D-AOC PCBs - the building and help Thread

[Peter A]

Hi

Thanks for doing the test Volker.

I'm not sure what to make of it. Does the test sugest to much hf roll off from the Edcor transformers??

Best regards

Peter

 

[[silent:arts]]

[quote author="Peter A"]I'm not sure what to make of it. Does the test sugest to much hf roll off from the Edcor transformers ??[/quote]
Peter,
the test shows too much hf roll off in this circuit, in my opinion.
but this is only measuring - may be the sound is right, or the combination with an output transformer, or while compressing :grin:
too many options to measure all combinations.
take this charts just as an idea what each part can do.
choose what ever you think it fits your need (on paper, or sound-wise)
anybody is welcome to post his result and opinions after the build :thumb:

 

[Purusha]

EDCOR WMS goes over 20KHz, do we hear the difference from 20KHz to 40KHz at all?

 

[[silent:arts]]

OUTPUT TRANSFORMERS

I have measured:
Edcor XSM10K/600, Edcor WSM600/10K backwards, an original NOS Haufe AÜ V74 and a (Altec) Peerless 15095. there have been a few others under test, but the circuit seams not to be sensitive to the output transformers.
anythings in the range of 10K:600 (4:1) will do.

forgot to take a photo, and lost the THD curves, sorry
but nothing special there.

FREQUENCY RESPONSE:

[edit: the 100R in the gif is 600R, of course]

PHASE SHIFT:

Measuring conditions:
no input transformer,
Output Potentiometer = 100%, Input Potentiometer set for +12dB gain without transformers.
Generator Level = 0dBu
Zout 15Ω, Zin 600R / 100K
no Zobel networks etc used, just the transformers

 

[rodabod]

That Edcor XSM isn't looking fantastic.... ~-3.3dB @10KHz, -6dB @20KHz for input.

As expected, the Lundahl really does perform well - funny how much better the distortion figure is from the rest of the group. I'm also surprised the Marinair/St. Ives did so well too.

 

[Peter A]

Well Edcor also makes the XS1100 which should be there alternative
to the Lundahll.
maybe this could be and option or perhaps the good ol' OEP's?

What dit bernbrue use in his proto?? His sound exsambles sounded nice.

best regards

Peter

 

[[silent:arts]]

[quote author="Peter A"]What dit bernbrue use in his proto?? His sound exsambles sounded nice.[/quote]
We will have to wait for bernbrue for this info - he is on vacation at the moment.

Can do some tests tomorrow with the XS1100 since I have one here.
for the OEPs - I don't own any.

but again - none of this measuring says anything about sound.
try it. like it. if not - change it.

 

[Purusha]

Volker, any chance to make a few simple sound samples?
Maybe Edcor WMS vs Lundahl vs Marianir?
This would really help all of us on the forum to decide what iron to order. :thumb:

 

[OneRoomStudio]

volker - can you try switching out the side chain tubes for something like 12at7 or 12ax7 and experimenting with some component values? A simple fix for the high threshold would be great.

 

[[silent:arts]]

Kubi was kind enough to send me this photo of his finished D-AOC, Frontpannel removed:

He already used it for tracking and mixing, loved it on Acoustic Guitar and Choirs.
Compared to the LA2A Kubi says the D-AOC is more inconspicuous and inaudible.
While mixing he missed his second D-AOC :green:

[since Kubi is in vacation he asked me to post this for him]

 

[Purusha]

Sounds fun, are those trafos on the photo Edcors?

 

[bernbrue]

Hi,
back from holiday. Here are some quick RMAA sine sweeps with various input transformer.

Pikatron ÜP 3910

EDCOR XS 1100

EDCOR XSM 10K 10K

Lundahl LL1521

OEP A262A2E

I finally took the Lundahls for my prototype, which is, except for the frontpanel not engraved yet, ready to go.
cheers
Bernd

 

[Purusha]

Lundahl LL1521, are you sure? I could not find these anywhere on the web...

 

[bernbrue]

Tat,
The LL1521 is a high impedance line input transformer, very similar to the LL1540 but with a slight stepup.
Turns ratio 1 + 1 : 2.28

Usage:

In+ pin 1 (left row, bottom pin when viewed from component side)
In- pin 3
connect pin 2 + pin 4

Out+ pin 5 (right row, bottom pin when viewed from component side)
Out- pin 8
Shields pin 6

LL1521 and LL1540 are pin compatible
regards
Bernd

 

[Purusha]

Thanks Bernd for the explanation. But where can I find some?
I could not find them even on the Lundahl official website.
I am just curious about their cost, the XS1100 look to have similar
curve and are cheap so Lundahls might be a nice option also but
it depends on the price.

 

[radiance]

[quote author="Purusha"]Thanks Bernd for the explanation. But where can I find some?
I could not find them even on the Lundahl official website.
.[/quote]

I don't think Lundahl makes those anymore. They where some for sale once at the black market..

Here more info about older types...

http://www.lundahl.se/old_types.html

 

[bernbrue]

TonydB had a whole bunch of them a few month ago, they are older, discontinued transformer, the LL1540 is almost the same. Try different input trannies and take the one you like best.
regards
Bernd

 

[bernbrue]

Hi,
for those who ordered the relay boards and don´t want to use the Neutrik XLR print but standard XLRs:

regards
Bernd

 

[[silent:arts]]

Bernd, great idea :thumb:

 

[PimD]

so easy, almost makes it a

moment
:thumb: