Ballfinger M063 both 1/4 track and 1/2 Track playback

[adrianywu]

I agree coping a tape is pretty straight forward, but the amount of loss really depends on the playback & record electronics used to duplicate that tape. With stock to stock machines the results will be the baseline. If there are custom record & playback amps in this chain, the loss will be much less.

My experience with tape playback amps, the differences can be quite surprising. For instance I have been using a tape playback amp based on the Western Electric 437a tube executed with all silver transformers etc. since I started UltraAnalogue Recordings. It's sound was very very good....

We just finished a tape amp using the Western Electric 300b amp & I have to say, the changes were surprising in all areas of sound... the timbres, transient speed, dynamics, naturalness, rhythmic pulse & drive of the music were all taken to another level.... There is no free lunch in audio!

So in tape duplication, as in all things, nothing is simple!

Ed

My experience is with the Nagra TA, and this is certainly the case. I built a balanced differential tape head preamp using Amperex 7308 as input tube and E88CC for gain stage and buffer. The B+ is shunt regulated. The sound is far more musical than the TA's native repro electronics. It took a bit of tweeking the input resistance and capacitative loading to get good HF extension, since the repro head has an inductance of 700mH. I usually record with a stock Nagra IV-S, and the sound is excellent. I suspect this is true of many pro machines; they tend to record better than they play back. I have collected a bunch of NOS WE437A years ago but never got round to doing anything with them. Would be interested to see your design if you have published it.

 

[Foxbat]

My experience is with the Nagra TA, and this is certainly the case. I built a balanced differential tape head preamp using Amperex 7308 as input tube and E88CC for gain stage and buffer. The B+ is shunt regulated. The sound is far more musical than the TA's native repro electronics. It took a bit of tweeking the input resistance and capacitative loading to get good HF extension, since the repro head has an inductance of 700mH. I usually record with a stock Nagra IV-S, and the sound is excellent. I suspect this is true of many pro machines; they tend to record better than they play back. I have collected a bunch of NOS WE437A years ago but never got round to doing anything with them. Would be interested to see your design if you have published it.

It is interesting that for 30 years I have been an active promoter of balanced circuits, and in 98% of all cases they are better... but I have been feeling for some time now that in the of the tape heads the single ended connection might be better.

The head is not a balanced source, and I have been getting surprisingly good results using single-ended connection. You get better sounds, I think, but also, importantly, you get less noise that way. So today my favorite recipe is not to build a balanced stage using two triodes, but instead to connect the two in parallel and then feed them with the single-ended signal.

700mH is very high inductance, the highest I have seen so far was 600mH and yes, it took a bit of special care.

 

[adrianywu]

It is interesting that for 30 years I have been an active promoter of balanced circuits, and in 98% of all cases they are better... but I have been feeling for some time now that in the of the tape heads the single ended connection might be better.

The head is not a balanced source, and I have been getting surprisingly good results using single-ended connection. You get better sounds, I think, but also, importantly, you get less noise that way. So today my favorite recipe is not to build a balanced stage using two triodes, but instead to connect the two in parallel and then feed them with the single-ended signal.

700mH is very high inductance, the highest I have seen so far was 600mH and yes, it took a bit of special care.

Yes, I initially wired the head with screened cable and connected to the King Cello tape stage, which is single-ended. However, I could not get a good HF extension. I then modified the tube pre, which I built 20 years ago as a phono pre, and used just a twisted pair of solid silver wires in Teflon insulation. The capacitance was much lower, and I was able to get a good HF extension with only -2dB at 20K. Connecting in single ended picked up more noise. I thought the tape head is like a phono cartridge, with floating output.

 

[Foxbat]

I suspect the HF loss with single-ended connection was simply due to too low input resistance. You need at least 150K there, and King Cello probably had less.