crown 150 "pops"

[aretrohillbilly]

Hi, 1st post...I have a DC150 that only occasionally makes loud transient pops....otherwise sounds great with my dual JBL speaker system(running Cabarets w/e140-2225 drivers in parallel w/ homebrew-3115A,d-140,2445's). Any ideas on the problem...caps?...using preamp side of a Marantz 1060 presently...Thanks! Oh yes, I have a MC2200 on the way...my 1st Mac....a good Mac?? Thanks again!!

[JBL 4645]

Welcome to site aretrohillbilly

Does this happen at different volume levels or only at certain volume level and beyond the level?

I think one of the other guys around here might have strong first hand answer to the problem, I don’t what to jump the gun on this.

[BMWCCA]

I can't help you with the symptom but it might help if you listed the right model number for those scratching their heads: Is it a D150, or a DC300? Have you tried asking on the Crown forums? They've got factory guys who monitor their forum regularly and there are often questions related to the older D-series amps. "Factory" repair is available through a facility related to Crown specializing in the old stuff. Go here: http://www.crownaudio.com/forums/

[Mike Caldwell]

There are a few versions of the D150 amps. Does yours have the IOC lights on the front or for that matter gain controls on the front. If it pop when driven hard it may be clipping. The D150's are only rated at 75 watts in to 8 ohms. and not quite 150 into 4 ohms. There could be a problem with the pre amp where it will put out a DC voltage spike, those amps will pass DC and that could be causing your woofers to bottom out making the popping sound. For that matter driver the system hard sub low frequency's below the tuning of the cabinets will case the speakers to bottom out and make a popping sound. Does it pop when the system is just turned and not amplifying any music.

Mike Caldwell

[aretrohillbilly]

Thanks guys...didn't know there was a crown forum, I'll try it too. Sorry about misnaming the amp model,I have an older D150 w/ the volume controls(attenuators) no IOC lights. The pop is not tied to driving the amp hard....just as likely to do it idling;the sound of the pop comes through my HF drivers too, Thanks for replies!

[Mike Caldwell]

Does it pop any time without the pre amp connected to the amp?

Mike Caldwell

[Mannermusic]

Does it pop any time without the pre amp connected to the amp?

Mike Caldwell

Great question - may not be the power amp. I just ran into this very situation and traced it to the old Luxman pre. It's more of a loud snap or crack - followed by one channel going flakey/heavy distortion. Took it out of service. Suspect power supply (noticed it is seeping oil) or output caps? Not an electronics expert. Re the D150 - have been using one for decades and had to "upgrade" the output transistors due to strange noises. Sent it back to the factory. Been fine ever since. Also Mike

[jbl]

You may have a cold solder on one of the boards.
I had the same problem with my Marantz 300 DC. Traced the problem to a cold solder on the protection circuit.

Ron

[aretrohillbilly]

Hi,I have not encountered the problem using other power amps, or when using power section of the Marantz 1060(it comes with handy-dandy jumpers to connect pre-out to the power amp section. A local Crown service lab (and one member of crown forum)has suggested it is probably one of three caps in front end of amp. But,cold solder joint is always a possibility. What fun to find! I may spend as much as I paid for the amp, but lab tech said the freshly capped 150 will really sound great!
On another note, got a tracking number for ebay purchased MC2200, bracing for Mac/JBL experience......Thanks guys for replies, I'll post when problem is rectified, Wendel