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Markbass F500 odd noise

P

pkomor

Feb 14, 2008
13
0
#1
My new Markbass F500 Sounds great, but it is making one or two strange noises!

When you turn the amp on, there is a small click (as expected) and when you turn it off the same click happens again, However, If you turn the amp off within (about) 15 seconds of turning it on there is a loud ascending whistle noise that is played through the speakers. (this happens with or without a bass plugged in)

Any ideas if this is normal?

Also, there is a very high pitched (very very high!) hiss (almost a whistle, but unrelated to the other whistle!) that happens constantly, even if the amp is muted or the high control is on zero, does anyone else get this?

if these things are normal, Im not bothered, I just want to make sure my new head isnt faulty!
 
#2
Normal... my F500 doesn't do it, my F1 does (you can hear it in one of my YouTube clips when I turn off the F1... the RH450/F1/AE40 clip). One of my Walters and one of my Thunderfunks did it also. It was explained to me that it is the 'caps unloading' when the amp powers down.

My F1 did that out of the box in 2007... never a problem. Don't worry about it!

If you are still worried, just PM Peter Murray (the MB rep) and get the 'official' MB viewpoint.

GREAT amp!
 
#4
pkomor said:
Cheers for the quick reply!

Do you also get a (quiet) electronicy sounding noise with nothing plugged into the amp?
(can only be heard with a tweeter on)
Click to expand...

Yes, very low volume hiss at very high frequency (i.e., above 5K or whatever). Normal background hiss that does not increase with volume (unless of course, you crank the 10K treble control). If you are using a MB cab with the piezo tweeter, this noise can be a touch louder, since the piezos extend WAY up into the upper level treble hiss range. With most tweeters, it is very subtle.
 
#5
That sounds like the noise! I'm using an aguilar cab, but it is still audible Its not bothering me, i just wanted to check that its normal!

ive Pm'd Peter Murray just in case, but thanks alot for you response, I feel alot better now!
 
#6
pkomor said:
That sounds like the noise! I'm using an aguilar cab, but it is still audible Its not bothering me, i just wanted to check that its normal!

ive Pm'd Peter Murray just in case, but thanks alot for you response, I feel alot better now!
Click to expand...

Cool. If Peter responds with anything different than what I posted, please post up.

Again, you will love that head. What cab are you using?
 
#8
pkomor said:
An Aguilar GS112, along with a Stingray, Makes for a great tone! :) Quite a step up from my old hartke! (although that was good in its own way!)
Click to expand...

Nice! That low mid semi-parametric is nice with that cab... dialing in a bit of boost around 200hz (with the yellow frequency knob set around 9 o'clock or so)... burps it up a bit!
 
#9
pkomor said:
My new Markbass F500 Sounds great, but it is making one or two strange noises!

When you turn the amp on, there is a small click (as expected) and when you turn it off the same click happens again, However, If you turn the amp off within (about) 15 seconds of turning it on there is a loud ascending whistle noise that is played through the speakers. (this happens with or without a bass plugged in)

Any ideas if this is normal?
Click to expand...
I have an F1, and mine does the same on shutdown. Maybe related to it being a class D amp? Not sure.
 
#10
When a SS amplifier powers up there is instability until the rails get to their proper voltage level. This also happens as the supply drains on power down. With some designs this manifests itself as a thump, others a whine or a whistle. Most decent amps have speaker timed on and instant off circuits often tied into the protection circuitry. This timed on allows for the amp to stabilize before the speakers are connected and on power down instantly disconnect the speakers before the amp becomes unstable. I'm a bit disappointed that MarkBass didn't properly design for this.

Paul
 
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#12
BassmanPaul said:
When a SS amplifier powers up there is instability until the rails get to their proper voltage level. This also happens as the supply drains on power down. With some designs this manifests itself as a thump, others a whine or a whistle. Most decent amps have speaker timed on and instant off circuits often tied into the protection circuitry. This timed on allows for the amp to stabilize before the speakers are connected and on power down instantly disconnect the speakers before the amp becomes unstable. I'm a bit disappointed that MarkBass didn't properly design for this.

Paul
Click to expand...

The F500 has a timed on delay (no thump!). Not sure about the 'off'... it does seem to be the supply drains thing you are talking about.
 

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