Nearly a DIY disaster

activexp · 29th November 2010, 03:33 PM

I made some changes to the XO in my Wilmslow Audio 'Nemesis' clones and was quite satisfied with the end result, cured a midrange honk. All good so far.

After an extended listening session I went to switch off my NAD C325BEE amp
and was shocked to find that it was extremely hot. It always gets a little
warm on the right side of the case but this was the entire unit. There's a
turntable sat on top and that was cooking too.

Obviously it was drawing high current for some reason so I put a meter
across the 'Nemesis' and was surprised at the result of 0.4 ohms! At first I
couldn't see anything wrong with the XO as there are only 3 components, an
inductor in series with the woofer, and on the tweeter, a parallel inductor
and a series capacitor. Then I noticed that I'd put the capacitor after the
inductor. When I rearranged the layout with the cap before the coil, all was
well. 6.5 ohms!

Credit must go to the stability of the NAD amp and I reckon I was lucky not
to have blown it!

Another lesson learnt.

richie00boy · 29th November 2010, 04:19 PM

Lucky you didnt blow the tweeter as well as you changed it to a mere 6dB/octave roll off!

activexp · 29th November 2010, 04:29 PM

Very good point! I'm using the Vifa XT25TG-30 in the clones, must be a robust little unit

kipman725 · 30th November 2010, 12:59 AM

ouch you just had the inductor accross the speaker terminals?

29th November 2010, 03:33 PM	#1
activexp diyAudio Member Join Date: Jul 2009	Nearly a DIY disaster I made some changes to the XO in my Wilmslow Audio 'Nemesis' clones and was quite satisfied with the end result, cured a midrange honk. All good so far. After an extended listening session I went to switch off my NAD C325BEE amp and was shocked to find that it was extremely hot. It always gets a little warm on the right side of the case but this was the entire unit. There's a turntable sat on top and that was cooking too. Obviously it was drawing high current for some reason so I put a meter across the 'Nemesis' and was surprised at the result of 0.4 ohms! At first I couldn't see anything wrong with the XO as there are only 3 components, an inductor in series with the woofer, and on the tweeter, a parallel inductor and a series capacitor. Then I noticed that I'd put the capacitor after the inductor. When I rearranged the layout with the cap before the coil, all was well. 6.5 ohms! Credit must go to the stability of the NAD amp and I reckon I was lucky not to have blown it! Another lesson learnt. __________________ https://sites.google.com/site/stevesstuffproject/Home

29th November 2010, 04:19 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Lucky you didnt blow the tweeter as well as you changed it to a mere 6dB/octave roll off! __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

29th November 2010, 04:29 PM	#3
activexp diyAudio Member Join Date: Jul 2009	Very good point! I'm using the Vifa XT25TG-30 in the clones, must be a robust little unit __________________ https://sites.google.com/site/stevesstuffproject/Home

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
[DIY] HEXFET AMP total disaster?	egberttheone	Solid State	68	2nd December 2011 05:30 AM
AM I Planning for disaster??	birdyman	Pass Labs	12	2nd October 2010 12:59 AM
Disaster NEED HELP PLS!	leander	Solid State	11	19th September 2005 06:59 PM
Near Disaster!	Bikeman	Everything Else	1	4th September 2003 05:18 AM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

30th November 2010, 12:59 AM	#4
kipman725 diyAudio Member Join Date: Jun 2007 Location: London/N.lincs	ouch you just had the inductor accross the speaker terminals?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read