Build a power amp!

Posted by Lynn Olson (M) on December 20, 2005 at 23:52:41

In Reply to: How to improve preamp? posted by stocker on December 20, 2005 at 21:34:02:

With all the sonic degradation of a generic transistor power amp, all the preamp can do is add a layer of syrup (2nd harmonic distortion) to a basically unmusical, and not very transparent SS amp.

But before you jump off the deep end on a SE triode amp, try something really simple like a modified Sonic Impact Tripath amp. This little sonic wonder, at $29, will give a little taste of what life is like outside of conventional Class AB high-feedback transistor amp. This way, instead of a preamp being little more than a glorified tone control, you'll start to hear what your preamp really sounds like, and can better assess what kind of sound you like.

I should also add that a tube preamp can seriously damage the input stage of a solid-state amp. There are very large charging pulses (50V isn't unusual) as the tube preamp warms up and charges the output capacitor. Even though the transistor amp is turned off, the input transistors can be seriously damaged by large voltage pulses across the input - anything more than 10V, and the input pair of transistors may fail, get noisy over time, or fail without warning at some time in the future. The only way to sidestep this problem is a relay circuit that shorts out the preamp output until the voltage at the output stabilizes.

You might want to temporarily disconnect the interconnect cable between the preamp and power amp and measure the voltage surge as the preamp warms up - if you're not already using a protection relay, you might be surprised at what you see.

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Follow Ups Full Thread

Topic - How to improve preamp? - stocker 21:34:02 12/20/05 (17)

Preamp is not your problem. - grhughes 09:32:58 12/21/05 (2)

Re: Preamp is not your problem. - stocker 16:58:53 12/21/05 (1)

Check out all the places you can buy used equipment. - tubesforever 11:40:36 12/23/05 (0)

Re: How to improve preamp? - stocker 07:09:50 12/21/05 (2)

Re: How to improve preamp? - Lew 11:28:02 12/21/05 (1)

Re: How to improve preamp? - stocker 16:19:10 12/21/05 (0)

Re: How to improve preamp? - stocker 00:36:02 12/21/05 (0)

Build a power amp! - Lynn Olson 23:52:41 12/20/05 (2)

Sonic Impact Tripath amp is good advise. - 2wo 20:50:03 12/21/05 (0)

It depends... - cheap-Jack 09:07:28 12/21/05 (0)

First thing I'd do is replace the coupling cap with, at minimum, a Cardas Golden Ratio... - jeffreybehr 21:55:58 12/20/05 (6)

Re: First thing I'd do is replace the coupling cap with, at minimum, a Cardas Golden Ratio... - stocker 00:41:47 12/21/05 (5)

Re: First thing I'd do is replace the coupling cap with, at minimum, a Cardas Golden Ratio... - castlesteve 13:47:19 12/21/05 (0)

I know nothing about the sound of Kimber caps. The Solens in your preamp... - jeffreybehr 11:12:54 12/21/05 (3)

Re: I know nothing about the sound of Kimber caps. Jeffery ... - JB 18:47:46 12/22/05 (2)

I too use the Mundorf S/Os as couplers in a SS preamp. - jeffreybehr 19:14:51 12/22/05 (1)

Re: I too use the Mundorf S/Os as couplers in a SS preamp. - stocker 22:48:49 12/22/05 (0)

Follow Ups

Build a power amp! - Lynn Olson 23:52:41 12/20/05 (2)

Sonic Impact Tripath amp is good advise. - 2wo 20:50:03 12/21/05 (0)

It depends... - cheap-Jack 09:07:28 12/21/05 (0)

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