BV said:
Can you provide some more informations on this but haven't seen something like that before? I am considering how to build my new LM4562-based line preamp!
LM4562 - blue alps - LM4562
LM4562 - reed-relais attenuator - LM4562
LM4562 - PGA2310 - LM4562
or DAC8043?
I dunno know but I think......do not use DAC8043 or so......why not use a DAC from Wolfson, TI or AD with built-in-Volume-Control? They work with higher Bit-Resolution than the DAC8043.
I prefer the Wm8816 Solution but the DAC-Volume-Control is also interesting..........or CMOS Switch Volumey Control.....they are some chinese DIY Projects in the web.
regards
Alan
I prefer the Wm8816 Solution but the DAC-Volume-Control is also interesting..........or CMOS Switch Volumey Control.....they are some chinese DIY Projects in the web.
regards
Alan
In multiplaying mode R-2R DAC´s ladder is conected in opamp´s feedback net, see
http://www.analog.com/static/imported-files/data_sheets/DAC8143.pdf
pic 10,14..
Regulation is in analogue domain, with 4096 steps (with 12bit DAC), it is more than enough. It is not digital regulation with 12bit resolution.
Regulation with reed relays and low impedance resistor network is best solution, with potentiometer worst (IMO). DAC 8143 and PGA are very good, WM8816 is slightly worse. I tried it all. Regulation with DAC8043 is used in ML383 integrated.
http://www.analog.com/static/imported-files/data_sheets/DAC8143.pdf
pic 10,14..
Regulation is in analogue domain, with 4096 steps (with 12bit DAC), it is more than enough. It is not digital regulation with 12bit resolution.
Regulation with reed relays and low impedance resistor network is best solution, with potentiometer worst (IMO). DAC 8143 and PGA are very good, WM8816 is slightly worse. I tried it all. Regulation with DAC8043 is used in ML383 integrated.
Thats not possible. I tested all PGA models and WM8816 is far better than PGA. With WM8816 you have more possibilities to use better OP Amps......than the crappy PGA with internal OPA134.
The HifiAkademie PGA2320 Pre is the only PGA which sounded very good but the developer integrated a second Output OP and much other work........to get it good!
The HifiAkademie PGA2320 Pre is the only PGA which sounded very good but the developer integrated a second Output OP and much other work........to get it good!
It is possible, I tried it all..😉 . Inside PGA is not OPA134, the same THD for 100k and 600ohm load speak clearly. (datasheet..)
Results for PGA2320:
http://www.bvaudio.sk/PGA/PGAE.htm
WM8816 (discontinued, MAS... is not better) was worse.
Results for PGA2320:
http://www.bvaudio.sk/PGA/PGAE.htm
WM8816 (discontinued, MAS... is not better) was worse.
This week end I got my 'minimalist' preamp going.
10k Alps Blue Velvet >> LM4562 single to balanced topology >> power amp. I'm currently running it in single ended mode.
I have to say it sounds really good - very smooth, clean bass and to my ears, a fantastic top end.
I'm using Panasonic AG miniture relays to do the signal switching. I will get the headphone amp running in the next 2 weeks or so (waiting for some BD139's and 140's).
I have taken a lot of care with the layout and PSU execution (LM317/337 3 terminal regs, Amveco transformer). I am particularlypleased that there is no noise at the speakers.
I was feeding my (entry level) CD player, which has a 6 step remote control volume, directly into the power amp. I'm now able to compare this original CD player to a Pioneer SACD player. The differences are substantial, but also, the original CD player sounds a whole lot better as well.
BTW - no caps in th e signal path - completely DC coupled.
Photos after th e H/phone amp is up and running.
Next project is a discrete based design . . . I'm still thinking about it but looks like I'll go for a bipolar input CFA topology followed by a diamond buffer. I'll be using a relay based attenuator in front of that.
10k Alps Blue Velvet >> LM4562 single to balanced topology >> power amp. I'm currently running it in single ended mode.
I have to say it sounds really good - very smooth, clean bass and to my ears, a fantastic top end.
I'm using Panasonic AG miniture relays to do the signal switching. I will get the headphone amp running in the next 2 weeks or so (waiting for some BD139's and 140's).
I have taken a lot of care with the layout and PSU execution (LM317/337 3 terminal regs, Amveco transformer). I am particularlypleased that there is no noise at the speakers.
I was feeding my (entry level) CD player, which has a 6 step remote control volume, directly into the power amp. I'm now able to compare this original CD player to a Pioneer SACD player. The differences are substantial, but also, the original CD player sounds a whole lot better as well.
BTW - no caps in th e signal path - completely DC coupled.
Photos after th e H/phone amp is up and running.
Next project is a discrete based design . . . I'm still thinking about it but looks like I'll go for a bipolar input CFA topology followed by a diamond buffer. I'll be using a relay based attenuator in front of that.
Why not a AAVA Volume Control by Accuphase? very interesting:
Accuphase Laboratory, Inc.?AAVA
Using 5 switch, we have 2^5 or 32steps
Accuphase Laboratory, Inc.?AAVA
An externally hosted image should be here but it was not working when we last tested it.
Using 5 switch, we have 2^5 or 32steps
Update December 9 2010.
I finally got my 'high end' pre-amp going.
Here is a brief description:-
-relay switched source slection
-Buffered by LM4562
-which feeds into PGA2320 (1 per channel, since I run in fully balanced mode)
-Output into summing (i.e. inverting) LM4562 stage
-LM49600 inside output summing amp loop
-separate headphone amp uses LME49600 in side LME496710 op amp loop.
mbed uController handling all control (volume, input selection etc), fully optically isolated - bit bang serial bus
Fully balanced design input thru output
Full dual mono design - separate transformers and PSU's for L and R channels
I still have quite some work to do on the s/ware - basic functions are working, but I have to write remote control routines, and the 5" color display driver.
I finally got my 'high end' pre-amp going.
Here is a brief description:-
-relay switched source slection
-Buffered by LM4562
-which feeds into PGA2320 (1 per channel, since I run in fully balanced mode)
-Output into summing (i.e. inverting) LM4562 stage
-LM49600 inside output summing amp loop
-separate headphone amp uses LME49600 in side LME496710 op amp loop.
mbed uController handling all control (volume, input selection etc), fully optically isolated - bit bang serial bus
Fully balanced design input thru output
Full dual mono design - separate transformers and PSU's for L and R channels
I still have quite some work to do on the s/ware - basic functions are working, but I have to write remote control routines, and the 5" color display driver.
Some pictures - you will need to scroll down to the bottom of the page.
Line Pre-Amplifiers | hifisonix.com
Line Pre-Amplifiers | hifisonix.com
The problem with this digital potentiometers is not the sound quality, but that they are not very reliable and can fail sometimes without any reason.Pga2310,11 and so on are known for this and one of my pga2311 also failed after short time, but the another is still working.But don't know for how long.
In defense of the TI PGA2320
I feel compelled to describe the opposite experience. I have used the PGA2320 parts in several personal projects and in commercial products and have yet to see a failure. My only comment is that they sound best when fed with a good FET buffer.
I feel compelled to describe the opposite experience. I have used the PGA2320 parts in several personal projects and in commercial products and have yet to see a failure. My only comment is that they sound best when fed with a good FET buffer.
Then you had luck, but this parts are prone to failure because of the manufacturing process.And they cost so much because there is a big amount of defective chips in the production.
Well hopefully I won't have that experience Leon08. I am feeding mine from a LM4562. A FET input op amp buffer will give a bit better noise performance if fed from high source impeadances.
It sounds great and the LME49600 buffers are really good.
It sounds great and the LME49600 buffers are really good.
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