John East Musicman preamp question

[joeyl]

I have the John East preamp along with a genuine Musicman pickup using the permanently active setup. I really like the sound combo as it sounds pretty close to the classic Stingray tone.

My question is this: if I wanted to put a passive switch (to use the bass with effects and such, sounds better to my ears) I would have to use a 250K pot for the volume. I know the volume goes after the preamp stage but would it affect the sound when the preamp is active, as in changing the classic Stingray sound?

 

[John East]

I have the John East preamp along with a genuine Musicman pickup using the permanently active setup. I really like the sound combo as it sounds pretty close to the classic Stingray tone.

My question is this: if I wanted to put a passive switch (to use the bass with effects and such, sounds better to my ears) I would have to use a 250K pot for the volume. I know the volume goes after the preamp stage but would it affect the sound when the preamp is active, as in changing the classic Stingray sound?

Yes it could do if the volume is a backed off in active. If the volume is max, no change. If the volume is backed off, depending on the cable and input impedance of the rig being fed, you could loose some of the very high end.

The circuit shown, is very old and not a true bypass BTW.

It ideally should be a full bypass (my bad!) because the preamp has variable loading on the pickup at higher frequencies according to the setting of the treble control, and will affect things in passive mode with that circuit.

In active, this interaction is all part of the charm of how the MM pickup interfaces to the electronics.

 

[joeyl]

Yes it could do if the volume is a backed off in active. If the volume is max, no change. If the volume is backed off, depending on the cable and input impedance of the rig being fed, you could loose some of the very high end.

The circuit shown, is very old and not a true bypass BTW.

It ideally should be a full bypass (my bad!) because the preamp has variable loading on the pickup at higher frequencies according to the setting of the treble control, and will affect things in passive mode with that circuit.

In active, this interaction is all part of the charm of how the MM pickup interfaces to the electronics.

Thank you for the reply, great to hear from the man himself .
As for the full bypass, me personally I am not worried that it is not a true bypass but are you coming with a revision?

 

[John East]

Thank you for the reply, great to hear from the man himself .
As for the full bypass, me personally I am not worried that it is not a true bypass but are you coming with a revision?

The unit itself has been revised to have a jumper system. Set one way, it's the same circuit with the loading and interaction.

Set the other way, there's a high impedance class FET input stage buffer which separates the source from the EQ. So no interaction and the the non true bypass will work.

When the documentation is fully revised, we'll add the full bypass.

 

[joeyl]

Very cool. :thumbup: love your work btw.

 

[Jeremy piquette]

Yes it could do if the volume is a backed off in active. If the volume is max, no change. If the volume is backed off, depending on the cable and input impedance of the rig being fed, you could loose some of the very high end.

The circuit shown, is very old and not a true bypass BTW.

It ideally should be a full bypass (my bad!) because the preamp has variable loading on the pickup at higher frequencies according to the setting of the treble control, and will affect things in passive mode with that circuit.

In active, this interaction is all part of the charm of how the MM pickup interfaces to the electronics.

Hello, I was curious if the MMSR preamp on the 3b 4k has the volume pull switch for bright mode i know the 2b 3k does but can't find if the 4knob has it, thanks

 

[John East]

The MMSR 3K2B & 4K3B don't have a Pull Switch. The stacked Bass/Treble on the 3K3B does have a Pull-Bright.

 

[ambrossjr]

The unit itself has been revised to have a jumper system. Set one way, it's the same circuit with the loading and interaction.

Set the other way, there's a high impedance class FET input stage buffer which separates the source from the EQ. So no interaction and the the non true bypass will work.

When the documentation is fully revised, we'll add the full bypass.

 

[ambrossjr]

The unit itself has been revised to have a jumper system. Set one way, it's the same circuit with the loading and interaction.

Set the other way, there's a high impedance class FET input stage buffer which separates the source from the EQ. So no interaction and the the non true bypass will work.

When the documentation is fully revised, we'll add the full bypass.

Greetings John--
Where is the revised documentation for this thread concerning a passive full bypass wiring for the MMSR preamp? Please advise or send directly to my email. Thanx.

 

[ambrossjr]

Also, why is it said that the MMSR 4k3B preamp NOT work with original Musicman Stingray5 3-coil pickups? Is it because of the coil resistance of 1.95kOhms on each coil?