output caps for protection-some insight needed

[semi932]

I'm running 3886's, one board for each chanel, two per board.
I'm not very technical but I like tinkering and got rained out on yard work today.

I've been searching this forum for ideas and reading lots of posts but nothing specific to what I'm looking for.

Today I tried 4 sets of caps for the ouputs for dc protection.
2200uf 100v, 3300uf 63v, 13000uf 50v, and 22000 35v.

I started with the 2200 yesterday and really like the sound. Super super
clean, great seperation but maybe a little rolled off in the highs.
But wonderful to listen to. Not at all fatiguing.

3300 and 13000 were uninspiring.

22000 pretty darn good but I'm not sure if I like it or the 2200 better.

Two questions.
Is 35v enough for the output caps?

What is technically recommended for my configuration of 3886's?

Appreciate the education.

[Redshift187]

You need to specify more than just 2 LM3886 per channel. Bridged? Parallel? Giving us a schematic would be very helpful.

[AndrewT]

if you intend running your speakers through DC blocking capacitors then consider using a single ended power supply and using the spare PSU caps in the speaker lead.

That way they will meet the voltage spec required and save some money.

[semi932]

Originally Posted by Redshift187

You need to specify more than just 2 LM3886 per channel. Bridged? Parallel? Giving us a schematic would be very helpful.

They are running bridged and they are this design.
PM21 Dual Audio Power Amplifier Module

Thanks.

[semi932]

Originally Posted by AndrewT

if you intend running your speakers through DC blocking capacitors then consider using a single ended power supply and using the spare PSU caps in the speaker lead.

That way they will meet the voltage spec required and save some money.

Thanks Andrew.

It is single ended. I've got some other caps from donor units that I have been trying.
I'm trying to protect my speakers from DC in case of failures.

As I said I'm not really technical but trying to learn.

Isn't there just mv of AC on output caps?

Personally I think the sound improved quite a bit after installing caps on the outputs.
I know sound is subjective but to my ears mine moved up a notch in listening pleasure.

[geraldfryjr]

yeh, Marchand still owes me some money from back in 1983. jer
Sorry about that !

[Ted205]

Originally Posted by semi932

Thanks Andrew.

It is single ended. I've got some other caps from donor units that I have been trying.
I'm trying to protect my speakers from DC in case of failures.

As I said I'm not really technical but trying to learn.

Isn't there just mv of AC on output caps?

Personally I think the sound improved quite a bit after installing caps on the outputs.
I know sound is subjective but to my ears mine moved up a notch in listening pleasure.

The caps need to be able to block any potential DC that could find its way to the output of the amp. I.e the DC from the power rail(s)

[AndrewT]

Originally Posted by semi932

It is single ended.
I'm trying to protect my speakers from DC in case of failures.
Personally I think the sound improved quite a bit after installing caps on the outputs.

This has confused me.
The earlier posts seemed to suggest the DC blocking caps were an addition to help protect the speakers in event of amplifier failure. This implies that the output of the amplifier is DC coupled and that requires a dual polarity power supply.

Now you state the amplifier is single ended.
Single demands a DC blocking cap on the output. There is no choice. Even a perfectly working single ended amplifier will destroy a speaker if you use the DC coupled output as the feed to the speaker.

Then you follow up with

Personally I think the sound improved quite a bit after installing caps on the outputs.

and this says the sound was worse without the DC blocking caps.
Is the amplifier and it's PSU single ended?
or
is the amplifier DC coupled at the output and using a dual polarity supply?

[Redshift187]

Andrew, he states earlier that the amp is being used in a bridged configuration, which I believe is the only possible way to get away with single supply and no output caps.

That said, the link is for a design that uses a dual polarity power supply. Can you confirm semi, what your power supply is?

[semi932]

Originally Posted by Redshift187

Andrew, he states earlier that the amp is being used in a bridged configuration, which I believe is the only possible way to get away with single supply and no output caps.

That said, the link is for a design that uses a dual polarity power supply. Can you confirm semi, what your power supply is?

Sorry for my lack of understanding terminologys.

Pwer supply is two torodials into diode bridge and out to two caps.
One to pos and one to neg.

From there out to the two boards.

I guess I don't know the basics of single ended and dual.

I'm over my head but trying to learn.

Thanks