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

[Spadehead]

Someone has a similar issue in this thread so maybe check back a few pages?

Also were the small pins out into the grey hill switches with them rotated fully CCW? You may have one gain pot set one notch further on than it should be if this is the case....

Best of luck with it.

 

[leitrim_lad]

Hey thanks for the reply.. i think that was me who was having the issues a few pages back.. never got it resolved tho unfortunately

thanks

Someone has a similar issue in this thread so maybe check back a few pages?

Also were the small pins out into the grey hill switches with them rotated fully CCW? You may have one gain pot set one notch further on than it should be if this is the case....

Best of luck with it.

 

[leitrim_lad]

Also i dont think its a pin in the switch issue as im having the same issue on both the mic and line.. if it was a pin id only be having it on 1 of them i reckon.. could be wrong tho..

regards

 

[who]

i did a nice classic frontpanel design for this great project and here is the complete Rack kit:

http://www.don-audio.com/Frontpanel-DON-EZ1073
  Don

 

[ding]

Maybe someone can help me understand what just happened. Q4 was overheating and getting way too much voltage. After trouble shooting forever I found a tech in town. 2 months and $170 later he told me that the 2N3055 was not functioning because of the insulator between it and the heat sink. He removed the insulator and was able to bias properly. I'm confused.

 

[ding]

I am having difficulties with this project and I am hoping someone will be able to guide me. After my whole ordeal with the transistor insulator now the preamp passes audio as expected but the sound is missing all the low end. It has no hum but absolutly no low or high end. I am hoping that my output tranny is not fried. Anyone have this problem before? Anyone have any ideas on what can be going on?  Here is a quick sample. Preamp 1 is the ez1073, preamp 2 is the focusrite interface. I was pretty close to the mic so there is lots of proximity on the focusrite but absolutly no low end or high end on the ez1073.

https://soundcloud.com/palevoid/preamp-test

EDIT:
Ok, weird thing happened. I plug it into my interfece XLR to TRS and I get no low or high end. Plug it into the interface XLR to XLR and get a little of the high and low back. Not where it should be. I also get a bit more noise/hizz XLR to XRL. I guess I will have to take it to the studio at work and run it thru the protools interface and see what is really going on. Any opinions?

https://soundcloud.com/palevoid/preamp-test-2

 

[Deepdark]

hi guys

I build a unit for a friend and he used it for 2 months now and suddenly, there is no more sound coming out of the unit. The led still lit, so I guess it's after power supply. no smoke, nothing burned, everything was good before now. No special use, just vocal sessions. the unit is powered through a furman. I really don't know what it can be

 

[Deepdark]

ok little update. The trouble seems to sit in the trim pot area. When playing with the trim, the signal become intermittent. Could it be a defective pot or it's more like  a cold solder joint symptome?

 

[leitrim_lad]

Hey Colin. . So I checked the stage 2 circuit.. checked all resister value.. resoldered everything to make sure of no soldering issues but I'm still getting the same 4db more at the output trim.. would you have any other ideas? Thanks a million..

 

[RJS]

Hello,

I would like to add an LED to the phantom power switch so it lights when phantom power is switched on--or at least when the switch is in the on position.  Basically to help me avoid accidentally putting phantom power through my ribbon mic.  Are there any issues with adding an LED indicator to the phantom power switch, tapping off the 48v?  Will doing this effect the mics that need phantom power?  Should I get the voltage from somewhere else to power the LED.

Thanks,
Robert

 

[saxmonster]

Does phantom power really hurt ribbon mics?  Maybe the newer ones are ok with it but I guess the vintage ones might have issues with it.  I thought I read that it would be ok if it was left on.  I'll have to read  up on it.

 

[RJS]

Does phantom power really hurt ribbon mics?  Maybe the newer ones are ok with it but I guess the vintage ones might have issues with it.  I thought I read that it would be ok if it was left on.  I'll have to read  up on it.

It's an AEA R84, not a vintage one, but I've heard conflicting reports about possible damage, so I'd rather be safe then sorry.  Then again I could just be extra careful when using the preamp.  I guess I'm  just used to seeing something light up when I hit the phantom power button  ;D

 

[Spadehead]

I've had issues with ribbons and phantom before and it's well documented so not worth risking - especially with more expensive mics.

Cheap option is to just ascertain the switch "on" orientation and mark it somehow on the faceplate - maybe a small round sticker or some sort. It's what I've done and certainly avoids mistakes without going back to the workbench......

 

[ding]

ez1073 with no low end.  Anybody?  :'( My guess would be a bad transformer or cold solder on the transformer points but I have checked the solder points. Plus I am getting plenty of gain. Also a good amount of hiss  . If any of the transfos were shorted or if I had cold solder joints wouldn't I have loss of gain? Any ideas? please.

 

[Spadehead]

Someone had a similar issue a few pages back so have a look - are the switches oriented properly with the stoppers so you don't have the HPF engaged when you think it's off?

 

[ding]

Someone had a similar issue a few pages back so have a look - are the switches oriented properly with the stoppers so you don't have the HPF engaged when you think it's off?

Thanks for your help. Switches are oriented properly and I have lack off bass even when the eq is off.

 

[ding]

I noticed the hiss is irrelevant of my gain settings. it is always as loud. Both mic and line inputs sound similar. I did some measurements on the line input and also noticed a small dip in the high end.

Here is the hiss

Here is the sweep

Anyone ever run into this? I know it almost never is but could it be the output transformer? Any cap that would cause this? I have searched this forum well but have not found this problem here. Anything would help.  :'(

 

[burtoni]

Hi this is my first post..

I have built 6 AML units.. EZP-1A,  EZ2254 AND 4x EZ1073....

All went very smoothly and work fine until I got to my last 1073.. I get no LED, only 4v on the 48V tab, a hum and low level on the output.. and the 48V rectifier heat sink it red hot.

24v is fine and I was able to set the Output bias ok.

Sounds like some kind of short but I can't see anything visually. Anyone come across this

 

[Squeaky]

Hello Everyone. I have a problem similar to what has been mentioned here before.  The preamps (two of them) both fired up fine and I was able to get correct voltages and then audio passed fine, eqs worked, &c. Then I screwed everything fully in place in the cases (lids on and so on), plugged them in again, and I burnt out r23 (it smoked) on not just one but both preamps. Methodically, one after the other (in my infinite and bottomless stupidity) I sequentially killed both preamps. Given that they only just fit into the cases, (and one of the bobbins on the OT on one of them was a bit askew making it even worse) I have just assumed I have created a short somehow when I screwed the PCBs into their cases (they barely fit, if squeezing can be considered fitting). Just to be clear, the squeeze is top to bottom and it is only the OT that is in contact with the chassis.

My first thought always goes to killing the OT, probably because I always think the worse. The OT bobbin is definitely hard up against the chassis top, but I didn't think this would matter. This is my first PCB kit (not quite true, I bought a ua-175B PCB, which I subsequently threw away and built the thing on a turret board instead), so I find it hard to follow the ground, power and audio paths, because I didn't lay them out myself I guess.

I replaced r23 to no avail, and now I have the problem of 28mV - 29mV over r26 un-adjustable with r20, which is an open circuit in the output section I understand. I have ordered a few of transistors for replacement.

I think the screw to the heat sink on one of the 2n3055 transistors might have been in contact with the chassis creating a short? This wasn't the case on both pres though. This is my first foray into the transistor world, only valve projects before this. I am at a bit of loss. Might be time to get back to that V76 I was working on (daunting as that is).

I can't help thinking that I killed the OT, would anyone be able to suggest a way to test the OT on the board? Otherwise I'll just replace transistors in the output I suppose.

I'm really hoping I can sort this out because the little I heard of the operational pres was very promising.

 

[weiss]

I noticed the hiss is irrelevant of my gain settings. it is always as loud. Both mic and line inputs sound similar. I did some measurements on the line input and also noticed a small dip in the high end.

Hey can you tell me where to find this analyzer application? Is it free?

thanks
weiss