Anyone built a Pass D1 I/V for a TI1794 or TI1794 DAC?

hifimaker · 5th May 2006, 02:15 AM

I understand that the current output of the TI1792 DAC chip is higher than other DACs. Has anyone had success buildign a D1 I/V for these newer TI DAC chips?

-David

hifimaker · 6th May 2006, 06:04 PM

The specs on this BB/TI 1792/4 chip look great. I'm surprise no one has implemented a DAC with a Pass I/V stage yet.

-David

stefanobilliani · 6th May 2006, 08:56 PM

I love D1 stage . And implementet at least with 4 dacs . Will need to modify the biasing network a bit if the dc point of the dac is different from 0 volt . An example is the Philips tda 1545 wich requires 3.3 volts as dc working point.
Currently I am using the lovoltech j fet in that circuit . I am very happy .

acaudio · 6th May 2006, 09:11 PM

Stefano,

I´m currently building my D1 stage with different options.
I´m still no really lucky. my CDP (shanling CD-S100MK2) has a PCM1738 inside. This chip seems to work best into a "virtual" ground, the common Voltage is set to 2,50V.
See this picture, and thread: http://www.diyaudio.com/forums/attac...amp=1081271528
D1 output stage and PCM1738
I tried already a few different adjustments and I thought it were good, but after long listening I´m sure, I´m missing dynamic.
Would you please posting your lovoltech D1? I´m working at a 2SK389 based D1, very different to original. I thought too about LU1014d, but those needs a lot of current to operate in "triode region"
Best Regards
Adam

stefanobilliani · 7th May 2006, 12:50 PM

No, really also in a single ended set up I like dynamics , very correct . But compressions and dynamics depends on power supplies implementation and a number of other things.
With j fet (lovoltech)there is a step forward by my point of view ,and often I can see the mixing consolle very clearly . It is a nice sensation .
I wasnt so happy with 2sk s .
Absolutely the lovoltech require matching between channels . The difference is quite audible and not at all subtle.

I started by inserting jfets in the same circuit , just adjusting the bias ... and all seems to work pretty well .

hifimaker · 7th May 2006, 04:21 PM

Quote:

Originally posted by stefanobilliani
No, really also in a single ended set up I like dynamics , very correct . But compressions and dynamics depends on power supplies implementation and a number of other things.
With j fet (lovoltech)there is a step forward by my point of view ,and often I can see the mixing consolle very clearly . It is a nice sensation .
I wasnt so happy with 2sk s .
Absolutely the lovoltech require matching between channels . The difference is quite audible and not at all subtle.

I started by inserting jfets in the same circuit , just adjusting the bias ... and all seems to work pretty well .

Thanks Stefano for your insights.

Could I ask, what DAC are you using?

-David

stefanobilliani · 7th May 2006, 04:38 PM

hehehe I have the Philips tda15145 but every part of the circuitry has separated supplies , laser motors drivers and clock included .
I can assure you that it works very very good .
I had also nice performances with sony current pulse , in that case in a balanced configuration .
The philips is 16 bit converter , sony is tipically 1 bit.

agent.5 · 8th May 2006, 02:46 AM

Quote:

Originally posted by stefanobilliani
I love D1 stage . And implementet at least with 4 dacs . Will need to modify the biasing network a bit if the dc point of the dac is different from 0 volt . An example is the Philips tda 1545 wich requires 3.3 volts as dc working point.
Currently I am using the lovoltech j fet in that circuit . I am very happy .

Assuming that I have 0 volt out from the DAC, what do I have to change to the circuit to use Lovoltech Jfet instead of IRF610. My thinking is that I need to change the two 1.5K resistors to a different value to bias the Jfet? The schematic that I am looking at is attached.

relder · 8th May 2006, 09:37 PM

Quote:

Originally posted by agent.5

Assuming that I have 0 volt out from the DAC, what do I have to change to the circuit to use Lovoltech Jfet instead of IRF610. My thinking is that I need to change the two 1.5K resistors to a different value to bias the Jfet? The schematic that I am looking at is attached.

JFET Vgs is negative, unlike MOSFET, so instead of tying r5a to +30 tie it to -30. The 1.5K resistors control gain, not bias, to change current bias change the 3.3K resistor.

hifimaker · 8th May 2006, 10:19 PM

I seem to recall someone built a D1 I/V stage with Jfets recently, Let me see if I can find it.

Would be very cool.

-David

5th May 2006, 02:15 AM	#1
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Anyone built a Pass D1 I/V for a TI1794 or TI1794 DAC? I understand that the current output of the TI1792 DAC chip is higher than other DACs. Has anyone had success buildign a D1 I/V for these newer TI DAC chips? -David

6th May 2006, 09:11 PM	#4
acaudio diyAudio Member Join Date: Sep 2004 Location: Germany	Stefano, I´m currently building my D1 stage with different options. I´m still no really lucky. my CDP (shanling CD-S100MK2) has a PCM1738 inside. This chip seems to work best into a "virtual" ground, the common Voltage is set to 2,50V. See this picture, and thread: http://www.diyaudio.com/forums/attac...amp=1081271528 D1 output stage and PCM1738 I tried already a few different adjustments and I thought it were good, but after long listening I´m sure, I´m missing dynamic. Would you please posting your lovoltech D1? I´m working at a 2SK389 based D1, very different to original. I thought too about LU1014d, but those needs a lot of current to operate in "triode region" Best Regards Adam __________________ http://www.acaudio.de

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
DIY Low Pass and Mid/High Pass (Bass Blocking) Filters	runslikealpaca	Everything Else	1	19th June 2009 10:59 PM
Paging Mr. Pass, Mr. Pass pull my finger please.	khundude	Pass Labs	2	5th December 2008 04:11 AM
Question about power amp built in high pass filter	crippledchicken	Solid State	0	22nd October 2008 06:09 PM
non-Pass amps youv'e built/heard	BrianL	Solid State	49	5th July 2005 05:59 AM
My opinion on Pass Labs and Mr. Pass (Nelson) himself	b_online	Pass Labs	11	21st May 2003 12:39 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

6th May 2006, 06:04 PM	#2
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	The specs on this BB/TI 1792/4 chip look great. I'm surprise no one has implemented a DAC with a Pass I/V stage yet. -David

6th May 2006, 08:56 PM	#3
stefanobilliani diyAudio Member Join Date: Jun 2002 Location: Italy	I love D1 stage . And implementet at least with 4 dacs . Will need to modify the biasing network a bit if the dc point of the dac is different from 0 volt . An example is the Philips tda 1545 wich requires 3.3 volts as dc working point. Currently I am using the lovoltech j fet in that circuit . I am very happy .

7th May 2006, 12:50 PM	#5
stefanobilliani diyAudio Member Join Date: Jun 2002 Location: Italy	No, really also in a single ended set up I like dynamics , very correct . But compressions and dynamics depends on power supplies implementation and a number of other things. With j fet (lovoltech)there is a step forward by my point of view ,and often I can see the mixing consolle very clearly . It is a nice sensation . I wasnt so happy with 2sk s . Absolutely the lovoltech require matching between channels . The difference is quite audible and not at all subtle. I started by inserting jfets in the same circuit , just adjusting the bias ... and all seems to work pretty well .

7th May 2006, 04:38 PM	#7
stefanobilliani diyAudio Member Join Date: Jun 2002 Location: Italy	hehehe I have the Philips tda15145 but every part of the circuitry has separated supplies , laser motors drivers and clock included . I can assure you that it works very very good . I had also nice performances with sony current pulse , in that case in a balanced configuration . The philips is 16 bit converter , sony is tipically 1 bit.

8th May 2006, 10:19 PM	#10
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	I seem to recall someone built a D1 I/V stage with Jfets recently, Let me see if I can find it. Would be very cool. -David