Pioneer SR-60 Reverb - Modifications Help

[Whoops]

​Hello,
I have a Pioneer SR-60 Reverb Amplifier unit and although it says "Reverberation Amplifier" it's actually a Delay, it uses a MN3008 BBD delay chip.

It would be great also to be able to change the Delay Time and the Feedback level.

here is the schematic for the unit:

https://i.imgur.com/JVhDN9V.jpg

The schematic is a bit confusing to me because of all the switching going on,
I need help from you guys.
How do you think I could implement a control the Delay feedback and change the Delay time even if Limited??

Thank you so much​

 

[U130421]

To adjust the delay time you can switch C49 different values. To adjust the reverb, feed the signal to R122 via 100k volume pot instead of R104

 

[Whoops]

This is the datasheet for the MN3008 Delay BBD Chip:

 

[Whoops]

To adjust the delay time you can switch C49 different values. To adjust the reverb, feed the signal to R122 via 100k volume pot instead of R104

Thank you I will try those ones out.

What do you mean by "adjusting the Reverb" is it the delay time when in the Reverb Setting?

The unit has 3 modes "Reverb" , "Echo" and "Duet"

Reverb and Echo sound almost exactly the same, the delay time in those 2 sound the same

The Duet mode is a king of fake double tracking, it sound a little bit weak, I would love to exaggerate it a big more

Thank you so much

 

[U130421]

The capacitor adjusts the delay time , higher - longer. The reverb feedback will be adjusted by pot. replacing R104. If you need to increase the reverb, replace R122 to 56k.

 

[Whoops]

Thank you so much,
I will try those out today and let you know

 

[Whoops]

The capacitor adjusts the delay time , higher - longer.

Tried changing the capacitor with different values using a decade box but it's easier to vary the delay time by Replacing R132 with a Potentiometer.
100K Log instead of R132 works fine.

The problem is with longer delay times there's a constant High Frequency whine pitch note that goes down in pitch and it's quite present.
I suspect that that high pitch note or noise is also there on the stock delay time but at an higher pitch above the hearing range.
Slowing down the delay brings that note into the audible range and it's quite irritating.

Do you know any solution for this?

Thank you so much

 

[Whoops]

The reverb feedback will be adjusted by pot. replacing R104.

For variable feedback I tried as you suggested and replace R122 with 56K and R104 with a 100K log pot.
It didn't work well, there was only a small range between 200R and 2.5K where something happened to the feedback but above 2.5k until the full rotation there was no difference in the repeats.

I tried to replace R122 with a fixed resistor and a Pot and it worked nicely.
I liked a 51K resistor with a 200K Log pot in series, it gives a good range between few repeats and it goes into Oscillation in the full rotation

 

[Whoops]

This are the conclusions at the moment for the mods:

 

[Kay Pirinha]

The problem is with longer delay times there's a constant High Frequency whine pitch note that goes down in pitch and it's quite present.
I suspect that that high pitch note or noise is also there on the stock delay time but at an higher pitch above the hearing range.
Slowing down the delay brings that note into the audible range and it's quite irritating.

This is system immanent, as the BBD device doesn't delay the audio signal continuously. Instead the signal is chopped into small pieces that are fed into the BBD. Chopping frequency is provided by the clock generator. If you decrease it into the audio range, it will appear in the output signal.
Only solution would be a redisign: Apply more BBD's!
Best regards!

 

[Whoops]

Thanks Kay,
no worries, I can live with it, I will mostly use it for faster delay times in the range where this BBD is most confortable