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Old 28th August 2010, 11:24 AM   #191
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Great technical summation, Ken.

May I add about #4. The capacitance IS very small in input trafos because of the use of shielding between windings. Input trafos have many more turns of wire in their construction than output trafos so the capacitance is very important. Output trafos are generally bifilar wound which means the coils are wound together, creating quite a bit more capacitance per turn, but they use many times less turns in their coils. They are also designed to drive a signal through a cable and use their output capabilities to overcome the capacitance. Theoretically, input trafos can be superior to output trafos but once you tie a cable to their outputs you have deviated so far from their designed use that just 2 ft of cable can have serious effects on performance. Add to that the general requirements of proper loading for input trafo secondaries and you now need a signal generator and a scope to set them up properly.

If you have the test equipment and the patience, try input trafos if you like.

If you want to simplify your task with great results, use fine quality line output trafos such as Sowter, Cinemag, Jensen, etc. They are generally less expensive and yield comparable real world results.

That's my rant, YMMV.

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Old 28th August 2010, 10:36 PM   #192
sendler is offline sendler  United States
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Default Caps vs trannies

I got my Jensen JT-11 FMCF transformers installed in my modified DEQ2496. The primaries are wired up balanced to the direct outputs of the AK4395 through 20 ohms of my favorite Yageo metal film resistors per leg. I would have used something smaller but that was the lowest value I had on hand of the metal film resisters. No additional load or filters. The AK4395 V out is already well filtered and doesn't need it. The resistors are connected to the same wires at the input of the caps with the trannies mounted outside of the case with their own output connectors wired up single ended with the orange wire grounded inside at the pin 1 that the caps are using. My cables take signal from pin 2 with pin 3 left open even though both legs are available through the caps if wanted for my balanced/ bridged 3875 amps. I currently use my modified Sure 2X100 amps which are single ended and when running a minimal output coil and big SMPS offer by far the best sound I have ever had home.
These are very good transformers. Loss seems to be about only .5-1db compared to the caps. They sound much better than the Sowter multi-tapped volume control transformers that I had tried a few years ago. The Jensens are very close to a good cap. When using the demanding load of my 4k series/ switched shunt stepped attenuators on the inputs of the amps, the balanced in transformers offer a nice full bodied and plump bass compared to a single leg of the dac output through 3uf stacks of Dayton foil caps. The caps sounding a little tighter and lower in level. With the attenuators gone leaving a 20k termination at the amps and using only -.5db digital volume control for the caps, -6.0db for the transformers to match the levels, The advantage in the bass is reduced to a non issue. Still different but more of a toss up of preference between a full bodied plump sound versus the tighter, quicker bass of the caps. From the midbass up the Dayton foil caps really shine. They present with a blacker background with less overhang. On Tattoo from the Janis Ian live cd, the steel guitar at 1:50 is placed much deeper in a blacker sound stage with the caps. The vocals are nicely fleshed out and lacking of additional sibilance with the transformers but the excellent large drums sound slightly filtered. The caps reveal the striking attack and sense of a vibrating membrane much better. The cap's advantage in micro dynamics is even more noticeable on San Andreas fault live where The transformers tend to sound a bit muffled in comparison with more overhang smearing up the presentation slightly. The power and accuracy of Natalie Merchant's voice and attack of the instruments are more engaging through the caps and the crowd sounds go back much deeper and cleaner. On Babylon Sisters, the faint noodling of the left guitar is easy to hear through the transformers but the backing vocals at 1:14 are more separate and distinct with the caps. You get the idea. I like the caps. For the mids and highs of a DCX, a $2 Dayton foil cap is a no brainer compared to spending a fortune on multiple channels of transformers. When increasing the value of the caps to get enough for the bass channel, the price advantage is less, especially if you need balanced which raises the required caps to $24. For full range in a dac with the AK4395/96 the caps will sound more dynamic and revealing.
Next up will be the CS43122 on a big dac board which may need a filter and the extra 6db so I will try the transformers again on that one.
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Old 11th September 2010, 03:05 PM   #193
sendler is offline sendler  United States
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Default Trannies better quiet

I discovered something by accident the other night. I was on a listening binge with my new DIR9001/ CS43122 Big Dac Board (way better than CS8420/ AK4395) when everyone else in my house went to bed so I had to install my 4k series/ stepped shunt attenuators onto the amp inputs and turn it way down which lowers the input impedance that the direct out dac chips are working into right down toward a punishing 4k whereas the attenuators present a 20k input at a louder -2db setting and the amp is at 20k with no attenuators and only digital volume control which is where I did most of the previous comparison where I preferred the caps. With the increased load and quieter listening level the Jensen transformers clearly sound better than the caps. Why, when the caps sound better at wide open loads and volume? Is it because the transformers are using both legs of the dac chip and the caps are only using one, thereby cutting the output impedance of the dac in half with the transformers. Do transformers inherently "do" current (or quiet?) better than caps? The current is still way less than 1ma. I have never placed much emphasis on the sonics of my system at ultra quiet listening levels but I do know that the AK4395 sounds better working into my amps at 20k than it does at 150k termination so it does enjoy some loading. I put the amps up to 150k to compare my 4k and 20k attenuators and the lower series output impedance of the 4k attenuators sounded best when wide open at -2db even though there is no cable (maybe 6cm of traces) following the attenuators which plug right onto the amp's RCAs. So it is not just that the easiest load wins but maybe 4k is too much load for one leg of these chips when running direct.
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Last edited by sendler; 11th September 2010 at 03:11 PM.
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Old 8th November 2010, 12:30 PM   #194
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The my solutions for the output stage:

Hi-Resolution System 192KHz 24bit with EMU 0404 USB
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Old 10th November 2010, 10:24 PM   #195
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Do anyone have the schematic for the ak4396 with spdif input? I wish to play around with it
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Old 20th January 2011, 11:59 PM   #196
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Hi - did anyone try the THAT corp line drivers instead of the transformers? Also, what are the popular best sounding D/As right now that feature differential outputs? thanks
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Old 21st January 2011, 12:12 PM   #197
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Default Big Dac Board

Quote:
Originally Posted by diy_lurker View Post
Hi - did anyone try the THAT corp line drivers instead of the transformers? Also, what are the popular best sounding D/As right now that feature differential outputs? thanks
Try this with DIR9001/ CS4398.
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Experience with this DIY DAC ?
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CS4397 is even better if you can get that module for it. Direct out through caps or transformers is still the best sounding output for any of these V out dacs.
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Old 28th January 2011, 04:17 AM   #198
AR2 is offline AR2  United States
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I posted this in Behringer thread but here it is as well since this is great thread as well. 6 channel output with Lundahl transformers and jFets buffers with no caps in the signal path. Signal goes straight from AKM 4396 DACs to transformers. Lundahls are linearized with RC filter - 9Kohm and 680 pF. I came to these values by measurement done on my HP network analyzer which gave me the flatest response. DACs are on Behringer 2496, here is the link for modification I did long time ago:
Behringer DCX2496 digital X-over
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Old 2nd February 2011, 01:08 PM   #199
sendler is offline sendler  United States
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Default Listening for the best attenuator load for direct out dacs

I listened to my AKM and CS direct out dacs to find the best load for a new stepped attenuator design. I like them into 15k the best. Read about it here.
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Listening for the best attenuator load for direct out AKM and CS dac chips
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It was also fun to revisit the AK4395 vs AK4396 vs CS43122. The 4395 really does sound way better than the 4396. I had been leaning heavily toward the CS dac chips since getting my Big Dac Board which also allowed me to find the PCM1798 to be not quite as good all of the hype unless you want to implement a no holds barred I/V stage with tubes or discretes instead of opamps. Building a direct out with a V out chip is so much easier for multi channel users and can rival the best sound anywhere with nothing more than a cap to block the dc. I am now liking the AK4395 again when working into the right load. The CS43122 is different but not necessarily better. It has a powerful sound with a little better pinpoint location of the instruments similar to the 4396 but the 4395 throws it's soundstage much deeper behind the front wall and does a really nice job of following the ambient decay and with excellent tuneful bass extension.
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Old 21st September 2011, 11:30 PM   #200
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Quote:
Originally Posted by sendler View Post
Is your volume control RCA in, single ended? If so, to make this test easiest, just cap couple the left and right + output of the dac chip to the center pins, take the original audio ground and then just leave the minus leg floating open for now.
hi Scot,
thanks for your contributions. i run a heavy modded AK4396 kit from eBay with ne5532 as output stage. the signal goes RCA via a stepped 20k shunt attenuator to the 100k-imp SS power amp.

i did this simple test using 2uf 400v Audycap mpk. the 3d was excellent to be on the pair Aureus! but no dynamic and bass!

is there any better "direct out" configuration that you run? with the - output legs as well?

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