8 Channel, 3U NEVE 1073 completed

[mitsos]

It should, since it puts out 2A (in parallel).  Martin recommends 500mA per channel (this is with lots of headroom, Neve's original spec was around 120mA per channel). Anyway, 500mA x 4 = 2A, so you should be fine.

 

[promixe]

I don't know either of those PSUs (can't find anything on Igor's) but I would have connected both secondaries to both PSUs.

Right, but Igor's PSU design I think calls for a single 22-25 secondary rail connection. You either hook up a center-tapped 12-0-12 trafo, or single secondary 22-25 (which is what I did). FiveFish PSU however calls for 22-0-22 with centertap and both secondaries connected because of the 48V rail (it uses CT as ground and each of the 22VAC secondaries as + and - and then also uses the "-" secondary as the ground for the 48V rail). So if I used my 22-0-22 trafo and connected both secondaries to Igor's PSU, it'd shoot about 55-60VAC into the LM317 which at 1A I don't think it can handle thermally etc.

 

[mitsos]

I'm starting to get confused. You will not put out 50-60 volts unless you put the secondaries in series, or leave the "center tap" disconnected and use one of the other wires as 0 and the other as 24V. then you will have double the voltage. What I am saying, and I would verify this with Igor, is to connect the five fish as you have it. Then take the "center tap" and connect it to Igor's 0V or ground. Finally take the other 2 wires, join them and connect them to the + or whatever it's called on his PSU.

My only doubt is if this type of connection would create problems of it's own between the PSUs (like with the voltage doubler) and that's why I say ask Igor.

Or (don't know why I didn't think of this before) you could build the five fish supply with the 78s24 regulator which is capable of 2A. Or, if Owel uses adjustable regs take a look at the LM150 (3A regulator). Should be pin compatible, but double check. And also check with Owel if the board can handle the current. Then you could get rid of the second supply. (btw, have you tried running all 4 channels of the five fish supply as is?)

 

[promixe]

This is how I had it hooked up before the toroid kicked the bucket:

The output voltages were all correct. I haven't tried running 4 channels on a single FiveFish, but I ran 2 channels in my previous design and the +24V reg gets extremely hot in a short time, that's why I decided to take a load off of it by using the second PSU (Igor's one, which I had sitting around all assembled already).

 

[mitsos]

After reading your first post about this, it's likely the trafo is done. Does it work with just one PSU connected? In the 10 seconds before it overheats, can you check your voltages? You may have a short in one of the PSUs and that could be causing the trafo to overheat.

If not, get a new one and connect it the way I told you. The way you had it set up you are running all 4 channels of of one secondary (each secondary can only handle 1A, hence your troubles). 

You should connect both PSUs in parallel to the trafo. To do that you connect the fivefish the way you had it, take the CT to the 0V on Igor's PSU and then join AC1 and AC2 and take them to the other pad on Igor's PSU.  I THINK that would work, but if your trafo is done, then nothing will help. 

Sorry I'm bad at explaining things. That's why I did not become a teacher.

 

[promixe]

Mitsos, thanks for the suggestions! I'm getting new trafos tomorrow and I will test the way you described.

In the mean time, any other suggestions are welcome. Thanks!

 

[owel]

The secondary CT of the transformer becomes my GND connection.  

You said:

The way you wired it above, (connecting another PSU which treats one of the 22vac line as the GND, is you're creating a short in the secondaries of the transformer. Thus, the transformer gets hot after a few seconds. (and you may even fried it).

Use the Avel transformer for my PSU, and buy another transformer to connect to Igor's PSU. i.e. you need to have (2) toroid transformers. Then tie my PSU GND with Igor's PSU GND.

i.e. don't connect the transformer secondaries to both my PSU and Igor's PSU.

 

[promixe]

Owel, thank you for the clarification! I'll do a dual toroid setup as you are suggesting.

 

[pedroplanet]

I've just finished my 2ch easy 1290.
Everything is ok, no hum, no noise and nice sound.

I didn't take it to the studio yet because I couldn't calibrate the bias.

I don't have a scope and don't know anyone who could have one...

Does anybody have calibrated it with virtual oscilloscope softwares on PC or MAC?
I tried but the soundcard clipped before the preamp.
Then I used this HOSA atenuator ( http://www.directproaudio.com/product.cfm?directid=60155 ) on the preamp outputs. After using this attenuators, I could see irregular clipping but the trimpots don't seem to have any effect...

my question is:
Is it possible to calibrate it without a "real" oscilloscope? any tips on that?

 

[briomusic]

hi pedroplanet,
one thing I did find out when doing the bias (albeit with a real oscilloscope) is that it's best to clip the signal just a little, to the point where you just start seeing the flat bit at the top and/or bottom of the sign wave. you get a more precise result that way. I also found that while clipping it very hard, it was difficult to see the effect of the trimpot, so this might be what's happening on your end.
FWIW, I thought the EZ1290 sounded great even before doing the bias, but it turned out that I didn't have to change the trimpot that much.
hope this helps,
briomusic

 

[mkoz]

I've just finished my 2ch easy 1290.
Everything is ok, no hum, no noise and nice sound.

I didn't take it to the studio yet because I couldn't calibrate the bias.

I don't have a scope and don't know anyone who could have one...

my question is:
Is it possible to calibrate it without a "real" oscilloscope? any tips on that?

Take it to the studio, feed it a sine wave signal from Pro Tools, adjust the gain until you get the appropriate signal level, start recording the output, maximize the track view, and monitor the waveform on the screen in chase mode while adjusting the trimpot.

Never as precise as a scope sure enough, but if push came to shove, it does the job.

B.

 

[pedroplanet]

one thing I did find out when doing the bias (albeit with a real oscilloscope) is that it's best to clip the signal just a little, to the point where you just start seeing the flat bit at the top and/or bottom of the sign wave. you get a more precise result that way. I also found that while clipping it very hard, it was difficult to see the effect of the trimpot, so this might be what's happening on your end.

Thank you Barish!

I could make it using "SignalScope PRO" for mac and a HOSA attenuator(pad) after the preamp outputs
It seems ok now but I haven't tested it on a real recording session

I'm trying a different approach on the front pannel, It's acrylic over a transparency layer and backlights.

My goal would be making a luminous pannel, but the backlight stuff is not ready yet, here are some pics:

 

[pedroplanet]

and inside

 

[gerardmanvuca]

Well, thus far, i've completed populating 8 cards(nearly passing out a few times)...and managed to get one hooked up.

.....Punchy as 'hell'....with just vocals, full sound, lots of gain...sounds really good.
Everything is pretty much on hold until i get frontpanel done. $220...youch...

Yo Desol! nice lookin boards.. was wondering wat caps those are? they are different from the BOM ones and look more like the type used by chandler and old neves ive seen with open hoods. do they sound better than the BOM ones?

 

[desol]

Not sure how they sound in comparison. The blue cap's are the well known BC type, vishay axial tantalums, pansonic carbon films(1/2 watt and 1/4 watt), motorola 3055's and styroflex poly's. The tantalums and bc's were pricey, but whatever. The carbon film's countered it a bit.

Close to getting the frontpanel etch'd, so till then cards are sitting. Shielding plates being made up...etc.
She's slowly gettin done.


EDIT: Also thought to add, I got the frontpanel price down to around $110. I had some things messed up in the software. So, not too bad a price considering.

 

[tazwolf]

Hi !
Just built two EZ1290's in one 1U rack with a seperate box for a JLM AC/DC. so far so good - they work fine. From the AC/DC i have +24 and +48 with a common ground as it shows in the build pdf. problem is when I try to connect a Igors DI - I've started by connecting up just one of the 1290s with the DI, however the way i have done it the R56 12ohm resistor starts to smoke on the EZ1290 board.

I don't know if i should ask here or in the Igor DI thread, so i hope its ok that I ask here.

The igor Di PSU connection has 24v, 0, 0, 48 so I have shorted the two 0v on the Di board with the one ov I have coming from the AC/DC.

Has anybody used this combination of ACDC, EZ1290 and Igor DI and can tell me what I am doing wrong? The other pre in the same box without the DI connected (yet) works fine and no 12R (R56) resistor burn.

Thanks

(/Taz

 

[trancedental]

AC/DC grounding scheme, the 0V on the JLM AC/DC is for audio ground

 

[tazwolf]

Transcendental - Thanks! That helped a lot!

 

[mrtrev]

Hi everyone, I'm new to the forum! Just ordered 4 boards from Martin & I can't wait to get my build going Loved seeing all your pics about your builds, awesome stuff you've all inspired me to give it a go!

 

[kambo]

you will be so glad