My new, old DAC

e30m3mon

Journeyman
Joined
Feb 9, 2013
Messages
342
Location
Hudson Valley NY
Tagline
---
#22
Well, I guess we’ll find out soon enough.

I can do a quick comparison of the converters in my $5 JVC DVD player to the DAC. Run them both to my boom box and see if it’s audible. I think the op amp experiments are better left for home with the good headphone amp and good headphones.
I did a rolling comparison between IC7 op-amps when I worked on the C1. Used an AudioControl SA-4140i SPL calibrated mic with integrated pink noise generator feeding the C1's AUX input. No EQ or other processing nor hologram processing. Nothing was changed in the room (placement, furniture, volume/SPL, etc.) except the op-amp in each of the tests.

My final verdict was to leave the (modern day production TI) 4136 in that position. I also replaced the other 8 4136 op-amps inside the chassis...just because. Also refreshed all the electrolytics, as well as installed non-polar electrolytics in the signal path (thank you Phoenix!).

The OPA2134 was most harsh to me - did not like that one at all.

And I realize this is not a scientific experiment, but thought it might be of interest.
Al
 

Attachments

Last edited:

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
5,819
Location
Connecticut
#23
Well, I have the following on hand, ready to test:

LT1358
LM6172
LM4562

Originals on the board are NE5532 (and possibly "fake", due to origin of the board)

I was advised that the LM6172 is not suitable, so that's off the table now. I may try it anyway, since I already have them on hand.

@Gepetto : care to chime in on the output op amps for the DAC?
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
11,904
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#24
Well, I have the following on hand, ready to test:

LT1358
LM6172
LM4562

Originals on the board are NE5532 (and possibly "fake", due to origin of the board)

I was advised that the LM6172 is not suitable, so that's off the table now. I may try it anyway, since I already have them on hand.

@Gepetto : care to chime in on the output op amps for the DAC?
The last choice seems the most appropriate for your application Jim. The first 2 are rather extreme. The 6172 is a video amplifier and more suitable for that application.
 

VSAT88

Veteran and General Yakker
Joined
Sep 7, 2017
Messages
1,646
Location
Phenix City Alabama
Tagline
Like my BlueTooth ?
#30

e30m3mon

Journeyman
Joined
Feb 9, 2013
Messages
342
Location
Hudson Valley NY
Tagline
---
#34
Thanks!

sat in a drawer for ten years… finally together.

No time to play with it yet.
Looking forward to your analysis. Do you know if the same board or an updated version is available from ebay? I'm sure there are others who have since put up their offerings by now. I've had mixed success with pre-built boards from over there ... quality of capacitors is always suspicious, in my opinion, but I guess you get what you pay for.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
5,819
Location
Connecticut
#35
No, this particular one is not. Plenty of newer ESS boards these days. Even a dual mono version with the eight converted paralleled for each channel.

The idea is very good but no one shares schematicsnof their implementation, so I can’t have it evaluated (since I can’t do that part) before I build.

This one was built by a bunch of members at DIY audio and I got one back then. I also got a pair of Lundhal output transformers, as that was supposed to be the hot set up, but I’ve since learned better- trannies add distortion and I’m not a fan. But that would give a more “tube like” sound I presume, if your into that sort of thing.

So, I do want to do a parallel ESS assembly, because done right, this is really special, but I need to know the circuit was done correctly before I dive in.
 
Top