AK4490 USB Dac with dsd support.

[sonnya]

PCB I/V to SE OPAMP V1.1

This is a new board that uses the same mute circuit as the Discrete output shield.

It shunts the output to GND during mute giving a pop/click free transition on switch between DOP/DSD and PCM and vice versa.

In the filter stage it is populated with OPA1641AID, thinfilm resistors 0.1% 25ppm, PPS film capacitor 2%

It will also work fine with ES9038Q2M but in Voltage output mode.

39€/pcs

- Sonny

 

[sonnya]

Preamp OPAMP based. (Have not given a name yet - Poor mans preamp .... nahh Ideas are welcome)

I have been working on this preamp board.

It will be finished by the end of the day.

The Volume control is based on the chip (R2R DAC) used in the Discrete preamp V1.1

The features are:

• Width x Length : 125x80mm
• Opamp based (OPA1641AID but alternatives can be used)
• 4 channels input instead of 5.
• 1 x XLR input
• 2 x SE input
• 1 x SE output on RCA and Molex 2 pin connector
• 1 x internal balanced input on molex with jumper for SE support
• Cable compatible with Preamp Discrete V1.1
• Same interface for OLED display

Price wise it is 254€. And as all the connectors are on board. It would be very easy to implement.

A solution could be :

OLED display : 127€
Preamp : 254€
LPS V2.1 : 120€

 

[michip]

I am working on the documents for the DAC and preamp right now.

Many has asked about current consumption of the DAC and Preamp.

The USB DAC V1.2 uses the following:

+5.5 to 7V : 350mA
+15V : 10mA (References for the DAC)
-15V : 0 mA

Discrete output stage:

SE: +/-15V 50mA
XLR:+/-15V 100mA

Preamp discrete board V1.1:
+5V - +5.5V : 100mA
+/-15V : 150mA

Sonnya,

Can you confirm the power supply range limits (lower and higher) for the dac v1.2a?

 

[pdb]

Preamp OPAMP based. (Have not given a name yet - Poor mans preamp .... nahh Ideas are welcome)

I have been working on this preamp board.

It will be finished by the end of the day.

The Volume control is based on the chip (R2R DAC) used in the Discrete preamp V1.1

The features are:

• Width x Length : 125x80mm
• Opamp based (OPA1641AID but alternatives can be used)
• 4 channels input instead of 5.
• 1 x XLR input
• 2 x SE input
• 1 x SE output on RCA and Molex 2 pin connector
• 1 x internal balanced input on molex with jumper for SE support
• Cable compatible with Preamp Discrete V1.1
• Same interface for OLED display

Price wise it is 254€. And as all the connectors are on board. It would be very easy to implement.

A solution could be :

OLED display : 127€
Preamp : 254€
LPS V2.1 : 120€

Just curious: Will the gain be selectable? All the best, Per

 

[sonnya]

Gain is fixed tp 6dB maximum

 

[Aboe]

Could it be a good idea to make space for dip8 sockets for the opamps? Then it will be really easy to swap them, and try different ones.

 

[sonnya]

Sonnya,

Can you confirm the power supply range limits (lower and higher) for the dac v1.2a?

+5.5 to 6V (Limited by a protection diode ... We can put in a 7V) : 350mA
+14.5V to 18V: 10mA (References for the DAC)
-14.5V to 18V : 0 mA

14.5V is due to the low noise LDO driving the +/-14V on the I/V header. They need 200mV to work correctly.

 

[sonnya]

Aboe think i should drop that preamp with opamp.... Anyone else has an input!??

 

[Joseph K]

Sonny.. I do not know, do not want to push strong but I did find it a nice idea.
With today's opamps I think very high grade circuits can be built.
OPA827, OPA828, but also OPA1641, 42, ADA4627 or ADA4898 come in mind. I have used all of them and all of them have very strong points..

Presently I'm using the OPA828 with great satisfaction in a key position.

A careful layout, good quality feedback and bypass parts and it is almost there with the discrete circuits..
And no, I am not using them right now in Your output stage. The present, modded Sito modules are just gorgeous..

Ciao, George

 

[pinnocchio]

Sonny.. I do not know, do not want to push strong but I did find it a nice idea.
With today's opamps I think very high grade circuits can be built.
OPA827, OPA828, but also OPA1641, 42, ADA4627 or ADA4898 come in mind. I have used all of them and all of them have very strong points..

Presently I'm using the OPA828 with great satisfaction in a key position.

A careful layout, good quality feedback and bypass parts and it is almost there with the discrete circuits..
And no, I am not using them right now in Your output stage. The present, modded Sito modules are just gorgeous..

Ciao, George

I do agree with you. Also, the price delta between the two preamps could make this opamp version very popular.

I would, however, put in DIP8 sockets for those who like to do opamp rolling (in the DIY spirit).

Do

 

[pinnocchio]

Sonny,

I see you've put in XLR and RCA jacks on that preamp module. Will you be doing conversion from and to balanced/unbalanced using the opamps?

Thanks
Do

 

[sonnya]

Sonny,

I see you've put in XLR and RCA jacks on that preamp module. Will you be doing conversion from and to balanced/unbalanced using the opamps?

Thanks
Do

All inputs are handled as differential to overcome problems with ground loops. From the differential it is converted into single-ended. So it has only single-ended output.

The opamp's can as Joseph K points out be any of the types mentioned. But i will consider the OPA827/828 to be standard.

Feedback network is thin film resistors.

Bypass caps are 0.1uF X7R 10% close to the opamps.

I will put 25MU105MA23216 (1uF PML CAP) in parallel.

They (opamps) are all isolated from each other by ferrite beads.

 

[sonnya]

Ok, i will make it!

 

[sonnya]

Ok, for a first time in a long time i am releasing the schematic of a board.

I am only doing it because there is no of my discrete designs in it.

For the DIY community it is good to have, for modification.

As said i am upgrading the opamps to OPA828ID as suggested by Joseph.

To keep the price with the changes done. I need to start a production of at least 10 pcs.

So the price is 254€ for this board including VAT excluding shipping.

The price for non EU citizen is 203,2€ excluding VAT.

 

[sonnya]

I am working on a new chassis for complete build of the shelf units.

The front is 220x70x10mm

 

[pinnocchio]

The new preamps will make it affordable and easy to assemble a nice integrated amplifier. Really like the idea of that!

Do

 

[sonnya]

Pinocchio.... Exactly what I have in mind.

This heatsink is 160x40x40mm..

I wanted to make an cheaper integrated amplifier, power and pre, dac phono on the same chassis.

 

[sonnya]

TSSA V1.8 replacement on workbench

 

[sonnya]

I am updating shipping for each of you during the weekend.

Regarding payment: Some of you have noticed that payment has been hanging by Paypal in 72 hours. But we have received the payments.... Only some of the parts purchase got a little delayed by this. Especially extra gain modules and UFL to I2S. So during the following week i should receive following items:

• UFL to I2S.
• Gain modules.
• Preamp opamp based.
• TSSA V1.8 replacement.
• OPAMP based IV to SE board.

We have the following boards in stock for :

• Preamp Discrete V1.1.
• USB DAC V1.2A (AK4493).
• USB DAC V1.0 (AK4490).
• OLED Display board.
• Simple frontpanel for dac.
• Softstart V1.1.
• DC protection.
• MIRAND A1 V1.2.
• Discrete shield daughterboard V1.3 (Latest revision).

I have several packages ready for shipment. I am writing emails about shipment to each of you during the next days. If you have not received an email by monday morning (10.06.19) then send me an email to mail.at.mirand-audio.dk

- Sonny

 

[sonnya]

3D pdf of opamp based preamp.

It can be moved around. Layers can be enabled and disabled.

Dropbox - preamp v11 3D 080619.pdf - Simplify your life