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New PCB for shoebox size NAC preamp part IV

LoBo

Fix it then modify it
Jim

What value should R1 be if using an LED?

Also - should the C line be linked out on the common mode and differential filter blocks?
 
Just a bit of fun, playing with the front panel

NaimFrontPanel0001.jpg
 
The panel looks good Gareth. I'm looking for people with milling equipment and skills to help with my Modushop 10mm panels. Will start another thread for this.

Here is my Starfish effort so far. PCB finished - full monty 1.2 build, everything there. Wanted to try the full complement of feedback components and start from there.

http://img64.imageshack.us/img64/6003/starfish1f.jpg
http://img407.imageshack.us/img407/3235/starfish2.jpg

Looks great, but how does it sound?
 
The panel looks good Gareth. I'm looking for people with milling equipment and skills to help with my Modushop 10mm panels. Will start another thread for this.

Here is my Starfish effort so far. PCB finished - full monty 1.2 build, everything there. Wanted to try the full complement of feedback components and start from there.

http://img64.imageshack.us/img64/6003/starfish1f.jpg
http://img407.imageshack.us/img407/3235/starfish2.jpg

Looking really good.

make sure that the heatsinks on the nert transistor dont touch each other - the tabs are at different potentials.
 
Hopefully find out this weekend. Need to test circuits, rig up a HP power supply and make some DIN interconnects.

I'd suggest using a linear offboard supply if you can. I use a wall wart one - although it's more of a brick than a wart.

The HP power supplies are usually SMPS.
This can work ok, but you can also get interactions between the HP SMPS and the traco SMPS onboard.
You could try a, say, 100uF cap directly between the input pins on the traco.

Jim.
 
The panel looks good Gareth. I'm looking for people with milling equipment and skills to help with my Modushop 10mm panels. Will start another thread for this.

Here is my Starfish effort so far. PCB finished - full monty 1.2 build, everything there. Wanted to try the full complement of feedback components and start from there.

http://img64.imageshack.us/img64/6003/starfish1f.jpg
http://img407.imageshack.us/img407/3235/starfish2.jpg

Looking nice. I'm worried about that oscon: there's 30V across that capacitor... does it have a high enough rating? It looks suspiciously like a 56uF/25V but I can't tell for sure. You should also do the BOM-specified mods to C110, C210, C114 and C214. Especially C114 and C214 ;)

Very clean build, I think you're going to be very happy. What's you current preamp?

Carl
 
Cheers guys. There's a few of us at the same stages of build. It's good to know.



make sure that the heatsinks on the nert transistor dont touch each other - the tabs are at different potentials.

Will sort this out Jim, cheers

I'd suggest using a linear offboard supply if you can. I use a wall wart one - although it's more of a brick than a wart.

The HP power supplies are usually SMPS.
This can work ok, but you can also get interactions between the HP SMPS and the traco SMPS onboard.
You could try a, say, 100uF cap directly between the input pins on the traco.

Jim.

Is the 100uF fix a good solution, as in does it sort the interaction problem completely? Could I power Starfish from my NAP 140 (24V I think) until i sort a better supply?

I have visions of the future where I will build a power supply into the same box as the fish using R-core transformers and maybe Avondale TPX module. Not yet though...

Which SMPS do you have Jim? Post a link.

Looking nice. I'm worried about that oscon: there's 30V across that capacitor... does it have a high enough rating? It looks suspiciously like a 56uF/25V but I can't tell for sure. You should also do the BOM-specified mods to C110, C210, C114 and C214. Especially C114 and C214 ;)

Very clean build, I think you're going to be very happy. What's you current preamp?

Carl

Ok Carl I'll do the mods. What exactly were the reasons for the mods and how much better without the components?

At the moment I have a NAC72/140 set which i think are brilliant. The 140 will be with the Starfish until I sort out my NCC200's whenever... be interesting to see how good the fish really is and how far it can go. I'll spend some money on this hobby but within the realms of sanity!

Where can I get them from please? is there a Farnell or RS number?

Gareth, give Neil a mail and he could get you some 10uF MKS2 wima's. There's a group buy on for the NJ boards. 22uF's are bloody hard to find. But ask him about those too.

Cheers

Rich
 
Is the 100uF fix a good solution, as in does it sort the interaction problem completely? Could I power Starfish from my NAP 140 (24V I think) until i sort a better supply?

Using a SMPS wallwart is not ideal. I believe the 100uF on the traco helps, but I still recommend that a LINEAR wallwart is used.


The 24V supply in your NAP140 would be ideal !
The StarFish has been designed so that it sounds good without the need for excessive external supplies - all the 'good stuff' is already integrated.
 
Which SMPS do you have Jim? Post a link.

Just so we are clear:
The traco PSU module is the only SMPS in the pre-amplifier system.
It requires a 9V to 36V (iirc, it says on the top) input to power it.

I use a linear wall wart from the mascot brand.
Aim for something around 20V and, say, 600mA or higher.

Jim.
 
Ok Carl I'll do the mods. What exactly were the reasons for the mods and how much better without the components?

At the moment I have a NAC72/140 set which i think are brilliant. The 140 will be with the Starfish until I sort out my NCC200's whenever... be interesting to see how good the fish really is and how far it can go. I'll spend some money on this hobby but within the realms of sanity!

Basically, just stuff the board according to V1.2 and you wont go far wrong. Many sets of ears agree this is the best StarFish config by far.

I specified MMK 10uF caps (the white coloured ones) for signal coupling duties as these are good quality and readily obtainable from RS.

I believe the little red 10uF wima mks2xl caps are superior for coupling duties. This is mentioned on the BOM, but not specified as default since they are harder to obtain.
 
Here is my Starfish effort so far. PCB finished - full monty 1.2 build, everything there. Wanted to try the full complement of feedback components and start from there.

http://img64.imageshack.us/img64/6003/starfish1f.jpg
http://img407.imageshack.us/img407/3235/starfish2.jpg

I've just had a closer look at this and it's definitely not built according to V1.2 or V1.1, there are quite a few resistors and capacitors that should be either no-fit or wire-link.

Also, is the ground link wire on the underside of the board?

Jim.
 


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