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Old 17th September 2008, 04:18 PM   #1801
stein2 is offline stein2  Serbia
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and one more showing the wiring layout, before closing the box
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File Type: jpg f5boxing9.jpg (94.4 KB, 2992 views)
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Old 17th September 2008, 06:46 PM   #1802
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"In pace requiescat"

- The Cask of Amontillado
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Old 17th September 2008, 08:49 PM   #1803
stein2 is offline stein2  Serbia
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Thanks to no capacitors in the path of signal, just during the last song ("Don't Give Up" - Peter Gabriel & Kate Bush) I noticed that the speakers have been pushed out quite a lot even though I kept the volume at lower levels... Turned on the multimeter and found 1.2VDC on both outputs, (got pi$$ed off instantly - the worst possible thing came to my mind= ) and turned the CD off, at the same time, the membranes went back... Hmmm... Turned the CD on again and BUMP, the DC on output of the amp reappears... Disconnected the RCA jacks and took out the CD, opened it... 3.2VDC on both RCA outputs! The previous owner was obviously fiddling with it and took out the capacitors on the signal path...

So, a warning for those who would use the F5 without a preamp, just a source device and a pot. Check the DC voltages on the output of the previous stage (unless you're really sure there's no DC voltage)

Then I measured the rest of my CD's (have four of them and all are Philips ) and realised that only the 303 has zero DC on it's output. So, in the next few days or weeks, I'll be combining the vintage flavored CD303 and the F5 which BTW made no complaints...

Edit: Forgot to tell you that I used both output devices made by IR and there is no audible distortion.
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Old 17th September 2008, 09:37 PM   #1804
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I like those heatsinks. Nice build.
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Old 17th September 2008, 10:36 PM   #1805
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Quote:
Originally posted by Nelson Pass
"In pace requiescat"

- The Cask of Amontillado
de mortuis nil nisi bonum

even if it was Domitian
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Old 18th September 2008, 07:57 AM   #1806
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by stein2


Thanks to no capacitors in the path of signal, just during the last song ("Don't Give Up" - Peter Gabriel & Kate Bush) I noticed that the speakers have been pushed out quite a lot even though I kept the volume at lower levels... Turned on the multimeter and found 1.2VDC on both outputs, (got pi$$ed off instantly - the worst possible thing came to my mind= ) and turned the CD off, at the same time, the membranes went back... Hmmm... Turned the CD on again and BUMP, the DC on output of the amp reappears... Disconnected the RCA jacks and took out the CD, opened it... 3.2VDC on both RCA outputs! The previous owner was obviously fiddling with it and took out the capacitors on the signal path...

So, a warning for those who would use the F5 without a preamp, just a source device and a pot. Check the DC voltages on the output of the previous stage (unless you're really sure there's no DC voltage)

Then I measured the rest of my CD's (have four of them and all are Philips ) and realised that only the 303 has zero DC on it's output. So, in the next few days or weeks, I'll be combining the vintage flavored CD303 and the F5 which BTW made no complaints...

Edit: Forgot to tell you that I used both output devices made by IR and there is no audible distortion.
Stein,
don't tell us.
Tell yourself.
You must check the output offset of the power amp
1.) with the input RCA shorted.
2.) with the source connected but switched off.
3.) with the source connected but this time switched on.
You must do all these offset checks cold and warm and maybe hot if the amp wants/needs to run hot.
After you have thoroughly checked the offset for all operating conditions then connect the speakers.

Removal of the DC blocking caps at the input and at the NFB should be based on (well) informed decisions. Not wading in like a bumbling fool.
__________________
regards Andrew T.
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Old 20th September 2008, 12:12 PM   #1807
estman is offline estman  Estonia
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Default Re: another diy f5 newbie layout

Quote:
Originally posted by khaho
I am going to build one to see if it works
Sure F5 works, just take care to connect everything right way
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Old 20th September 2008, 12:37 PM   #1808
stein2 is offline stein2  Serbia
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Default Re: Re: another diy f5 newbie layout

Quote:
Originally posted by estman


Sure F5 works, just take care to connect everything right way

I can confirm that. It surely works, and for that matter, works good. (event though saying "good" doesn't give it a credit that it deserves)
Once your PCBs are populated, box prepared be sure you do the wiring the proper way. The image I posted (http://www.diyaudio.com/forums/attac...amp=1221668297) shows some of it, and take care you don't ground the 0 potential directly but through the TH (I used a 8R NTC, one for each supply/channel)
On the image these thermistors are at the center of the rear panel. The heatsinks are grounded directly.
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Old 22nd September 2008, 10:05 PM   #1809
hc167 is offline hc167  United States
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by the way, anyone know where I can get F5 broad and start building one?
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Old 22nd September 2008, 10:32 PM   #1810
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If you throw out the protection and temperature compensation, there's
hardly enough parts to justify a pcb.

Why not try that point-to-point?

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