I also have an A77 machine and though the circuitry is a bit dated and distortion higher than necessaary - all decrete - can easily be replaced with better topology and even 8-pin devices.... all would be an improvment. However, it was the mechanicals that are really good and make the basis of a good DIY base unit. I originally bought mine as 1/4 track 7.5-15 ips home version.... wood case and all when living in Germany and later had it converted to 1/2 track 15-30 ips. Great mastering machine if electronics (including bias osc) were up-dated.... and, all on plug-in pcb's.
I assume similar situation to exist in the other Revox and Studer machines.
THx-RNMarsh
I assume similar situation to exist in the other Revox and Studer machines.
THx-RNMarsh
Last edited:
none of the tape machines mentioned so far begins to cut it, they are production decks and many of them work well, but do not begin to make master level recordings. To do that you need to start with Studer A-80 and then include the later A-820, that was the last mastering level 2 track Studer designed. In Ampex its the ATR-100 series, nothing before or since. And less present here in the US the Telefunken M-15 and 20. There are a couple other ones but that is pretty much the top of line for mastering 2 track recorders. All of them have their problems sonically, some of which can be dealt with, but the first thing any/all tape machines must do is move the tape past the heads in a consistent manner, that is not a trivial task. The electronics can never be better than the mechanical design.
Cheers
Alan
Cheers
Alan
They may not make master level recordings but I have some superb performances off them that I take great pleasure listening to. Two mics straight into an A77 does not end up with a record where I go 'damn if only they had used a Studer.
OTOH there are a lot of 'audiophile spectaculars' that you don't actually want to listen to other than to show off to friends.
OTOH there are a lot of 'audiophile spectaculars' that you don't actually want to listen to other than to show off to friends.
How true!
And that can be proven easily, just plug one decent mic into the mic input and recrd a friend playing a guitar, then play it back and marvel at what's on that tape even at 19 cm/s.
And that can be proven easily, just plug one decent mic into the mic input and recrd a friend playing a guitar, then play it back and marvel at what's on that tape even at 19 cm/s.
What is the reason for this strange nostalgia for analog old machines ?
Noise (Hiss and hum, pre-post echo for tapes, vinyl rumble clicks and surface noise), non linear response curves, distortion, frequency errors (Wow and flutter), limited dynamic, degradation with wear and even time ...
Noise (Hiss and hum, pre-post echo for tapes, vinyl rumble clicks and surface noise), non linear response curves, distortion, frequency errors (Wow and flutter), limited dynamic, degradation with wear and even time ...
Entirely off the current topic. I recently got a product note.
OPA837 datasheet Low Power, Precision, 105 MHz, Voltage Feedback Op Amp | TI.com
One of my pet projects has been a battery powered mixer and stand alone analog equalizer.
The typical AA alkaline battery is good for 1.2 A/Hr.s That should yield a battery life of 2,000 hours. Using a D cell would raise that to 40,000 - 50,000 hours. Thus one could build gear without a power switch and no "Ground Loop" issues.
With the D cell the battery reasonably would last the life of the gear.
For a mic mixer the design would be 600:10,000 ohm step up transformers feeding individual volume controls mixed to a variable gain summing op-amp. If needed an output transformer to get the voltage up a bit, as the op-amp's 1 V RMS or so is a bit low.
The equalizer would be a typical design with one op-amp per band. To preserve battery life a power switch would be incorporated into the output connector. Still will require an output transformer.
For the intended application moderate to cheap transformers should be fine.
The end user need not even know there are active components inside!
OPA837 datasheet Low Power, Precision, 105 MHz, Voltage Feedback Op Amp | TI.com
One of my pet projects has been a battery powered mixer and stand alone analog equalizer.
The typical AA alkaline battery is good for 1.2 A/Hr.s That should yield a battery life of 2,000 hours. Using a D cell would raise that to 40,000 - 50,000 hours. Thus one could build gear without a power switch and no "Ground Loop" issues.
With the D cell the battery reasonably would last the life of the gear.
For a mic mixer the design would be 600:10,000 ohm step up transformers feeding individual volume controls mixed to a variable gain summing op-amp. If needed an output transformer to get the voltage up a bit, as the op-amp's 1 V RMS or so is a bit low.
The equalizer would be a typical design with one op-amp per band. To preserve battery life a power switch would be incorporated into the output connector. Still will require an output transformer.
For the intended application moderate to cheap transformers should be fine.
The end user need not even know there are active components inside!
Hi Waly,
CMOS switches can operate very well if you design the surrounding circuitry for it. The 8 legged monsters aren't a problem if you use the right ones. Certainly a lot better than the discrete circuits many brands tend to use.
To use a CMOS switch properly, drive it with a low impedance and run the output into a high input impedance buffer (or gain stage). The problems created by doing it this way are less of an issue than the signal on the tape itself. Nakamichi tended to use CMOS switches in the auto-cal circuits were signal distortion and noise were not a problem. So look again at the playback amplifier with those points in mind.
-Chris
CMOS switches can operate very well if you design the surrounding circuitry for it. The 8 legged monsters aren't a problem if you use the right ones. Certainly a lot better than the discrete circuits many brands tend to use.
To use a CMOS switch properly, drive it with a low impedance and run the output into a high input impedance buffer (or gain stage). The problems created by doing it this way are less of an issue than the signal on the tape itself. Nakamichi tended to use CMOS switches in the auto-cal circuits were signal distortion and noise were not a problem. So look again at the playback amplifier with those points in mind.
-Chris
Eveready lists 0 drain shelf life at 5-10yr. on alkaline. I thought this was funny.
EDIT - I see you are only looking 5yr. as lifetime. I pulled an old piezo stylus cleaner out of a bin after the last move and it had a 30+ yr. old RS rechargeable in it and it still worked!
Last edited:
Indeed, runs rings around any mechanical recording/reproducing system for clarity and realism.
Not that the mech stuff cannot be enjoyable, but not very Hi-Fi in the original sense.
https://linearaudio.net/sites/linea...kHz) recorded Wurcer mic preamp nov 2011.flac
https://linearaudio.net/sites/linea..._recorded_with_Wurcer_mic_preamp_nov_2011.wav
Jan
0 Drain is temperature related. Interestingly enough at very low drain the lifetime goes up!
I used to keep a Radio Shack alarm switch panel by the outside back door of my shop. Rather than run a wire to it the Red LED was powered by a battery. 3 D cells fit in the case nicely. At 1 mA the light stayed lit for a bit more than 3 years under all weather conditions. It got replaced still working when we got a real alarm. (Insurance company discount paid for the real thing.)
Of course the alarm light panel was not connected to anything else. It just served as a deterrent.
BTY more on topic there are op-amps with 5 or 6 legs around these days. They must sound better as they are approaching the nearly perfect 3 legged thing-a-ma-jigs.
When an op-amp gets to 3 legs it is powered quantum mechanically from the aether. Or maybe the demon is in there pedaling frantically on his stationary bike and generator.
Nothing wrong with lots of legs... Just package it into an octal valve base... Maybe add some leds for glow, and spray with warm dust scent....
We did that for Varian. They wanted to use IC electrometers to sub for electrometer tubes in vacuum gauges. The leads were bent and spot welded into standard octal tube bases then they put on the glass and sealed them.
I built several of these just this year, using the good old LM3909 (IC that flashes a 1.9V LED using a 1.3V battery). Sprinkled them around the house (along with an Amazon 4-pack of CCTV cameras, 4 for $49) before having a termite fumigation tent put on. While I was out of the house and the fume team was inside, I wanted them to see ominous blinking LEDs and video cameras everywhere. It worked well: no theft and no property damage.
_
Attachments
As with all Mems mics they are 10+ dB below SOTA on SNR. It's simply a size physics issue, the thermodynamics of air and the diaphragm size determine the SNR there is no beating it. A 1/2" mic beats it there is no circuit sophistry or magic FET that can do better.
- Status
- Not open for further replies.