LAWO DV975/3 15khz roll off question

Looking at the schematic from kubarth, are the small V1/V2 plugin boards
doing the roll off here ?
They're after the opamps and before the output transformers.
Part of the reason I ask is that two have arrived and on one board "V2" has
been sheared off in transit !!

I hope my assumption is correct and they can be removed/jumpered in the
same was as the matching Neumann V475's can.
Many thanks,
Marty.

Thank you Darius , so the V1/V2 boards are required, re the damaged one!
L1/L2 are small inductors correct ?
I'm having trouble seeing what V1/V2 are, is it a "goop" covered opamp on a
vertical board .....looks almost like SMD parts on it .... in 1982 !!

MM

Yes, the discrete op-amp on one side is snapped near the bottom :-(
They were well packed but it looks like one has banged into the other and
caused damage during postage ..... shit
I have sent a photo to the seller, so perhaps he will help me out, otherwise
is it possible to remove the "red paint" and perhaps fix the broken traces with some component lead and re-glue it ??

..... sad .....

MM

Bless you Darius, that's a very kind offer
I'll scrape the paint off and take photo's later this week.

PM'd you back.
Marty.

MartyMart said:

Bless you Darius, that's a very kind offer
I'll scrape the paint off and take photo's later this week.

PM'd you back.
Marty.

Click to expand...

Hi,

Just curious if your DV975 is alive'n'summing by now perhaps  .
Ran into such a card as well for a quick-to-build summer and
was wondering how your project has been so far.


Bye,

  Peter

Peter, I didn't get past a power up 'n test on the Lawo as yet !
They are very fine cards though .... not much DIY has happened in the last 6 months :-(
It's on my list .... but it's a long one !

MM.

MartyMart said:

Peter, I didn't get past a power up 'n test on the Lawo as yet !
They are very fine cards though .... not much DIY has happened in the last 6 months :-(
It's on my list .... but it's a long one !

MM.

Click to expand...

Hi MM,

I understand, a common situation 

BTW, does anyone happen to know what the difference is between the various versions of the DV975 ? There are variations w.r.t. the opamp-implementation (the -1 having the 'normal' components etc), but there's also the common -3 and also the -3S.
The DV975-3 & -4 are on Kubi's site, but the -3S variation I couldn't find info on.

Thanks,

  Peter

Peter, the versions relate to the maximum number of channels that the card can sum.
I think mine is the /2 version the details are in my pdf, which I think was from Kubi's site.

Regards,

Martin.

MartyMart said:

Peter, the versions relate to the maximum number of channels that the card can sum.
I think mine is the /2 version the details are in my pdf, which I think was from Kubi's site.

Regards,

Martin.

Click to expand...

Hi Martin,

Yep, the Kubi-Lawo-pdf details the various component values resulting in those /3 & /4 versions etc,
but the seller has both the /3 & /3S which made me curious. It won't be a big detail I figure,
perhaps just like all this external summing thing craze won't actually be too different probably
(but I wanted to experience it for myself, hence buying this card).

If nobody happens to know the '-S' difference then let's just say it's the -S of Special (Sonderausgabe  )

Bye,

  Peter

clintrubber said:

perhaps just like all this external summing thing craze won't actually be too different probably
(but I wanted to experience it for myself, hence buying this card).
Bye,

  Peter

Click to expand...

I feel the same way about it, it's a load of horse manure in reality, a great song well put together
with a good vibe and decent marketing can be a hit, even done in a bedroom totally ITB ( in the box )
AND it can sound really great too.
It's what you do with the tools you have and NOT what the tools are that makes all the difference.

MM.

Fully agreed. Cold soldering iron = no problem, can be more time spent actually playing music...

And w.r.t. OTB-summing... FWIW, the SOS-AMS-Neve-8816-review was pretty funny and sobering - at least about this summing box:

I tried remixing a variety of eight-track material — rock and pop, classical and choral — both internally in a SADiE System 5, and externally through the 8816. Technically, I couldn't really differentiate between the mixes, but sonically I favoured the 8816 every time! Annoyingly, though, mixing internally in the DAW and routing the stereo output through the 8816 seemed to have much the same effect and sonic benefit. It makes no sense to my head, but my ears like it all the same!

Click to expand...

8)

http://www.soundonsound.com/sos/aug06/articles/neve8816.htm

Makes one think that at least for this box internal or external summing doesn't matter much, as long as the stuff has been routed through this box.
Ha, having understood these Lawo-cards are clean, I guess we won't be getting much euphonic additions from our to-be-built-summers.  : ;D

Cheers,

  Peter

Ha - that's not the first time that SOS have said that, same thing happened with the Audient "SUMO"
box.
http://www.soundonsound.com/sos/feb06/articles/audientsumo.htm

Perhaps the answer ( if required ) is to either have something at the back end or have inserts, so  as to
be able to "add" some character to the stereo signal.

I thought the issue was the combining "in the computer" of all the "0's" and "1's" into a single stereo out !

RE: The neve box, a mate of mine who's a really good mix engineer bought one a few months ago, it
developed a fault and is still not back with him ( new replacement )
The "Loan machine" also has issues and cannot be turned off at all, as it is almost impossible to get it
to turn back on ! ( switch or relay probably )
Not too encouraging for a £2000 item of kit from a "name" !!!

MM.

Hi,

Indeed, I thought that the 'justification' for external summing
was always that 'as analog signals' it could be done in a more healthy
fashion than 'in digital'.   
Fun indeed that it seems to come down to just adding some analog grunge.

Haha, about time somebody writes a plug-in for External Summing EmulationTM ! 


Too bad that 8816 suffers those problems, I had a look at the demo-video etc
and it looked like a nice box, despite it's probably questionable relevance...

BTW, anybody knows how that mentioned transformer-summing is done in the Neve 8816 ?
Zero-ohms bus just like for instance the Lawo DV975 ?


Bye,

  Peter

clintrubber said:

Fully agreed. Cold soldering iron = no problem, can be more time spent actually playing music...

And w.r.t. OTB-summing... FWIW, the SOS-AMS-Neve-8816-review was pretty funny and sobering - at least about this summing box:

I tried remixing a variety of eight-track material — rock and pop, classical and choral — both internally in a SADiE System 5, and externally through the 8816. Technically, I couldn't really differentiate between the mixes, but sonically I favoured the 8816 every time! Annoyingly, though, mixing internally in the DAW and routing the stereo output through the 8816 seemed to have much the same effect and sonic benefit. It makes no sense to my head, but my ears like it all the same!

Click to expand...

8)

http://www.soundonsound.com/sos/aug06/articles/neve8816.htm

Makes one think that at least for this box internal or external summing doesn't matter much, as long as the stuff has been routed through this box.
Ha, having understood these Lawo-cards are clean, I guess we won't be getting much euphonic additions from our to-be-built-summers.  : ;D

Cheers,

  Peter

Click to expand...

Makes me think that the SOS reviewer accidentally left the WIDTH enhancement button engaged, which is IMO the best feature of the 8816. I would love to see a schematic and just extract the circuitry involved in that one feature (the block-schematic in the manual just has a big rectangle with "width control" written on it  : ).
I wonder if there are any DIY type people around who would wanna look into this...  8)

briomusic said:

Makes me think that the SOS reviewer accidentally left the WIDTH enhancement button engaged, which is IMO the best feature of the 8816. I would love to see a schematic and just extract the circuitry involved in that one feature (the block-schematic in the manual just has a big rectangle with "width control" written on it  : ).
I wonder if there are any DIY type people around who would wanna look into this...  8)

Click to expand...

I'm not familiar with this unit, but I'd take a look into M/S encoders and decoders...

clintrubber said:

Haha, about time somebody writes a plug-in for External Summing EmulationTM ! 

Click to expand...

OMG/haha what a world, I recently saw there is indeed already such a thing around.  ;D

clintrubber said:

clintrubber said:

Haha, about time somebody writes a plug-in for External Summing EmulationTM ! 

Click to expand...

OMG/haha what a world, I recently saw there is indeed already such a thing around.  ;D

Click to expand...

OMFG, that´s plain sick. I´m already laughing about the day when this plugin will be considered to be vintage

Hi guys...

Did anyone get one of these up and running as a summer? I understand that there's a 15Khz LPF in there, and as far as I can make out from the schematic (German is not my forte!) if I remove C11/12, 14/15, 16/17, and R 15/16 from the circuit I will be filter free! so far as I can see I would only need to jumper the resistors in order to maintain a signal... Am I on the right track here?!?

there's a schematic at http://audio.kubarth.com/rundfunk/getfile.cgi?f=L%2C3%28T.%23%3CR%2CS4Q-5%5DR97-T%2BVQA%3DV%5D%3F1%258Y-S4M%2CRTT7U-C%3A%265M871I8RYP9%268%60%0A

Thanks again guys!

Mo

From Darius :

HPF Adjustments for the LAWO DV975-3.

C18, C19, C22, C23 are the highpass filters, increase the values for more low end.
C11, C12, C14, C15, C16, C17 are parts of the lowpass filters, remove them and insert 10nF per channel for C11 and C12 to avoid oscillations. Replace L1 and L2 with a wire bridge.
That should give you around 50kHz at the upper end of the bandwidth

It was posted here and don't understand where Darius's answers went ??

Marty.

Hi MartyMart!

Thanks for your help! Hopefully this time it'll stay put... I'd been scratching my head for a wee while!!

Is there really any need to adjust the lowpass filter? I was given to understand that these are very nice sounding units, except that they have a 15K LPF on them due to Broadcasting restriction in Germany?

Mo