Balanced Impedance connections
an output transformer is good but not absolutely necessary according to the transformer manufacturer.
An input transformer is the best according to the transformer manufacturer.
I don't think they would tell you that and lose potentially 50% of their sales, unless there is some truth in their statements.
read Jensen's apnote an003,
an output transformer is good but not absolutely necessary according to the transformer manufacturer.
An input transformer is the best according to the transformer manufacturer.
I don't think they would tell you that and lose potentially 50% of their sales, unless there is some truth in their statements.
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Balanced impedance connections is about balancing impedances.
It is not about providing two antiphase signal voltages.
Both voltages can be of the same phase, or one can be 180degrees out of phase, or one can be zero volts.
The Receiver reads/measures the DIFFERENCE between the voltages and processes that signal.
The noise attenuation is down to the quality of the impedance balance.
Thanks Andrew for reminding me about An003. If given a JT11P1 I would wire it according to Fig 2.3. an input transformer as duly noted by you.
AS060 pic on right is also listed under Line Input in the Jensen Schematics and as you see it uses a JT11P1 in reverse. Frankly I dont understand the different approaches.
This discussion of using transformers as converters is in response to my curiosity as to how to achieve the conversion mentioned by Salas below and thats why I thought it should be wired as in AS060 right pic.
"4) If you want to make an SE source behave like a truly balanced source your best bet is to use a special precision chip for such conversion jobs. So to potentially have the second harmonic null of picture 1 like Kostas was after. As much as it is possible by CMRR in a practical fully differential system (source to speaker)." Post# 1334
nash
SE vs Balanced!
With headphones too, and hopefully without any prejudice...
For my set up, please refer to posts #1216 and #1243. Just to add that source and amps are fully balanced. I can only report listening impressions. In particular, I checked for differences in the soundstage orientation which are almost "visible" if I may use this term. Also, the results were similar with amps-speakers and headphones so I think I have a clear picture of how DCG3 sounds in different configurations. "Clear picture" is a big word though as differences were not spectacular but playing well known tracks I could "see" them.
Only way to get a proper headphone output was to use my -allready former - tube DAC output stage and connect DCG3 after it. It worked fine and I managed to listen through my AKG K180 600 ohms cans! They have got balanced wiring plus an adaptor for SE stereo jack. Like others report for their builts resolution is great. Unfortunately, headphones do not work with me. I cannot get the 3D illusion and this leads to fatigue. This said, I loved this track:http://youtu.be/hFaHkchWWw4
But one thing is sure there is difference between SE and balanced mode! In balanced the instruments are more defined and separated. Also, the sound is louder! I guess the theoritically predicted increase of 6db.
I had a better chance to confirm this by listening through amps-speakers.
Soundstage width remains the same in SE and balanced mode since in both cases the psu is separated for the two channels. But in SE mode the outer limits fade out leaving the center and especially voices more pronounced. In balanced mode all instruments get more authority no matter where they are placed in space. I did a rather unusuall test. I compared SE mode with three different configurations: one phase fed with positive and the other with negative but SE output only from positive phase (A) vs one phase fed with positive signal and the other idle and floated (B) vs both phases fed with positive signal and SE out only from one (C). From A to C there was a gradual loss of details like strings vibrato for example. My idiosyncratic system is not a reference for what others may expect from their systems but I report what I was able to listen. Lately, I thought to explore the theoritical advantage of the differential amplifiers to present a constant load to the psu so there would be less interaction between them and I think I witness to this with DCG3 too. I hope it's not the result of a biased opinion...
With headphones too, and hopefully without any prejudice...
For my set up, please refer to posts #1216 and #1243. Just to add that source and amps are fully balanced. I can only report listening impressions. In particular, I checked for differences in the soundstage orientation which are almost "visible" if I may use this term. Also, the results were similar with amps-speakers and headphones so I think I have a clear picture of how DCG3 sounds in different configurations. "Clear picture" is a big word though as differences were not spectacular but playing well known tracks I could "see" them.
Only way to get a proper headphone output was to use my -allready former - tube DAC output stage and connect DCG3 after it. It worked fine and I managed to listen through my AKG K180 600 ohms cans! They have got balanced wiring plus an adaptor for SE stereo jack. Like others report for their builts resolution is great. Unfortunately, headphones do not work with me. I cannot get the 3D illusion and this leads to fatigue. This said, I loved this track:http://youtu.be/hFaHkchWWw4
But one thing is sure there is difference between SE and balanced mode! In balanced the instruments are more defined and separated. Also, the sound is louder! I guess the theoritically predicted increase of 6db.
I had a better chance to confirm this by listening through amps-speakers.
Soundstage width remains the same in SE and balanced mode since in both cases the psu is separated for the two channels. But in SE mode the outer limits fade out leaving the center and especially voices more pronounced. In balanced mode all instruments get more authority no matter where they are placed in space. I did a rather unusuall test. I compared SE mode with three different configurations: one phase fed with positive and the other with negative but SE output only from positive phase (A) vs one phase fed with positive signal and the other idle and floated (B) vs both phases fed with positive signal and SE out only from one (C). From A to C there was a gradual loss of details like strings vibrato for example. My idiosyncratic system is not a reference for what others may expect from their systems but I report what I was able to listen. Lately, I thought to explore the theoritical advantage of the differential amplifiers to present a constant load to the psu so there would be less interaction between them and I think I witness to this with DCG3 too. I hope it's not the result of a biased opinion...
Tested with R7 as is it doesn't work. I guess R7 should be lifted and connected but I didn't test that. I liked mine with balanced input even if SE output was used. Transformers or chips? If silicon has to be coupled via capacitors I would prefer transformers. Any of these should be done at the input of DCG3 at least IMHO.
Is JT11P1 an input transformer?
Input and output transformers are made differently. Jensen and other manufacturers tell us they cannot be swapped to the other duty.
Could be you are a future user of only too expensive headphones with better sense of space if you will ever accept any cans at all. Like these:
https://www.youtube.com/watch?v=6doG8vTKaAs
DCG3 I designed it primary for my rack in line duty but to can also have a decent headphones output at the same time just because I could. No extra build to cater for those, rack space, time, money, savings. Not a must use in both modes, matter of choice, but they are there when needed. All mod cons
Cables lost their way this weekend! One good thing with balanced amps is that you can switch interconnects on the fly! My exploratory temperament forced me to do all those tests. Now I feel relaxed
I'll finalize the chassis and let it permanently on the rack
If I ever would go for these cans, there won't be any DIY projects for a long time and I' m not willing to make such a tradeCould be you are a future user of only too expensive headphones with better sense of space if you will ever accept any cans at all. Like these:
https://www.youtube.com/watch?v=6doG8vTKaAs
DCG3 I designed it primary for my rack in line duty but to can also have a decent headphones output at the same time just because I could. No extra build to cater for those, rack space, time, money, savings. Not a must use in both modes, matter of choice, but they are there when needed. All mod cons
Good designs find many applications. And I forgot to tell that this thing gets better day by day! Thanks for sharing it Salas
Nice detailed report. Do let us know how the balanced sound compares with the R7's combined. Some reading on the subject
https://passlabs.com/press/super-symmetric-amplification
Best. nash
Thanks Nash! To lift R7 probably would take a complete deconstruction of my built, I can't promise... DCG3 allready measures great for THD and noise. I only wanted to explore how it interacts with the psu which is also great! One thing to add is that balanced wiring permits a better grounding scheme for noise and for channel separation.
If I ever would go for these cans, there won't be any DIY projects for a long time and I' m not willing to make such a trade
Good designs find many applications. And I forgot to tell that this thing gets better day by day! Thanks for sharing it Salas
You are welcome, nice that you enjoy it.
BTW can still be handy to have a comfortable & affordable pair of cans for louder music in those neighbors no go zone hours but with some decent sense of space characteristics at the price. As far as how space is meant in headphones terms at least.
Maybe Sennheiser HD 598 (HD 598SE & HD 599 also). Can be driven to good levels from mobile devices or the PC too.
Much closer target! Honestly I have to get a desent pair at some time. We' ll see about it...
Also, after DCG3 I found my self digging in Pass forums for power amps. Never say never! I only need 15 watts class A with enormus input sensitivity and preferably balanced interface. Any suggestions? Or should we wait for something?
Also, after DCG3 I found my self digging in Pass forums for power amps. Never say never! I only need 15 watts class A with enormus input sensitivity and preferably balanced interface. Any suggestions? Or should we wait for something?
You don't need to lift R7s from GND and connect them together when you are having a direct balanced source or a converted to balance SE source through input line transformer or differential driver chip. That's needed when you want to drive directly from an SE source with the second input grounded. Pseudo balanced mode in other words. It would work in exactly the same spec as your now configuration theoretically when fed a true balanced source* except in practice you extend the layout with a bridging R7s between channels wire for no reason if you don't need that convenience.
*SE/BAL 2nd input short to GND lift switch or shoring jumper pull out from its female XLR needed to change modes
Pass DIY are usually low voltage gain but I am not too versed in their historical diversity. Maybe there is one for you that members here will readily point out.
One from Jesper's land. Sito Audio V1.7 SMT small boards. Its a current feedback double die MOSFET type power amp. I set it at 26dBV 40+40W at 800mA bias for the rails level I combined from a heavy duty 2nd order filtered Darlington multiplier with large Toshiba BJTs I designed for it. Nothing special, bog-standard PSU design. Common between channels also. Just one 300VA plain doughnut Tx.