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Old 7th September 2012, 05:31 PM   #1171
EUVL is offline EUVL  Europe
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How many PCM1702s do you have in your DAC, and do you have a schematics of the analog output stage after the 1702 ?

Without the schematics it is rather difficult to help, unless you only have 2x PCM1702 inside.
Best is to find a fellow DIYer nearby and skill enough to understand and willing to help.


Patrick
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Old 8th September 2012, 01:39 AM   #1172
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Talking Thanks for the clarification

I will build this sen/cen for an Adcom cd player which has only one PCM1702 per channel. The player has a class A opamp IV and filtering system with relays muting. Just needed a little clarification. Thanks again.
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Old 8th September 2012, 02:37 AM   #1173
bcarso is offline bcarso  United States
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Quote:
Originally Posted by optimationman View Post
I will build this sen/cen for an Adcom cd player which has only one PCM1702 per channel. The player has a class A opamp IV and filtering system with relays muting. Just needed a little clarification. Thanks again.
I suspected as much (the single 1702). Thanks!
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Old 8th September 2012, 03:39 AM   #1174
EUVL is offline EUVL  Europe
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For ONE PCM1702 per channel, you need one SEN or CEN PCB on which there are TWO single ended IV circuits.
That also means TWO floating supplies 2 channels.

A standard evaluation kit will have 2 SEN and 2 CEN PCBs.
That gives you plenty to experiment with different devices and components, etc.


Patrick
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Old 10th September 2012, 06:14 PM   #1175
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Red face trying for simplicity

I have been thinking about the overall scheme of this simple and reported excellent sounding IV circuit. I like simple, and minamalistic systems that make the sound to my taste(acoustic, light Jass, Blues). I have a simple system, that is a cd player into mono block tube amps, into monitors in a 12x17x8 room that has had some acoustic modifications. One capacitor in the signal path, even one on/off switch. The interconnect cables are 18 inches long and the speaker lines are 36 inches in length. Minimalistic as I can make it. Additionally, I have done all the mods, PS, resistors, caps, diodes, cables, etc. on a very tight DIY budget. I have even used pulled components from the Skip/dumpster and surplus equipment to experimetnt with. That has been quite an eye opener, as there is a substantial amount of nice component being thrown away.

What I am thinking about here is the PS that is although simple sounding, requires(recommended) 32 AA batteries at a cost of 3 euro each. It would also appear that a charging circuit would be recommended, incorperated into the on/off button. This requires a lot of shall we say real estate, and expense for only the IV segment of our systems. I realise that a 9v battery system(requires 4each) would get a person at least to the evaluation phase and possibly longer term. That will be my solution in keeping this as simple as possible. Thank you for this opportunity!

What I am finding is that although there are many excellent projects here on DIY Audio, the ones I seem interested in building have a "snag" somewhere. Be it hard to get or very expensive components, or additional spacific requirements not at first addressed in the early discussion. That is why I must wait until the thread has reached maturity, so I may fill in all the holes before moving forward.

Mind you, I wouldn't be without my membership here. I really appreciate the thought and efforts all the memebers put into this website. Without this, I would still be using the old RCA console my parents had.......
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Old 13th September 2012, 06:22 AM   #1176
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Quote:
Originally Posted by EUVL View Post
L = 10mH Fastron 77A series
DCR = 12R
dV ~ 0.5V @ 45mA

C = 10000uF 16V Vishay BC 056 Series

f_RC = 1.3Hz (1st order)
f_LC = 16 Hz (2nd order)


Patrick
Would it be ok if I change the C to 15,000uf ? Reason being I have them in stock instead of 10,000uf

Thanks
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Old 13th September 2012, 07:35 AM   #1177
EUVL is offline EUVL  Europe
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Of course. Just try it and listen.
BTW the 16V was a mistake of mine.
You should use 25V or whatever voltage that is higher than your rails.


Patrick
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Old 13th September 2012, 12:25 PM   #1178
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Quote:
Originally Posted by EUVL View Post
Of course. Just try it and listen.
BTW the 16V was a mistake of mine.
You should use 25V or whatever voltage that is higher than your rails.


Patrick
Great !!! I'll take a note on voltage rating of the capacitor.

Thanks.
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Old 15th September 2012, 08:52 AM   #1179
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One question on the battery-supply:

Instead of using

- 4* 18v with many AAA for two v18 (used as balanced output to drive a balanced input stage of a tube amp) would it not as well possible to use

- 2 19.9V A123 based supplies (channel separation is already there than, but not for each phase...is this really a disadvantage ? If you use a balanced signal path you want to introduced in the two phases the same noise so it can cancel itself out....)

- Is 19.9V fine ? The A123 has 2300mA and very low ESR...and compact...


Additional question:

The V18 will drive a 6922-input stage in a UL40 of menno VanderVeen ( a EL34-PP). I will modify the input stage so it is balanced and get rid of the phase splitter and have a fully balanced system. The 6922 is cathode biased, so in theory I can give it an inout resistance upto 1 MegOHm...today it has 100kohm.

What would be the sufficient coupling cap than ? I ommitted all electrolytics out of my system an do not want to put any in now again...(currently I am using the unbalancer from broskie with Mundorf tubecaps).

Last edited by Blitz; 15th September 2012 at 09:03 AM.
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Old 15th September 2012, 03:11 PM   #1180
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Default Experience with SEN in ES9018 /Buffalo DAC

Hi all,

After a long designing phase (due to lack of time) of my homebrew PCB of a stackable SEN/CEN board for the buffalo DAC, I am at last able to comment on this (fantastic by most aspects) I/V converter!

First, for curiosity: the homebrew PCB which has room for 3 pairs by channel (my logic was that three 2SK170BL pairs would give same transconductance and Idss as two 2SK369V pairs, but a slightly lower total input capacitance) :
I made it for personnal use, so no need to ask for a group buy... (see EUVL comment earlier in the thread..... if you need advices to design your own, you may contact me though...)

Click the image to open in full size.

Then the stuffed proto board.
I am using a 1% matched 2SK170 hexadeca-tet (16 JFETs) for now.. I will increase to 3 pairs by channel later, ......I know the wires are flying but that's for a first try...
I did not use the famous heatsinks and got the output stable at less than 2mV.. I might see later if the expense of these heatsinks is worth..

Click the image to open in full size.

Finally The full assembly:
...in my very tight (but sufficient !) casing..
As you can see it stacks directly under the Buffalo DAC, making a nice stockpile of boards with all these regulators above !

Click the image to open in full size.

On the sound:
It is very good! As NicMac said, probably the best single upgrade in my system. I am being very subjective of course and I will not go as far as using superlatives, but the realism and details increased noticeably (I do not have the patience / experience / ears and equipment to do ABX tests, but bottomline I like the result a lot). Very happy about the build.

Drawbacks of my build: I do not have a balanced system, and I did not use a Bal-> SE conversion (yet)... just took one phase from the SEN. When having my ears close (but even not so close) to my 95dB speakers, I can hear a buzz similar to a ground loop which I did not have previously with the Legato IV.... with floating batteries I really don't see how I could have possibly created a ground loop, but .... even with this, I can still hear an improvement in the sound of my system... just leaving me wonder how great it could be if I can solve the buzz! (and where the buzz is coming from...? I will check the Buffalo Power supply layout later....)

I then tested the system in balanced mode by feeding my F2J directly from the SEN in Balanced (mono) mode. It is DEAD SILENT when idle (finally I can understand what that means!) and plays really good music.. even though I can not appreciate the stereo and depth of the music, but definitely, leaves me wanting to either solve the buzz, either use a Bal/SE, or build another amp to appreciate the balanced sound.
For now I'll just listen to the Beatles Mono recordings collection.....

Fred
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