DAC build TDA1541A/SAA7220P/B *will take som time*

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A

AndrewGM

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Joined 2008
Jonas Hi

Modest as always Mr wlowes is pretty darn close to an expert as far as driving TDA to it's limits plus connecting valves to it .
He's the original ' been there done that ' with this stuff and was responsible for me driving out the hum in my attempt - good evening Walter - always a pleasure to see you around :)

He is going down different routes with playback but his understanding is wide. Like.. NO cd's... just straight from his phone socket music via pc type stuff - is that correct ?
His advice re valves is top draw and he's great to have on your shoulder.

I wondered a few weeks ago if he maybe was be watching this !!

Alpha section gets some updates soon plus my friend Kingwa of Audiogd has new developments which I'm trying out.
Won't be long

Andrew
 
Mayday

Mayday

Member
Joined 2004
AndrewGM said:
Jonas Hi

Modest as always Mr wlowes is pretty darn close to an expert as far as driving TDA to it's limits plus connecting valves to it .
He's the original ' been there done that ' with this stuff and was responsible for me driving out the hum in my attempt - good evening Walter - always a pleasure to see you around :)

He is going down different routes with playback but his understanding is wide. Like.. NO cd's... just straight from his phone socket music via pc type stuff - is that correct ?
His advice re valves is top draw and he's great to have on your shoulder.

I wondered a few weeks ago if he maybe was be watching this !!

Alpha section gets some updates soon plus my friend Kingwa of Audiogd has new developments which I'm trying out.
Won't be long

Andrew
Click to expand...

Ok :)

I hope I wasn't being a jerk or anything I'n my answer. That wasn't my intention.

Nice to have someone who with that kind of experience reading my thread :)
 
Mayday

Mayday

Member
Joined 2004
wlowes said:
I am no expert but I'll share my approach which is dead quiet. On a 1541a dac with 6n2p tube output cascade of star ground points mostly starting with each tube. In fact on the neg of the RCA output. Tube grounds all to this point on each channel. Dac ground also taken to same point on each channel. Nothing grounded to the case. I then take a fairly heavy ground wire back through the tube b+ filter and ultimately to the safety earth 3rd pin on the IEC plug. At that point and that point only the case is solidly grounded also to the safety ground. My understanding is you don't want current running around the case. It is just used for safety.

As I said, no expert. I defer to others better schooled than I.

Don't forget to ground
the dac
the rca
the b+ power
the filament power supply
the tube

all to the star ground. otherwise you'll get ground loops and hum.

I've done the dac and a couple of cdp's with tube output with this scheme. All dead quite with the volume on full and ear to the speaker. All you hear is some hiss which may be tube noise. Remember to keep ac lines short and away from DC. twist all your power wires nice and tight. Sometimes you need to move them around a little to eliminate a little noise, but no hum.
Good luck. When you first fire it up it will be lovely but tight and constrained. after 10 hours it will open up and after 100 hours it will be magic.
Click to expand...

Please explain the above to someone who someone with english as his second language(me) :eek:
 
Mayday

Mayday

Member
Joined 2004
One pair of braided silverinterconnects done. As I expected they "sound" great :D

DSC00748.jpg


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Hooked up to the SB for now...
DSC00754.jpg
 
A

AndrewGM

Member
Joined 2008
Mayday said:
Ok :)

I hope I wasn't being a jerk or anything I'n my answer. That wasn't my intention.

Nice to have someone who with that kind of experience reading my thread :)
Click to expand...

No no - not what I meant - no jerk.
He's just a guy who I owe a beer or two - he understands what he's doing - I just copy stuff and hope like hell !
But if it's a valves topic - I'd PM him first

Are you any closer now ?
 
Mayday

Mayday

Member
Joined 2004
No, not really.
Still waiting for the I/V resistors(got DALE, HOLCO and Amtrans AMRG comming), the BNC-male for the digitalcable...and?? Hmm, nothing that I can remember now.
Oh, the 4-pin chassis connector and plug that I'll use to connect both Wallwarts(24Vdc and 6Vdc) to the dac. These are for the ECC86.
 
Mayday

Mayday

Member
Joined 2004
This.
BNC_male.jpg


And gridstoppers, I/V-resistors and 4-pin male&female connector for the ECC86 PS is all I'm waiting for before I can test this DAC.

I hope with all my heart that it sounds good considering the extreme hours I've put into this build researching and finding the best parts.

Not to mention the cost compared to the kit....:eek:
 
Mayday

Mayday

Member
Joined 2004
Mayday said:
I have ordered 220R 0,25W Allen Bradley carbon film resistors.
Any value between 100R and 1K should work fine they say.

I'll also buy some more ETFE-cable from a friend who'll send some more resistors along with the cable.
Click to expand...

Got some more of this amazingly easy to work with cable comming along with four low-inductive gridstoppers from my friend. So now I'm set for gridstoppers for a while since I've gott 10pcs of 220R Allen Bradley Carbonfilm 1/4W resistors on the way too.
 
T

Torchwood421

Member
Joined 2011
Good progress

Hi Jonas, Getting closer everyday I see. Well I finished the Pedja I/V. Afraid I may have toasted the AD844's.... One small error in the DAC nulling circuit. Fixed that and the output nulls just no signal.... Didn't hurt my S1 Crown DAC is the good news. I may convert to a standard I/V with a standard opamp just to make sure it works. Well I guess I need to expect a few mistakes along the way. This is a hobby. Well wishing you luck on firing up your DAC. I will help you if I can. Dave
 
Mayday

Mayday

Member
Joined 2004
Braided the first of another pair of silver interconnects. This time I used 4x0,6mm pure silverwire in PTFE-tubing. It was a bit harder to braid the thicker and stiffer wire. Doesn't really show in the pics, but the connectors take up to 10mm cable so they are rather sturdy.

DSC00780.jpg

DSC00778.jpg
 
Mayday

Mayday

Member
Joined 2004
Gridstoppers in place.
An externally hosted image should be here but it was not working when we last tested it.


The wires that dissappear out of the picture is for heaters, they will be twisted and connected to chassis connector. All that't left to do on the socket is to solder the wires to the plates.
An externally hosted image should be here but it was not working when we last tested it.


Wires to be connected to plates
An externally hosted image should be here but it was not working when we last tested it.
 
Mayday

Mayday

Member
Joined 2004
Got the BNC-male today, had to modify it to make the cable fit
DSC00796.jpg

DSC00795.jpg


Put all IC's in. 500mA fuse blew straight away. 1A Fast fuse doesn't blow. SAA7220P/B gets a little hot, but that's normal right?

Dare I connect it to the stereo considering the 500mA fuse blew?
Sure the transformer is 60VA and PS caps are 40000uF, could this be the reason the 500mA fuse blew?
An externally hosted image should be here but it was not working when we last tested it.
 
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