Feeler: an "Eee-Zzz" christmas present...ez1073 and ez1073-500

[Slenderchap]

Looks correct for 230v operation.

Colin
www.audiomaintenance.com

 

[Ninuz]

After spending quite some time trying to find the problems of my 4 units it seemed to be a stupid one.
The fuses I been buying from a big supplier here in Sweden ( Kjell & Company ) were the ones of bad quality even it the specifiactiones were right. Blown around 25 of them and after getting some Schurter fuses of better quality my 4 units have been working without problems.
Calibrated them and they all work like they should and sounds wonderfull. Big headroom, very pleasant sounding Eq and very quiet. 
Thanks everybody for helping answers. Specially Colin...and thanks for a very nice product.
Will post some pictures of the finished units soon

Sorry

That is correct for 220/240v operation..... it should only take about 15mA from the mains so a 100mA Slow Blow should be OK

Do you have a bench power supply with current limiting outputs ?

If you can.... power up your unit using the DC feed spade terminals and limit the bench power suply to about 400mA at 24v..... see if it power up OK..... this way you will know if the fault is in the audio circuit or power supply circuit.

Also check that the case of teh 2N3055 isn't shorted to the analogue ground plane..... the screw pad is only just big enough for the shakeproof washer.

Colin Adshead
www.audiomaintenance.com

I been putting some time aside to try and get 2 of my units to work but still get blown 100mA fuses.
The 48v rail works fine with the rail connected to the secondary wires from the main trafo as long as I don't have the white 24v cables connected to the PCB.
I got a bench power supply to Feed the 24v tab limiting to 400mA as Colin recommended and then I get the power led glowing.
Feeding the 24v rail I get a current draw of around 100mA without adjusting the BIAS Output.
Yesterday I tried connecting Line audio through both units one att a time and both units seems like they work as they should including the EQ section. This was done taking 48v from the main trafo and 24v from the bench supply.
I measured the white cables ( sec trafo ) and get around 27v AC
From this I suppose the problem is somewhere between the main trafo and the 24v tab. Looked for shorts and components placed facing the wrong side but can't find anything wrong there.
Any suggestions anybody? Places to measure or other tips?
Would really like to get them racked up so I can start using them.

Thanks in advance!

Sorry for nagging all of you
Anybody with any thoughts on my problem?
Have all 4 units with the same problem so Im wondering if the problem is in the PSU Wire'ing. They are all blowing fuses immediatly when the main transformer is conected to the main power outlet ( 240v ). Fuses used 100mA slow blow. 
Att this point I even tried to feed current with my Lab Power Supply all the way back att the + point on the bridge rectifier on the 24 DC rail. I get the unit working powering this way with the 2 white transformer wires diskonekted. All the units are taking around 100mA in current. With the Lab power supply I get no indikations of problems.
Att the same time I do have the 2 red wires on the 48 rail connected to the main transformer and getting the "power ok LED" to light upp.
Any thoughts?

 

[Ninuz]

2 of my finished units.

 

[Ninuz]

And all 4 units but missing some knobs...

 

[BryanJHarris]

are you not doing the 500 series kits anymore?

 

[Aaronrash]

are you not doing the 500 series kits anymore?

No longer available. They are a commercial product now. Check on vintageking

 

[pfandlermichael]

Hey my name is Michael and I´m new here.

I built the EZ1073 as my first bigger project and so far it sounds amazing (thanks Colin!).

But I have one problem:

There is a crackling noise when I switch to Mic. It´s not there when I select Line.
Moreover it´s just there when I switch on the 48V-Phantom Power. First it´s louder and within some seconds it gets quieter but it doesn´t go away completely.
The crackling is louder if there is no microphone connected to the Preamp and gets quieter as I connect the microphone but still doesn´t go away completely.
To me that sounds like there´s a problem in the Mic-Section or the Phantom Power-Section.

I checked everything for dry solder joints (re-soldered every joint) but it didn´t fix the problem.

As I first turn on the Preamp there was smoke from the r23 because of a short in the 2N3055 and it´s heatsink, but I fixed this and changed the resistor.
Is there a chance that the crackling problem has something to do with that?

Has anybody an idea what to check next?
I have a basic multimeter so I can measure some components but I don´t realy know where to start.


Greets
Michael

 

[Aaronrash]

Well guys my 1073s are done! They have been for a while but I've been having too much fun with them to post. So a few things I did differently. I used polystyrene in all the gain stages and opamps... As well as tantalum capacitors and since I'm a Neve freak I ordered fairchild BC184Cs all over 600hfe from a Neve tech.

I can crank this thing all the way with absolutely zero noise. I haven't got a chance to compare them to a vintage unit yet but believe me I will. Also grounding the unit properly makes a big difference. I noticed the noise floor dropped after grounding the xlr jacks to star ground.

I have to thank Dan for the incredible cases he custom made me. We worked back and forth over email for nearly 2 months to make them, he's gotta be the coolest diy guy around here... So thanks Dan

I gotta thank Collin too for creating such a easy straightforward kit. It was a blast to build and they both fired up with no issues... So people with hum issues check your solder joints and make sure you ground things properly.

 

[Aaronrash]

Picture 2

 

[dane999]

Hi there,
I've got a problem with my ez1073. I finished the build, calibration went very well, no problem, all voltages checked ok. At first, the bias adjustment went fine, but after a while something went wrong with my output stage. I had scratches which came I guess from a wrong contact of the 2N3055, but sound. Then a strange sound, and then next to nothing…
(The sound can be heard here : http://pygmeestudio.wordpress.com/2013/11/22/1073-test/ )
I swapped the 2N3055 that died because of a wrong contact between the case and the pcb. This fixed the scratches.

My problem is now that I can't set the output bias, it's stuck at +/- 340mV, as it was after the crash, and the 48V rail, which also worked fine before can't go above 47,1V now.
Other symptoms are a very very low output level with intermittent hum, and the fuse blowing when I try to measure output bias across r26 (sparks appear before that…). I'm running it at 230V through a filtered block…
Gain switches and EQ seem to work fine, and this happens both on mic and line inputs…
Something else than the 2N3055 must have been damaged but I can't figure out what it could be, could someone please help me with that ?
Thanks for your time and help !
Cheers !

 

[dane999]

I tried to find by myself everything my small knowledge allows me, rechecked every solder, every resistor, AC transformer wiring and input transformer feeding, tracked signal, hunted shorts everywhere, and still have the same problem. It can't be something very complicated, because I'm kind of a noob, and because the most part of the circuit seem to work fine.
I'm really sorry to annoy you with that, but I think I really need some help, and hope I can be helped…

 

[dane999]

Allright, the machine works fine now  8). Somehow R26 was connected to the ground plane, causing all the trouble… EQ is very very nice, and the pre fabulous… Thanks a lot Slenderchap for making these !

 

[stribor1]

Just finalizing my built, go the collective case and have some problems. The  grayhill/bourns holes in the front panel are not countersunk so I end up having the PCB pretty close to the front panel in order to have sufficient threads to mount the nuts. Because of that there is not enough clearance and the grayhill/bourns pins touch the bottom plate. Anyone else encountered this problem?
Of course I could route out  the 14mm countersunk holes but the faceplate is already painted and I'm afraid the paint will chip...

 

[dacapitan]

Hey my name is Michael and I´m new here.

I built the EZ1073 as my first bigger project and so far it sounds amazing (thanks Colin!).

But I have one problem:

There is a crackling noise when I switch to Mic. It´s not there when I select Line.
Moreover it´s just there when I switch on the 48V-Phantom Power. First it´s louder and within some seconds it gets quieter but it doesn´t go away completely.
The crackling is louder if there is no microphone connected to the Preamp and gets quieter as I connect the microphone but still doesn´t go away completely.
To me that sounds like there´s a problem in the Mic-Section or the Phantom Power-Section.

I checked everything for dry solder joints (re-soldered every joint) but it didn´t fix the problem.

As I first turn on the Preamp there was smoke from the r23 because of a short in the 2N3055 and it´s heatsink, but I fixed this and changed the resistor.
Is there a chance that the crackling problem has something to do with that?

Has anybody an idea what to check next?
I have a basic multimeter so I can measure some components but I don´t realy know where to start.


Greets
Michael

I have this exact same problem  - is there any solution?

 

[stribor1]

Just finalizing my built, go the collective case and have some problems. The  grayhill/bourns holes in the front panel are not countersunk so I end up having the PCB pretty close to the front panel in order to have sufficient threads to mount the nuts. Because of that there is not enough clearance and the grayhill/bourns pins touch the bottom plate. Anyone else encountered this problem?
Of course I could route out  the 14mm countersunk holes but the faceplate is already painted and I'm afraid the paint will chip...

Nevermind, tweaked it out. Anyhow, power is up! Measuremnts are OK, ez calibration (130mV across R26) done, time for a test drive....

 

[stribor1]

Sound check passed! The low mid section of the EQ is amazing!

 

[Aaronrash]

Lol,

Dan gave you my Silkscreen design

 

[stribor1]

Lol,

Dan gave you my Silkscreen design

I noticed it was a little different form the design posted on his webpage. I hope I can get another one like that, now that I've tried it I want to have a pair.....

 

[olebrom]

Hi,

I am just about to get starter on my ez1073 build and I was wondering if anyone on this thread has done a A/B test with a Vintage or AMS 1073 vs. the ez1073. I just saw this thread :  http://groupdiy.com/index.php?topic=54748.60  and it got me a little bit curious. Anyone else on this thread experiencing what Aaronrash is having troubles with? So far i have only heard good things about this project

 

[stribor1]

Did some more tests with my ez1073, I really like this pre. Can't compare it to an original, but I like it better on guitars then the 312 I have (API A2D). Great low mids. The EQ is also very useful, it really shines in the lower freqs.
A short clip of some electric guitars: sm57-ez1073 (EQ off) through a RME multiface into cubase. right channel is dry, left is a lexicon hall plugin (a little bit too much hall..)
   
https://dl.dropboxusercontent.com/u/27310277/The%20Beast%2063%20PAF%207.7.k.mp3