M5-HPB Redux

[Gsal]

It appears that I may have a bad High Pass Filter. Here's what I've found:

My amplifier specs call out an input impedance of 470K ohms so I set the dip switches on my High Pass Filters for 1M ohms, depressing only the #8 dip switch.

Let's call one of the High Pass Filters #1 and the other #2.

 I fed a 1K Hz signal through my preamp, through #1 and on  to one of the channels of my amp. I set the volume of the preamp so that I got a 1.008 V reading at the output of my amp. I then sent a 100Hz signal and got a reading of .720V.  I'm thinking so far so good. Not dead on but pretty close.

I then substituted filter #2 and fed it the 1K Hz signal. The volume control on the preamp was unchanged. I got a reading of only .558 V.  Switched to the 100 Hz signal and read .414 V. Both readings being way lower in output than Filter #1. Not so good.

Finally, I set the volume of the preamp higher so that Filter #2 gave me a reading of 1.02 V at 1K Hz. Switched to 100 Hz and read .754 V on my meter. OK but not the .720V I got previously. Swapped out Filter # 2 with #1 and with the preamp volume unchanged got a reading of 1.84 V given a 1K Hz signal and 1.315 V with the 100Hz signal.

Can someone please tell me what's going on? RV? Is one of my M5-HPBs faulty or is my test procedure incorrect?

[stratocaster]

@Gsal you are doing the setup correctly. Your volume knob should remain the same while setting up the crossovers (at least that’s my understanding) and since you have to tweak it between crossovers, I would suspect that there’s something wrong with the crossovers. Question is which unit is faulty..

I am assuming that you don’t have a spare amp to try the crossovers on. That way you know that the crossovers behave the same way on another amp.

[Richard Vandersteen]

44 minutes ago, Gsal said:

It appears that I may have a bad High Pass Filter. Here's what I've found:

My amplifier specs call out an input impedance of 470K ohms so I set the dip switches on my High Pass Filters for 1M ohms, depressing only the #8 dip switch.

Let's call one of the High Pass Filters #1 and the other #2.

 I fed a 1K Hz signal through my preamp, through #1 and on  to one of the channels of my amp. I set the volume of the preamp so that I got a 1.008 V reading at the output of my amp. I then sent a 100Hz signal and got a reading of .720V.  I'm thinking so far so good. Not dead on but pretty close.

I then substituted filter #2 and fed it the 1K Hz signal. The volume control on the preamp was unchanged. I got a reading of only .558 V.  Switched to the 100 Hz signal and read .414 V. Both readings being way lower in output than Filter #1. Not so good.

Finally, I set the volume of the preamp higher so that Filter #2 gave me a reading of 1.02 V at 1K Hz. Switched to 100 Hz and read .754 V on my meter. OK but not the .720V I got previously. Swapped out Filter # 2 with #1 and with the preamp volume unchanged got a reading of 1.84 V given a 1K Hz signal and 1.315 V with the 100Hz signal.

Can someone please tell me what's going on? RV? Is one of my M5-HPBs faulty or is my test procedure incorrect?

Some dealers and users have tried to replace the batteries themselves and don't know how to test for damage caused by heat when they finish.  Sounds like #2 is operating single-ended.  .720v is well within spec.   Maybe a broken wire in the XLR connector.  RV

[Gsal]

9 minutes ago, Richard Vandersteen said:

Some dealers and users have tried to replace the batteries themselves and don't know how to test for damage caused by heat when they finish.  Sounds like #2 is operating single-ended.  .720v is well within spec.   Maybe a broken wire in the XLR connector.  RV

Thanks for the diagnosis RV. I have never touched the batteries as per the instructions.

 

23 minutes ago, stratocaster said:

@Gsal you are doing the setup correctly. Your volume knob should remain the same while setting up the crossovers (at least that’s my understanding) and since you have to tweak it between crossovers, I would suspect that there’s something wrong with the crossovers. Question is which unit is faulty..

I am assuming that you don’t have a spare amp to try the crossovers on. That way you know that the crossovers behave the same way on another amp.

No, no spare amp. The Atlas was just upgraded to the Eclipse version 2 months ago.

[Gsal]

12 minutes ago, Richard Vandersteen said:

Some dealers and users have tried to replace the batteries themselves and don't know how to test for damage caused by heat when they finish.  Sounds like #2 is operating single-ended.  .720v is well within spec.   Maybe a broken wire in the XLR connector.  RV

I'll check and see if I can see any faulty wiring. If I can't find anything obvious what do you suggest? The x-overs are only 2 years old. Thanks.

[Gsal]

By the way, I misspoke earlier in my discussion. The dip switch is set with # 3 and 5 depressed as this is the correct configuration for 1M ohms. My amp is 470K ohms x2 = 940 K ohms. I figured close enough to use the 1 M ohm settings.

[Richard Vandersteen]

4 hours ago, Gsal said:

I'll check and see if I can see any faulty wiring. If I can't find anything obvious what do you suggest? The x-overs are only 2 years old. Thanks.

It has nothing to do with age, but the XLR cable connectors can get abused when inserted or extracted with system changes.  Take the one having a problem to your dealer and have them resolder the wires inside the XLR connectors.  Probably happened when you had your amps out for modifications.  No big deal but this should cause a channel imbalance.  RV

[Gsal]

12 hours ago, Richard Vandersteen said:

It has nothing to do with age, but the XLR cable connectors can get abused when inserted or extracted with system changes.  Take the one having a problem to your dealer and have them resolder the wires inside the XLR connectors.  Probably happened when you had your amps out for modifications.  No big deal but this should cause a channel imbalance.  RV

Thank you RV. Will do.