Monica --no output caps or trans

[kp93300]

Hi all,
I build the Lindsey Hood 69 class a amp a few days ago.The schematic attached .
It is powered by the cap multiplier in Elliot sound .
Sounds surprising good with my test speakers and so I remove the output cap in Monica since there is an input cap in the amp.It is much better without the output caps. It is more dynamic, deeper and wider sound stage

Before i hook up to my 93 db speaker with powered subwoofer, I want to ran the idea through the members.
I am using the LDR as volume control and no preamp involved>
Is there any danger to my speakers?

thanks

kp93300

[yeo]

hi kp

since this amp has an input cap, it's okay to remove the output cap in monica.

yeo

[ole]

That's actually very interesting - the LDR volume control is in your case a simple voltage divider, correct? So the DC offset from Monica would run across both LDRs, with varying DC at the power amp input depending on the position of your volume control. Well - if you turn it too quickly, you'll see your woofers bounce.

I actually just made a new LDR volume control, too, with two B1 buffers behind it - one output for my tube amp, and another for my plate amp for bass only. Sounds great already, but this might even make it better. Good idea, I'll try it!

Ole

[ole]

I just tested this. Sounds very nice, lots of more ambience and more natural. I think the DC offset on the LDRs contributes there, it may also help with their nonlinear conducting properties. Or maybe it's just the missing coupling cap. Whatever.

Still, when I turn the volume knob I do see the woofers bounce because of the huge DC bias change. I better go easy on volume changes. There is also some low scratching noise from the potentiometer, even I bypassed the LEDs with 15uF caps each - but probably that's not enough.

Anyway, great idea - and absolutely free 

Ole

[kp93300]

hi Ole,
I removed the output caps and in deed sound much better as you described
I saw the woofer cone moving as i turn the volume of the LDR.
I decided to keep the output caps !
BTW, the Lindsey Hood amp is a very different sound when compared to the AlephJ, I think i like the amp better than the Aleph J that has a much more elaborate power supply.
regards

kp93300

[ole]

I don't think the woofer issue is dangerous. You could also limit it with some large capacitor across the potentiometer, so the speed of the offset voltage change is limited.

However, I noticed that there is some low crackling noise at higher volume levels that wasn't there with the caps. Perhaps this is due to the current passing through the LDRs? In my case it should be about 0.5mA, not really much, but before it was zero without signal.

Ole