Hi kukynas,
You don't need to replace the LM7805. It's only used for the micro controller and LCD display. Lowers the costs, right?
The LT1085 is not a fixed regulator, so you must do some pcb rework if you want to fit in a 78xx replacement. You have to remove the resistors and cap around the 5V regs, and you have to remove all components of the analog stage psu (2nd version PCB).
It's not just a simple replacement, it's some work.
LT1085 =also Three-Terminal 3.3V, 3.6V, 5V and 12V
LT1085-5 is a 5v regulator
The pin out is not the same than the LM7805 ,but if you cross the pins ...
Serge
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Hi Guys,
sorry I mixed up few thinks together, I was thinking of exchanging LM7805 to DEXA DX7805 which is direct swap (except output cap), if I'm right LT1085-5 (thanks Sergelisses to correct it) is high current fixed positive reg. so there should be also direct swap with belleson SPJ78 but not sure if it's just about it, anyway I'm not going to pay 60 bugs for each LT1085 replacement, I didn't found better solution for LT1963A and as Nino mentioned LM7805 won't give me any improvement so will leave it for now, thanks a lot for your comments anyway...
sorry I mixed up few thinks together, I was thinking of exchanging LM7805 to DEXA DX7805 which is direct swap (except output cap), if I'm right LT1085-5 (thanks Sergelisses to correct it) is high current fixed positive reg. so there should be also direct swap with belleson SPJ78 but not sure if it's just about it, anyway I'm not going to pay 60 bugs for each LT1085 replacement, I didn't found better solution for LT1963A and as Nino mentioned LM7805 won't give me any improvement so will leave it for now, thanks a lot for your comments anyway...
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Dual AKM4399 modification
In the past two months, I further modify this little DAC. (See my mods in page 3 and 4 of this thread).
I changed the two analog filter cap from 2200uF BC to 8700uF Elna for Audio. the improvement is very significant. The low frequencies go deeper but not the volume. This is very pleasant because you are not hearing punching bass but goes very low. I love cello and this is certainly for me. Later, I also changed the 2200uF BC for digital to 5500uF Elna but this time, there is not much different.
I purchased two discrete opamp from NewclassD and when first installed, I can hear there are more details (not volume) in highs and lows immediately. I am burning in it for 24 hours now and I believe it can even improve more after 100 hours.
I still have no time to try out tube output but for sure, I will try it later.
In the past two months, I further modify this little DAC. (See my mods in page 3 and 4 of this thread).
I changed the two analog filter cap from 2200uF BC to 8700uF Elna for Audio. the improvement is very significant. The low frequencies go deeper but not the volume. This is very pleasant because you are not hearing punching bass but goes very low. I love cello and this is certainly for me. Later, I also changed the 2200uF BC for digital to 5500uF Elna but this time, there is not much different.
I purchased two discrete opamp from NewclassD and when first installed, I can hear there are more details (not volume) in highs and lows immediately. I am burning in it for 24 hours now and I believe it can even improve more after 100 hours.
I still have no time to try out tube output but for sure, I will try it later.
LT1085 =also Three-Terminal 3.3V, 3.6V, 5V and 12V
LT1085-5 is a 5v regulator
The pin out is not the same than the LM7805 ,but if you cross the pins ...
Serge
Yes, you're right about the fixed versions. But on this PCB (2nd version) only adjustable LT1085 is used. See schematic, resistors are used to set voltage to 5V.
If you want to swap the LT1085, you can also buy the LM317/337 pin-out of Belleson. It's the same as LT1085 pin-out. After removing the resistors, you have to connect the adjust pin (pin 1) directly to ground.
IMHO, I wouldn't just replace all regulators, I doubt it is worth the money at this point. Better spend some money for some nice components. I would concentrate on analog stage, .
Modifying dual AKM4399
In the course of modification, giving clean power supply to digital part will provide finer details and darker background. The analog power supply provides significant improvement to musical output, especially changing the filter cap to larger and better option.
A comment from my die hard LP friend says using Belleson for digital power regulator kills the "LP taste" of this DAC. However, I opt for fine details because I love classical VS my LP friend loves female vocal. Matter of personal taste.
By the way, the Belleson SP is quite tall that you have to insert it to the PCB (with a little big of gap) and incline a little bit before you can close the case.
In the course of modification, giving clean power supply to digital part will provide finer details and darker background. The analog power supply provides significant improvement to musical output, especially changing the filter cap to larger and better option.
A comment from my die hard LP friend says using Belleson for digital power regulator kills the "LP taste" of this DAC. However, I opt for fine details because I love classical VS my LP friend loves female vocal. Matter of personal taste.
By the way, the Belleson SP is quite tall that you have to insert it to the PCB (with a little big of gap) and incline a little bit before you can close the case.
Attachments
Hi everyone.
I was going to order the Belleson voltage regulator and do the mod that others have already done.
Belleson are expensive and want $25 postage to the uk so I was thinking of using another make.
Are the NewClassD DX7803 3.3v regulators any good is my first question.
Is there any gain in changing the other regulators to better regulators becouse I am mostly using tube output.
I was going to order the Belleson voltage regulator and do the mod that others have already done.
Belleson are expensive and want $25 postage to the uk so I was thinking of using another make.
Are the NewClassD DX7803 3.3v regulators any good is my first question.
Is there any gain in changing the other regulators to better regulators becouse I am mostly using tube output.
Your line (AC) filter seems connected wrong.
You should have used "AC IN" at mains plug side. "AC OUT" must go directly to transformer.
Thanks for sharing Sunsun22, nice picture also
Dave: You can order the Belleson/Dexa regulators with partconexion too. They have 20% discount as well this month. Their location is Canada, shipment to Netherlands is not expensive, most of the time about 10 US dollars for a small package.
Nino: problem might be import duty and tax, don't know how about other EU countries but I would pay for items over $25 around 25% of total value (including shipping cost) so for me is cheaper hificollective or directly from NewClassD in Denmark even if it's few dollars more expensive on parts itself, this is of course related to Dexa products, don't know about EU shop selling Belleson
alternative output filter
Hi guys,
Just for fun I've designed an alternative filter for the ones that are using opamp output. It has a Bessel characteristic. The main goal was to take advantage of the nearly constant group delay of a Bessel filter. As you can see in the figures, the Bessel filter also has a less sharp roll-off.
-3dB point is approx. at 120kHz. All values for the resistors and capacitors are commonly available.
Because of the -3bB point of both original and Bessel filter is far beyond the normal 20kHz end of audio band, I don't think the gain figures would influence sound a lot. I'd expect sound improvement from the better group delay of the Bessel filter though.
The first 4 resistors come in place of the 4 11k or 12k (2nd version pcb). The total resistance of a pair should ideally match the other pairs. Lowering total resistance of a pair increases gain.
The filter can also be used for other DAC boards with a single AK4399 or AK4396 with single op-amp output. Then you have to replace the resistor pair at the front with one single 4k7 resistor (2.7 dB gain).
If you want to try this circuit, keep in mind that you get best results (with any filter) when the actual values of the capacitors and resistors are as close as possible in each channel. For capacitors I would use polystyrene. They must be soldered quickly, because their value can change when heated for too long ;we're talking pico farads here.
Any comments or improvements are welcome ofcourse.
Hi guys,
Just for fun I've designed an alternative filter for the ones that are using opamp output. It has a Bessel characteristic. The main goal was to take advantage of the nearly constant group delay of a Bessel filter. As you can see in the figures, the Bessel filter also has a less sharp roll-off.
-3dB point is approx. at 120kHz. All values for the resistors and capacitors are commonly available.
Because of the -3bB point of both original and Bessel filter is far beyond the normal 20kHz end of audio band, I don't think the gain figures would influence sound a lot. I'd expect sound improvement from the better group delay of the Bessel filter though.
The first 4 resistors come in place of the 4 11k or 12k (2nd version pcb). The total resistance of a pair should ideally match the other pairs. Lowering total resistance of a pair increases gain.
The filter can also be used for other DAC boards with a single AK4399 or AK4396 with single op-amp output. Then you have to replace the resistor pair at the front with one single 4k7 resistor (2.7 dB gain).
If you want to try this circuit, keep in mind that you get best results (with any filter) when the actual values of the capacitors and resistors are as close as possible in each channel. For capacitors I would use polystyrene. They must be soldered quickly, because their value can change when heated for too long ;we're talking pico farads here.
Any comments or improvements are welcome ofcourse.
Attachments
If anyone is interested in Dexa, please go to Newclassd's website and have a look of their price. Partsconnextion's "original" price is a little bit more expensive than Newclassd but a little bit cheaper after 20% discount. However, please bear in mind that Newclassd is offering free shipping for purchase above Euro 100 AND BESIDES, you get 5 pcs regulators by paying only 4 (look at the bottom line of price list in UWB regulators); that is only $30 each. I regret that I missed this discount in my recent purchase.
If anyone is interested to use Belleson in this DAC, you can consider to use the mini SPM version provided you don't have a high drop out voltage because SPM model cannot mount on heat sink. Two +5V regulators of this DAC draw 50mA each while the remaining one draws a few mA only. Consult Belleson's datasheet on relationship between current and drop out voltage.
If anyone is interested to use Belleson in this DAC, you can consider to use the mini SPM version provided you don't have a high drop out voltage because SPM model cannot mount on heat sink. Two +5V regulators of this DAC draw 50mA each while the remaining one draws a few mA only. Consult Belleson's datasheet on relationship between current and drop out voltage.
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What say about these products?
TPS7A3301 -15V 1A 16uVrms Ultra Low Noise Negative LDO Regulator 7915
Discrete Op Amps | Sparkos Labs.comSparkos Labs.com
TPS7A3301 -15V 1A 16uVrms Ultra Low Noise Negative LDO Regulator 7915
Discrete Op Amps | Sparkos Labs.comSparkos Labs.com
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