Finally, an affordable CD Transport: the Shigaclone story - Page 413 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

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
Reply
 
Thread Tools Search this Thread
Old 16th September 2010, 11:09 PM   #4121
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
I would certainly try them, but where can I find them locally?
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 16th September 2010, 11:10 PM   #4122
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Agreed, Fran, let's not go bananas on this thread, please
  Reply With Quote
Old 16th September 2010, 11:18 PM   #4123
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
You can get them from minicircuits.com

link: Attenuators, Plug-In & Coaxial, Fixed

Its the HAT-XX-75 series you want. Try maybe 6, 10 and 15 dB ones. I used 2x 15dB on my shiga after removing the 300/92 pair. But just even try a single 6 or 10dB one and see what you hear.


Fran
  Reply With Quote
Old 16th September 2010, 11:22 PM   #4124
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Somebody just emailed me that they went from a 15 to 20dB on their modified Hiface & heard " provides even more focused imaging and improvement in the layering of the soundstage than the 15dB att."

I believe it is also DAC dependent as to what is the best dB value i.e what SPDIF signal level the DAC is happiest at. Fran will concur with this - we have seen the Hiface high SPDIF output causing problems on a Buffalo (Sabre DAC) which completely disappeared with an attenuator.

By rights, these should be no different to the 300/92 pair as long as this is a true 75ohm?

Last edited by jkeny; 16th September 2010 at 11:33 PM.
  Reply With Quote
Old 17th September 2010, 12:08 AM   #4125
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Can I ask about something that was posted way back in 2009 when this T-pad was first mooted. Audio1st asked if this T-pad was suitable:Click the image to open in full size.

And Kevinkr answered:
Quote:
No, use the circuit detailed elsewhere on this thread (300/100) - it provides the proper loading on the DSP digital output, the proper attenuation required for the SPDIF standard, and the proper terminating impedance for the coaxial cable. What more do you want?

The dsp chip's digital driver stage on the spdif output is guaranteed for about 11 - 12 mA - your T attenuator will overload it, degrading performance and causing unnecessary die heating, possibly it will destroy the driver as well over time. Note that the T attenuator is meant to be driven by a source impedance of 75 ohms, not the < couple of ohms of source impedance provided by the Sanyo DSP IC.
Does this still hold as the RF attenuator is a T-pad? If the output from the dsp chip has a 100nF cap in series, is the load on the dsp chip now not overloaded?

Last edited by jkeny; 17th September 2010 at 12:12 AM.
  Reply With Quote
Old 17th September 2010, 12:54 AM   #4126
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Dunno? Anyone else know about this?


Fran
  Reply With Quote
Old 17th September 2010, 01:06 AM   #4127
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Sorry, I'm wrong - it was pointed out to me, the cap is very low impedance at RF. SO my question is how come the attenuator sounds so good, particularly if it's overheating the dsp? Is it, Fran? Can you feel a hot chip when operational with attenuator?

Last edited by jkeny; 17th September 2010 at 01:20 AM.
  Reply With Quote
Old 17th September 2010, 08:24 PM   #4128
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
I've had it on playing for about 2 hours now and can feel no heat from it - now I'm feeling the top side of the board, right above the LC7860,,, chip.

Fran
  Reply With Quote
Old 17th September 2010, 09:38 PM   #4129
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Bearing in mind what KevinR said, it might be wiser to leave the 300/100 divider in place & use an attenuator in series with this, particularly as there seems to be no sonic advantage to removing this divider & using a higher dB attenuator.

Last edited by jkeny; 17th September 2010 at 09:54 PM.
  Reply With Quote
Old 19th September 2010, 10:54 AM   #4130
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
IMPORTANT!!!!
IMPORTANT!!!!
IMPORTANT!!!!
IMPORTANT!!!!

jkeny's points about the current that the sanyo chip can output is a warning we need to be careful about!!

My system is working fine becuase I have Peters CEC reclocking mod implemented - and I beleive that this mod buffers the output of the sanyo chip.

The mod is at post 3786 and here is the circuit:

Click the image to open in full size.


So basically don't remove the 300/100 pair unless you have some way of compensating for this!!


If I find out more later, I'll be sure to post it.


Fran
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 09:51 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2