Using 10 metre interconnect question

[ToTo Man]

Nothing to be confused about! It all depends on the source impedance. 100m could be fine in one situation but 2m pushing it in another... The Croft has a source impedance of 47K from tape out (possibly/probably anyhow! Croft keep making changes so often that the problem with Croft is that you really need to open any particular example up and see what spec it is) according to schematics I've seen, and rather higher on phono.

Many amps simply connect the source direct to tape out and so are capable of driving whatever the source can (or cannot) drive. The 47K resistors used in the croft give some isolation from non linear loads of switched off equipment at tape out.

The OP could of course just short out the 47K resistors and jobs a gud 'n... on most sources... but you couldn't use phono without unplugging the lead from tape out and couldn't record from phono.

I guess the ideal solution would be to build a small SS buffer into the Croft and power it from the heater supply. I would charge £200 to do this.

So the Croft is unusual then in having a high Zout from it's tape outputs?

According to the manual of my A-S3000 the Zout of its REC output is 1.5kΩ, which is almost 150x smaller than the Zin of a Revox B77 at 220kΩ, for example, so I assume should pose no issues regardless of cable length, given that the goal is to make sure that Zin = at least 10x higher than Zout?

However, how meaningful is this 1.5kΩ figure if, as you say, the REC outputs of most SS amps are unbuffered, in which case the Zout is not 1.5kΩ but is instead whatever the Zout of the upstream source component is?

Also, if Zout of an amp's unbuffered REC output = Zout of the upstream source component, then does Zin of the amplifier's line inputs have an indirect effect on the Zout of the amplifier's REC out?

Sorry for all these questions but I'm trying to get a better grasp of how all this plays out in reality.

 

[Arkless Electronics]

So the Croft is unusual then in having a high Zout from it's tape outputs?

According to the manual of my A-S3000 the Zout of its REC output is 1.5kΩ, which is almost 150x smaller than the Zin of a Revox B77 at 220kΩ, for example, so I assume should pose no issues regardless of cable length, given that the goal is to make sure that Zin = at least 10x higher than Zout?

However, how meaningful is this 1.5kΩ figure if, as you say, the REC outputs of most SS amps are unbuffered, in which case the Zout is not 1.5kΩ but is instead whatever the Zout of the upstream source component is?

Also, if Zout of an amp's unbuffered REC output = Zout of the upstream source component, then does Zin of the amplifier's line inputs have an indirect effect on the Zout of the amplifier's REC out?

Sorry for all these questions but I'm trying to get a better grasp of how all this plays out in reality.

Had a butchers at the schematics for your Yam as the above sounded likely that it HAS tape buffers.... It indeed does.
It will drive any sensible length of coax and any tape recorder/HDD recorder etc no problem.

Valve amps are the ones you will pretty much never find buffered tape outputs on as it means another valve (dual triode) or pair of valves and so means a significant increase in cost. It can of course be done with SS in either a valve or SS amp and this keeps the cost down but I can't think of a valve amp that has this (politics! "nasty SS sand in my valve amp" etc).

Zin of line inputs will have virtually no influence on Zout of tape output.

There are many situations where the "Zin should be a minimum of 10X Zout" rule of thumb really doesn't matter BTW but I won't complicate things by addressing that!