DIY Dodd Buffer

jtsnead · « **Reply #900 on:** 11 Apr 2011, 01:32 pm »

I thought most dac/cd players had a 2 volt output and that should be fine with the Dodd'

I have a Jasmine phono and a Sony cd player that have plenty of output.

If you must use the pre I would put the buffer after the pre, I would set the volume of the pre at three quater to full volume, then you use the buffer volume control only.

usp1 · « **Reply #901 on:** 11 Apr 2011, 02:09 pm »

I tried using the buffer after the pre and played with both volumes. Even with both volumes maxed I can barely hear anything. I am beginning to wonder if the input on the buffer that I am using is bad. I will try switching that when I get home tonight.

usp1 · « **Reply #902 on:** 12 Apr 2011, 02:33 am »

I feel like a real dummy now

. It seems that there is something wrong with the third input on my buffer. Since this is the first time I used that input I did not notice this problem before. I hate to mess with Gary's handiwork so I will just wait until he is back to full strength and see what I need to do.

TrungT · « **Reply #903 on:** 12 Apr 2011, 02:36 am »

^^^^^
Send the buffer to me, I will be happy to help.

S Clark · « **Reply #904 on:** 12 Apr 2011, 02:52 am »

Quote from: TrungT on 12 Apr 2011, 02:36 am

^^^^^
Send the buffer to me, I will be happy to help.

Trung found the wire that I had soldered incorrectly. I searched for hours and hours trying to find my mistake

. Your a good guy, Trung.

usp1 · « **Reply #905 on:** 12 Apr 2011, 02:53 am »

TrungT,

Appreciate the offer. I may call you to see if I can fix it myself. I may call you one of these days. I have your number form a previous message. Thanks.

TrungT · « **Reply #906 on:** 12 Apr 2011, 03:00 am »

I'm usually staying up late, so no problem when you call.

2wo · « **Reply #907 on:** 12 Apr 2011, 03:33 am »

Hey Trung,

Thanks for all your help. My buff is working...John

TrungT · « **Reply #908 on:** 12 Apr 2011, 03:48 am »

John

You are welcome, glad to help.

usp1 · « **Reply #909 on:** 12 Apr 2011, 04:29 am »

Just looked at the buffer page on Gary's website. He has a quote from one of my posts on AC (even though he has me listed as UPS1 rather than USP1)!
http://www.audiocircle.com/index.php?topic=88985.msg883899#msg883899

I am so thrilled!

praedet · « **Reply #910 on:** 17 Apr 2011, 03:47 am »

Does anyone have a link to a diagram or instructions on how to use diodes to prevent noise on DC lines? I am about to hook up something on the same battery as the buffer and I don't want to feed it any noise...

Thanks!
Ted

2wo · « **Reply #911 on:** 20 Apr 2011, 04:29 am »

Bare in mind that a diode in line will drop, 0.7V. doesn't seem like much but now you're down to 11.3V. If you hook it up to something like a tube stage, it might want the full 12V. For something like a DAC that might only need 9V or so, hey give it a go...John

praedet · « **Reply #912 on:** 20 Apr 2011, 11:37 am »

Well, I would like to keep the Buffer line as is. I thought I could integrate the noise Isolation circuit into the power cord I am building for the linux music server. I needs between 7 and 20V, so I am good on the drop, I just want to make sure it will work before I do it

Ted

HAL · « **Reply #913 on:** 20 Apr 2011, 11:49 am »

Ted,
Here was the original idea I had for using the diode and cap to possibly work as a noise block.

I have not tested it at all or figured out a cap value for bypassing the noise. The cap would value would depend on the load noise frequency range.

praedet · « **Reply #914 on:** 20 Apr 2011, 12:04 pm »

I think I am going to build a cheap version of the cable and see what it does/what noise is there. If I want to block noise from the Alix from coming BACK to the battery, does the diode still go on the positive side of the cord? Should I just choose something like the 0.1uF/50VDC Cap to try out? If it is on the PC it can only help and not hurt, correct? Any recommendations on the specific cap?
Either one of these?
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=027-830
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=020-1620

HAL · « **Reply #915 on:** 20 Apr 2011, 04:21 pm »

You would wire it as shown in the diagram to keep noise from going back from the Alix to the battery.

The diode should be at least a 50V/6Amp rated device if the Alix uses less than that amount of current. At 12VDC that is 72watts max. If that is not enough try a higher current rated diode.

The cap should work at high frequencies for and switching noise. I would use film caps like polypropylene rated at least 50VDC. Parallel a 0.01uF, 0.1uF, 1.0uF cap with a 1000uF/50V electrolytic as a test. The positive terminal of the electrolytic should go to the + side of the diode in the diagram. Panasonic caps from Digi-Key should be a great start. Panasonic makes polypropylene and electrolytics.

This is where the experiment should begin.

praedet · « **Reply #916 on:** 20 Apr 2011, 04:36 pm »

Ahh, so use a small value polypropylene bypass (0.01-1uF) with a large value electrolytic? Then, the diode will be in series with the Alix on the positive/input side, And the cap should run parallel to the Alix starting on the input to the diode, correct? Sorry, I am relatively new to this

I am also just looking at getting a BatteryBUSS

HAL · « **Reply #917 on:** 25 Apr 2011, 07:51 pm »

I am sure the BatteryBUSS will be better than the simple filter I posted.

dBe · « **Reply #918 on:** 26 Apr 2011, 02:56 pm »

Quote from: HAL on 25 Apr 2011, 07:51 pm

I am sure the BatteryBUSS will be better than the simple filter I posted.

Yup.

Dave

cujobob · « **Reply #919 on:** 27 Apr 2011, 12:27 am »

Can anyone recommend an inexpensive high quality AGM battery source?

The better prices I've seen had some of the worst shipping prices...local sources are all quite a bit more expensive, unfortunately.