Hi paoloilpizzo, the price for assembled i/v hat is 170$ including shipment. Payment via Paypal. Manufacturing time ~1 month due to existing orders. PM to me please for details.
Regarding the difference with lundahl: people sais mine are simply better:
more body, better on LF, depper soundstage, more precise, more details, more natural\analoglike sound. Some impressions you can find in this thread btw.
Regarding comparison with OpAmps - some guys still trying to find\mention some advantages of OpAmps, but I don’t think that OpAmps can be at the same level with (my) transformers in terms of SQ+simplicity+cost... Yes, you can find some benefits of OpAmp (after making comparable investments to the OpAmps itself (burson, etc... and their... say... not simple PSU). And after that... I believe it is more about "style" of music "delivery\casting", not about pure SQ... I know that OpAmp approach is much more complex task than transformer' "plug and play" case.
Regarding the difference with lundahl: people sais mine are simply better:
more body, better on LF, depper soundstage, more precise, more details, more natural\analoglike sound. Some impressions you can find in this thread btw.
Regarding comparison with OpAmps - some guys still trying to find\mention some advantages of OpAmps, but I don’t think that OpAmps can be at the same level with (my) transformers in terms of SQ+simplicity+cost... Yes, you can find some benefits of OpAmp (after making comparable investments to the OpAmps itself (burson, etc... and their... say... not simple PSU). And after that... I believe it is more about "style" of music "delivery\casting", not about pure SQ... I know that OpAmp approach is much more complex task than transformer' "plug and play" case.
D
Deleted member 537459
Yes. Both yours and termoto are great designs. It has been almost two weeks since I got them. After my subjective listetning tests I finally decided to write this short review:
I have termotos to sell. PM me please
Thanks Ivan!!!
Attachments
Yes. Both yours and termoto are great designs. It has been almost two weeks since I got them. After my subjective listetning tests I finally decided to write this short review:
I have termotos to sell. PM me please
Thanks Ivan!!!
Missing review link?
Hi,
Based on expirience witn es9038q2m in OSF-bypass mode, I can confirm, that Zobbel network across the secondary works great. You can try to make -0.7dB at 10kHz with -2dB at 20kHz (1kHz=0dB). I can not give you the exact values, but someting around 0.5-2nF+5-15kOhm should work for your setup. The exact values depends of the loaded impedance - better to find using generator\oscilloscope on the real load (amp/preamp).
Based on expirience witn es9038q2m in OSF-bypass mode, I can confirm, that Zobbel network across the secondary works great. You can try to make -0.7dB at 10kHz with -2dB at 20kHz (1kHz=0dB). I can not give you the exact values, but someting around 0.5-2nF+5-15kOhm should work for your setup. The exact values depends of the loaded impedance - better to find using generator\oscilloscope on the real load (amp/preamp).
Very nice work, bisesik!
If you have time, I need some information about this.
1) at yours post #08, you said that the primary inductance for the 1:1 transformer (voltage DACs output) is 80H.
What is the frequency that measures that? I saw at my Lundahl LL1545A that this Ls varies by frequency. With a DER EE DE-5000 I saw Ls 63H for the
100Hz, 2.8H at 1KHz and 8-22mH at the 10K (9-10, 15-16 windings), this is meaning that we need three LTSpice models to simulate the frequency performance. The Deree can be measured and Lp Inductance of windings.
2) I had done some measurements with a double AK4490 (dual mono setup) on Lundahl LL1545A 1:1 - see the schematics - each AK4490 have a LL1545A.
I had a quickly THD @-1dB, not bad with a draft and quickly cables.
3) At the above schematics the primary DCR of Lundhal LL1545A is 313 Ohm each winding, i.e 313 Ohm to each differential AK4490 output, according to initial schematics that I had used. The DCR of secondary windings if they combined all together in series, is 620 Ohm for SE output.
4) Can we have at your voltage DACs transformers, two primaries windings each for differential AK4490/93/97 output (dual mono) and the output such as combined xlr or SE outputs?
If you have time, I need some information about this.
1) at yours post #08, you said that the primary inductance for the 1:1 transformer (voltage DACs output) is 80H.
What is the frequency that measures that? I saw at my Lundahl LL1545A that this Ls varies by frequency. With a DER EE DE-5000 I saw Ls 63H for the
100Hz, 2.8H at 1KHz and 8-22mH at the 10K (9-10, 15-16 windings), this is meaning that we need three LTSpice models to simulate the frequency performance. The Deree can be measured and Lp Inductance of windings.
2) I had done some measurements with a double AK4490 (dual mono setup) on Lundahl LL1545A 1:1 - see the schematics - each AK4490 have a LL1545A.
I had a quickly THD @-1dB, not bad with a draft and quickly cables.
3) At the above schematics the primary DCR of Lundhal LL1545A is 313 Ohm each winding, i.e 313 Ohm to each differential AK4490 output, according to initial schematics that I had used. The DCR of secondary windings if they combined all together in series, is 620 Ohm for SE output.
4) Can we have at your voltage DACs transformers, two primaries windings each for differential AK4490/93/97 output (dual mono) and the output such as combined xlr or SE outputs?
Attachments
Bisesik thanks for the quick reply.
About (3), I remembered different aspect as the post 12
For the (4), what is the mainly difference btw this and those of post 25
Probably for the price and the rest, it will be more pleasure by pm.
About (3), I remembered different aspect as the post 12
For the (4), what is the mainly difference btw this and those of post 25
Probably for the price and the rest, it will be more pleasure by pm.
Regarding high or low DCR. Yes, it is a good and interesting question. AK4490 has one comment in datasheet about the load on DC - it should be not less than 1.5kOm... But this statement is with respect to GND and seems relates to the questions of safety more than for sound. In case of using transformer without galvanical connection of the load to the AK4490' GND, seems it is not needed to fulfil this condition. At least I have experimented on my 4490 with shorting the + and - outputs together - and it is alive after for now without any impact to the sound quality in normal usage. But if you will short any of outputs to the GND, probably this will destroy (overburning) the chip (I have such expirience and some guys too). In terms of transformer quality - it is always better to lower the DCR of the coils, but oftenly it is too hard to do due to straight relation with wire diameter (you are always limited by the available window around\inside the core). Moreover a lot of transformers in the market are rated to use with AK449x, but has much less than 1.5kOhm of DCR. Say... High DCR was just a version earlier.
Difference between 80H+80H:80H+80H (320H:320H) and 0.5+0.5:0.5+0.5 from post#25 is that it was 20H+20H:20H+20H (80H:80H). For now I am using better cores\wires\approach.
Difference between 80H+80H:80H+80H (320H:320H) and 0.5+0.5:0.5+0.5 from post#25 is that it was 20H+20H:20H+20H (80H:80H). For now I am using better cores\wires\approach.
Very useful information.
I don't used the DACs ground on primaries windings. If you connect the DAC gnd you have a dc on primaries windings!
Regards with DC load, page10 Note11 says : The load resistance value is with respect to ground. Analog characteristics are sensitive to capacitive load that is connected to the output pin. Therefore the capacitive load must be minimized.
If you leaved floating, I don't think so that this important.
In dual mono setup AK4490/93/97 each chip plays a different channel, one chip for L and the other for the R, you win a 3dB SNR and you have a better linearity due to multiple chips.
I am wondering (for lower price), if I need a dual primary-secondary winding or a single for SE or XLR Outputs. I have attached a schematics about this. Probably a single winding is the same of dual and it has lower price for manufacturing.
I don't used the DACs ground on primaries windings. If you connect the DAC gnd you have a dc on primaries windings!
Regards with DC load, page10 Note11 says : The load resistance value is with respect to ground. Analog characteristics are sensitive to capacitive load that is connected to the output pin. Therefore the capacitive load must be minimized.
If you leaved floating, I don't think so that this important.
In dual mono setup AK4490/93/97 each chip plays a different channel, one chip for L and the other for the R, you win a 3dB SNR and you have a better linearity due to multiple chips.
I am wondering (for lower price), if I need a dual primary-secondary winding or a single for SE or XLR Outputs. I have attached a schematics about this. Probably a single winding is the same of dual and it has lower price for manufacturing.
