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Old 19th October 2011, 08:12 AM   #331
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Thanks,

Any part number for this dual transistors ? I cannot really find them on mouser.

D.
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Old 19th October 2011, 08:16 AM   #332
EUVL is offline EUVL  Europe
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BCM846/856, BCV61/62, LS312/352, MAT12/03, ....


Patrick
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Old 19th October 2011, 08:24 AM   #333
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Guess all SMD. I have to match :-(

D.
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Old 19th October 2011, 08:42 AM   #334
EUVL is offline EUVL  Europe
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You can also make an adaptor board to wire them to my PCB.
But yes, we did match (BC850/860) ourselves, as I do not consider the standard match good enough.
Apart from that, I also wanted to use high hfe (>500).

BTW, MAT12/03 are not SMD, but too expensive IMHO.


Patrick
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Old 19th October 2011, 09:54 AM   #335
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Mathias is very busy so i have to wait a bit for his commend.
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Old 19th October 2011, 11:59 PM   #336
rtd is online now rtd  France
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Quote:
Originally Posted by EUVL View Post
As to distorted sound (never happened to us), first check output with no input connected (open, no DAC).
If you see oscillation, you can add 2x 100R gate stoppers between Gnd and JFET gates.
Distorsion vanished with the 2x100R gate stoppers... Amazing Is this IV worth it ? the answer is YES.
I quickly compare it to Spencer D1 jfet I/V (also 2sk170/sj74, R Vishay Bulk metal foil, PIO coupling cap) for the left channel, CEN using basic material for the right.
Comparison was made with CD having the same mono sound on both channel.
Sound was great in both case, for sure really better than opamp IV. I cannot tell whether Spencer D1 or CEN is better... They are closed... CEN is opened to simple improvement (Better RiV...) and should be better as my try is really not optimized (see picture)...

One default it will be difficult for my wife to change battery each 10 hours if i adopt it.

So really, thx Patrick for sharing

CenBrd.jpg

PS : Have you compared CEN/SEN to one of your previous concept Hawksford Discrete IV with a Twist

Last edited by rtd; 20th October 2011 at 12:04 AM.
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Old 20th October 2011, 04:28 AM   #337
EUVL is offline EUVL  Europe
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Thanks for reporting the results.
You should do the circuit some justice by using proper PCBs, etc.

The PCB for the GB has already allowed for the gate stoppers.
So you did have oscillation.

You can use rechargable batteries and use a relay to switch it to charge as you switch off the player.
We do exactly that.

As to other circuits.
We have our own version of all.JFET D1, and the Hawsford as you mentioned.
They do not offer any sonic advantages but are much more complicated.
And the CEN / SEN are dead quiet !!!

As said, we use SEN ourselves for PCM1704.


Patrick
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Old 20th October 2011, 06:22 AM   #338
Calvin is offline Calvin  Germany
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Hi,

tested the Hawksford after th C111-article, Fig 4.4.
While it sounded better than a OP-IV it was no better than a improved Jocko, which is still my personal favourite for DAC-chips with an offset current output, because of the simplicity of the circuit (1x JFET-CCS and 1x biolar Dual + output Buffer stage).
There remained a certain grainyness in the sonic character of the Hawksford-circuit that I know so well from globally fed-back circuits. Regardless of featuring error-correction the distortion was not as low as Id expect from a feedback circuit, hardly better than -70dB@0dBfs.
The optimized Jocko shows much less THD at better -90dB@0dBfs (2.1Vrms from a +-2mApp Input). Further improvements in THD are rather an academic than a sonic issue.

jauu
Calvin
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Old 20th October 2011, 06:28 AM   #339
EUVL is offline EUVL  Europe
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The Hawsford variant that I published has some improvements over the original.
And it has a lot more driving capabilities (e.g. for a low impedance headamp).

But I agree that the error correction does not deliver the promised sonic advantage.
And the CEN/SEN are really hard to beat for its own intrinsic distortions.

We have some ideas how to improve the SEN further.
But work in progress, and not ready for publication for another 6 months or so.


Patrick
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Old 20th October 2011, 06:30 AM   #340
EUVL is offline EUVL  Europe
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Guess this is what Calvin was referring to :

Easy-to-build I/V stage


Patrick
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