Switching between HRM and Non-HRM

[ElectronAvalanche]

Hi there,

a question to all and Dogears especially:

I have the HRM switchable in my amp.

I tap the signal after the OD2 anode resistor, going into a 0.005uF cap over a 150k to the OD Level and to the HRM tone stack (47k, 330pF, 0.022uFs). So the HRM and the 0.005uF are in parallel after the OD anode resistor.

I switch the outputs of the 150k and HRM to the OD Level (500k) and have to put a resistor between the Level and ground to compensate for the HRM volume drop.

The HRM is loading down the 0.005uF/150k combo as well, thus the OD is not as loud as usual. I have to almost run it on 3pm to get equal volume to the Clean section.

How do you guys do the switching and what do you do against the volume drop?

I think about using a 1M OD Level control and a 330k compensation resistor between ground lug and ground for the HRM.

Any ideas welcome!

Cheers,

Electron

[dogears]

You need to isolate the two circuits. We lift whichever circuit is not in use from ground.

Only way IMO.......

Fwiw, in my amp, the HRM and non HRM have similar outputs. I have not experienced the volume drop you describe. If you get a sec, shoot me an email..... I think you have it.

[ElectronAvalanche]

Hi Scott,

would you share a view of your amp and how you do it?

Do you use a relay or a smal switch? You would need a Triple Pole single throw I think (switching the ground of the HRM stack, switching the 0.005 uF over 150k from the OD Level and some sort of compensation resistor to lift the OD Level for the HRM.

Thanks in advance,

Dominik

[dogears]

Not if you have a 100k trimmer after the 150k nonHRM resistor to keep the correct load on the non HRM circuit! You just adjust the trimmer from the non HRM side.

I'm only allowed to share that it is currently a manual dpdt. However, it will be relay controlled in the future to neaten things and reduce shiedling requirements.

Hi Scott,

would you share a view of your amp and how you do it?

Do you use a relay or a smal switch? You would need a Triple Pole single throw I think (switching the ground of the HRM stack, switching the 0.005 uF over 150k from the OD Level and some sort of compensation resistor to lift the OD Level for the HRM.

Thanks in advance,

Dominik

[ElectronAvalanche]

Thanks dogears!

I guess I have to try it as suggested and maybe Gary chimes in


Cheers,

Dominik

[dogears]

When you get a sec, shoot me an email.

Why don't you use a 1M master. I think maybe the HRM works better..... Then make sure you put the 100k trimmer in circuit after the 150k series from the nonHRM

[ElectronAvalanche]

Email sent!

Cheers,

Electron

[dogears]

Check yours....

Email sent!

Cheers,

Electron