ceriatone 2204 layout with an FX loop question

[Curranproducer]

so I am looking at the layout drawing of the ceriatone 2204 marshall they offer, and i have notice that they have put in an FX loop into the amp between the treble control and the MV with no other components involved other than the jacks. ummmmmmmmmmm does this actually work without ruining the amp?

[xtian]

Sure, there are lots of amps that use passive loops. Why not, for the cost of two 1/4" jacks?!?

Do they work? Sure. Do they sound awesome? Maybe. Depends a lot on the pedal used.

[Curranproducer]

I just want to pop and analog delay though it that I built. just for some wet love

[xtian]

I just want to pop and analog delay though it that I built. just for some wet love

Sounds like a plan. You'll just have to gather your own empirical evidence!

[psychepool]

Sure. They will operate, but if preamp out level is higher, the stompboxes will distort.
It's the reason that use active fx loop.

Active fx loop has the function that lowering the impedance(send) and recovering the level(return).
It makes maintain the total output level without distorting the stompbox in the fx loop.

There's many good circuit that made with tube, opamp, FET and MOSFET.
If you want to make it completely, I highly recommand to apply active circuit.

[M Fowler]

That passive loop works very well.

[pdf64]

Such a loop may seem the polar opposite of 'transparent'.
The source impedance and max signal level of such a loop will be dependent on the setting of the master volume control.
Assuming that the master has a 10% taper, below ~30% it should be fine; beyond that, the send signal level may become excessive and the treble loss unacceptable, unless using rack fx connected by very short patch cables.

At 50%, the source impedance will be ~100k, and so just 500pF of cable capacitance will give a -3dB corner frequency of 3k2Hz.

Depending on what's in the loop, the overdrive character of the power amp may be affected, as any fx units in the loop may clip the signal before it gets to the phase splitter.