Behringer SRC2496 mods

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I have an src2496 I am going to mod. Mine is the one with parts on the underside of the board. I have the schematic from Lampizor. I noticed that the power supply is a good design for getting the required voltages as cheaply as possible. I am building four Jung super regulators. I am going to use two power transformers. I have a dual secondary 2x 15v torroid, and a dual secondary 2x 8v. I will use 4 FWB with fast diode rectifiers, one for each secondary.
I have a 4396 DAC chip to swap. Reading the data sheet AKM says the 4396 is "semi pin compatible" with the AKM4393. Some pins should be connected differently. I will hook it up per the data sheet.
Also have an AKM5396 ADC to swap. I'll take the "sense" wire from the psu and connect it directly to the 5v analog connection on the ADC. Finally I'm replacing the signal op amps with LME43923's
 
I posted some pics. The regulators are all hooked up now. I was tryiing to use connectors so I won't have to desolder but the connections proved unreliable as the 10ohm remote sense resistor needs to be right at the connector on the wire harness and while testing the supplies one of the resistor lesds broke and with no remote sensing it passed 22Vdc . . . not good. I soldered pins into the Ground and Vout holes of the four exixting 7800 series regs. Then I built up the little boards with the solder terminals and the 10ohm resistors for the remote sense at the input on the board.
I replaced the AK4393 with an AK4396. Very carefully it's a tiny chip. I took the output after the ist OP Amp from the 47uf cap. As you see in the next pic I have four 6.8 uf caps made of 2, 3.3uf and one .22uf Wima MKP10 caps. If the thing works that will be the next mod with a passive output stage.
I just finished working all the bugs out of the regulators and wiring everything together last night. I'm taking a day off before I use the Variac to bring it up and see if it works.
 

Attachments

  • Vin.jpg
    Vin.jpg
    804.5 KB · Views: 900
  • regulators.jpg
    regulators.jpg
    823.5 KB · Views: 884
  • rearview.jpg
    rearview.jpg
    834.1 KB · Views: 943
  • outputcaps.jpg
    outputcaps.jpg
    669.6 KB · Views: 933
  • IMAG0103.jpg
    IMAG0103.jpg
    450.6 KB · Views: 807
After debugging some issues I have it up and running. The AKM4396 "miracle DAC" is working perfectly. It is super quiet. I replaced the dual Op Amps in the gain stage, and the differential to single ended converter after the DAC with LME49723. I haven't done the direct out through caps mod yet. I'm picking the signal from the first amp after the DAC.
 

Attachments

  • srcside.jpg
    srcside.jpg
    528.9 KB · Views: 313
  • frontsrc.jpg
    frontsrc.jpg
    896.1 KB · Views: 391
Hi, im bought used Behringer SRC2496 and i have problem with slight silent noise in analog output at sample rates 48,88,96, in 44,1khz is everything deadly SILENT , is design flaw - feature or my Behringer have a problem ? This noise is generated by behringer on all digi inputs (SPDIF, XLR) in D/A mode .
 
Some modifications to get the Ultramatch a little closer to hifi level

My Ultramatch is a 2015 model. It uses a CS5361 ADC which is capable for 192kHz,
but only 96kHz are used. Don't know if this unit is better or lower noise than
the 5993 in the older revisions of the Ultramatch. Furthermore the parts are
mounted on the underside of the board whereas the older revisions the the parts
mounted on the upper side. So the older revision is better to "debug"...

+ original transformer replaced by a 50VA toroid transformer to eliminate hum.
1x 18.5V/1A (yello wires)
1x 8V/2.5A (orange wires)
1x 8,5V/1A for muting circuit
+ better and more precise voltage regulators
2x LM2940 +5V
1x LM2940 +15V
1x LM2990 -15V (must be insulated because the plate is input voltage not ground)
these regulators need bigger output capacitors, so I replaced the 10uF by 47uF
+ bigger capacitors 2x 10.000uF for the OPamps and 1x 10.000uF for the 5V supply
important: Don't use the the case for ground. The ground at the capacitors
solder connection differs from the ground of the case and the rest of the circuit.
A nearly 0 Ohm resistor is placed in the ground line. If you use the case for
ground you get a silent hum...
+ replaced all OPamps RC4580 with ultra low noise AD8599.
Is a little improvement. The most noise is created by the DAC
+ replaced all 47uF/25V coupling electrolytic capacitors with bipolar capacitors
from Panasonic ECEA1EN470U
+ output muting
when switching on or of there always was a loud plopp in the speakers.
That was not acceptable for me. Therefore i I used the uPC1237 which has an
AC detection which switches the relais off immediately and therefore I needed
a transformer with a spearate third output voltage. I used a ready to use
Hong-Kong board. But there was an error in the design. I fixed this with a
separate wire from the AC input with resistor and diode, as you can see in
the picture. The relais are used as openers when the relais is powered. When
the relais is not powered the + and - outputs are shorted to ground.
+ As the ultramatch works at studio levels the output volume is too high for
hifi audio equipment. Therefore I used the coupling capacitors between asymmetric
and symmetric ouput stage to insert a poti. It is an Alps 10k linear. I used
the case as ground and shielded wires (shield connected only at one side)
=> no hum
+ same problem for record level as for the output level. To increase gain I
solderd 2 2.7kOhm resistors parallel to the existing 3.6kOhm. Now you can
use silent hifi sources to get full scale at the ADC.
- I'm still not pleased about the signal noise ratio for the digital to analog
conversion. My CD-Player from 1983 produces much less noise at the outputs.
Perhaps someone has a hint for me for a low noise pin compatible DAC to
replace the 4393
- I'm still looking for a wiring diagramme of my revision of the ultramatch

greetz
hpsp
 

Attachments

  • original_cirrus_logic_adc_CS5361.JPG
    original_cirrus_logic_adc_CS5361.JPG
    679.4 KB · Views: 277
  • op_amps_replaced_with_ad8599.JPG
    op_amps_replaced_with_ad8599.JPG
    678.9 KB · Views: 284
  • filter_capacity_improvement_connection.JPG
    filter_capacity_improvement_connection.JPG
    505.7 KB · Views: 248
  • filter_capacity_improvement.JPG
    filter_capacity_improvement.JPG
    774.2 KB · Views: 404
  • complete_mod_with_toroid_transformer.JPG
    complete_mod_with_toroid_transformer.JPG
    654.3 KB · Views: 410
  • better_voltage_regulators_3_insulated_lm2990.JPG
    better_voltage_regulators_3_insulated_lm2990.JPG
    524.9 KB · Views: 413
  • better_voltage_regulators_2_with_bigger_47u_caps.JPG
    better_voltage_regulators_2_with_bigger_47u_caps.JPG
    468 KB · Views: 440
  • better_voltage_regulators_1.JPG
    better_voltage_regulators_1.JPG
    386.5 KB · Views: 402
Some modifications to get the Ultramatch a little closer to hifi level part 2

some additional pictures...
greetz
hpsp
 

Attachments

  • record_out_gain_improvement.JPG
    record_out_gain_improvement.JPG
    521.1 KB · Views: 222
  • output_volume_control_poti_10k.JPG
    output_volume_control_poti_10k.JPG
    525.9 KB · Views: 249
  • output_muting_circuit_with_UPC1237.JPG
    output_muting_circuit_with_UPC1237.JPG
    646.9 KB · Views: 200
  • output_muting_plugs.JPG
    output_muting_plugs.JPG
    463.8 KB · Views: 212
  • output_volume_control_plug_with_bipolar_caps.JPG
    output_volume_control_plug_with_bipolar_caps.JPG
    466 KB · Views: 206
Last edited:
Some modifications to get the Ultramatch a little closer to hifi level part 3

rgbeach told me that there is a mistake in the pcb in newer revisions of the 2496:
R- (pin 20) and R+ (pin 21) go through 10uf electrolytic capacitors. I bridged
these as you can see in the picture.

greetz
hpsp
 

Attachments

  • da_out_rp_rn_cap_bridged.jpg
    da_out_rp_rn_cap_bridged.jpg
    550.8 KB · Views: 275
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.