kit differences: chipamp.com vs audiosector.com

[danielwritesbac]

As to dc offset....
Using Ci in the feedback path (between the inverting input resistor and ground) will eliminate the DC offset problem by reducing the gain of the amplifier to zero for DC.
. . .
As usual, these things probably sound better with fewer caps in the signal path. There are other ways to handle DC offset such as with an error servo but they have their own issues.

Well, the NFB Cap (Ci on some National Semiconductor documents), does contribute additional dynamics and greater durability. Whether those enhanced dynamics are pleasant or not depends on the cap. Its influence is in proportion to the gain anyway. With some hard work, its actually possible for the amp to sound better with the NFB cap; however, possible doesn't mean easy. The NFB Cap (Ci) is a good thing to use whenever the voltage is a bit high, the heat is a bit high, or anytime the amplifier is operated AT or over specifications. It does increase durability and that prevents harm to speakers.

There are also output transformers available as an option. This allows single rail operation, if desired.

A simple output capacitor is an easier alternative to an NFB cap or output transformer.
Because an output cap (or output transformer) doesn't affect the small signal, its effect is not in proportion to the gain factor. Yay!! These gainclones and chipamps that typically use split rail power, don't output enough DC to harm or wear out an output capacitor. So, this is a pretty good option if you don't like the sound from (or don't enjoy the selection process of) an NFB cap.

With the chip amp, a very easy option is to reduce the resistor values by half (for the four "main" resistors that operate the input divider and the nfb divider). For instance, it was 20k, now its 10k. This amp won't make dc offset, but it sure sounds different. People who love their bass loud might get a big kick out of that.

OH, and on the topic of this thread. . .
Audiosector: A reference amplifier with low-component-count (gainclone).
Chipamp.com: A power amplifier starter kit (not a gainclone).

 

[pacificblue]

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[wlowes]

Best volume control on a budget

On the subject of attenuator, a future project for you that's well worth the effort is to build a lightspeed attenuator.
http://www.diyaudio.com/forums/showthread.php?postid=1273484#post1273484
For something like $30 in parts you will have what some argue is the best passive attenuator possible. It is a great partner to Peter's premium kit. I have been running one for 18months and love it. I first tested the amp using an attenuator made with series / shunt metal film resistors. Putting in the lightspeed was like a quantum leap in sonic quality.

 

[pnyoung]

Gain clone

awesommee, thanks for all the quick replies guys, especially Peter. I've been a little busy since I first posted or I woulda been back sooner. I'm still trying to decide exactly what I want to build (stereo or dual mono, integrated or power amp), and reading up some more, mainly this

wait, it comes with Blackgates? I thought the site said Panny FCs?

 

[AndrewT]

where's the message?