Yes, I know this is an old thread...
Anyway, inspired by this & this , I recall the wonderful DIY DAC I used several years ago, which came with transformer line stage.
That DAC was an evaluation board of CS4397 & I skipped the whole analog stage on the board with a pair of Lundahl 7902. That was inspired by this.
Tranformer-coupled DAC is awsome, period.
By comparison, the OP analog stages sound mechanical & grainy. On the other hand, transformer-couple sound lifelike & fluid. In good recordings, the sparkle & airy decay of the cymbals are simply amazing. In those records without noticeable trebles, the "atmosphere" are also remarkable....
Sadly the evaluation board died after only about 1year of use, and I could not fix it. (tried but failed)
Later I bought DEQ2496. Using it with digital input & analog output, it serves both EQ & DAC functions. In the EQ portion, it's doing great. In the DAC portion, it's not.
Looking into the boards inside the DEQ2496, those tiny SMD scared me away everytime. (you guys who can deal with them just amaze me! ) So, despite the imperfection of the analog stages, eventually I get used to its sound.
Until now.
I think, I made a tranformer-coupled analog stage before, why not now?
I traced the analog output pins of AK4393, I found they connet to R13, 14, 16, 17 (2k in value) on the back of output board. R13/R14 are L-/L+; R16/R17 are R+/R-.
I just attach thin wires on them & connet to pin2/3 of the output connectors. (Of course those connector are disconnected from the board) I need the AUX output for other usage so I leave everything else untouched. Now the DA chip is driving both downstream coupling transformer & the analog stage of AUX output. Maybe or maybe not, I'm not sure. With extra load of 10k, I'm not worried.
Anyway, all those tiny SMD and copper foil traces are so complex to me and I'm not willing to destroy any of them. So I'd better leave it that way...
Now the output of the XLR connetors is differential with 2.5V DC offset. Luckily those wonderful Lundahl 7902 are now sitting at the input of my preamp with floating primary winding. So the DC offset dose not matter.
The fluid, airy, open sound came back immediately. Oh, how I miss that. So, with only 4 short & thin wire, the sound of this box transforms a great deal.
The drawback is, the output level drops a lot. I must turn up a lot more on the knob. And the punch, dynamic, energy of the bass seem weaken a bit. This dosen't bother me very much, since the textures & overtones are now much much better which overshine.
Anyway, inspired by this & this , I recall the wonderful DIY DAC I used several years ago, which came with transformer line stage.
That DAC was an evaluation board of CS4397 & I skipped the whole analog stage on the board with a pair of Lundahl 7902. That was inspired by this.
Tranformer-coupled DAC is awsome, period.
By comparison, the OP analog stages sound mechanical & grainy. On the other hand, transformer-couple sound lifelike & fluid. In good recordings, the sparkle & airy decay of the cymbals are simply amazing. In those records without noticeable trebles, the "atmosphere" are also remarkable....
Sadly the evaluation board died after only about 1year of use, and I could not fix it. (tried but failed)
Later I bought DEQ2496. Using it with digital input & analog output, it serves both EQ & DAC functions. In the EQ portion, it's doing great. In the DAC portion, it's not.
Looking into the boards inside the DEQ2496, those tiny SMD scared me away everytime. (you guys who can deal with them just amaze me! ) So, despite the imperfection of the analog stages, eventually I get used to its sound.
Until now.
I think, I made a tranformer-coupled analog stage before, why not now?
I traced the analog output pins of AK4393, I found they connet to R13, 14, 16, 17 (2k in value) on the back of output board. R13/R14 are L-/L+; R16/R17 are R+/R-.
I just attach thin wires on them & connet to pin2/3 of the output connectors. (Of course those connector are disconnected from the board) I need the AUX output for other usage so I leave everything else untouched. Now the DA chip is driving both downstream coupling transformer & the analog stage of AUX output. Maybe or maybe not, I'm not sure. With extra load of 10k, I'm not worried.
Anyway, all those tiny SMD and copper foil traces are so complex to me and I'm not willing to destroy any of them. So I'd better leave it that way...
Now the output of the XLR connetors is differential with 2.5V DC offset. Luckily those wonderful Lundahl 7902 are now sitting at the input of my preamp with floating primary winding. So the DC offset dose not matter.
The fluid, airy, open sound came back immediately. Oh, how I miss that. So, with only 4 short & thin wire, the sound of this box transforms a great deal.
The drawback is, the output level drops a lot. I must turn up a lot more on the knob. And the punch, dynamic, energy of the bass seem weaken a bit. This dosen't bother me very much, since the textures & overtones are now much much better which overshine.
I got a new DEQ2496 v2.4. it seems that the DSP board have been heavily modified. A first look show that crystals have been moved to another locations, LM317 to produce the digital 2.5v removed (and replaced by a dedicated regulator), new uController, some capacitors better placed close to the chips, etc...
No yet checked analog board.
.
No yet checked analog board.
.
Re: Deq2496 direct out mod
I added your link on my web site.
Below is a summarize of the changes found in the new DEQ v2.
On the DSP board:
- new specialized uController: an Analog Device ADSP-BF531 remplace the Triscend TAS04
- new SDRAM memory chips
- LM317 removed and replaced by a dedicated circuit close to the BF531. Seems to be SOT223 reg but not checked yet in detail. Ref printed on reg google nothing.
- crystals moved to a new location, better placement (shorter traces)
- complete new traces and ground plane (a lot better than old version)
- large smd coils on the 9v input
On the input/output analog board: nothing except RoHS. I hate new solders. Need to be clean-up a lot to solder something else.
On the switched mode psu: shielded box around the transformer
No more thermal adhesive on the connectors (good !!!)
AC input connector inverted.
More stickers and signs on the TOP (a real marketing tool for Behringer !!!).
Sound same apparently.
sendler said:
I added your link on my web site.
Below is a summarize of the changes found in the new DEQ v2.
On the DSP board:
- new specialized uController: an Analog Device ADSP-BF531 remplace the Triscend TAS04
- new SDRAM memory chips
- LM317 removed and replaced by a dedicated circuit close to the BF531. Seems to be SOT223 reg but not checked yet in detail. Ref printed on reg google nothing.
- crystals moved to a new location, better placement (shorter traces)
- complete new traces and ground plane (a lot better than old version)
- large smd coils on the 9v input
On the input/output analog board: nothing except RoHS. I hate new solders. Need to be clean-up a lot to solder something else.
On the switched mode psu: shielded box around the transformer
No more thermal adhesive on the connectors (good !!!)
AC input connector inverted.
More stickers and signs on the TOP (a real marketing tool for Behringer !!!).
Sound same apparently.
On my web pages, you will find new details on the capacitor modification. I added 2 tables with the use and replacement parts for each of the capacitors on the Analog Input/output and DSP boards.
http://www.awdiy.com/index.php?page=various-deq-caps-mods
.
http://www.awdiy.com/index.php?page=various-deq-caps-mods
.