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Old 25th February 2013, 07:47 PM   #2751
Salas is online now Salas  Greece
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That resistor is to discharge a coupling capacitor's small charge build up. It should be connected to its output side permanently. A thump can also be the DC amp closing lower in frequency with the preamp now with 4 times+ the previous value and having a higher transient for its input differential amp and input base currents. So if it proves its not the caps, you may try a mute switch to ground is better because just switching the output to null signal position will surely do some other contact click noise and its also introducing a moving connection in your signal path. Not a very good addition.
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Old 25th February 2013, 08:14 PM   #2752
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Mute switch... Hmmm... Where should that be? Shorting the output to ground after the caps?
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Old 25th February 2013, 08:28 PM   #2753
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Yes.
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Old 25th February 2013, 08:56 PM   #2754
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Bingo!!
Switched off with no thump at all with the outputs shorted.
No thump when shorting them either
I just hope it was not random. It stayed on for only a couple of hours in comparison to last days where it stayed almost all day on.
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Old 28th February 2013, 12:08 AM   #2755
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Hello,
I recently finished an F5 and was so amazed by its quality that I jumped right into building a DCB1. I am planning on "hotrodding" with 10R resistors to start. I have bought large enough heatsinks to withstand more heat (i think) if i decide to take it to the next level. Anyway, I built my F5 with top quality components and I am doing the same with this build. I am still waiting on a couple of parts in the mail. I haven't made up my mind on a chassis yet.. I am also trying to decide on a transformer. I got a quote on a SumR toroid (80VA, 2X15V). I believe I will buy one of these but am still searching for alternatives. Since the fire at Antek I have had to do some research on quality toroids. I have also found an R-Core that is a fraction of the price. Any suggestions on this decision would be nice.

My main question is about my heatsink configuration. Can i mount the heatsinks with the fins facing downward (toward the bottom plate of chassis). It seems (because heat rises) that this might not be beneficial. I posted a photo of what I am considering.

I splurged and bought a 10K Khozmo 48 step attenuator. I have never had a nice volume control in my signal path so i am excited to see what it can offer. I have been inspired by the Lightspeed (or "Lighter Note") LDR volume control and may build a stand-alone unit in the near future.

I am planning on running AC mains through a Schaffner EMI line filter (FN2070-3-06). I originally bought it for the F5 but decided against it.

I just got my 2SK170BL's in the mail (Thanks Spencer). I was very diligent when matching the LEDS. They were already very close but they are spot on now.

Any comments/suggestions would be nice. Especially about my heatsink configuration and any ideas on a transformer. If anyone has any experience with SumR and can relate their toroids to Antek, that would be great. Antek says they will have their full stock back in mid-April but I do not want to wait that long.

Anyway, thanks for the inspiration on both of these builds. I have only been "tinkering" for about a year but it has been an amazing hobby. I knew absolutely ZERO about anything to do with electrical work of any kind. I have a TON more to learn..

Thanks in advance,
Madison (Tennessee, USA)
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Old 28th February 2013, 12:14 AM   #2756
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Facing the sinks down is a no no when using them to capacity. You will not need their capacity with 10R or 4.7R even.
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Old 28th February 2013, 12:19 AM   #2757
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Don't know about the transformers but do get 4 FT-1 0.022uF CCCP Teflon Ebay caps to bypass the Wimas at their pads under board and see if you like it after you had listened with only the Wimas for a while. Use some tape around the FT-1s not to short PCB something on their metallic can. Use 1 per red Wima. Since you aspire to top components assortment some Teflon may suit your taste in the mix or not. Those suggested are dirt cheap to test anyway.
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Old 28th February 2013, 12:34 AM   #2758
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Thanks for the quick reply. I was waiting to hear back so I can tap the sinks accordingly. I will face the sink downward for now. I doubt I will go any lower than 4.7R anyway. I can always adjust if i decide to...

Thanks for the advice of the teflon caps. I will order some.. Have the Wima's (MKP10) been frowned upon in this build? I discovered the Wima "Black Box" film caps after I bought these. Can't seem to find much information on them. Do you have any experience with them. They seem to be Wima's top of the line. Thanks for the advice and i will be keeping everyone updated as i gain progress.

Regards,
Madison
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Old 28th February 2013, 12:51 AM   #2759
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The red Wimas in the particular type and value came out best in a mini survey we run among some users in the past to recommend in the BOM. Best among proven and widely available industrial options in manageable sizes and prices though. Having an ultra pot you may be interested in some Teflon mix was my drift. About the black box Wima I have no direct comparison experience to convey.
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Old 28th February 2013, 12:53 AM   #2760
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The SumR transformers are excellent as are the Anteks. Many here are happy with the Anteks. SumR is local to me and Antek shipping to Canada is expensive, so I asked for a quote. I was surprised to find that they were significantly more expensive that Antek (about double IIRC). When I asked what the advantage was, they never replied. Several people have bought the Rcore found on eBay and are happy. In theory, an Rcore is the ultimate, but many are wary of Chinese product.

The Lighter Note is a great product at a great price. Several on this forum have used them successfully with a DCB1. Keep in mind that an LDR attenuator is sensitive to heat so you want to arrange and plan your enclosure and layout accordingly. There was a recent discussion of this on the Lightspeed forum.

Very nice looking build so far. Thanks for sharing.
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