Hi John, I'm sure no expert by any stretch but I'll tell you what I know.
The transformer you want is a 600/600 ohm line matching transformer capable of handling a +20 db signal, about 5V or so without saturating the core. There are many manufacturers and many different quality levels, some are damn expensive but there are always used pieces on Ebay if you want to experiment. They supply a comfortable load for the DAC chip and also give you a degree of high frequency filtering without intruding into the audio band at all. Good ones are totally transparent and my personal experience so far is actually increased dynamics over the PCM63 with the Borbely FET I/V stage, not at all like a passive line stage. I think magic must be involved, you must try it. Don't forget the link to the Jensen filter arrangement that legarem posted, very simple and effective.
Bill
The transformer you want is a 600/600 ohm line matching transformer capable of handling a +20 db signal, about 5V or so without saturating the core. There are many manufacturers and many different quality levels, some are damn expensive but there are always used pieces on Ebay if you want to experiment. They supply a comfortable load for the DAC chip and also give you a degree of high frequency filtering without intruding into the audio band at all. Good ones are totally transparent and my personal experience so far is actually increased dynamics over the PCM63 with the Borbely FET I/V stage, not at all like a passive line stage. I think magic must be involved, you must try it. Don't forget the link to the Jensen filter arrangement that legarem posted, very simple and effective.
Bill
john65b said:I actually tried the LM4562, the OPA627, OPA2134, LT1364, and the LM6172 sounded more clearer and revealing. Kinda what I was looking for...
OK, I want a try transformer. I have heard this thread mention all sorts of transformer manufacturers, but what exact specs am I looking for? Edcors, Lundahl, Sowter, Sescom, UTC,
I am a total neophyte on these transformers. What exactly do they do better than Opamps in this application? Utilized for Gain? Are they stardard output trannies like for tube amps? I have a set of those laying around, but they are 4300 ohm Hammond 1650N...I don't think these are what you all have been using.
I plan to have an 6SN7/6SN7 Aikido Tube preamp after the CS4398 DAC (or the CS4397 if it sounds better) and wonder if I can toss the Opamp/tranny and go directly into the Aikido inputs?
I built a Kusonuki style (?) TDA1543 x4 DAC a long while back and it had no opamp or transformer on the back end. Sounded good, but prefered the CS4397...
Op amps whatever they are were designed to save costs and to simplyfy circuits. Their gain is controlled by tons of negative feedback so in a circuit like the CS4398 dac, they use a lot of negative feedback because the gain required is lower than 2.
Don't loose your time with the Aikido. I tried it with 6SN7 and while it is good, it doesn't reach the sound with a good transformer.
Another recommendation: Never use any Hammond transformer. They are cheap and you have for what you pay. Even their power transformers are always buzzing.
Has anyone tried experimenting with the Digitecs? Franz do you still recommend using just the 10-ohm resistors from L+/L-/R+/R- to the transformer primaries?
Many thanks,
- John
Many thanks,
- John
The transformer you want is a 600/600 ohm line matching transformer capable of handling a +20 db signal, about 5V or so without saturating the core.
Would a 150/150 ohm line matching transformer work in this app??
I read 600/600 ohm or lower?
I can't answer that one, but if you have a couple you should try them and experiment with different series resistors. Keep in mind that they will be part of a voltage divider circuit so you will lose output voltage. If they have multiple secondaries you can wire them in series to retrieve some output.
I'm not sure I'd spend much money on items that weren't proven to operate optimally.
I'm not sure I'd spend much money on items that weren't proven to operate optimally.
john65b said:
Would a 150/150 ohm line matching transformer work in this app??
I read 600/600 ohm or lower?
The primary impedance of the transformer will depend of the load placed at the secondary.
With all the transformers I tried with this dac, you have to try many loads with each transformer to get the sound you like. It is easier to begin with a generator and a scope (as described elsewhere) but yo have to finish by ear.
This remains me when I was using a moving coil cartridge and I had to play with the load to get correct sound.
As of this morning there is another pair of Sescom MI-14 transformers on Ebay for $50 Buy it now price. If someone wishes to try transformer output with these DACs you wont find a better deal, they are fine units, retailed for about $135 a piece.
Bill
Bill
I won a pair of UTC HA-108 on eBay so another pair will be tried with this dac. They are big transformers.
I'll write a transformer battle soon. Here are the candidates
Yamaha Tamura GA80080
Lundahl LL1690
Digitec
Little Studer uncapsulated
UTC HA-108
Chicago A-xx
I'll write a transformer battle soon. Here are the candidates
Yamaha Tamura GA80080
Lundahl LL1690
Digitec
Little Studer uncapsulated
UTC HA-108
Chicago A-xx
That should be fun, but subjective comparisons by an individual are not that useful to people unless they have similar musical tastes and hearing. They are all going to sound different but not necessarily better or worse for someone else. Still, it could demonstrate deficiencies in any of them such as premature rolloff or low frequency saturation. Should be very interesting.
Bill
Bill
I bought a pair of those Sescoms this morning.
I also just recieved my DAC yeserday. I put the LM4562 in both locations and fired her up. Sounds very nice!
A while ago I purchased these cheap trannies from APEX Jr on clearance for $8. With 14-0-14 and 9-0 taps it is perfect for this DAC, allbeit way oversized at around 200VA
I also just recieved my DAC yeserday. I put the LM4562 in both locations and fired her up. Sounds very nice!
A while ago I purchased these cheap trannies from APEX Jr on clearance for $8. With 14-0-14 and 9-0 taps it is perfect for this DAC, allbeit way oversized at around 200VA
examining this dac designs I see
cs4397 and cs8416 - two pcbs - one ne5532
cs4397 and cs8416 - one pcb - two ne5532
cs4398 and dir9001 - one pcb - two ne5532
which of the 3 is best
I think first - It Is claimed to do 192 kHz and you can do mods - change tha caps
the ones with dir 9001 got lesser jitter but no 192 kHz
what are your choices
cs4397 and cs8416 - two pcbs - one ne5532
cs4397 and cs8416 - one pcb - two ne5532
cs4398 and dir9001 - one pcb - two ne5532
which of the 3 is best
I think first - It Is claimed to do 192 kHz and you can do mods - change tha caps
the ones with dir 9001 got lesser jitter but no 192 kHz
what are your choices
samloko,
the dac i bought has the cs4398 with the 8416
it has input transformer on spdif
just thought i'd let you know there is another option to your list, which i personally thought to be the best option
stuart
the dac i bought has the cs4398 with the 8416
it has input transformer on spdif
just thought i'd let you know there is another option to your list, which i personally thought to be the best option
stuart
Actually, I think that the best is to buy the one with the upsampling board and USB and adding a digital transformer at the spdif input.
If you don't like upsampling, you can use it without the upsampling board
If you don't like upsampling, you can use it without the upsampling board
legarem said:I won a pair of UTC HA-108 on eBay so another pair will be tried with this dac. They are big transformers.
I'll write a transformer battle soon. Here are the candidates
Yamaha Tamura GA80080
Lundahl LL1690
Digitec
Little Studer uncapsulated
UTC HA-108
Chicago A-xx
Take care Marc ! price will increase on ePay with such revelations😱 just send me your choice under personnal email😀 much more secure😎
Edcor
I didn't get the 600:600
I got the 10k:15k for experimental purposes.
I haven't had time to wire it in. I will try tonight. I know it will take several days to break in so I'll report sometime next week.
I didn't get the 600:600
I got the 10k:15k for experimental purposes.
I haven't had time to wire it in. I will try tonight. I know it will take several days to break in so I'll report sometime next week.
could any experienced person explain the role of the audio transformer used in output stage and also what has to be the type 1:1 600/600 or whatever and why
Sorry for the silly questions.
In legarem's diagram in post #418, the black wire is connected to the ground connection. Is that the analog ground of the DAC?
http://www.diyaudio.com/forums/attachment.php?s=&postid=1817093&stamp=1241223954
Also, on the same diagram, is the type of capacitor across the transformer primaries important (0.0047uF)?
In legarem's diagram in post #418, the black wire is connected to the ground connection. Is that the analog ground of the DAC?
http://www.diyaudio.com/forums/attachment.php?s=&postid=1817093&stamp=1241223954
Also, on the same diagram, is the type of capacitor across the transformer primaries important (0.0047uF)?
Those aren't silly questions.
The caps should be good quality polypropylene film.
The grounding issue is best answered by legarem, I wouldn't think it wise to defeat the isolation provided by the transformer by connecting one side of the secondary to the audio ground.
Bill
The caps should be good quality polypropylene film.
The grounding issue is best answered by legarem, I wouldn't think it wise to defeat the isolation provided by the transformer by connecting one side of the secondary to the audio ground.
Bill
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