Double the Inductance

[Nick]

In terms of smoothing two stages are better than one as two identical stages will form a 12dB/Octave filter so reduce ripple.

[Lee S]

Nick, is that two stages as in series (RC>LC>LC) or two stages as in parallel (RC>LL>CC)? This is the info I was looking for at the start I think. Not only how to calculate these choke values, but why use two chokes? The Rankin designs use two LC sections in parallel (one per channel not in series) as do the EAR designs. David said Philip had thought of using two chokes in this configuration for his LW kit. I thought there must be a reason for it other than two smaller chokes are cheaper than one big choke.

[Nick]

Yes, I was only referring to series use, CLCLC that sort of thijng. But there are others who whould disagree, and then there is the low DCR viewpoint. In reality, you need to try it all and decide which one you like.

[Lee S]

In reality, you need to try it all and decide which one you like.

Yes... I agree. I guess this is probably one of those subjective areas. I will go with the simple, single choke first and see how it goes from there.

Many thanks for the input all,

Cheers,

EDIT: Just out of curiosity, would the equivalent circuit that one would put into PSUD for the above schematic, be 20uF > 7H > 20uF ?

[Nick]

No, I would model as 20u, 14H, 10u and expect a higher final voltage, or add a current tap before the choke.

[andrew Ivimey]

Not quite Lee, Splitting the B+ into two separate HTs each with its own choke and cap can improve things - sorry to say that it could well be suck it and see!

I believe that Philip finally went the extra mile and monoblocked the amp. You could do the as specc'd circuit and as long as there was room, go for two chokes (one for each channel) later.

I'm just an inveterate messerabouter and never let not having the right components stop me building something. Experience has shown that 'as orginally ' specc'd is pretty much the right way though ... nearly always.

[pre65]

Hi-the power supply you picture is the Rankin one for the 45 DC,CC as i have used for my PT15 monoblocks,except my transformers are 360-0-360.

[pre65]

Hi-thinking about that power supply.

I have monoblocks,but with the first cap still at 20uf on each.

Should i have used 10uf and would that raise the HT a bit ?

I have got 2 spare 10uf motor runs.

Perhaps i should just fit them and stop asking questions ?

[Nick]

Changing the cap will only affect the voltage if its running between choke and cap input. Otherwise changing the cap will affect the charging current peak and duration.

Trying and listening is a good thing though