Peavey Power up pop ?

Tony Prior · Post by **Tony Prior** » 7 Dec 2001 5:08 am

Just acquired a very nice Nashville 400, sounds great. Very Loud, excellent tone right from the git go. One question which I am sure I will get a few responses on. When I power up the amp regardless of input volume level, could be zero, I get a power on pop thru the speaker.Is this common on these amps or not ? I would think probably not but I am not overly familiar with peavey, been a fender guy forever.

TP

Bill Ferguson · Post by **Bill Ferguson** » 7 Dec 2001 6:33 am

Tony, every NV400 I have had made a pop sound when powerering up. It has never caused me any problem.

If you are concerned, call Mike Brown at Peavey and let him listen to it over the phone. 1-877-732-8391

If you got a good NV400, you have a great amp.

Bill

Mike Brown · Post by **Mike Brown** » 7 Dec 2001 8:19 am

Hello Tony,
Thank you for using the Nashville 400 amplifier. I would guess that you have always used a tube Fender amp and never encountered this characteristic as tubes warm up gradually, therefore no pop is audible. In the case of a solid state amp, when you power it up, the sound is instantaneous with no warm up. I would suspect that you will hear this similar sound when you turn the amp off. The basic rule of thumb is that if the speaker does not move when this "pop" occurs, there should be no concern. But, if the speaker pushes out upon power up, you might have a technician to bench test it.

Unless a solid state amp has turn on/off relays(the Nashville 400 does not have this feature), all solid state amps will have a turn on "pop" to some extent, whether it is audible or not. It is caused by the charging and discharging of the filter caps and is normal.

Mike Brown
Peavey Electronics Corporation
[This message was edited by Mike Brown on 07 December 2001 at 08:35 AM.]

Tony Prior · Post by **Tony Prior** » 7 Dec 2001 9:41 am

Thanks to Bill and Mike for the quick reply's. I had a chance to speak with Mike directly and am very greatful for his time and attention. Seems like I have an amp built in '86 with a 1502 BW, not sure about the mods but will open the amp later this weekend and check it out. The popping is no problem.
'Tell ya what , this amp rocks !

TP

Mike Brown · Post by **Mike Brown** » 7 Dec 2001 10:51 am

Thanks for choosing the Nashville 400 for your steel guitar application!

Ralph Willsey · Post by **Ralph Willsey** » 7 Dec 2001 12:57 pm

Now you've got me worried. My Nashville turns on without a peep and gives only a very mild pop when I turn it off. The Bandit I used to use gave a horrible pop both ways.

Gene Jones · Post by **Gene Jones** » 7 Dec 2001 2:27 pm

My 500 drops me to my knees....just lettin' me know that it's there and waiting!

richard burton · Post by **richard burton** » 8 Dec 2001 3:26 am

Dumb question:
If a switch was installed on the cable to the speaker to isolate the speaker on power up/down, would it damage any part of the amp? In fact, could this be achieved by plugging a 1/4 jack into the Power Amp In socket to isolate the speaker?

Mark Herrick · Post by **Mark Herrick** » 8 Dec 2001 4:42 am

Try turning down your reverb control to minimum when powering up or down.

(I think that's the one, or the Pre-Gain... don't have my amp in front of me to try it right now.)

It annoyed me too until I figured this out.

Jack Stoner · Post by **Jack Stoner** » 8 Dec 2001 6:00 am

Turning down the reverb shouldn't really make a difference. The "instantaneous" voltage on power up and the power off discharge through the power amp section is the part most affected.

Mark Herrick · Post by **Mark Herrick** » 17 Dec 2001 9:44 am

I just wanted to revisit this for a moment because I knew I wasn't dreaming it...

Here is what I noticed when testing my Nashville 400 w/LeMay mod.:

Rev. up; PreGain up; PostGain up = Loud pop.
Rev. up; PreGain down; PostGain up = Loud pop.
Rev. down; PreGain up; PostGain up = Loud pop.
Rev. down; PreGain down; PostGain up = Soft pop.
Rev. down; PreGain down; PostGain down = Almost no pop.

I always turn my PreGain and Reverb down when powering up and down to avoid the "pop". The "pop" may not be detrimental to the amp, but it is annoying.

Just my observations. I make no claims regarding the reasons these electronic things happen or don't happen...

Blake Hawkins · Post by **Blake Hawkins** » 17 Dec 2001 12:15 pm

Mark, Jack, and the group. Possibly there are differences in the NV400s.
On mine, with all the gains down, I still have the pop. In fact, the pop is the same level regardless of any control setting.
About a year ago when Jack and I were discussing this problem with Mike Brown, I put my NV400 on the bench and using a wideband oscilloscope, traced the pulse that causes the pop and here's what I found:
The pop comes from the charging of C-63, the filter cap for the +52 volt supply rail.
It is coupled to the base of Q5, through CR20 and CR21. From there it is amplified and travels to the Output Transistors and on to the speaker.
The pulse enters after all the gain controls , reverb and processing, so none of them have any effect on it.
A similar pulse is produced by C64 on the -52 volt rail but it does not have the same effect.
So, I am satisfied that this is the cause of it in MY NV400. Maybe it works differently on some of the others.
Blake

Mark Herrick · Post by **Mark Herrick** » 17 Dec 2001 1:01 pm

Just want to see if this message shows up.

Apparently my last one did not...

Gene Sharp · Post by **Gene Sharp** » 17 Dec 2001 6:31 pm

I have 2 N-1000's. One of them has one pop and the other has 2 separate pops when I turn it on. Both amps' eq are set the same.

Does any one else have two or more pops on startup?

Neither amp has a decernable pop on shutdown.
Gene

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Dave Kocher · Post by **Dave Kocher** » 18 Dec 2001 10:18 am

My experience with this problem in a Session 500 is described in this thread: http://steelguitarforum.com/Forum11/HTML/000260.html
I think Peavey does not worry about this problem because, in the Session 500 at least, there is a current limiting circuit in the output amplifier.

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-Dave Kocher

Bill Crook · Post by **Bill Crook** » 18 Dec 2001 1:20 pm

I think that if some kind of a "Bleeder" resistors was placed across the 2 filter caps(C-62 and C-63),this "pop"may be minimized. The exact value of these resistors should be calculated to have a 5-10 milliamp current drain across them. This will keep the caps from chargeing up so suddenly,(like in the first 2 or 3 cycles. We won't go into a lot of details here) Therefore,while a small noise will still be heard, it shouldn't knock you off your feet or shatter wine glasses.....

I feel the reason this is not a "factory" installed thing is because every time you add a conponnet to the circuit, you increase the cost of the amp. Now givin' that the "pop" (in most cases) isn't a problem to the amp or speaker system, It just isn't done by most Manufacturers.....
[This message was edited by Bill Crook on 24 December 2001 at 05:39 AM.]