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

[innercityman]

Problem solved. In fact it was as simple as the connection with the molex on the PCB. I don't know why the wires are not clipping into the molex. It's supposed to be like this right? when you fit the wire inside withe the special pin, it clips on it ? I didn't hear any clip sound even with trying hard to put them in so, now that my unit is just working as it should, I think I'm gonna solder the wires coming from the XLRs to the board.

I look forward to build a second unit for stereo tracking or feed them with my mixer'x main output buss to get that warm sound on my mixes.

Thanks Colin for this project!

Pierrick

 

[U87610]

Hey Everyone!

Quick question for the group.  I have completed my build for the 1u rack ez1073 and am about to fire it up, but am concerned about a possible grounding issue.  The paint on my faceplate came slightly "pooled" in the through holes and was preventing the switches and greyhill's from fitting through the holes so I took a drill and carefully ground the paint down (using reverse and slow speed).  Although the pcb successfully fits in place now, there is continuity to ground on the greyhills and switches that is not present without the faceplate connected.

Will this cause any issues with the circuit?  Will I ruin the greyhill's if I fire it up?  I have everything else grounded to the star ground and am using nylon spacers.

Thanks!

Edit: So I checked for continuity between the pins on the greyhills and ground with the faceplate on and off and did not find any short to ground, so decided to risk it and fire it up since the rest of my build went without any problems.

So other than my light not coming on, the calibration was easy and the unit works perfectly!!

Thank you for putting this kit together Colin!  I am amazed at how incredible sounding this unit is.  I've not had a chance to work with an original 1073 or a clone (BAE, Vintech, etc)  but have a buddy who has a BAE and I'm planning on doing a shootout with his unit.  Either way, I'm really happy and can't wait to rack it and start mixing!!

I'll try to post pictures in a bit. 

 

[bobtheninja]

Hi all.

I'm putting together one of these units now and have a quick question:

the m3 nylon washers between the mic and line transformers and their small pcbs are too thick for me to be able to fit them between the transformer and the pcb and still get the screw to catch inside the transformer casings. Is this just me or is this a general problem? And how have you made them thinner if so? Sanding them down seems fiddly. Am I just too weak? Force them in hard?

Hmmm, questions question.

 

[phaedra74]

In the kit, you can find the m3 screw to fit it, without problem.....
take off the screw of the transformer and change it with the other similar screw (is simply a bit longer).

 

[bobtheninja]

Been a while since I logged in. Thank you for the reply. I already soldered the transformers in place without the spacers, and it seems to be fine, but I'll might unsolder them and do it properly again.

 

[TwentyTrees]

Hi all,

Just finished my 1U ez1073, and it's an absolute beauty! Huge congrats and thanks to Colin for such a quality piece of kit, and such a (relatively) easy build. It sounds *fantastic* - a wonderful compliment to my CAPI VP28s.

One point - picking up what Colin said about R134 connecting the bottom of the 'Trim' pot to ground, I've simply jumped that resistor with a snippet of wire (socketed) and the 'Trim' pot now attenuates down to silence at its full range.  I am assuming that's not going to cause any complications anywhere (can't see why it would) but if anyone thinks differently, please shout!

Like some other builders, I had problems with intermittent pops / crackles / static type noises on first test. That was a bad solder joint (or two) somewhere - I went over the whole board with a magnifying glass and redid any joint that looked wobbly, and it's fine now. The noise floor is insanely low.

I also (clearly) misread the schematics when I was planning my front panel, and had the 'EQ IN' and phase labels on the wrong side of the switch (doh!). Phase was an easy switch (simply flipped the pins in the molex header), and for the 'EQ IN' switch I just snipped the terminals and popped in some wires so that the switching matches the panel.

For the panel and the cases, I went with Frank at frontpanels.de. I've used Schaeffer a few times and this panel is every bit as good as their best from what I can see. The case itself is one of Frank's NRG 1U cases, and it's leagues ahead of the modushop cases I've used before - much more robust and user-friendly (on my previous modushop 1Us, the back panels actually bend when inserting XLRs, no chance of that happening here). Can't recommend highly enough.

For the knobs, I got some of the Chinese Marconi-style cheap - and the grub screws are mounted too high to bite on the very short pot and switch shafts. Have popped some random ones on for now, and will get some push-fit ones to tap for grub screws myself lower down where they'll bite properly.

OK, time to head off and sell those GAP Pre573s to fund a second ez1073!

Cheers,
Andy

 

[innercityman]

Hi everyone,

my unit was working perfectly, I did some very good recording takes with it but yesterday when trying to record some vocals I got an issue with the pre... Signal seems to be filtered, no lows and mid lows, only mids and highs... Really weird ! As I said, my unit was working well before. The line input signal is ok, eq is ok. EQ works on signal coming from the preamp but a big lack of lows...

Any ideas ?

 

[tmuikku]

Hi everyone,

my unit was working perfectly, I did some very good recording takes with it but yesterday when trying to record some vocals I got an issue with the pre... Signal seems to be filtered, no lows and mid lows, only mids and highs... Really weird ! As I said, my unit was working well before. The line input signal is ok, eq is ok. EQ works on signal coming from the preamp but a big lack of lows...

Any ideas ?

Hi, such sound can happen if one of the output transformer secondaries is floating so check your cabling. Also if it is a different device than before you are outputting to, it could have weird connector in it and leave other side of the signal floating. Check your cabling

 

[innercityman]

Also if it is a different device than before you are outputting to, it could have weird connector in it and leave other side of the signal floating. Check your cabling

Same device, I take the output from the ez1073 and plug it in one line input of my console, like I always did. I'll check my cables and let you know. The weird thing is that I only have this issue with the Mic Preamp, the line input works great.

 

[tmuikku]

ah sorry, then it must be issue in the mic pre. Hopefully some one following this can give you more help

 

[chrispsound]

Just recently hooked up a NTI MR-Pro Minirator to the MIC input of my ez1073.  In the 300(low Z) setting it is showing an input impedance 3.6k  at 1khZ.  Is this normal?

 

[chrispsound]

Just recently hooked up a NTI MR-Pro Minirator to the MIC input of my ez1073.  In the 300(low Z) setting it is showing an input impedance 3.6k  at 1khZ.  Is this normal?

Apparently(duh), in the 300 position, the mic input impedance is supposed to be 300 ohms and in the 1200 position its supposed to have an impedance of 1200 ohms.  I am getting 3.6k in 300 and 16k in 1200, but I can't for the life of me find a incorrect component.  Impedance is fine at the line in.  I am using a new MR-Pro for the readings.  Before I start pulling capacitors out and testing them, is there any place in particular that I should be looking?  The sad part in all of this is that I built this unit years ago, I have used it a lot and love it.  It would be nice to at least know how I modded it, haha.

 

[StillNotWorking]

R134 (5k1) effectively sets the bottom of the trim pot signal level....just imagine if it were zero ohms, then when the pot was fully counter-clockwise the wiper would be attached to ground (through the zero ohm link) and there would be no signal going into the stage 3 amplifier.... so for 30dB attenuation it would need to be somewhere between 0 Ohms and 5k1.... I'll let you calculate that !
...snip...

Colin
www.audiomaintenance.com

Reading this I’ve got the idea I could use a logarithmic scale pot for R149 so the Trim now function as a fader.

Not sure how good idea this is thought? As it looks to me R134 and R149, 15k1 in series also function as the load the passive HPF look into? If this is correct wouldn’t this also change the frequency response for the HPF when the Trim is altered?
Don’t own this preamp yet so wondering anyone are able to confirm or dismiss this?

thanks
Hans

Edit:  ahh, must include R135.  Then  trimmer variation on standard unit becomes 3k to 5k.  But still,  shorting R134/R135 and  replace R149 to 5k LOG how will that fare with the HPF?

 

[bobtheninja]

Hmm, just fired up my latest build of this and I'm having trouble with the +48V. It only goes to 19.6 V when measuring from J3 to J5.

https://www.dropbox.com/s/96gpd7dp9hu83ou/48vtoagnd.jpeg?dl=0

So I started to trace the problem and I find that I'm only getting 9 VAC from the toroidal transformer, and it should be 44 VAC according to the schematics when measuring from Agnd (J5) to the red cables coming from the toroidal transformer.

https://www.dropbox.com/s/1rb3ryy85kqocwm/redtoagnd.jpg?dl=0

When measuring from positive terminal of the voltage regulator (BR2), it increases to 21.6 VDC.

https://www.dropbox.com/s/mi5cjsn58qlawro/br2toagnd.jpg?dl=0

What have I done wrong? I'm on Norwegian power, so 220-240V from the outlet, probably closer to something like 235V. See under for a photo of my wiring from the fused and switched IEC to the toroidal transformer. Grey and purple are connected, and brown and blue goes to the iec. Earth goes to the chassis earth. Should be correct, right?

https://www.dropbox.com/s/6ymb582mimo8ni2/iecwiring.JPG?dl=0

Any help would be much appreciated!

Edit: can't get the photos to embed in the post, so you'll have to follow the urls, I guess.

 

[bobtheninja]

Humbly bumping this post. Can I safely assume that the toroidal transformer is bad if it gives voltage readings that are too low straight out of it's leads, or can the fault be later in the circuit?

Thanks

 

[Potato Cakes]

Pull the transformer and wire it directly to the the outlet (without injuring yourself) as it written on the transformer for your power and then measure the secondaries. If it's still reading too low then it's bad. Probably.

Thanks!

Paul

 

[Harpo]

Hmm, just fired up my latest build of this and I'm having trouble with the +48V. It only goes to 19.6 V when measuring from J3 to J5.

Double check resistor parts values, especially R12, R15, R18 and trimmer R10. One might be a decade off.

So I started to trace the problem and I find that I'm only getting 9 VAC from the toroidal transformer, and it should be 44 VAC according to the schematics when measuring from Agnd (J5) to the red cables coming from the toroidal transformer.

The cables coming from the toroid have no relation to Agnd (J5). Measure AC voltage across both red cables. These probably will measure fine (with a 9VAC feed you won't get 19.6VDC out).

When measuring from positive terminal of the voltage regulator (BR2), it increases to 21.6 VDC.

BR2 is a bridge rectifier, not a voltage regulator.
Keep in mind, both voltage regulators U1 and U2 are different parts and have a different pinout. Maybe look up their parts datasheet.
Good luck.

 

[Gbracam]

Hey guys,
The Mic pre and line input work nice and sound very clean, the problems I am having is with my EQ section.

1st, when I engage the EQ I get a slight buzz and hum. this is not that noticeable at first but as I increase the higher frequencies it become more noticeable.

2nd problem I have is with the high shelf EQ section. It seems to be turned down by default making everything sound muffled, as I increase the gain all the way to the right it almost sounds normal.

I never noticed this this problem before, any ideas why this is happening?

Thanks

 

[bobtheninja]

Double check resistor parts values, especially R12, R15, R18 and trimmer R10. One might be a decade off.
The cables coming from the toroid have no relation to Agnd (J5). Measure AC voltage across both red cables. These probably will measure fine (with a 9VAC feed you won't get 19.6VDC out).
BR2 is a bridge rectifier, not a voltage regulator.
Keep in mind, both voltage regulators U1 and U2 are different parts and have a different pinout. Maybe look up their parts datasheet.
Good luck.

Thank you for the reply, and my apologies for not writing earlier. I got a last minute mixing gig for a record with a deadline, so I ended up spending a lot of my time of that, and then summer came and family obligations. But now! Finally, I've found the time to drag out this project again.

So, I've desoldered and checked  R11, R15 & R18, and they all measure correctly, alas. I soldered them back in, and I've double-checked that the correct trimmers are where they should be, and that the same goes for the voltage regulators. So far everything seems to be in order. Hmm.

I measured across the red wires from the toroidal transformer and I get around 17.2 VAC. When measuring across the white wires from the toroidal transformer I get 21 VAC. See the attached pictures.

The toroidal also gets quite hot to the touch shortly after I switch on the circuit.

Any ideas? I'm sort of thinking that the toroidal is the culprit, but I also know that there's high chances of me being incompetent is the culprit  as well!

 

[bobtheninja]

...and when measuring across the white cables from the toroidal transformer