. The tape came on 10.5-inch metal reels and is still in the original boxes.
Thanks. It was kept in the basement for 50 years, not subject to any temperature extremes. I used 3 reels and have 9 unused reels left. The tape came on 10.5-inch metal reels and is still in the original boxes.