Speaker boom while unplugging amps

[stratocaster]

So in my quest to experiment with tubes, I ended up building an all tube rig with Manley phono stage, preamp and monoblocks.  A few weeks ago, I threw in the 2WQ in the mix as well and I am noticing that each time I switch off the amps, there's a loud boom from the 2CE's. It's loud enough to cause concern and I have disconnected the subwoofer. I am using the X2 crossover (200K) and the input impedance of the Manley's is 475K. Previously, I was using a Mccormack with the Manley preamp and I never got the boom when I turned the amp off. Is this something related to the tube gear or is it more localized to the crossover value?

Edited February 17 by stratocaster

[Richard Vandersteen]

1 hour ago, stratocaster said:

So in my quest to experiment with tubes, I ended up building an all tube rig with Manley phono stage, preamp and monoblocks.  A few weeks ago, I threw in the 2WQ in the mix as well and I am noticing that each time I switch off the amps, there's a loud boom from the 2CE's. It's loud enough to cause concern and I have disconnected the subwoofer. I am using the X2 crossover (200K) and the input impedance of the Manley's is 475K. Previously, I was using a Mccormack with the Manley preamp and I never got the boom when I turned the amp off. Is this something related to the tube gear or is it more localized to the crossover value?

The loud boom must be coming from both the 2Ce's and the 2Wq.  For some reason the X-2 in the circuit is causing a DC pulse when the amp is turned off.  The X-2 is not transparent enough for your system and compromising your sound noticeably, but its value is close enough and has nothing to do with this problem.  Are you turning off the Pre-amp and power amp at the same time?  Could try the power amp first in your sequence.  Borow a M5-HP someday as it is dramatically more transparent.  RV

[TomicTime]

swing by and borrow my M5 filters - have to warn you they have the upgraded Teflon caps 😉

Jim

Edited February 17 by TomicTime

[ctsooner]

Those Teflon caps are very very special 

 

[stratocaster]

1 hour ago, Richard Vandersteen said:

The loud boom must be coming from both the 2Ce's and the 2Wq.  For some reason the X-2 in the circuit is causing a DC pulse when the amp is turned off.  The X-2 is not transparent enough for your system and compromising your sound noticeably, but its value is close enough and has nothing to do with this problem.  Are you turning off the Pre-amp and power amp at the same time?  Could try the power amp first in your sequence.  Borow a M5-HP someday as it is dramatically more transparent.  RV

I am turning the amplifier off first and then the preamp. Should I be trying the other way round?

[stratocaster]

1 hour ago, TomicTime said:

swing by and borrow my M5 filters - have to warn you they have the upgraded Teflon caps 😉

Jim

Thanks Jim.. will call you this weekend..

[Richard Vandersteen]

2 hours ago, stratocaster said:

I am turning the amplifier off first and then the preamp. Should I be trying the other way round?

No, you are doing it correctly.  Check your DC offset on the output of your amplifier especially when you turn it off.  If the pulse is less than 2 volts don't worry about it as it won't hurt the sub or your speakers.  RV

[stratocaster]

On 2/17/2023 at 11:17 AM, Richard Vandersteen said:

The loud boom must be coming from both the 2Ce's and the 2Wq.  For some reason the X-2 in the circuit is causing a DC pulse when the amp is turned off.  The X-2 is not transparent enough for your system and compromising your sound noticeably, but its value is close enough and has nothing to do with this problem.  Are you turning off the Pre-amp and power amp at the same time?  Could try the power amp first in your sequence.  Borow a M5-HP someday as it is dramatically more transparent.  RV

So I got my hands on a set of M5-HP and there’s certainly a significant improvement in sound from the X2s. The loud boom is now replaced by a soft thud when I turn off the amps. This happened for a couple of different values I selected. Am guessing this is normal…

[ctsooner]

Glad to hear that you like the difference. 

[stratocaster]

13 minutes ago, ctsooner said:

Glad to hear that you like the difference. 

Yeah, it's quite uncanny..I didn't think the improvement would be so significant. The litmus test of component upgrade is when high command asks if I have spent money again since things are sounding different and better....

[Steve Edwards]

1 hour ago, stratocaster said:

The litmus test of component upgrade is when high command asks if I have spent money again since things are sounding different and better....

That is a solid marital foundation Udit.  While my “high command” has been lovingly supportive of my passion, when the subject of an upgrade (of any proportion) comes up, her usual response is “how much better can it sound?”
 

 Oh, the curse of being among the enlightened few  ……….  🥴

[ctsooner]

Funny as I have the same with with my wife. She rarely even hears the system, but when she does, she remembers what it used to sound like.  I have no idea how, but she does and she knows when something changes, good or bad.  Pretty funny to me.