HELP,no sound from Cal Audio DAC

[adam]

I lost the sound from my Cal Audio Alpha DAC,so i just thought the valves had broke,even though I only bought the 4 months ago.Today I replaced the valves,fitted them wired it up,but to my suprise no sound.

I took the lid of the DAC to see how the valves were,they looked fine,they were new,and they were glowing,the fuse wasn't blown but no sound,I've checked everything,and all is ok,

When you first put on the Cal you have to give it 2 mins,I do that,wait and I can here the thing make a pop noise through the speakers,but no sound,

Any Ideas?

 

[technobear]

Are you sure it's the DAC? How many digital sources have you tried? Is your amp OK? I guess if you hear a pop then the amp is doing something.

 

[adam]

The Pre is a Conrad Johnson,works fine on its phono stage,and tape,so I don't think its that,thought maybe it was the transport,so tried my DVD player same thing,so I am pretty sure it the DAC,it makes a pop when the sound should begin but nothing,valves glow,and fuse is perfect,there not much more to it.

 

[bottleneck]

It might have ''lost communication'' with the transport - sorry thats not a technical explanation, but I dont really understand the inner workings of CD players.

The only reason Im chipping in, is cos Ive got one too.

When I get nothing (like youve described) I press the buttons on the front that choose between different inputs, and cycling round seems to make it find itself. Its rare that I need to do that, and was more the case when I had a cheapy digital IC. Come to think of it, the micromega dac I used to have needed me to do that sometimes too.

If that doesnt do it, over to the more knowledgable diy chaps like madhippy!!

Sorry if youve exhausted that option already.
Cheers
Chris

NB
An email/PM to Lilolee might help you, he's more technical than me and had a CAL for a few years.

 

[technobear]

Bottleneck raises an important point - it might be the cable! Are you using an electrical or an optical cable. Breakage is more likely with the latter but not impossible with the former. Can you test the cable?

 

[adam]

Hi,

Tried the AES/EBU cable and the co-axil,changed over the valves in the CJ pre so they were ok,the dac just makes a big POP when it's ready,intrestingly if I move the volume up and down,the cones in the speakers really move to and fro,it must be something to do with the valve output I guess but what?......Tried the DVD player,it worked fine,but yuk what a horid noise.

 

[adam]

Hmmmmm...just noticed the valves when warm inside the CJ are really bright,inside the CAL they are just about glowing,hardly any light,very vague in comparision,does this have any meaning???

 

[technobear]

I'm not an expert on valves but you seem to be assuming that they are the culprit here. This ain't necessarily so. Could be another component has died. How many DAC chips are there? One per channel? It's strange that both channels have stopped working. Suggests a power supply problem maybe. A fault in the signal path would more often than not affect only one channel.

When you say the cones move back and forth, do you mean they move forward when you turn the volume up and then move back when you turn the volume down. If so, you are feeding DC to your speakers (not good ). If they are in constant motion then there is some low frequency oscillation going on somewhere in the system. If this only happens when the DAC is selected, then that would tend to point to the analogue stage in the DAC I guess.

Where are all our electronics experts tonite?

 

[adam]

Hi Chris,

I'm thinking its the valves because a few months ago I was playing around moving my speakers and I lost the sound again from the Cal,first one valve,then the other,I changed them for new ones and they were fine,the other day it was fine,then I had to turn it off and unplug the sysyem,when I turned it on allas no sound again from the Cal,so i thought,valves,bought new ones,and no difference,it's just they are hardly glowing,the light is very vague,as if they were not heating up properly

Yes if it turn the volume up and down the cones move back and forth; i presumed this meant current was being passed,but no output,so not sure what you mean by DC,or am I being silly.as its just the juice that comes from the wall,so how do you change that,without powers supplies that do thios for you,or am I missing something.

 

[adam]