Unknown EC (Electrocompaniet) Model from AW (Ampliwire) Series

[tiefbassuebertr]

The attached images show the device, that is in question. No sticker on rear and no naming on the front regarding the model (only the brand name is to read on front).
The amplifier was purchased between 1981 and 1983 in brandnew condition. On rear panel is to find only a white sticker with the number 8646 - the serial number - so I think (in the same kind as to see on the forth and fifth image from attachment, but without the blue stickers).

Maybe with help of the serial-No 8646 (which is also to find on a second sticker on the bottom plate) and the year of purchase in not used condition it is possible to say from any member, what is the associated model naming. Thank you very much in advance.

As you can see on the images from follow URLs there are five different models without model naming on the front and rear panel. Only later manufactured power amp devices from the models "AW-65" and "AW-100" show the model naming below the brand name on the front panel and from AW-II and AW-IIa on the rear panel.

URLs from AW-1
https://www.ricardo.ch/de/a/xxx-rare-electrocompaniet-'ampliwire'-1138733358/
https://megazakaz.com/ebay/product/154520059918
URLs from AW-II
https://www.diyaudio.com/community/threads/fs-electrocompaniet-amp-preamp.386118/
https://sorscha.org/Content/html/Specials/AW-II-html/html/AW-II.html
https://www.aussieaudiomart.com/det...-ampliwire-ii-power-amplifier/images/1396055/
https://www.ukaudiomart.com/details...-ampliwire-ii-power-amplifier/images/1396051/
https://www.dba.dk/effektforstaerker/id-1104299504/
URLs from AW-IIa
http://www.audiotecnico.it/riparazi...liwire_IIa/Electrocompaniet_Ampliwire_IIa.htm
https://www.audiocircle.com/index.php?topic=185472.0
URLs from AW-65
https://www.classicaudio.fi/product/electrocompaniet-aw65-ec-1-paate-ja-etuvahvistin/
https://www.hifiengine.com/manual_library/electrocompaniet/aw-65.shtml
https://www.usaudiomart.com/details...paniet-ampliwire-65-amplifier/images/2818978/
URLs from AW-100
https://allegrolokalnie.pl/oferta/electrocompaniet-aw-100
https://www.kleinanzeigen.de/s-anze...MI7qHhmvbigwMV5pSDBx03Zg9-EAQYASABEgLCCPD_BwE

 

[tiefbassuebertr]

here some images of the model "Ampliwire II" "Ampliwire IIa" and "Ampliwire 100" (last image), which looks inside similar to those from the model in question, but without model naming to read on the device itself

 

[tiefbassuebertr]

Maybe with help of the serial-No 8646 (which is also to find on a second sticker on the bottom plate) and the year of purchase in not used condition it is possible to say from any member, what is the associated model naming. Thank you very much in advance.

There is a second sticker below those with serial No "8646" (go to the first image of post #1) :
I read there this: "13/12 b4" and "12 G"
This may be further important information to be able to say which model in question it is.

 

[Dante]

Hi,
These amplifier is the Ampliwire IIa, second generation.
The first generation (Ampliwire II) haved the BD911 and BD 912 TO-220 as output transistors, directly soldered to PCB.
The second generation (Ampliwire IIa) haved the 2SA1141 and 2SC2681 TO-247 (much bigger) placed under the PCB and connected with wires to the circuit.
Finally, the third and last generation haved the output transistors soldered directly to the circuit with a newer PCB. The same PCB used in the AW65.
Hope this will help you.

 

[Boydk]

Don´t really have a clue on these models, but just to show you, that Per Abrahamsen also had some sense of humor,
when designing his PCB´s.
This is the EC 1301 mkII. Anyway, you have to be a technician and take it apart to se this 🤣 🤣 :

 

[Dante]

@Boydk
You make my day 🤣🤣🤣

 

[Boydk]

@Dante
Happy to be able to ........... 🤣 🤣 🤣

 

[tiefbassuebertr]

Hi,
These amplifier is the Ampliwire IIa, second generation.
The first generation (Ampliwire II) haved the BD911 and BD 912 TO-220 as output transistors, directly soldered to PCB.
The second generation (Ampliwire IIa) haved the 2SA1141 and 2SC2681 TO-247 (much bigger) placed under the PCB and connected with wires to the circuit.
Finally, the third and last generation haved the output transistors soldered directly to the circuit with a newer PCB. The same PCB used in the AW65.
Hope this will help you.

good information - thank you very much.
What is interesting is that on the device from images in this post one can clearly see the type designation on both the sticker at the back plate and on the sticker on the bottom, while on the device in question (image No 1 in post #1) one only see the stickers already mentioned without this model information.
I am looking for the schematic of the periphery (inrush current limiter, voltage regulators for front-ends and the speaker protect relay driver etc.).
Maybe one of the member can post it or know, from which other model this is the same.
https://www.diyaudio.com/community/threads/transformer-output-in-phase-and-out-of-phase.387540/

 

[Dante]

Hi,
Yes, before 1983-1984, Electrocompaniet did not have a serious sticker for the serial number and model number. Only latest Ampliwire IIa have a more robust ones and beyond. I personally have six of these babies and only two of them have serial number, none on the others.
Actually, I am in the process of completely rebuilding them with new PCB circuit, new PSU and soft start. All of those enhancement make a lot of difference in the sound. All the qualities without all the default.
Is it your amplifier in the pictures that you've send in your latest post?

 

[tiefbassuebertr]

No, but this pictures show identical power amp PCB's. Pictures from my amplifier (actually from a friend) are to find in the first three images from post #1.

If you realize a new PCB circuit, the URL under
https://www.renardson-audio.com
and
https://linearaudio.net/sites/linearaudio.net/files/renardson new class B.pdf
provide some helpful hints.

If one use only the inverted power amp section with signal input on R18 - 390 ohms (= input resistance), i. e. without the previous transconductance amplifier the sonic quality is much more better than with this transconductance amplifier (most easy modification step)
The low input resistance of 390 ohms is only an issue, if you use a preamplifier with tubes and high output impedance.
In general medium input impedance is rather an advantage, because the influence to the sound quality through cable character of RCA signal cables is considerably lower.
P.S.: until this day I haven't understand, why this additional transconductance amplifier in serial connection should provide advantages resp. improvements in sound quality.

 

[Dante]

Hi,
Thanks for the URL, I apreciate but my PCB are already built, but for others projects, who knows.
If I look at your amplifier (picture number 3), I saw a lot of capacitor added to the main board. Could you explain to me those modifications ?
Also I note that the MPQ2484 was replaced with four single transistor. I hope that you have match them. And what is the value of the bias you are using ?

 

[Guerilla]

Wonderfull wonderfull stuf those EC. Best sound Ive heard was a few years newer fronted by Oracle Delphi and drivinf Cerwin Vega AT-40!!! Might just buy a set of VC-40 up for 90 dollars amp included. Those are supposed to be even better.
Cheers!

 

[Dante]

Very wonderfull Indeed. And much better in Mono Bloc Mode. Simply stunning.

 

[tiefbassuebertr]

Hi,
Thanks for the URL, I apreciate but my PCB are already built, but for others projects, who knows.
If I look at your amplifier (picture number 3), I saw a lot of capacitor added to the main board. Could you explain to me those modifications ?
Also I note that the MPQ2484 was replaced with four single transistor. I hope that you have match them. And what is the value of the bias you are using ?

This modification was from me - unfortunately 20 years ago. Probably additional caps for the reference currents (for the associated current sources).
The old genuine documentation incl. two schematic variantes from Electrocompaniet (ordered in 1985) I don't find currently - there I have all details explain.

 

[Studley]

Very wonderfull Indeed. And much better in Mono Bloc Mode. Simply stunning.

Which model did you have in mind please when you said this?

 

[Dante]

Electrocompaniet Ampliwire IIA in mono bloc mode and heavily modified