Mastering monitor control with relays so many contact points between in out

[SIXTYNINER]

Hello everybody
just to "chat" a bit about the expensive mastering monitor control units

with dozens of relays and so many contact points between in out
and about the durability of the relays and their eventual replacement when they fail

is it really worth it ?
but isn't the rule that less points of contact better is for the signal ?

thanks in advance for any post about
cheers

 

[ruairioflaherty]

Dozens?

A typical design will have 6 in the resistor ladder, and then a maybe another 6 for input/output selection, mute. polarity flips etc.

I've measured or listened to all of the popular relay based units - Cranesong, Grace, Dangerous etc. If they have issues (and they often do) the relays are not the cause.

We use a custom relay based solution at the studio I master at and it's sonically and electronically transparent. Take a look at the Topping Pre90 measurements available online to see just how low distortion relay based can be.

 

[JohnRoberts]

I used to find it amusing when audio phools would complain about how many switch contacts were in a signal path (they never saw a console)... If you can hear one, you have a faulty switch or faulty whatever.

JR

 

[fazer]

Topping 90, Very clean unit and priced very affordable. Would be hard to build something at that price/performance.

 

[rob_gould]

Never had problems with my Igor crm. There are dozens of relays in there.

 

[JohnRoberts]

Hello everybody
just to "chat" a bit about the expensive mastering monitor control units

with dozens of relays and so many contact points between in out
and about the durability of the relays and their eventual replacement when they fail

I have seen reliability concerns with relays switching high power amplifier output currents but not for decent quality low level switching.

A general design constraint is to reduce the number of points of failure, and complexity. Relays have been used in premium audio path switching with good success for a long time.

is it really worth it ?

opinions vary, I have rarely used relays in audio paths but mainly because I am cheap... They are about the only way to implement a power down signal bypass, with full fidelity.

but isn't the rule that less points of contact better is for the signal ?

A good quality relay is far from the weakest link in any audio path... Arguably less is better and any design using switches or relays should minimize interruption points as much as practical while preserving functionality.

JR

thanks in advance for any post about
cheers

 

[SIXTYNINER]

I have seen reliability concerns with relays switching high power amplifier output currents but not for decent quality low level switching.

A general design constraint is to reduce the number of points of failure, and complexity. Relays have been used in premium audio path switching with good success for a long time.

opinions vary, I have rarely used relays in audio paths but mainly because I am cheap... They are about the only way to implement a power down signal bypass, with full fidelity.

A good quality relay is far from the weakest link in any audio path... Arguably less is better and any design using switches or relays should minimize interruption points as much as practical while preserving functionality.

JR

Hey John
much thanks for all the info !!!

I often find the saying " less is more "
here and around the various forums dedicated to sound and analogue audio technologies ,

there is absolutely no intention of questioning regarding the fact that
each designer does what he thinks is best ,

but it is also true that a top quality potentiometer
can do the same thing as the long row of relays....

and for a gain control also a rotary switch with lot of positions and related resistors
can do the same job..
(...although perhaps with about the same number of pins to be soldered..)

except that by adding a control logic to the relays row
various volume level positions can also be stored and quickly recalled "on fly"....

perhaps the only real advantage compared to a simple potentiometer
or a rotary switch....?

cheers

 

[Newmarket]

Hey John
much thanks for all the info !!!

I often find the saying " less is more "
here and around the various forums dedicated to sound and analogue audio technologies ,

there is absolutely no intention of questioning regarding the fact that
each designer does what he thinks is best ,

but it is also true that a top quality potentiometer
can do the same thing as the long row of relays....

and for a gain control also a rotary switch with lot of positions and related resistors
can do the same job..
(...although perhaps with about the same number of pins to be soldered..)

except that by adding a control logic to the relays row
various volume level positions can also be stored and quickly recalled "on fly"....

perhaps the only real advantage compared to a simple potentiometer
or a rotary switch....?

cheers

You may be overthinking this.
Is it worth it ? - Well what's the alternative if you require the functionality ?
I suppose it's direct point to point connection with lots of manual patching.
Same idea as avoiding patchbay connections - and I have seen a mastering engineer eschew that wrt digital audio connections - evoking much eye rolling from the studio's technical bod.
So - relays - the thing is you have to select the correct type for the application.
As JR as indicated - in high power / current situations you can get issues. If you get it wrong contacts may 'weld' together.
At the opposite small signal end contacts that have no or very small currents may fail due to pollution (oxidisation/tarnishing) of the contacts. You need to select the correct contact type.
And think about where they are in the signal path.
In a previous position (not audio but the same principle applies) I noticed a steady stream of service returns of units that had been manufactured and sold before I had been there. They were all around five years old. Talking with the service tech and looking at the schematics it became clear that the issue was that there was negligible current - basically just OpAmp input bias current - going through the relays.
imo relay remain the premium switching solution. Well preferred over normal switches.
Generally in a mastering scenario I'd suggest that the increase in productivity afforded by a good switching solution outweighs the possible cost of relay failure.

 

[Matt Syson]

Correctly rated signal relays with 'self wiping' contacts are pretty hard to beat as after all it is a very mature technology. Using 10Amp 4 pole changeover industrial power relays to switch line level audio is 'bonkers'
At least with PO type 3000 relays you can waft your 'diachrom spatula' cleaning tool in there once in a while.
Matt S

 

[FIX]

When I designed the Slate Control, I used a ladder attenuator for the gain (instead of a POT, VCA or DAC) and all I/O. They never are the source of the problem...

The FIX console has cool switches, but sometimes cool aren't the best sounding, so EVERY switch controls a relay, and NO audio goes through any switch, ever. The relays are telecom types, that are rated for gazillions of closures, lightning strikes, water, etc. All have nothing in the cavity that would cause out-gassing and tarnish the contacts, and all are bifurcated contacts, so every contact is redundant. The contact points are either crisscrossed knife blades, cone/platform, or other knife style that is self wiping.

 

[Newmarket]

All have nothing in the cavity that would cause out-gassing and tarnish the contacts, and all are bifurcated contacts, so every contact is redundant. The contact points are either crisscrossed knife blades, cone/platform, or other knife style that is self wiping.

+1