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

[bobtheninja]

I swapped out the toroidal transformer from one of my previous builds and as I suspected all voltages is fine now, and the unit is passing gorgeous sound (well, as gorgeous as it can get with me grunting into a mic). Problem solved. Thanks for your help, everyone.

 

[ilfungo]

Hi
I've bulit 2 AML 1073 kit.
GREAT GREAT SOUND!!!
GREAT KIT!!!
Only 2 questions:

I've noted that if I listen the eq at hight level when mid frequency is on  .36 and  .7 frequncy, there is hum  ( not at 1.6-3.2-4.8-7.2).
Same on hpf only at 50 and 80 ( less noise).
Have someone noticed the same problem?
I can't trim the phantom below 48.7 v
It's this on tollerance or can create some problem for the mic?
THANKS!!!


Thanks!!!

 

[samguaiana]

This sounds like a dumb question, but how... do you get the knobs off of the ez1073-500?  ;D

 

[Potato Cakes]

This sounds like a dumb question, but how... do you get the knobs off of the ez1073-500?  ;D

Aren't they collet style knobs? You would remove the cap and unscrew it from the inside.

Thanks!

Paul

 

[untune]

Hello all; I thought it might be better to ask here than start a new topic. I've built the ez1073 rack version and tested it. Everything seems to function just fine apart from one thing - the last five clicks of travel on the MIC GAIN pot do not pass any signal. The previous ones all gradually increase the gain, but then it goes silent. My first thought was that I put the stop pin in when the switch was in the wrong position (I didn't actually note the orientation before doing so but I believe it was unchanged.)  Given that there is only the one pin in the mic gain switch (12 positions), I'm guessing that this will actually make no difference, and the problem lies with the soldering somewhere - possibly the first gain stage.  Can anyone offer any insight?

Cheers

 

[Potato Cakes]

Bad solder joint on switch or gain resistors.

Thanks!

Paul

 

[untune]

Thanks Paul - I remember the switch seemed to be fine when I did it but some resistors were a pain. I've isolated the likely suspects from the schematic and will take a closer look.

Cheers!

 

[untune]

Getting on for 4am and I've tried everything I can think of - checked the area around the gain switch, resoldered anything that looked like it was a bit off and still the same problem persists.  Nothing for the last 5 positions of the mic gain switch. Still assuming it can't be the stop pin... duff component perhaps?

 

[Potato Cakes]

You can take a multi meter and see if you get continuity between the pole and the positions in question on the switch. If they seem fine then we're back to the bad solder joint around the gain switch section. Keeping looking at the schematic and follow signal path.

It's unlikely it's the switch but not impossible.

Thanks!

Paul

 

[kante1603]

It's unlikely it's the switch but not impossible.

Thanks!

Paul

Absoluteley,I remember when I got my first Grayhill ages ago and fooled around with it.......had some hard times to get it back to work since there was nearly nothing to find in the internet about how to set it right.....and nothing to get it back to normal!
In case you want to check this here's how it works including removing a stop pin

https://www.dripelectronics.com/new-blog/2016/9/23/setting-stops-in-your-greyhill-71-series


Best regards,


Udo.

 

[untune]

Thanks guys, I tried again this morning and rechecked all major solder joints around the 1st stage. The switch pins actually did seem a bit sketchy, I retouched them and they are conducting properly but still no joy. I checked the three BC550s and they seem ok. If I shout loud against a dynamic mic I do get a very small signal through, not sure if that demonstrates anything though.

With the pins, since only the 12 o clock is set I imagine that can't be the issue, ie 5 positions not working.

Maybe a dodgy cap or something, I'll see if I can have another look tonight, but any other ideas welcome.

Cheers!

 

[leadpoisoning]

Thanks guys, I tried again this morning and rechecked all major solder joints around the 1st stage. The switch pins actually did seem a bit sketchy, I retouched them and they are conducting properly but still no joy. I checked the three BC550s and they seem ok. If I shout loud against a dynamic mic I do get a very small signal through, not sure if that demonstrates anything though.

With the pins, since only the 12 o clock is set I imagine that can't be the issue, ie 5 positions not working.

Maybe a dodgy cap or something, I'll see if I can have another look tonight, but any other ideas welcome.

Cheers!

Did you try following the circuit path through the attenuator resistor bank?? Could easily (most obviously) be something in there?

 

[leadpoisoning]

Phew - i spent a few evenings reading nearly EVERY ONE of these posts and commisserate with some of you for some of the problems you had or are having. I feel blessed for everything to have gone relatively smoothly - but wanted to add a couple experiences I had as well. Most of which were RIDICULOUS  oversights on my part since they were almost as obvious as having forgotten to plug in the power cord. I was so focussed on the tiny details that I was overlooking the major ones and lost a few nights over them.

First one: I was having a HELL of a time trying to calibrate the 48v circuit. I could only get it up to 32 something volts and the trimmer seemed to have NO EFFECT whatsoever on the circuit. (a few of these posts rang familiar to me). Turned out I'd SOMEHOW soldered the red trafo leads into the white sockets and vice versa (!!) - NO idea how i did that - maybe i was working on it with the board inverted (from the bottom) .... live and learn. Maybe because i wasn't EXPECTING to be able to make a mistake there - it made me less than vigilant (?) After switching them back - it fired right up and calibrated to 48v nicely.

Second:  one one of my two units - I simply COUDLN'T get my mic amp working no matter what - SOMETIMES i was getting a signal (though faint-ish) even when 'dialed up' ... and other times not. So i disassembled everything, pulled the board and started going over solder joints (was driving me a bit nuts because I'm usually quite pleased with my attention to detail in soldering!) - thinking there must have been a poorly wetted or bonded joint SOMEWHERE ... - i resoldered about 40 odd joints and even did a number of not-so-necessary joints on the top of theboard - when i noticed something .... I had COMPLETELY FORGOTTEN to solder the pins on the Carnhill transformer to the daughtercard (!!!!!!!). So i soldered those and stitched everything back up and what do you know??? A monster mic pre!!

Third: Here's a silly trap. When i first tried test firing my two units I'd mis-soldered and switched the hot and screen leads for my output jack - since I'd forgotten what it might mean that I'd flipped that jack 180 degrees on the back of the enclosure (have all my jacks oriented sidways due to space constraints behind my rack). So luckily no messed up or blown components etc ... just me being my own worst enemy ...

I'm so relieved now that I've gotten through these issues ... it's surprising what one can overlook. I don't know - maybe it's only me that has these problems. But I thought I'd share my experiences. Now to start working on my front panel and start the final assembly (not to mention figuring out the knob situation -too short shafts).

thanks everyone for sharing and feel free to reach out if you have questions on your build.

 

[untune]

Thanks again for the responses, lots of useful tips there from leadpoisoning.

The only error I made (which I spotted right after I'd done it) was that I was on autopilot doing the XLR connections and reversed the hot and screen on the output due to that one being male.  That, and I also missed the vias (which I thought could be the culprit but alas not!)

In terms of the resistor banks etc - going off the schematic it's probably no coincidence that the last 5 steps of the mic gain control go through gain stage 1, and nothing else does. SW2a (+50 to +70) all head that way, and then hit R92-95 attenuating +50 to +65 on the way out (SW2b). I'd expect some signal on at least one of those settings even if there was a funky resistor in that bank.

It's baffling because other than this, the rest of the unit is *perfect* - line in and gain are fine, EQ is all fine, switches and trim all fine, and the first steps of the mic gain are functioning as they should. I went over the resistors in gain stage 1 last night and they're all in the right places. I measured the resistances in circuit but that's not much use anyway. Electrolytics are all correct polarity, the transistors all tested ok.  I can't see it being a power issue, because stage 2 shares it. All I can do is inspect it all again and hope something stands out!

Cheers

 

[untune]

Solved this tonight... not entirely sure what did it exactly, but I retouched a couple more solder points and cleaned the whole area with IPA and a toothbrush - working perfectly now. Cheers for the help

 

[leadpoisoning]

Solved this tonight... not entirely sure what did it exactly, but I retouched a couple more solder points and cleaned the whole area with IPA and a toothbrush - working perfectly now. Cheers for the help

congratulations! just goes to show how important cautious work can be! I suspect that half the problems in this thread have the same solution....

 

[leadpoisoning]

the one other thing i would add - is DON'T BE CHEAP! Shell out for the prefabricated enclosures which a few are offering. I decided to do my own and probably spent even more than that for all the ancillary bits needed to do a decent job - but most importantly all the time lost trying to tweak this or that or having to order the wrong parts/supplies etc.  I underestimated also how difficult it was to get the drilling for the pot shafts JUST SO.  I ended up having to do quite a lot of remedial filing out of holes to get to where i needed to be. Not only that - but the lack of exactitude on my part (and I'm a PRETTY CAUTIOUS person) makes me worry about stress to the solder joints due to compression between the front plate holes and the pot shafts ... so ... just a word of caution from someone who's gone this way ... only do it if you absolutely need to for whatever reason ...

 

[miscend]

Has anyone built the ez1081-500 yet? 

Looks like a fun build but where is the EQ.

 

[TillM]

as you can see its just the preamp.
Maybe Colin can told us more about it.
I think he sell it not so long, last week I don't found it on his site.
But the price is a bang for the buck in my opinion.

 

[PeteC]

Hi everyone.  Tonight I just completed my 1u ez1073 build and calibrated.  Everything works perfectly first time - so really pleased with that.  However when I come to fit the pcb  into the collective cases 1u rack I find that there is no way it's going to fit without the bolts on the underside of the pcb fouling the bottom plate of the case.  When I look even closer I find that the front panel mounting holes
Look to be drilled too far down the faceplate.  There simply won't be any space to use standoffs etc under the pcb.  This is very disappointing as I waited a long time for U.K. Customs to clear my order from Dan.  I think it's just a duff case where the tolerances weren't being met by Dans supplier and its slipped through QA.    So now my only option seems to be to jointly house the 1073 inside a 3 unit rack case I have spare and have it housed with some other preamps and my headphone amp.  My question is really this - will the pcb be ok self supporting from all the pots and switches on the faceplate and if not then what can people suggest I do to support it if it's housed with other stuff inside a larger rack case?  Bit frustrated as I want to track either the ez1073 as soon as possible having heard what it can do tonight.  All ideas greatly welcomed    Cheers Pete