Effects return to PI grid #2

[Guitarist]

Will this work: inserting another signal (as has been done with a preamp's second channel) at what is normally the feedback point of the PI? Should be a great point to jam in some phase90, reverb or delays.

Get my drift? Will it mix well with the rest? I also had an idea to remove the 500 k or 1meg resistors and swap in a pot as a blend control.
Hey, you heard it here first!

One could do without NB and a presence control if necessary, without shedding any tears whatsoever.

[tubeswell]

Well I'm keen to hear what the responses are because I asked a similar question on the Theory and Design forum a week or so ago and haven't had an answer yet. So I'm listening...

[cbarrow7625]

The answer is yes...and sorry, we didn't hear it here first. Vox (and others) did that a long time ago with their reverb. It will mix very well.

You can do without NFB or you can just design a more sophisticated circuit with NFB and presence inserted before the LTP phase splitter (this has also been done before, not my idea).

Give it a try.

[d95err]

There could be a problem if the fx return gets opposite phase from the original sound. Should be no problem for delay and reverb, but it could be problematic for e.g. chorus, phasers, etc.

[tubeswell]

Sorry to hijack the thread

I was wanting to put the return back in the signal path before the PI, with just a coupling cap and 1M resistor to ground and without any gain stages in a 5G9.

I was wondering if the signal voltage from the first stage would be enough to feed the FX send, and whether the coupling cap and 1M to ground after the return would be enough padding before it hits the PI? or would it need some sort of voltage divider with maybe a pot in place of the ground resistor (like what Guitarist was suggesting)?

The other thing I was hoping to discuss before drilling more holes in the chassis, was whether locating the sockets about an inch away from the pilot light would be likely to be a problem from the point of 6VAC induced hum?

[Guitarist]

OK, thanks gents. Man, tubes are so design friendly.

Insert off the MV for serial effects such as phaser, compression or fultron.
Parallel for reverb and delay- and these are the digital tone-thinners, so even better.

But this will NOT work with a the feedback going to the same grid, right?

I'll try and draw up a schematic to post.