Aaronrash said:
Hi AE,
How are you setting this up. If you're just patching the EZ 1073 into a B283 card you etched it won't yield much of a difference even though there is one.
Hi aaron,
the original layout board got its own PSU, its own input/output transformers, and gain switch. It's a fully independant channel and doesn't share any part with the ez.
You also have to plate the cards.
Actually you don't have to if the copper layer is thick enough..the place where there is some current is the driver , about 100mA and standard 2oz material can handle it....some varnish can do it for the oxidation. If you really want to plate (since old neve boards are plated), I would recommend to use solder paste+paint burner like I do instead of chemical products. Those last ones just replace the copper with tin, meaning your layer thickness remains the same...kinda pointless regarding resistance decrease.
There is a entire other gain stage on the B284 did you etch that as well
if you look carefully you can see that my original layout board is 1 x ba283 AM and 2 x ba283 NV (meaning that I've got the other gain stage which is normally on the B284 board)
Also what transformers are you using? I am using the green can AMS transformers, as well as the AMS output transformers. Yes they say they are the same but I've already found differences in both during building and measuring.
Since I preferably wanted to compare the layout impact, I used the same parts between both units (meaning caps, resistors, transformers, but there are always some % error in value).
Regarding transformers, even between two carnhill with the same #part I could measure differences. especially with output Tx since the gap size is hard to reproduce.. so I'm not surprised that you could measure differences between blue cans and green ones. It doesn't necessarily mean that they're not the same #part. Yet for me it's another subject soundwise. Meaning I could'nt hear the differences I could measure between the output trannies....
Also If you're going Line instead of Mic the gain staging will be completely different and not yield the same results. All my test are MIC in. It's easier here because I use the same mic for all my test in the same room with the same converters. It's quick and easy to hear the differences between the two.
Well, if you carefully look the schem , you'll see that up to the 50dB position the mic input like the line input is just a voltage divider then an 283NV gain stage then the 2N3055 driver. The second 283NV gain stage is only used from 55 to 80db position (do you remember what position you used ?)
For a matter of reproductability I didn't want to use microphones. I used line input, the same converters, software delay/gain compension. Also quick and easy.
Now next step for me is to split a mic in the ez and in the original board at the same time using the mic input and a position over 50dB. I'll see if the layout is critical for that kind of use. My conclusion for the time being is that at line level it is not.
I have the EZ1073's back as well due to the case being damaged during shipping so while repairing the EZ units I ran test . I compared them directly to my AMS 1073. They sound different... Same exact sound and conclusion as before in my previous samples. It also sound's very different from the EZ1073.
Cool....do you feel like running the same test I did at line level (using line input) ?
On my side I'll do it using mic level...
