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DAC ouput using Transformer
DAC ouput using Transformer
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Old 27th November 2009, 01:31 PM   #131
Michel_MRS is offline Michel_MRS  France
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Quote:
Originally Posted by Havoc08 View Post
So using that layout I can use a ordinary pot on the analogue inputs to control volume instead of the digital way? I'm using it with the shigaclone -> 4398 DAC -> Lundahl LL-1517 -> T-amp
Does it mean that you can just have one transformer between a voltage dac output and a tripath amp input AND just add a pot (without any cap for DC coupling) ?

Where do you connect the pot ?

Can we use the pot across the primary instead of the R load?

Thanks
Michel
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Old 27th November 2009, 02:17 PM   #132
Ciu is online now Ciu  France
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DAC ouput using Transformer
Quote:
Originally Posted by frozen wing View Post
Thanks everyone, anbello i'll wait for your findings.

For the chinese dac Legarem say's that the lundhall 1690 is the best,

What would you suggest for the Buffalo?

Also voltage mode means with a series resistor on the input of the trafo?
Hello !
I'm using a Sabre Buffalo24.
I've tried many 600/600 transformers (Utc, Tamura, various Jensen) , with, for all of them, a lack in low frequencies
Then changed to upper impedance : Edcor, Rane, Jensen , Lundahl, then I got a better response with low frequencies
I found my "Heaven" with Jensen JT-11P1, 10k/10k, , low, mid,trebble, everything is better !!!
Maybe someone would say "Jensen are very expansive " ! yes but the results given by a Jensen (140$/pair) is far far far away from a UTC (~100 $/pair) !

I ve added 100 Ohms on +-, and 3nF on primary side, only to filter HF, and on secondary , 13k + 620pF , to a McIntosh C24 pre
What a happiness !!!
R.C.
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Old 1st December 2009, 09:16 PM   #133
SamL is offline SamL  New Zealand
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Quote:
Originally Posted by Ciu View Post
Hello !
I'm using a Sabre Buffalo24.
I've tried many 600/600 transformers (Utc, Tamura, various Jensen) , with, for all of them, a lack in low frequencies
Then changed to upper impedance : Edcor, Rane, Jensen , Lundahl, then I got a better response with low frequencies
I found my "Heaven" with Jensen JT-11P1, 10k/10k, , low, mid,trebble, everything is better !!!
Maybe someone would say "Jensen are very expansive " ! yes but the results given by a Jensen (140$/pair) is far far far away from a UTC (~100 $/pair) !

I ve added 100 Ohms on +-, and 3nF on primary side, only to filter HF, and on secondary , 13k + 620pF , to a McIntosh C24 pre
What a happiness !!!
R.C.
Wau... that is quite a long road to get there, I admire your persistent.

I wonder have anyone try this on a Philips TDA1541 DAC on NOS setup with good results. Appreciate if you can share your finding.
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Old 1st December 2009, 09:23 PM   #134
jkeny is offline jkeny  Ireland
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Quote:
Originally Posted by Ciu View Post
Hello !
I'm using a Sabre Buffalo24.
I've tried many 600/600 transformers (Utc, Tamura, various Jensen) , with, for all of them, a lack in low frequencies
Then changed to upper impedance : Edcor, Rane, Jensen , Lundahl, then I got a better response with low frequencies
I found my "Heaven" with Jensen JT-11P1, 10k/10k, , low, mid,trebble, everything is better !!!
Maybe someone would say "Jensen are very expansive " ! yes but the results given by a Jensen (140$/pair) is far far far away from a UTC (~100 $/pair) !

I ve added 100 Ohms on +-, and 3nF on primary side, only to filter HF, and on secondary , 13k + 620pF , to a McIntosh C24 pre
What a happiness !!!
R.C.
I thought I posted this already but here goes anyway:
So does the analog outs from the Sabre work best into 10K? I can't find any mention of minimum impedance for the Vouts - it does in other Vout DACs datasheets, doh!

Did you try a series resistor of 10K with your other 600:600 transformer & the Sabre DAC?
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Old 1st December 2009, 10:47 PM   #135
Ciu is online now Ciu  France
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DAC ouput using Transformer
Hello !

Among many transformers 600/600 I've tried with Buff24, I've noticed as a first conclusion is that the best listening was always with transfos which had the upper DCR, this is why UTC A-20, with 72-75 Ohms gave a "good" result...
I've tested 600/600 transfos, with up to 2 x 1.2k , and stopped to think about : if you add more resistance , it's become a voltage divider, and the level at the secondary output becomes very low
The input impedance of each side of the Buffalo (+ and -) are something like 185 Ohms, if you insert 2 x 1k, the result gives you 1/5 of the primary voltage
The fisrt try with a high impedance was Edcor 10k/10k, 13$ each, and a better result than any 600/600...I was on the good way ....
The Jensen 10k/10k I choose are about 1.5k primary DCR, so the ratio Source/load is about 9.
I don't want to say that my solution is the best, but the "best simple solution" !
R.C.
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Old 1st December 2009, 11:05 PM   #136
jkeny is offline jkeny  Ireland
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Thanks Ciu,
I'm a little confused & would like to ask some questions if I may:

Quote:
Originally Posted by Ciu View Post
Hello !

Among many transformers 600/600 I've tried with Buff24, I've noticed as a first conclusion is that the best listening was always with transfos which had the upper DCR, this is why UTC A-20, with 72-75 Ohms gave a "good" result...
I've tested 600/600 transfos, with up to 2 x 1.2k , and stopped to think about : if you add more resistance , it's become a voltage divider, and the level at the secondary output becomes very low
Does a 600:600 transformer have a primary & secondary of 600ohm? I don't understand your ref to UTC A-20 of 72ohm!

Quote:
The input impedance of each side of the Buffalo (+ and -) are something like 185 Ohms, if you insert 2 x 1k, the result gives you 1/5 of the primary voltage
Is this 185ohm measured or did you get it from a datasheet?
Quote:
The fisrt try with a high impedance was Edcor 10k/10k, 13$ each, and a better result than any 600/600...I was on the good way ....
The Jensen 10k/10k I choose are about 1.5k primary DCR, so the ratio Source/load is about 9.
I don't want to say that my solution is the best, but the "best simple solution" !
R.C.
Thanks for your help in this - I find transformers confusing so any help is appreciated.
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Old 1st December 2009, 11:33 PM   #137
Ciu is online now Ciu  France
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DAC ouput using Transformer
Yes, sure, but may be unable to answer all of them (lack some vocabulary ) !!!
About the transformer, like UTC A-20 :
The given value is a 600/600 if you connect all primaries in series , but this is the impedance , not the DCR : dcr is ~75 Ohms (pure resistive windings)
The inductance L is not (never) given,
Z = L 2Pi x F
When the transfo receives a low frequency, the impedance Z is rather low (how much ? don't know !),the Buffalo gives a lot of current, and with a internal resistance, the voltage goes down, and you feel a lack in low frequencies...
With high frequencies...Z goes upper, the output current is low, ....
The value of 180 ohms, has an internal impedance of the Buffalo is given, in many places, even in ESS short sheet, the chip ESS9008 is in fact 8 dacs coupled 4 by 4, (4 L & 4 R) each "small-dac" having ~800 Ohms internal impedance .
Have a look on Buffalo posts, page 48 to 50, some idea to run Buffalo in "current mode" with transfos...
Hope this helps ?
R.C.
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Old 2nd December 2009, 02:28 AM   #138
frozen wing is offline frozen wing  Canada
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very interesting, what were the lundahls that you tried.
Your explanations are very apreciated.
With your set up is the gain (not the sound) comparable to the TP ivy

Merci ciu, très aprecié.
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Old 2nd December 2009, 03:33 AM   #139
Ciu is online now Ciu  France
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DAC ouput using Transformer
I've tried Lundahl ll1540
The gain is rather the same, may be a bit lower level than TP IVY in SE mode
Have forgot my first tests with TP IVY, because I've done some with Broskie CF (balanced out from Sabre) , and Bipolar CF, using only + dac Output

R.C.
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Old 2nd December 2009, 11:35 AM   #140
revintage is offline revintage
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Quote:
I found my "Heaven" with Jensen JT-11P1, 10k/10k, , low, mid,trebble, everything is better !!!
Maybe someone would say "Jensen are very expansive " ! yes but the results given by a Jensen (140$/pair) is far far far away from a UTC (~100 $/pair) !

I ve added 100 Ohms on +-, and 3nF on primary side, only to filter HF, and on secondary , 13k + 620pF , to a McIntosh C24 pre
Hey Ciu,
Your findings are correct. Any suggestion to run a voltage DAC(Sabre is both) at 600ohm with series resistors is a mistake. I am sure this sounds great.

What you should try though, if you haven´t yet, is to run your Jensen without secondary loading more than your preamp(100k?). Then load the primary with a parallell pure resistive load without series resistors. If you absolutely want filtering you do this on the primary parallell to the loading resistor. This off course is dependant on transformer but most of them like light loads.
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