[igorpadrao]

Has Loxjie P20 not one red LED and one blue LED? That should be purple color default.
Btw I agree the blue lights are terrible fashion. My Marantz amp has a lots of them

The internal LEDs (the ones below the tubes) are purple (probably one red and another blue). But the front panel is blue (and very annoying).

 

[dimoniet79]

Has anybody try the p20 with the akg 712 pro?

I have just bought a Pro ject s2 pre box dac and an AKG 712 pro, and I am a little dissapointed listening flac, I hoped much more because the are my first hi-fi hd and dac, and I am not getting much more improvememt from my superlix 30€ headphones and spotify streaming. So I am thinking tha maybe this headphone need some amplifier.
Thanks a sorry because my english.

 

[DBaldock9]

A couple of observations about the P20 circuitry -

1.) For the Output Op-Amp power supply circuit - they're using a LM317T / LM337T pair of regulators, set to ±18Vdc.
So, if you're planning to do op-amp rolling, they need to be rated for at least a ±18Vdc supply.
Or, by changing a couple of SMT resistors (the "102" connected to the Adjustment Pin 1 on the regulators), the voltage could be reduced to ±15Vdc or ±12Vdc.
.
2.) While there are 47Ω current limiting resistors in series with Pin 1 of the four op-amps, which drive the L+, L-, R+, R- outputs --- those resistors are inside the feedback loops created by the adjacent 47Ω resistors that connect to the non-inverting input Pin 3 on the four op-amps. Having the current limiting resistors inside the feedback loops, means that the circuits appear to have 0Ω output resistance. An explanation is here - Stackexchange.com - measuring-output-impedance-of-op-amp
.
3.) The taller components (Relay, Capacitor, Output Jack) that are very near to the op-amp sockets, still means that larger discrete op-amps won't fit.

For #1, I've determined that the LM317T / LM337T pair of regulators are actually being used to output the ±7Vdc.
I can't figure out which components are being used to make the ±18Vdc, so I don't how to reduce the voltage to ±12Vdc (to use a wider range of op-amps).

 

[DBaldock9]

For #1, I've determined that the LM317T / LM337T pair of regulators are actually being used to output the ±7Vdc.
I can't figure out which components are being used to make the ±18Vdc, so I don't how to reduce the voltage to ±12Vdc (to use a wider range of op-amps).

I've sent an email to Loxjie, asking how I might reduce the ±18Vdc to ±12Vdc.
Hopefully they'll answer.

 

[bogginhead]

If anyone here has a couple of either Amperex Holland made 6DJ8 or RCA / RCA Command 5670 tubes they'd be interested in trading for a matched pair of Tesla 6N3P-type tubes I'd be willing to trade with them. The Teslas are NOS and never used a single time. Come with their original boxes as well. I'll gladly send pics if anyone is interested. Just message me if so; thanks! Oh, by the way these tubes were purchased specifically to use with my LAP if that helps.

 

[Abyss77]

Hello all,

I had the luck that my brother gave me his P20 for free - and I can honestly say that i like the sound the amplifier produces very much, though I have to admit that my experience with amps is very limited.

Because I would like to try the P20 in balanced mode I am looking for a "cheap" DAC. After a little search I found the iBasso DC01. According to iBasso it is a "Hi-Res Balanced DAC" - so the dongle should do the job???

Sorry for my - maybe stupide - questione, but I am a totally noob .

Abyss

 

[igorpadrao]

Hello all,

I had the luck that my brother gave me his P20 for free - and I can honestly say that i like the sound the amplifier produces very much, though I have to admit that my experience with amps is very limited.

Because I would like to try the P20 in balanced mode I am looking for a "cheap" DAC. After a little search I found the iBasso DC01. According to iBasso it is a "Hi-Res Balanced DAC" - so the dongle should do the job???

Sorry for my - maybe stupide - questione, but I am a totally noob .

Abyss

I don't know the iBasso DC01 per si, but thinking that it is a portable dac, I believe he is also an amplifier. So, I am told that put an amplified signal in another amplifier degrades the signal very much. So I believe that your best alternatives are:

iFi Zen DAC
https://www.amazon.com/iFi-Zen-DAC-Converter-Unbalanced/dp/B07YZK5MDS

Drop + Grace Design Standard Balanced DAC
https://drop.com/buy/drop-grace-design-standard-dac-balanced

Geshelli Labs Enog2 Pro
https://geshelli.com/shop/ols/categories/enog2-pro

SMSL M300 MkII
https://www.amazon.com/dp/B07PJQDSF2
https://www.aliexpress.com/item/4000619131130.html

I believe iFi is the best for fun, the Geshelli is best for critical listening, the SMSL has the best features. But I am also a noob. Let's see if any member more experienced could add something to my resume.

 

[DBaldock9]

Hello all,

I had the luck that my brother gave me his P20 for free - and I can honestly say that i like the sound the amplifier produces very much, though I have to admit that my experience with amps is very limited.

Because I would like to try the P20 in balanced mode I am looking for a "cheap" DAC. After a little search I found the iBasso DC01. According to iBasso it is a "Hi-Res Balanced DAC" - so the dongle should do the job???

Sorry for my - maybe stupide - questione, but I am a totally noob .

Abyss

While the Balanced output voltage of the iBasso DCO1 is at least 1.2V, which is appropriate for the XLR Balanced Input of the P20 - the DCO1 only has L+, L-, R+, R- connections, and doesn't have a GND (the third pin on the XLR jack). So, there may be an issue with noise.
.
Doing a check of DACs with Balanced outputs, I'm not seeing any strictly portable units, and it looks like the SMSL SU-8 might be the least expensive model - at $250.
https://www.amazon.com/Decoder-SMSL-2ES9038Q2M-768kHz-Balance/dp/B07DQDNF6S/

 

[igorpadrao]

While the Balanced output voltage of the iBasso DCO1 is at least 1.2V, which is appropriate for the XLR Balanced Input of the P20 - the DCO1 only has L+, L-, R+, R- connections, and doesn't have a GND (the third pin on the XLR jack). So, there may be an issue with noise.
.

I believe that the iFi DAC that I mentioned could suffer of the same problem since the balanced output is 4.4mm.

Doing a check of DACs with Balanced outputs, I'm not seeing any strictly portable units, and it looks like the SMSL SU-8 might be the least expensive model - at $250.
https://www.amazon.com/Decoder-SMSL-2ES9038Q2M-768kHz-Balance/dp/B07DQDNF6S/

Besides the iFi DAC, the other units that I mentioned are full balanced and less expensive than the SU-8. The M300 MkII is about the same price, but you gain Bluetooth input and a DAC that measures better than the SU-8 (according to audiosciencereview.com).

The HiFi Express has the SMSL M300 Mark II in stock (as opposed to Amazon).
https://hifi-express.com/products/s...1&_sid=76ae4d7e4&_ss=r&variant=31495631208548

 

[DBaldock9]

I believe that the iFi DAC that I mentioned could suffer of the same problem since the balanced output is 4.4mm.


Besides the iFi DAC, the other units that I mentioned are full balanced and less expensive than the SU-8. The M300 MkII is about the same price, but you gain Bluetooth input and a DAC that measures better than the SU-8 (according to audiosciencereview.com).

If you have a DAC with a 4.4mm output, it should have a GND connection.
But, most devices that have a 4.4mm jack, are designed to drive headphones.
.

 

[igorpadrao]

If you have a DAC with a 4.4mm output, it should have a GND connection.
But, most devices that have a 4.4mm jack, are designed to drive headphones.

Did not know that. So maybe the iFi Zen DAC is also a fully balanced. But is better to double check.

 

[DBaldock9]

It looks like the portable iFi Hip-DAC, at $150, also has a 4.4mm Balanced jack -
https://www.amazon.com/iFi-Hip-dac-Portable-Headphone-Balanced/dp/B0842W67F1

 

[cirodts]

I bought the smsl sp 200, it has balanced inputs and outputs but it is not a true double mono balanced amplifier, the loxie instead?

 

[DBaldock9]

My project this weekend - Install a set of Tantalum & Ceramic bypass capacitors for the op-amp sockets. There's just enough space between the case and the back of the board, for the capacitors to fit. Photos to follow.
.
OK - Finished with the mod, and here's the set of capacitors, connected to the ±18Vdc power pins, and to GND -
(the Kapton tape is insulating the output relay pins)
.

.
.
The P20 still sounds good, and should be less likely to have issues with noise, when op-amp rolling.

 

[igorpadrao]

I bought the smsl sp 200, it has balanced inputs and outputs but it is not a true double mono balanced amplifier, the loxie instead?

As far as I know, the Loxjie P20 is a true balanced headphone amplifier. I have a P20 and a Magni Heresy, from Schiit. Two different beasts. I think you will like to compare the P20 to the SP200, specially if you try different tubes.