This is just an area I can blab on about stuff without it using up bandwidth in the threads 
Hopefully someone will find it interesting or useful.
Tony.
Hopefully someone will find it interesting or useful. Tony.
Having a 21 month old daughter really eats into your DIY time!
Posted 10th September 2009 at 01:20 PM by wintermute
Updated 25th November 2009 at 12:09 PM by wintermute (added to categories speakers and amplifiers)
Updated 25th November 2009 at 12:09 PM by wintermute (added to categories speakers and amplifiers)
I'm finding DIY'ing a very different ball game now that I have started again. The difference being I have a 21 month old daughter now. Gone are the days when I could sit down for 10 hours straight working on something. I have to take on tasks that I can complete in 2 hours (or work on into the night and suffer sleep deprevation!)
Yesterday I did some more sanding on my speaker boxes, I think I could just keep sanding until the 25mm MDF was only 20mm
I better stop soon and get on with the veneering.
Tonight I attacked the problem of the switching thump in the amp. I found some 47uF Nichicon FG caps in the cupboard and soldered them into the negative feedback circuit in the preamp. That brought the DC coming out of the gain stage in the preamp down from -1.1V to about -210 mv. I'm not sure if I will try and tackle getting rid of the rest of the dc, but it is a substantial improvement. The cap basically put between the second resistor in the feedback network, and ground blocks DC and sets the gain of the opamp to 1 at DC.
This has reduced the thump form a scary woofer slapping thump to a fairly small thump (maybe 5mm excursion) I recon it was closer to 15mm before the caps.
Hopefully that is enough to save the speakers from any serious damage until I can build my new preamp. (another hazzard with a 21 month old, she loves switching switches and turning knobs).
Anyway it is now 11:20PM so I really should head for bed!
Tony.
Yesterday I did some more sanding on my speaker boxes, I think I could just keep sanding until the 25mm MDF was only 20mm
I better stop soon and get on with the veneering. Tonight I attacked the problem of the switching thump in the amp. I found some 47uF Nichicon FG caps in the cupboard and soldered them into the negative feedback circuit in the preamp. That brought the DC coming out of the gain stage in the preamp down from -1.1V to about -210 mv. I'm not sure if I will try and tackle getting rid of the rest of the dc, but it is a substantial improvement. The cap basically put between the second resistor in the feedback network, and ground blocks DC and sets the gain of the opamp to 1 at DC.
This has reduced the thump form a scary woofer slapping thump to a fairly small thump (maybe 5mm excursion) I recon it was closer to 15mm before the caps.
Hopefully that is enough to save the speakers from any serious damage until I can build my new preamp. (another hazzard with a 21 month old, she loves switching switches and turning knobs).
Anyway it is now 11:20PM so I really should head for bed!
Tony.
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