About Sonic Clipping

[Ciu]

Hello !
I'm a recent user of Sonic T5066, and I can't turn the volume more than half , without clipping. The PSU is a regulated one ,at 12.5 v.
Does anyone has a solution, or this is a normal limitation of the S.I. ?
Thanks !

[Pano]

Salut Ciu,
This may be normal, the S.I. version has a lot of gain as it is made for portable devices that have a low output signal.

It sounds like your signal source must be pretty strong. My stock S.I. will go to more than half (about 1 o'clock) on the output of a standard CD/DVD player.

Remember that this amp will give you no more than about 8 watts peak. That means only around 1/8~1/5 watt RMS level on music.

How efficient are your speakers? Do you need to go past half?

[Ciu]

Hello Panomaniac, Thanks !

My Sonic is in the original configuration, no modification.
My speakers are 91db efficient, but I'm going to buid a Supravox LB, that would be 94-96db Eff.
May be my input source (direct CD ) is too high, I'm going to connect via my Pre-amp, with the ajustable output level.
What is the "good" PSU voltage ? 12v, or 13.2 v, the upper limit ?

R.C.

[MEXXX]

What is the "good" PSU voltage ? 12v, or 13.2 v, the upper limit ?

I've been running one on a 14v regulated supply with 4ohm loads and the amp runs fine. I've never had it go into thermal protection, but that may be do to the heatsink I added.

If your supply has enough current to up the regulated voltage to 13.2v or even a little higher, you shouldn't have any problems.

MEXXX

[Pano]

And if you are going to use a preamp to set volume, turn the Sonic pot all the way up (to the right). Or better yet, remove it.

Let us know how it goes.

[Ciu]

I tried ,first to add a pre-amp before the SI input, to lower the input signal : quite no change in clipping.
The idea was given by MEXXX (up !). I was using a small regulated PSU at 12.5v .
In few minutes, I build a basic PSU, from a 80VA toroidal trans 2x9v ( only one used ) , 4 hight speed rectifiers BYW 98-200, and a 10 000 uF capacitor (Philips low ESR), no regulator added !!! (I think a regulator is a serious bottle-neck ).
With the SI switched on, the output voltage is 12.4v.
Now, I'm in another world ! The sound is better (fluent, coloured) , and up to the output I can support, there's no more problem with clipping.
A good advice for newbies : before tweaking the SI, feed with a large power supply !

R.C.

[shelt]

Make sure the ground side of your speaker terminals aren't connected to each other. I had an accidental connection between the two negative speaker terminals on my first SI test amp, and my amp had the following symptoms:

- very fuzzy upper mids and treble. not horrible, but certainly not audiophile quality. Sounded like a $20 amp!

- horrible clipping and intermittent amp shutdown at about 75% of the normal max level for a T-Amp

My "short" between the two terminals occurred when I was testing the amp in my main system, and didn't disconnect all of my old components before wiring this up (long story)...

-Rich