PSU buffer in Proto42 / META42 type of amps.
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Dreamslacker

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I was wondering about the buffer used in such amps.

If I've a single EL2001CN buffer for each channel in the amp. Would having a single EL2001CN buffer in the Power supply side be sufficient or would there be a need to stack the EL2001CN on the PSU (ie. match the total current of the 2 channels).

I'm also contemplating the use of a TLE2426 with BUF634 rather than the TLE2426 w/ EL2001CN on my next revision of the Proto 42.
 
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ppl

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yes one buffer per ch and one as the VGD is what i do. Yes the BUF-634 makes a great VGD at low bias pin 1 N/C
 
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I use BUF634 in all relevant versions of my PDAC, mostly because I think EL2001 is way too precious to be "wasted" on something other buffers can do as well, and because it has higher current capacity so it can serve both channels no matter what. EL2001 is however far less expensive... until next month. I am sitting on about 170 of them so I'm not worried... yet.

ppl also mentioned earlier that he thinks EL2001 sounds (marginally) better in P/S splitter than BUF634.
 
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Quote:

Originally posted by aos
I use BUF634 in all relevant versions of my PDAC, mostly because I think EL2001 is way too precious to be "wasted" on something other buffers can do as well, and because it has higher current capacity so it can serve both channels no matter what. EL2001 is however far less expensive... until next month. I am sitting on about 170 of them so I'm not worried... yet.

ppl also mentioned earlier that he thinks EL2001 sounds (marginally) better in P/S splitter than BUF634.


170??

Woah! That's quite a lot of them there....
 
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Quote:

Originally posted by ppl
yes one buffer per ch and one as the VGD is what i do. Yes the BUF-634 makes a great VGD at low bias pin 1 N/C


How do I stack BUF-634 buffers?

They don't stack like EL2001CN's do right (directly connect pin to pin).

I vaguely recall there being some business about having to have a to connect a resistor between the pins of the BUF-634...
 
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Yes you can stack them upon each other and connect The Bandwidth Pin's Together without any problems.
 
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Quote:

Originally posted by ppl
Yes you can stack them upon each other and connect The Bandwidth Pin's Together without any problems.


Oh? I thought there was some business about a current limiting resistor. In this case, I shall use 3 stacked BUF634 for my new power side circuit and 2 stacked HA3-5002 per channel in my next revision of the Proto42 amp.
 
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The BUF-634 has Electronic Current Limit just like the Elantecs. The only resistor is the one internal to set the Bias between Pin 1 and the Internal Curent source so with pin 1 connected together this will place these internal resistors in par and thus the value will be less and increse the Bias Current. Some others might use a Resistor on the Output in series wih the load, But This is mostly used when paralelling opamps for curent sharing and is not required on open loop Buffers like the Buff-634, EL-2001 or the Ha3-5002. a Pair of 5002's should only require one BUF-634 as the VGD the Capacitors used in the Power supply Handle most of the Curent flow on Music or any AC signal.

WARNING the HA-5002 dose not have any output current limiting so a shout circuit of the output will dystroy the part. so no music should be playing when Pluging in your phones or when unpluging them as this shorts the output each time the Plug is inserted or removed.
 
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Quote:

Originally posted by ppl
WARNING the HA-5002 dose not have any output current limiting so a shout circuit of the output will dystroy the part. so no music should be playing when Pluging in your phones or when unpluging them as this shorts the output each time the Plug is inserted or removed.


Thanks for the advice.

I do switch off my amp whenever I want to unplug the headphones. The Neutrik jack is a locking jack so I can't accidentally unplug the plug anyway.


Say... What do you think of using 7.5uF Solen caps for replacing the 1uF Evox metalized polyestor caps in my power side circuit? Would it help?

How about a 3,300uF electrolytic capacitor on each side (+/-) instead of 4 * 1,000uF electrolytic caps?
 
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Dreamslacker> Sounds like you got the short circuit covered. IMHO output current limit is bad sonicaly and Amps that do not employ this sound Better Because the Current limit comes active too soon. This is for not just Headphone Amps but Loudspeaker Amps also. Regarding Power supply caps Randomly parralelling Electrolytic and Film type capacitors can cause resonent traps and make the Amp Ring on fast transients. Test your Capacitor combo with a scope and a 10-20 KHz. Sq wave to see if the wave rings or not. Otherwize it might be best to use smaller value Low ESR Electrolytics located close to the Chips along with the Larger Ones that may be located father away from the Chips. Using a good Polypropylene film cap to bypass Electrolytics wnen properly done will result in the best sound, However proper test equipment will be required to get the best from unproven caps.
 
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Quote:

Originally posted by ppl
Dreamslacker> Sounds like you got the short circuit covered. IMHO output current limit is bad sonicaly and Amps that do not employ this sound Better Because the Current limit comes active too soon. This is for not just Headphone Amps but Loudspeaker Amps also. Regarding Power supply caps Randomly parralelling Electrolytic and Film type capacitors can cause resonent traps and make the Amp Ring on fast transients. Test your Capacitor combo with a scope and a 10-20 KHz. Sq wave to see if the wave rings or not. Otherwize it might be best to use smaller value Low ESR Electrolytics located close to the Chips along with the Larger Ones that may be located father away from the Chips. Using a good Polypropylene film cap to bypass Electrolytics wnen properly done will result in the best sound, However proper test equipment will be required to get the best from unproven caps.


I see..

Another thing I did note was that my amp seemed to sound better when I was using a resistor divider instead of a TLE2426CP voltage splitter in the supply side. Any idea why that is so? I only have 1 EL2001CN buffer in the supply.
 
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Are you using the EL-2001 as a VGD and then a Resistor divider to Drive The EL-2001 rather than the TLE-2426?
 
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Quote:

Originally posted by ppl
Are you using the EL-2001 as a VGD and then a Resistor divider to Drive The EL-2001 rather than the TLE-2426?


I was using the EL2001 as VGD and resistor divider to drive the EL-2001 before this. Now I've a TLE-2426 driving the EL-2001.
 
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So you think the sound was better using the Resistor Divider driving the EL-2001 than using the TLE-XXXX to drive the EL-2001?
 
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