Siemens W295 modification question

[thomasdf]

Hi all

Be searching for a while and could not find any answer.., so I'll try!
Does anybody know if it is an easy mod to add a switch to a Siemens W295 in order to choose between boosting (stock) or cutting (mod) the mid frequencies? My units have the 2 little slider switches and can only boost by 2 dB steps the mid freqs.
I'd love to be able to cut these freqs by 2dB steps if needed.
I know the other W295s models do, and I tried comparing schematics... but was not very successful...

Thanks a lot

Thomas

 

[ruffrecords]

I had a look at the W495 schematic. The mid boost works by adding a parallel LCRl impedance to the part of the NFB network between the inverting input and ground of the output amplifier. I also looked at the W495B scehmatic which has mid cut as well as boost. It achieves boost the same way yours does. It achieves cut  by a passive cut circuit across the non-inverting input of the output amplifier. The the basic topology of the output amlifier is the same in both cases but the comoenent values are quite different. However, the LC values in both circuuits look almost identical.

The obvious solution is to rebuild the output amplifer so it is just like the W395B and switch your  boost network between boost and cut modes. Not the easy mod you were looking for I am afraid.

Cheers

Ian

 

[iprovlek]

I have W295 and W295b,and they are amazing sound Eq's!!!

Here is schematics of W295b if can help you!!!!

 

[iprovlek]

And w295!!!

 

[salomonander]

if i was you i would not bother. i use a w295b daily. but cutting mids is something i never did with it. might just be me...

 

[thomasdf]

Wow I didn't expect so many answers
Thanks a whole lot!

Indeed, it sounds like quite a complicated mod... So I will not risk it on these vintage units.
I compared the schematics from W295 and W295B. Lots of parts are identical, but they have different ways of feeding the output amp from the mid freq section indeed... That would mean being able to switch some component values as well... Sounds like trouble

I do not boost the mids quite often with this EQs as I feel the mid freq boost's Q is a little narrow to my taste.. Would be great for cutting some harshness from acoustic guitars or vocals from time to time but I have other tools to do that job...

Thanks again!!

 

[iprovlek]

I was always wondering is this Eq's can be renewed!?

There is one guy from this forum ,Etheory I think that his username,who start to remaking this Eq and never finished!


Dormel inductors are the hard parts to be replaceable in this Eq's and transformers,but I think that there is some way to find replace part for it!!!

 

[etheory]

There is one guy from this forum ,Etheory I think that his username,who start to remaking this Eq and never finished!

They're not really that complex, and I still intend on doing so at some point.
I've just had zero spare time for a few years running now, but I will definitely get around to it, I just can't say when.
I know a few people have run out of patience for some of the clones I'm working on, but that's the way it goes. I'll get there eventually.

 

[etheory]

Does anybody know if it is an easy mod to add a switch to a Siemens W295 in order to choose between boosting (stock) or cutting (mod) the mid frequencies?

If you look at the W295b version, you can see the key differences you'd need to make.

Basically you just want to rewire the W295 to be the same around the mid LCR section as the W295b.

 

[Adrianovanta]

i need some information about the big and the small coils called "Dr1" and "Dr2". Did someone have any kind of info? Thank you