Chameleon DAC listening and modifications - Page 70

Quote:

Originally Posted by PatOMalley 

i did a little something. i removed the 110R smd and replaced with a Texas 110R on the clock on the input card. And it is a wee bit better on the resolution tip. Crazy. Getting tight in that area with all the wire and the Texas jutting off a wee bit.

 

It was more a dropping away of something rather than an adding of something for this trick. another drop in jitter? yes.

Which 110R resistor do you mean? Why didn't you order a Z-foil smd resistor from Texas or did you have this one laying around?

I still want to advice you to remove that 74HC04. It is just there for one purpose: adding jitter to the XO signal... You only need to buy two (smd) 47r resistors.

It might look like a scary job to do, but it isn't at all. There was no need for magnifying glasses. Only a small, sharp knife and a steady hand ;-)

     Quote:

Originally Posted by PatOMalley 

i had one laying around that someone gave me.

so i didn't have to order anything.

can you send a link back to the exact post with directions?

my camera broke and i have to get another so i can't show a latest photo.

but if you look at this picture it is the one top left. i removed it and tapped the texas resistor right to the two spots above and below it.

Ah, that resistor. :-) When you do the 74HC04 mod, you don't need it anymore. It is there to avoid reflections between the XO and the 74HC04. When you remove the 74HC04 you need lower values (47R).

You have the schematic of the Chameleon right? Compare it to this picture so you know what you will be doing:

In the old situation the 74HC04 divided the XO signal into two, one going to the S/PDIF receiver, the other one to the USB receiver.

When removing the 74HC04 the XO will feed them with just one clock signal. In order to avoid reflections between the XO and the receivers and also between the receivers themself two 47R resistors need to be placed (see picture).

The link: here

In the 'mass produced' version of the Chameleon the 74HC04 has been remoced. Though they made a mistake and kept the resistors at 100R, which is too high.

if you have any questions, just let me know.

P.S. Holland in the finals!

Quote:

Originally Posted by rhodes54 

     Quote:

 

Ah, that resistor. :-) When you do the 74HC04 mod, you don't need it anymore. It is there to avoid reflections between the XO and the 74HC04. When you remove the 74HC04 you need lower values (47R).

You have the schematic of the Chameleon right? Compare it to this picture so you know what you will be doing:

 

 

In the old situation the 74HC04 divided the XO signal into two, one going to the S/PDIF receiver, the other one to the USB receiver.

When removing the 74HC04 the XO will feed them with just one clock signal. In order to avoid reflections between the XO and the receivers and also between the receivers themself two 47R resistors need to be placed (see picture).

 

The link: here

 

In the 'mass produced' version of the Chameleon the 74HC04 has been remoced. Though they made a mistake and kept the resistors at 100R, which is too high.

 

if you have any questions, just let me know.

 

P.S. Holland in the finals!

Hi rhodes54,

I am thinking of following your footsteps with this dac.

I know you may have mentioned this before, but is the SQ improvement significant when removing the 74HC04? does it matters if i only use USB input? 

also any chance of a detailed guide on the tentlabs xo installation?

thanks

Yes, it sound matter because the XO is both feeding the USB receiver as well as the SP/DIF receiver. The difference is small compared to replacing the clock completely but i'm sure you will hear it.

Replacing the clock for the Tentlabs XO is very easy.

These two pictures (don't forget to read the description) tell it all. It's a 10 minute job, and reversible if done with care.

Quote:

Originally Posted by rhodes54 

Yes, it sound matter because the XO is both feeding the USB receiver as well as the SP/DIF receiver. The difference is small compared to replacing the clock completely but i'm sure you will hear it.

 

Replacing the clock for the Tentlabs XO is very easy.

These two pictures (don't forget to read the description) tell it all. It's a 10 minute job, and reversible if done with care.

If i only use the USB input, would i need to replace the XO on the other board? it's bloody expensive :)

replacing the xo on the up sampling board look easy enough, however it's a bit difficult to see how you wired the other board, looked like you have two set of wires going into the board but i can't make out clearly the connections.

i have a problem with my Dac, i get noise and distortion randomly, but goes away when i turn it off for a while. So i am a bit reluctant on spending $$$ on other parts for it.

Quote:

Originally Posted by taiphan 

 

If i only use the USB input, would i need to replace the XO on the other board? it's bloody expensive :)

 

replacing the xo on the up sampling board look easy enough, however it's a bit difficult to see how you wired the other board, looked like you have two set of wires going into the board but i can't make out clearly the connections.

 

i have a problem with my Dac, i get noise and distortion randomly, but goes away when i turn it off for a while. So i am a bit reluctant on spending $$$ on other parts for it.

If you use the upsampling board then I would start by replacing that clock. Replacing the clock on the USB/SPDIF board is done the exact same way except that you really need to remove the 74HC04.

If you want a detailed description in the future, just let me know.

p.s. I wouldn't invest one single euro (dollar) as long as your Chameleon is having that noise/distortion issues.

A view thing to try:

1. Have you measured the voltages during these distortions?

2. remove (and bypass) the upsampling board

3. It is very handy if you have a scope available, or try to find somebody who has one.

4. redo all solderspots on the PCB with leaded solder.

5. try replacing the TDA dac chips one by one.

circumstances dictate that i need to shop for a new dac. chameleon is the only dac on the list right now but i still would like to know more of it's possibilities before bringing in the contenders. is there any reason why a tube stage or balanced output is not desirable on chameleon? anybody with future plans for it if it's even do-able? also what do you gentlemen would consider as the biggest bang for the buck mod and how much is the cost of it? i can't wait to get my own unit to tear apart and then slowly resurrect it. 

Lots of recommendations for mods in this thread but Bill Allen lists several core mods in the order of perceived sonic improvement and bang for the buck on page 67 of this thread.

Muffin; any reason to put in a DAC stage, whether balanced or not?

16 TDA chips pack some punch and have a low Zout, so why add another stage...just to add tubes for tubes sake?

Pat; you could also say that a potential reason could be to overcome design flaws in the succeeding stages.....I'm not sure the solution to add a stage is always advisable (coming from a less-is-usually-more standpoint) without knowing the reasons....