Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jewishjay on April 24, 2022, 11:08:26 am

Title: Add an effects loop to this Wurlitzer 700
Post by: jewishjay on April 24, 2022, 11:08:26 am

Hey gang, I recapped this Wurli for a friend and now he'd like me to add an effect loop or at least a record out. Where and how would you do it? I'd really appreciate if someone could draw it clearly on this schematic. Thanks for everything!

Title: Re: Add an effects loop to this Wurlitzer 700
Post by: tubeswell on April 24, 2022, 11:21:00 am

On this amp, you’d need another stage in front of the paraphase inverter for an FX loop methinks.


Although, if you only want a line out, you could put a voltage divider (with an output Jack) in parallel with the speaker(s) - across the secondary winding.

Title: Re: Add an effects loop to this Wurlitzer 700
Post by: jewishjay on April 24, 2022, 11:24:58 am

Quote from: tubeswell on April 24, 2022, 11:21:00 am

Although, if you only want a line out, you could put a voltage divider (with an output Jack) in parallel with the speaker(s) - across the secondary winding.

Are you saying the "External Speaker" jack just needs a resistor or two to become a line out?

Title: Re: Add an effects loop to this Wurlitzer 700
Post by: shooter on April 24, 2022, 11:53:24 am

2 resistors, but you only have a PA amp, NO pre-amp.  the pre amp would be the best for an FX, line out

Title: Re: Add an effects loop to this Wurlitzer 700
Post by: jewishjay on April 24, 2022, 03:26:08 pm

Quote from: shooter on April 24, 2022, 11:53:24 am

you only have a PA amp, NO pre-amp.  the pre amp would be the best for an FX, line out

The pickup goes into the "pre amp" the first triode, directly into the paraphase, to the 6V6s. Is there no good place to put a loop? Maybe off the volume control like robrob suggests here?....

https://robrobinette.com/Generic_Tube_Amp_Mods.htm#FX_Loop