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DDA Console Transformer Retrofit ???'s
Old 9th February 2014
  #1
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GreenAudioPro's Avatar
 

DDA Console Transformer Retrofit ???'s

Long time reader, first time poster, any help is greatly appreciated.

I own 2 DDA Consoles from the INTERFACE Series, which I've heard can be retrofitted with input and output transformers, which were a factory option. The service manual however does not give a part number or value for the transformers; they are included but marked optional on the block diagrams.

I use these consoles as part of the front end in my studio, and also for mixdown/summing. I'm already pretty fond of how they sound, and I'd really like to try retrofitting them with transformers.

I haven't found any explicit info about these transformers anywhere, and the email link for DDA Spare Parts on the 8 yr old DDA legacy site addressed to Nigel [email protected], goes nowhere. Can anyone point me in the direction of someone who would know where to start looking?

I have found a spot marked T1 on the input channel board, which has several holes, but only a pair of resistors bridging 2 connections out of 8(?), instead of what I assume would be the "optional" transformer. Are most transformers designed for this going to have a similar Pin Structure/footprint?

Thanks,
Ben Napier
Green Audio Productions
Fort Worth, TX
Old 10th February 2014
  #2
Gear Nut
 
kcswingmaster's Avatar
 

Watching this....

Here is a bit of info...

dda consoles?


Side note: I have channel strips with jumpers (no trannys) as well as several with a resistor jumper. I hear a difference in the sound - I think
Old 10th February 2014
  #3
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GreenAudioPro's Avatar
 

That's exactly what I was after! Thanks KCSwingmaster. Now I have a part that I can buy and at least try something. It sounds like Jim Williams is the man to talk to about hod rodding the consoles as well. I was hip to him modifying lots of other stuff, but hadn't come across the dda mods yet.

Now to figure out where output transformers go....
Old 21st February 2014
  #4
Here for the gear
hey ben
its the neutrik NTM1 transformer for Inputs and Lundahl LL5402 Outputs
i own a d series desk completely fitted with these!
if you need any further information, tell me, i can send you pictures and also schematics with the changings in the EBO (electronically balanced outputs)

cheers Jörg

the email adress for DDA support is: [email protected] (Nigel Turner)
Old 2nd April 2014
  #5
lyo
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hi

Quote:
Originally Posted by kptpeters View Post
hey ben
its the neutrik NTM1 transformer for Inputs and Lundahl LL5402 Outputs
i own a d series desk completely fitted with these!
if you need any further information, tell me, i can send you pictures and also schematics with the changings in the EBO (electronically balanced outputs)

cheers Jörg

the email adress for DDA support is: [email protected] (Nigel Turner)

hello
i've got a dda d series
i've tried the ntm1. good result
i'm interested by the outputs mod.
i'm interested by the schematics and pictures.thank u for your help
cordially
lyo
Old 28th May 2014
  #6
Here for the gear
Hi Lyo, sorry, wasn't here since weeks... i try to make pictures this weekend and ckeck the boards for changings in the EBOs for use with O/P trafos

cheers Jörg
Old 3rd November 2014
  #7
Quote:
Originally Posted by kptpeters View Post
Hi Lyo, sorry, wasn't here since weeks... i try to make pictures this weekend and ckeck the boards for changings in the EBOs for use with O/P trafos

cheers Jörg
can you post pics of your EBO/ transformer out out mod. im very interested in doing this with my Q sereis
Old 25th September 2015
  #8
Quote:
Originally Posted by kptpeters View Post
hey ben
its the neutrik NTM1 transformer for Inputs and Lundahl LL5402 Outputs
i own a d series desk completely fitted with these!
if you need any further information, tell me, i can send you pictures and also schematics with the changings in the EBO (electronically balanced outputs)

cheers Jörg

the email adress for DDA support is: [email protected] (Nigel Turner)
I've had my DDA D series console for about a year now and only recently realized that input and output transformers could be added to the channels. I was wanting to get your opinion as to whether the transformers really made that much difference to the overall sound. I'm considering buying/building some high end 500 series preamps for each channel, but if adding the transformers to each channel make a significant difference then I might just go that route. Also, from looking at the PCB and the schematics, I can tell where the input transformer goes, but not the output transformer. I appreciate any insight you can give me. Thanks.
Old 24th November 2015
  #9
Any news on this?

I`m also interested in the Lundahl output transformer mod!

I have a Q2.

Quote:
Originally Posted by Earth Tone Audio View Post
I've had my DDA D series console for about a year now and only recently realized that input and output transformers could be added to the channels. I was wanting to get your opinion as to whether the transformers really made that much difference to the overall sound. I'm considering buying/building some high end 500 series preamps for each channel, but if adding the transformers to each channel make a significant difference then I might just go that route. Also, from looking at the PCB and the schematics, I can tell where the input transformer goes, but not the output transformer. I appreciate any insight you can give me. Thanks.
Old 24th November 2015
  #10
I have restored an S series that I have used for about two years now. The power supply was rebuilt, and all electrolytics have been replaced in the PSU and all channels of the desk. Signal path caps were upgraded throughout to 220uf, and the main caps in the PSU were raised to 15000uf from 10000uf.
Recently I added .1uf WIMA polypro bypass caps to the signal caps in the Master section and this made the biggest improvement on the overall sound of the mixer. If I remember correctly, there were only six of them, so quite a bargain, IMHO.
The high end just shines now on the board, and mixing drum overheads is a delight. Instead of struggling to get definition, I am finding I have to be subtle with any EQ, and generally don't need it if the tracks are well recorded, other than HPF.
Jim Williams has said that changing the signal path caps to 220uf solves some phase issues on low end, and I have done this to a few TL072 equipped mixers with great results.
Changing opamps just seems like too much trouble to me, and the few times I've tried it, the sound results were not even close to the electro and bypass cap changes mentioned above.
Would consider the bypass caps on input channels, but almost afraid it will make the board too bright. guess I should try a few and see what I think. Same for the group or bus channels.
Haven't considered the transformer additions mentioned in this thread, because I'm not using the mic pres for recording, and from the schematics, it looks like the transformers are only on the mic inputs, not the line inputs. It also would get expensive real fast. Don't think this board has the output transformer option.
Just fine by me. I love this thing now. The only other thing I might attempt is going to WIMA polypros in the channel EQs.
Old 25th November 2015
  #11
Yepp, Looks like you're right about the optional transformer only going in the mic input. not sure, but looks like it on the schematics.

I also use outboard pre`s and go line in from tape. Would be nice to have the line ins fitted with some transformers though..

I just got a Soundcraft mh3, i did a few rough mixes on it, but so far i can`t say i`m in love.

In comparison, the DDA (Q2) is more punchy and still "soft and warm" sounding. It has mojo in my ears while the MH3 is more modern, clean and kind of "flat sounding". just my opinion about that.

My plan with the soundcraft was to install Lundahl 1527 trafo`s. I installed one, but it didn't blow my mind. Maybe on eight channels it would make more difference?
Its mainly kick and snare that i think is lacking punch (compared to the Q2). I`m one of those who loves to peak the kick and snare a bit, and the soundcraft doesn't do that trick in a very nice way.

If someone knows more about getting the transformers into the line in circuit (in the DDA Q2) i would be happy to hear about that!!

About replacing the caps in the output section, Can you tell me more about that?
I think i`m gonna go back to my DDA, but would be nice to hotrod it a bit, so its gonna be even sweeter coming back!

Doesn't look like it has space to fit any output transformers on the outs, but switching caps for newer and different values for more definition and clarity seems like a good ticket!

Btw, im not very skilled on electronics, so a noob explanation would be great!
PM me if I'm hi jacking the thread with jibberish.
Old 25th November 2015
  #12
Well, on my S series, if I wanted to spend the money for 24 channels of transformers (and I don't) I could bring the line inputs into the mic ins, and then use the 20db pad. I do this with some FX returns, and it works fine.
But I think all this stuff about transformer "mojo" is BS, and your best bet on an old console is to replace all of the electrolytic capacitors to bring it back to the way it sounded when it was new.
In short, electros are the only parts in these mixers that get old and degrade with time. This should be the first thing anybody checks when they begin using a "vintage" mixer.
To be brief, look up electrolytic capacitors on the web, and you'll find they are easy to identify. They are also inexpensive to buy in the quantities you will need to replace all of them in the mixer, which will come to a few hundred caps.
Then you get into "mojo" issues with how different brands sound, etc..etc....etc.
I'll make it easy. Get Panasonic FM or FCs. I buy them from Digikey.
Maybe just start with the Master Output section. Actually, if you haven't replaced the electros in the PSU, that's where you should begin. If the power supply caps are old, nothing will work the way it should. If it's putting out reliable, stable voltages, you can let it go for now, but it's a good idea to throw in some fresh ones.
These caps are used in two ways in the mixer itself: linking different sections of the circuit together where the signal passes thru (coupling caps) and filtering the power voltages as they arrive on location to power sections of the board (filtering caps). All should be replaced, but it's possible to make the job easier by checking the sections with an oscilloscope, and a signal generator. If the channel doesn't distort the signal being put thru it, it's probably OK.
However, if the gear is over 20 years old (like my DDA was when I got it), I just replace them all. The simplest thing to do is replace them with the same values as originally installed. I love the way the channels pop out in the DDA, making this task very simple.
Learning how to read a schematic (not as hard as you think if you don't know) can help easily distinguish the two types. There are tutorials on You Tube. If you have them for the mixer, look at the input channel schemo, and try to follow the signal path from the mic or line input, and you will see how the signal passes thru the preamp, into the EQ, and down to the faders. If the signal passes thru a cap, it's a coupling cap.
Obviously, a good soldering station and some experience with soldering will be a big help. If you don't feel experienced enough, get a good soldering station and spend some time with it making cables or de-soldering some components from old boards, until your work is clean and quick. A good soldering station will cost the same as two or three transformers, and you'll get a LOT more happiness from it.
The Master section is where all the input channels get ganged together, so it's important that it be working it's best. Start there if you think the PSU is healthy.
DDA was smart and used as few electros as possible for coupling in the Master channels, which is best for sound quality. If you can figure out which are the signal caps, upgrade them to 220uf. Don't up-size the ones on the EBO boards. Just keep those at the original value (100uf on mine).
All replacement caps should have the same or greater voltage ratings.
Across the two terminals of the newly replaced 220 uf caps, solder a .1uf WIMA polypropylene capacitor (MKP, I think!). This is called a bypass capacitor. Look it up .
This was the "mod" that really opened up my DDA. I got these from a place here in SoCal called TAW. Nice folks, reasonable pricing. Get a huge bag, They are useful, and one big bag won't cost you as much as one of the Neutrik transformers.
If you like this mod, I think Jim Williams has recommended doing this to every signal cap on the mixer. Hence the big bag. I would do the group channels next, and am considering this for my own DDA. Not sure I will do the input channels, as the mixer sounds great right now.
This might seem complex, but if you really want to get into modding this stuff, you're gonna have to learn this crap.
I believe Jim has also recommended, bypass caps on the filtering caps too, and suggests .1 axial monolithic capacitors. Again, you'll have to research this, I just don't wanna explain right now.
Here's some reading for you. This is for a Soundcraft Ghost, but the circuit is similar, and most of this applies to our DDAs. This guy has done a good job of organizing all this info.
Nick Peck's DIY Audio Gear Information Repository : Soundcraft Ghost Restoration Project
If you get into a lot of soldering, be sure to use a fan to blow the smoke away from you. Not good stuff to breath.
Just remember that you don't want to ruin the circuit boards as you solder, so get a good soldering station, and learn how to solder/desolder clean and quick.
Old 27th November 2015
  #13
Wow! Thanx for all the info! Excellent! Really appreciate it!
Old 8th December 2015
  #14
Gear Maniac
 
Aniol1349's Avatar
 

great info here. Could you please tell me @ tchgtr how could I route the line in into the mic input transformer on a D series? I wanted to add the neutrik input transformer and the Lundahl on the outputs. Could you please tell me how would I add the output transformer into the channel strip?

Thanks!
Attached Thumbnails
DDA Console Transformer Retrofit ???'s-screen-shot-2015-12-08-18.10.54.jpg  
Old 8th December 2015
  #15
@ ani ol
Just plug the line input into the mic input, and use the -20db switch on the channel so the level is not too hot. Start with the mic input level all the way down also. You just need a way to have the line level arrive at the board via an XLR connector.
HOWEVER, when you put a line level input into the mic pre, you are causing that signal to go through more electronics than it would normally pass, and adding extra noise. This can be seen in your schematic just by comparing the components from the mic and line inputs to where the two paths join.
You also have the danger of putting 48V phantom power back into your audio interface (or FX device), which could damage gear.
But don't let that stop you, if you want to try this. Just be careful.
As for installing transformers-this is something I do not suggest in the first place. As I mentioned above, I think you would be better off by making sure you have new capacitors in the output section, and putting bypass capacitors across them to keep the high end nice and clear. This can be done for a fraction of the cost of transformers on all channels at $50 per tranny, and the DDA mixers are easy to work on, since the channels remove easily.
I suggest you get your transformer "mojo" from your microphones and mic pres.
Why alter a well-designed circuit like the DDA D Series? Just make sure it is not pushing audio through 30 year old capacitors. Have the caps on your board ever been replaced? Electrolytic caps get old and the signal degrades with time.
And I will say again, if the same is true of the power supply, you should rebuild that first. At least measure, and make sure it is putting out correct voltages.
Sorry if this is not the answer you want, but it comes from experience. Get the board back into new condition, and you might like what you hear.
Old 16th December 2015
  #16
Here for the gear
Hi Guys,

Have an issue, wondering if anyone can help...

I have an issue with the positioning of my sub groups on the ribbon for the console.
The ribbon seperates into two for this section, unfortunately I am not getting sound out of both channels, only the right hand side channels on the sub groups, also they are not lining up properly in terms of sends for these sub groups, i.e. click on the buttons for sub groups 1 and 2 and the sound is sent to the channel 8 (but not 7).

Any ideas?
Do you know of any techs that could help?

Im based in London.
Old 16th December 2015
  #17
Here for the gear
sorry, should have mentioned.. this is a d series desk.
Old 17th December 2015
  #18
Best I can do is give you a link to the schematics.
http://www.ddaconsoles.com/pdf/schem...schematics.pdf
How the ribbon cables are wired should be documented in there.
This should help you make sure you don't accidentally plug a ribbon carrying phantom power into the wrong place.
Old 24th December 2015
  #19
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Issue resolved, I believe the sub group channels have to be inserted on the ribbon in a specific order.
Old 9th January 2016
  #20
Gear Maniac
 
Aniol1349's Avatar
 

Quote:
Originally Posted by tchgtr View Post
Recently I added .1uf WIMA polypro bypass caps to the signal caps in the Master section and this made the biggest improvement on the overall sound of the mixer.
in what places have you added those caps? I'm recapping now a DDA Q2 series Master module and I'm thinking to add these as well.
Old 12th January 2016
  #21
Quote:
Originally Posted by Aniol1349 View Post
in what places have you added those caps? I'm recapping now a DDA Q2 series Master module and I'm thinking to add these as well.
I added them to the capacitors that carry the signal through the master section. They are in parallel, which means that you simply solder the two leads of the .1 caps to the two leads of the larger electrolytic caps. Mirror image, usually on the back of the circuit board.
You need to look at the schematic to determine which caps carry the signal. On my mixer they were 100 uf (though I changed them to 220uf, which I also suggest you do). I did not solder them to the caps that were part of the electronic balancing circuit, and I think there were only three per channel that needed them.
Some people suggest doing this to every signal cap on the mixer. I only did it on the master section, though I DID change all signal caps in the mixer to 220uf. I am considering doing it to the group channels, and might try it on input channels, especially the ones I commonly use for drum overheads.
It is important to read the schematics. It's not that hard to learn, if you don't know how.
For example, get the schematic of the input channel for your Q series, and find where the mic/line inputs enter the channel. If you follow it along, you will see where the different sections of the mixer are linked by capacitors. These are the coupling caps you want to upgrade.
Old 18th February 2016
  #22
Here for the gear
hey guys
wasn't here since ages..
lot of stuff to read!

if anyone is still seriously interested in this transformer thing I would open my desk for you and make pictures. what I can say now is, the output trannys are not placed on the output pcb's due to missing space on it. they are mounted on extra pcbs to the ground plate of the desk. the wiring is done very professional within those plastic wrapped looms.

i cannot say if the input trannys NTM 1 have any effect to the sound you might expect from external vintage (or expensive modern) pre's. Its just good to know I have some built in:-) could't compare it yet to a desk w/o trannys
I meen its a standard transformer, unspectacular...
The lundahls are very good I think, but in the end they have to do a job - balancing the signal. without any changes in sound. they do, I guess:-)

a first pic is attached...

best Jörg
Attached Thumbnails
DDA Console Transformer Retrofit ???'s-lundahl.jpg  

Last edited by kptpeters; 22nd February 2016 at 04:35 PM..
Old 18th February 2016
  #23
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Quote:
Originally Posted by akeel View Post
Issue resolved, I believe the sub group channels have to be inserted on the ribbon in a specific order.
the pcbs of the subgroup/matrix channels are "programmed" with a little wire link

e.g. there are two rows on the pcb with 8 linking points each
board for grp/mtx 1 is linked on position 1, board for grp/mtx 2 is linked on 2, etc.

no matter on which position you put the strip into the frame, it will work as that specific number of grpchannel you programmed it to

Last edited by kptpeters; 22nd February 2016 at 04:29 PM..
Old 18th February 2016
  #24
Here for the gear
took some more pics now, image 2+3 show input tranny NEUTRIK NTM1 in the "Theatre" Input module, soldering side shows the holes for the links that placed when no transformer is fitted. img 4+5 show the "programming" the number of Grp/Mtx Modules. pic 6 shows the changing in the EBO for usage with output trafos (only matrix) my grp O/Ps are still elctronically balanced. you can see the place for the trimpot (with 3 holes) which is no longer needed for balancing the circuit. pic 7 shows the changes in (my) Aux Modules for using with trannys (1 resistor and 1 cap is missing in the circuit) don't know why its different to the MTX module, pic 8 shows the programming whether its an AUX or Foldback Module

O/P trannys are simple inserted in the signal path between the connector on the PCB and the board where all the XLR/Phono connectors are mounted on the backplate

as you can see, i have a 16mono Theatre In/8stereo In/ 8 AUX Returns/ 8 Grp/MTX/ 4 Foldback/4 AUX send configuration.

mods I did by myself:
-add phantom power for the talkback mic
-AUX sends of the subgroup section are changed to post insert (I can now use the insert returns as additional line level I/P if needed, and have them pre fade, for monitor/cue purposes

for more questions contact me!!
cheers Jörg
Attached Thumbnails
DDA Console Transformer Retrofit ???'s-img_2623.jpg   DDA Console Transformer Retrofit ???'s-img_2625.jpg   DDA Console Transformer Retrofit ???'s-img_2626.jpg   DDA Console Transformer Retrofit ???'s-img_2627.jpg   DDA Console Transformer Retrofit ???'s-img_2628.jpg  

DDA Console Transformer Retrofit ???'s-img_2629.jpg   DDA Console Transformer Retrofit ???'s-img_2633.jpg   DDA Console Transformer Retrofit ???'s-img_2634.jpg  

Last edited by kptpeters; 22nd February 2016 at 04:25 PM..
Old 20th February 2016
  #25
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Sounds good guys!
I'm gonna start recapping my QMR next summer. I'll hope this thread helps for it since DDA's seem to be bit of sleepers and theres not so much info about them.
Old 14th October 2016
  #26
Here for the gear
 

Hi guys,my first post here...I just recently bought a DDA interface 16ch
(4 groups) console and was wondering if anyone had any experience with this unit.I would definitely consider mods as above mentioned for other models...would these mods be suitable for my console as well ?
FYI I make electronic music and would also like to know if this unit would be good/decent/bad for electronic music in terms of punch for example?
What is the sound signature/dynamics of these units ?...how is the EQ like for shaping kicks and bass ?
Cheers guys, Diego
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