Salas hotrodded blue DCB1 build - Page 5

Salas · 13th August 2010, 07:46 PM

Quote:

Originally Posted by Russellc

I've been asking around about that too. The suggestions I've had is to put it on the input of the F-5. I would prefer to leave the F-5 as is, and put it on the output of the B-1, although it wont be exactly DC then, which was the point, but I like a little insurance. The person who was commenting seemed to suggest it would be better on the input of the F-5, I'm not clear on why, so I continue to ask around. Nelson apparently chose to put the caps in the B-1 (standard non DC version of course) for what ever reason.

Russellc

What is the performance difference beyond physical location? None. I would stick 4 output RCAs in the DCB1's box, two straight, two C coupled. Choice for any amp or worry.

RichLund · 07:55 PM

Quote:

Originally Posted by Marra

When I build my DCB1 to make things "safe" I will need to install a capacitor on the input of my yet to be built F5 [still waiting for the heatsinks; 6 weeks & counting] What value cap do people recommend and would it make any difference if I installed one on the F5 input or the output of the DCB1? I am reading through all relevant threads so hope I havent missed this bit of info.
Thanks.http://www.diyaudio.com/forums/image...s/confused.gif

I had also considered this and will be re-installing the input cap on my NCC poweramp. Something like a 3.3 - 10uF polyprop would do.

I recommend the K4700 speaker protection kit from Velleman. Very effective and no loss to sound quality as far as I can tell:

ESR Electronic Components - Velleman Kits

Decent kits are also avilable from SKA Audio and ebay -

SKA sponsored Audio Forum - Products

Stereo Speaker protection kit components DIY NEW A16 on eBay (end time 26-Aug-10 10:15:24 BST)

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Marra · 13th August 2010, 08:11 PM

Thanks guys. I think the Velleman kit is the way to go if I can shoehorn it into the back of the amp.

RichLund · 13th August 2010, 08:34 PM

Marra, if your'e planning a true dual mono F5 you should probably use two Velleman kits one for each channel. Although one kit will do the job.

Marra · 13th August 2010, 09:23 PM

Salas; thanks for the suggestion regarding having dual outputs on the DBC1. I will do it that way.

Richlund; my F5 will initially have a common supply so I will use one Velleman kit; but who knows if I really like it I may well go dual mono.

A question for AndrewT; do you still suppl matched 2SK170's?

Keith.

LucasAdamson · 13th August 2010, 09:50 PM

Quote:

Originally Posted by Marra

Salas; thanks for the suggestion regarding having dual outputs on the DBC1. I will do it that way.

Richlund; my F5 will initially have a common supply so I will use one Velleman kit; but who knows if I really like it I may well go dual mono.

A question for AndrewT; do you still suppl matched 2SK170's?

Keith.

I recommend the last DC protection on that list, from eBay seller Jim's Audio. It can be supplied from 1x transformer for single case use, but is dual mono too, for down the road.... I have used this guy's stuff before and it is very well put together indeed.

Macronaut · 13th August 2010, 10:48 PM

Quote:

Originally Posted by Salas

If the audio quad JFETs are very closely matched per pair its good for offset, and I recommend best match possible especially in the Blue. If tight, an average DVM will not be dependable to show 2 times which one is slightly less Idss anyway, and if you blow over or touch they will jitter. But if they have a slight and reliable difference, use the lesser one for inner position per pair.

Thanks for making that clear. I had not understood that correctly. And thank you for all that you have done to help make this project a reality. I have enjoyed building the DCB1 and am impressed by how good this preamplifier is. It fits in perfectly between my DAC and electronic crossover. I am a bit surprised to find out that the DIY side of doing this is as fun as it has been.

sandbasser · 13th August 2010, 11:26 PM

Quote:

Originally Posted by Salas

What is the performance difference beyond physical location? None. I would stick 4 output RCAs in the DCB1's box, two straight, two C coupled. Choice for any amp or worry.

Hi Salas -

Excuse the dumb question... so you're saying just split the outputd from the 'Blue' - 1st direct to RCAs and 2nd through Capacitor to separate RCAs??? Am I understanding that correctly???

Salas · 14th August 2010, 03:26 AM

Yes, a parallel split so not to lose the DC option if a capacitor output is also needed.

AndrewT · 14th August 2010, 08:45 AM

I recommend a 200r output resistor to all 4 RCA outputs.
i.e. don't share the existing 200r between a DC and an AC output.

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13th August 2010, 08:11 PM	#43
Marra diyAudio Member Join Date: Nov 2009 Location: Near Lincoln	Thanks guys. I think the Velleman kit is the way to go if I can shoehorn it into the back of the amp.

13th August 2010, 08:34 PM	#44
RichLund diyAudio Member Join Date: Jan 2009 Location: Shropshire, UK	Marra, if your'e planning a true dual mono F5 you should probably use two Velleman kits one for each channel. Although one kit will do the job.

13th August 2010, 09:23 PM	#45
Marra diyAudio Member Join Date: Nov 2009 Location: Near Lincoln	Salas; thanks for the suggestion regarding having dual outputs on the DBC1. I will do it that way. Richlund; my F5 will initially have a common supply so I will use one Velleman kit; but who knows if I really like it I may well go dual mono. A question for AndrewT; do you still suppl matched 2SK170's? Keith.

14th August 2010, 03:26 AM	#49
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Yes, a parallel split so not to lose the DC option if a capacitor output is also needed.

14th August 2010, 08:45 AM	#50
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I recommend a 200r output resistor to all 4 RCA outputs. i.e. don't share the existing 200r between a DC and an AC output.