Hmm, Crown amps!
First I had the XLS 1500. Was getting hum on vol settings beyond 75%, well that's the whole point of a power amp isn't it?
The trusty Behringer Nuke and Cerwin Vega - totally silent, even on 11:)
So that went back and I got a new generation XLS 1002. 215w is plenty and the setting for turning off lights / display etc excellent, the intelligent fan brilliant, but the bloody thing hums the same as the 1500!
So, it's a feature!
I like the Crown sound but not keen on the hum.
Have it set on 75% and the output from Najda up a bit. Can still hear it just when nothing is playing.

Perhaps the only option is another Cerwin.
I'm going to swap the crown and the Cerwin over to evaluate...

can't be that both Crown's are faulty surely?

Could be, but can't really see what else I can do.
PA amps should be totally interchangeable, no?

To keep this blog updated:

The plot thickens.
Having relocated the Crown amp, I changed the mains cable to my bespoke one made from uber German shielded cable.
After that it's totally silent, no hum at all.
So it seems my set up / other equip upsets the Crowns, where the other amps don't mind.

Now I can focus on the sound quality I'm getting. I'll do another measurement session for the new amps, see if the room corrections still apply with beefier amps.

Happy not to have hum for the moment

The intelligent fan continues to impress. As does the ability to control all the front panel lights / display. Not to forget the sound quality / punch and grip on the JBL 2220 drivers. They are very low Qts, I chose that for my horn application.

Lillyhammer was excellent
Last two GOT were awesome

Sons Of Anarchy is worth a go.

Do refer to the thread about reference recordings, too!


Common One by Van Morrison has fantastic bass.

Loving the reference music thread btw!

I put the Crown back where it needs to be. Hum is back to some extent
I had a good read about the Crown XLS and earth / ground. Loop hum.
As for all others, lifting the mains earth connection, completely resolved the issue! I'm not running an amp like that though!

I have all amps / equip on the same mains block as recommended.
No amount of signal earth lifting works!
Now remember neither Behringer or Cerwin Vega amps have any problem at all.
It seems very much a case of all Crowns do this sir, in home theatre / hifi / pa and other equipment mixes!
Read up on induced hum too.

I then set about cleaning the rats nest that my cabless had become.
Before the move they were rreligiously sorted... Got lazy since then.

I removed the turntable and moved all 5 power amps to where I can easily dress the speaker cables, interconnects and mains cables with plenty of physical separation.

Result, a little less hum, but still there.

I also read Crowns recommendations and running them with the vol knobs down should be considered the same as attenuating the input signal.
So I set them to 75% and adjusted the gain in Najda's wonderful analogue chip output control settings.

Job done!

I'm sure the whole thing sounds much better now all the cables are separated. Everything I play sounds better! More cohesive etc.
Anyone else experience this?

Great outcome. Yes, I often find that dressing all the signal cables nicely and away from power cables helps sound quality. As does getting the earthing just right.

I feel like buying a used Crown on eBay just for playing with. Always fancied trying one.

I've not been listening so much lately, kinda lost a bit of spark for it, but I started again with a couple of new albums and a minor change to the deep bass and turning down the tapped horn subs volume just a bit overall and there I was back listening 4/5 evenings in a row!
Having the time helps too as tennis playing is not much fun weather wise and team training is in the off season.

I also put the 550Hz tractrix horns back on the Vitavox S2's - I turned these out of birch ply rings laminated together and they replaced a pair of composite 600Hz ones I'd bought from Poland - I think it was. Anyway the softer wood the better so birch ply is not the best really. Balsa would be the very best but it's quite expensive and getting big enough chunks might be a problem - I'll look into that.
The next best option is redwood pine - I have made a pair of those but they now reside far away.

Anyway back to the change. From 400Hz to 550Hz. The 400 on the floor.



Now I preferred the 400Hz I'd made at the time, about 15 months ago. Not a huge thing but at the time I definitely liked them - perhaps a change is as good as a rest and all that..
Anyway the 550's are now out performing the 400's by some margin the last couple of evenings! Perhaps my ears are 15 months older or perhaps it is the room change?

Enthusiasm re-kindled. I'm after some even better 3uF caps to try in the ~1200Hz 1st order X/O#s now

Oh and I really much get around to repainting the tapped horns - dreadful in that pic!