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AudioSector-chip amp kits, dacs, chassis

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karma

karma

Member
Joined 2003
markgall said:
Hey Karma,

What circuit are you using for the tube buffer? Which tube? Do you have a schematic? Are you using another transformer for the tube buffer or powering it from the dac transformer? I've decided I'm going to get one of Peter's DAC's and was thinking I may like to add a tube buffer also.

Thanks,
Mark
Click to expand...

ill post stuff when finished on my webpage.

this thread is for peter.


cheers;)
 

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G

gjo

Member
Joined 2003
Hi Peter

I got my DAC up and running a couple of days ago, and it sounds very good..

I've put it into a temporary enclosure for now while I plan a better long term solution. I am only using the optical input at this time. since my Onlyo CD player has only optical output. I plan to use coax at a later stage when I transfer it into it's permanent enclosure.

Being not too tech savvy, a question- the coax output jaco on my DVD player looks a bit different from the BNC output connector that I got with the kit, am I missing something?

Thanks again!

George
 
ashok

ashok

Member
Joined 2002
........the coax output jaco on my DVD player looks a bit different from the BNC output connector..............
Click to expand...

If I am not mistaken the DAC inputs are 75 ohms connections. So the BNC and RCA sockets and plugs should be 75 ohm types and you should use 75 ohm coaxial cables. If there is any mismatch along the way it will result in reflections. Now that is an ideal situation.
Non 75 ohm types will also work . You could change to the genuine 75 ohm types later on and determine if you have any audible improvement. We'd like to know what you find.

Does it matter audibly ?..... I'm not sure about that.
Most RCA sockets that we get here are not 75 ohms types.
I think Canare make 75 ohm RCA and BNC sockets and plugs. These might be available in Mumbai.

To clarify the significance of the 75 ohm connectors. The material and physical dimensions / construction of the connector determines it characteristic impedance . So unless you are an expert , I guess it will be impossible to look at it and say if it is a 75 ohm part !
Most Toshlink connections are also prone to cause more jitter than coaxial cable connections. Especially the ones with plastic fiber which are the ones we see most often.

Check out :
http://www.canare.com/index.cfm?objectid=11A89B86-3048-7098-AF9EA0F8D00A85A9
 
J

jleaman

Banned
Joined 2002
plus.google.com/photos/104656656065604242634/albums/5725366675475046257?banner=pwa&gpsrc
ashok said:


If I am not mistaken the DAC inputs are 75 ohms connections. So the BNC and RCA sockets and plugs should be 75 ohm types and you should use 75 ohm coaxial cables. If there is any mismatch along the way it will result in reflections. Now that is an ideal situation.
Non 75 ohm types will also work . You could change to the genuine 75 ohm types later on and determine if you have any audible improvement. We'd like to know what you find.

Does it matter audibly ?..... I'm not sure about that.
Most RCA sockets that we get here are not 75 ohms types.
I think Canare make 75 ohm RCA and BNC sockets and plugs. These might be available in Mumbai.

To clarify the significance of the 75 ohm connectors. The material and physical dimensions / construction of the connector determines it characteristic impedance . So unless you are an expert , I guess it will be impossible to look at it and say if it is a 75 ohm part !
Most Toshlink connections are also prone to cause more jitter than coaxial cable connections. Especially the ones with plastic fiber which are the ones we see most often.

Check out :
http://www.canare.com/index.cfm?objectid=11A89B86-3048-7098-AF9EA0F8D00A85A9
Click to expand...



This is why i use bnc still and make all my dac cables are 75Ohm :)
Of course ill make a rca > rca cable but i also make a BNC > rca coax cable for dac's.
 
Destroyer OS

Destroyer OS

Member
Joined 2005
My transformer is bigger than yours.

Well this is a Sola transformer. It weighs as much as most mothers. I am pretty sure I am going to make this independant of the rest of the amplifier. I will make the cords as short of a run as possible but.... if I made it one amplifier it would be HEAVY.

I am pretty sure this thing will not vibrate.

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


I had no idea that it was.... like this... how I got this umm.... it has really nice features (I forget what).
 
G

gjo

Member
Joined 2003
>Both BNC and RCA are standard SPDIF connectors and can be used >alternatively. I choose BNC as it is regarded as more appropriate >digital connector.

Hi Peter

My question shoud have probably been worded a bit differently-if I were to use the BNC DAC input and need to connect it to the coax out on my DVD player, what kind of connectors should I use on my interconnect?

Thanks Ashok, noted your email. BTW, welcome here for an audition..

Rgds

George
 
ashok

ashok

Member
Joined 2002
Hi George,
You can pick up a BNC plug at Texonic Instruments on SJP road and an RCA connector made by MX. MX has a new range of RCA connectors that look very nice but I have no idea if they are 75 ohms or not. Most probably not. But go ahead and use the BNC plug on one end and an RCA plug at the other end. You can use RG59 cable as the interconnect cable. That is 75 ohms and freely available. They may not be as pliable as a normal mic cable. Try to get a good brand like Commscope etc. Some Delhi made cables are pathetic and cheap !

If you have a problem I could send you one.
I'll take up your audition offer. Have to come there within the next two weeks or so. Will let you know in advance.
Cheers,
Ashok.
 
S

safetyman

Member
Joined 2004
Peter Daniel said:
The isolation pad that I sipplied to you supposed to be used without thermal compound.

Peter
Click to expand...

Thanks Peter for your consistently quick reply. Your products are excellent and your back up is Creme de La Creme.

:D After this, I am going onto the LM3875, also from yourself. My LM4780 should be completed by tomorrow and I was wondering where can I post some pics up to showcase a nice amp but a lesser enclosure and hopefully, I'll get advice for the LM3875 enclosure. Gotta give it something it deserves. :D
 
S

safetyman

Member
Joined 2004
One other question. Peter, do you have any idea what value resistor I should use on the rectifier board to light up the LED. I am using a 25-0, 25-0 secondaries and the LED is the super blue LED. I know there are formulas to calculate this, but I don't have any info on the LEDs outside they are the Super bright blue and the Ultra bright Green?

Thanks.
 
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