Different voltage rating caps

[TieBravo]

Hello can i use a 16v 1000uf capacitor in this circuit Instead of 25v ones? And another question what's the 820E? An 820ohm resistor? Shouldn't it be 82ohm instead of 820ohm?

 

[schmitt trigger]

The input connector says 6 to 12 volts.
As long as you keep within that range, then 16 volt electrolytics are fine.

 

[Nigel Goodwin]

And another question what's the 820E? An 820ohm resistor? Shouldn't it be 82ohm instead of 820ohm?

Why would you imagine that?, it clearly says '820' - what don't you like about the zero?.

The 'E' at the end is usually European (Dutch I think?), and is common in the Dutch Magazine Elektor, I presume it replaces the letter R? - so 820R.

As for the capacitors, 25V ones will most likely be lower ESR, but as long as they are higher than the maximum supply voltage they will be fine.

 

[rjenkinsgb]

The PCB is not much help on its own; this appears to be the complete design with a schematic:

Make Your Own Simple Stereo Amplifer | Full Electronics Project

Here is a simple stereo amplifier you can make with a CD6283 audio amplifier and a few passive components. It provides an output of 4.6 watts per channel.

www.electronicsforu.com

With a 12V supply you could use 16V caps.

However:
A common reason for using higher voltage types is that the capacitor life is proportional to the voltage across it, the current through it, and it's working temperature, as a proportion of the cap's maximum ratings. With many caps, running at half ratings (current, voltage and temperature) can increase the life by thousands of times.

As a lot of cheap electrolytic have a rated life of only 1000 hours or so (at haximum values) under-running them is pretty essential if you want something to last long term.

And looking at the scematic, 820 Ohms does appear to be an appropriate value.

 

[TieBravo]

Why would you imagine that?, it clearly says '820' - what don't you like about the zero?.

The 'E' at the end is usually European (Dutch I think?), and is common in the Dutch Magazine Elektor, I presume it replaces the letter R? - so 820R.

As for the capacitors, 25V ones will most likely be lower ESR, but as long as they are higher than the maximum supply voltage they will be finet

The PCB is not much help on its own; this appears to be the complete design with a schematic:

Make Your Own Simple Stereo Amplifer | Full Electronics Project

Here is a simple stereo amplifier you can make with a CD6283 audio amplifier and a few passive components. It provides an output of 4.6 watts per channel.

www.electronicsforu.com

With a 12V supply you could use 16V caps.

However:
A common reason for using higher voltage types is that the capacitor life is proportional to the voltage across it, the current through it, and it's working temperature, as a proportion of the cap's maximum ratings. With many caps, running at half ratings (current, voltage and temperature) can increase the life by thousands of times.

As a lot of cheap electrolytic have a rated life of only 1000 hours or so (at haximum values) under-running them is pretty essential if you want something to last long term.

And looking at the scematic, 820 Ohms does appear to be an appropriate value.

Absolutely, as the output is for 4ohm can i connect a box on each channel with two 8ohms in it like this diagram?
And what are the gray rectangular shapes on the pcb? They dont connect any components so what do they do? Please dont mind that "total impedance thing"

 

[TieBravo]

Why would you imagine that?, it clearly says '820' - what don't you like about the zero?.

The 'E' at the end is usually European (Dutch I think?), and is common in the Dutch Magazine Elektor, I presume it replaces the letter R? - so 820R.

As for the capacitors, 25V ones will most likely be lower ESR, but as long as they are higher than the maximum supply voltage they will be fine.

I came accross another same schematic with only the two 820ohm were replaced by 82ohms, that's what made me wonder. And power supply would be 12v dc.
If i attach a diode bridge rectifier to my step down transformer, do i need to add bridge rectifier to the amplifier too?

 

[TieBravo]

The input connector says 6 to 12 volts.
As long as you keep within that range, then 16 volt electrolytics are fine.

Tonk

 

[rjenkinsgb]

Absolutely, as the output is for 4ohm can i connect a box on each channel with two 8ohms in it like this diagram?

I'm not sure what you mean?
The diagram shows a single speaker assemby, with a woofer, tweeter and crossover. The whole thing is still eight ohms & can be considered a single 8 Ohm "speaker" as in a boxed unit / speaker cabinet.

You could connect two, eight ohm speakers / cabinets in parallel to each channel out of the amp.

The rectangles appear to just be area fillers, possibly to reduce the amount of copper that must be removed during PCB production.

 

[TieBravo]

I'm not sure what you mean?
The diagram shows a single speaker assemby, with a woofer, tweeter and crossover. The whole thing is still eight ohms & can be considered a single 8 Ohm "speaker" as in a boxed unit / speaker cabinet.

You could connect two, eight ohm speakers / cabinets in parallel to each channel out of the amp.

The rectangles appear to just be area fillers, possibly to reduce the amount of copper that must be removed during PCB production.

So in the diagram aren't two 8 ohm speakers connected to each other parallelly? So how the total impedance is still 8ohm?
And here is the circuit that confused me with 82 and 820ohm. It appeared to be a 8ohm amplifier, and the pch i showed is a 4ohm one.

 

[rjenkinsgb]

So in the diagram aren't two 8 ohm speakers connected to each other parallelly? So how the total impedance is still 8ohm?

The additional components form a "crossover" network. The woofer is fed via an inductor, which progressively cuts higher frequencies & the tweeter is fed though a capacitor, which progressively cuts lower frequencies.

If everything is properly designed, the power is distributed across the two speakers in proportion to frequency, so the two together give a reasonably "flat" response.

Three way crossovers are also fairly common, using woofer, mid-range and tweeter elements.

More info:

Crossover Networks for Loudspeakers

http://www.ebay.co.uk/sch/i.html?_f...570.l1313&_nkw=loudspeaker+crossover&_sacat=0

 

[Nigel Goodwin]

To explain the speaker 'thing' a little more - a speakers impedance is just a nominal value, and it's actual impedance will vary greatly, based mainly on it's inductance. The 8 ohm figure is usually an approximation of the value at 1kHz.

The crossover posted is actually a fairly complex one - the crudest is simply a capacitor feeding the tweeter. While the crossover does effectively put the two in parallel, it's not until a higher frequency, where the drivers impedances (and certainly the bass unit) will be much higher than 8 ohms, and the resultant paralleled impedance will still be higher than 8 ohms.

It's also fairly common for speakers to have low 'dips' in impedance, and some speakers (usually fairly top end ones) may have a reputation for been 'difficult to drive' because of it - but you're likely to be using a top end amplifier anyway, which would usually be able to cope.

So don't over think speaker impedances, it's mainly a 'wild' guess in the first place.

Have a read here:

The Truth About Speaker Impedance

Impedance, it’s a fairly straight forward concept, all electrical circuits and components resist the flow of electricity (or current) to some degree and the way we measure that resistance is impedance. The unit of measurement of impedance is ohms, often symbolized by the Greek letter omega: Ω...

www.aperionaudio.com

And in particular have a look at the graph of speaker impedance against frequency.

 

[TieBravo]

So in the diagram aren't two 8 ohm speakers connected to each other parallelly? So how the total impedance is still 8ohm?
And here is the circuit that confused me with 82 and 820ohm. It appeared to be a 8ohm amplifier not 4.

To explain the speaker 'thing' a little more - a speakers impedance is just a nominal value, and it's actual impedance will vary greatly, based mainly on it's inductance. The 8 ohm figure is usually an approximation of the value at 1kHz.

The crossover posted is actually a fairly complex one - the crudest is simply a capacitor feeding the tweeter. While the crossover does effectively put the two in parallel, it's not until a higher frequency, where the drivers impedances (and certainly the bass unit) will be much higher than 8 ohms, and the resultant paralleled impedance will still be higher than 8 ohms.

It's also fairly common for speakers to have low 'dips' in impedance, and some speakers (usually fairly top end ones) may have a reputation for been 'difficult to drive' because of it - but you're likely to be using a top end amplifier anyway, which would usually be able to cope.

So don't over think speaker impedances, it's mainly a 'wild' guess in the first place.

Have a read here:

The Truth About Speaker Impedance

Impedance, it’s a fairly straight forward concept, all electrical circuits and components resist the flow of electricity (or current) to some degree and the way we measure that resistance is impedance. The unit of measurement of impedance is ohms, often symbolized by the Greek letter omega: Ω...

www.aperionaudio.com

And in particular have a look at the graph of speaker impedance against frequency.

Thank you for great information, i was just worried about the wattage getting divided by two if i connect a 8 ohm speaker on each channel instead of 4ohm.
And good catch, that a Sonodyne SCX 555 bought by my dad before i was even born and Heard stories about its beat thumping and how powerful it used to be while the actual amplifier was SCR1080 (which I'm trying to restore).
As you said each boxes total impedance stays 8ohm, isnt it better that i replace the two 10uf with 1uf, and the 820ohm with 82ohms just like this one? Or should i go for the first circuit (pcb one).
And i will take some time to understand the link you just shared hang on.

 

[Nigel Goodwin]

Thank you for great information, i was just worried about the wattage getting divided by two if i connect a 8 ohm speaker on each channel instead of 4ohm.
And good catch, that a Sonodyne SCX 555 bought by my dad before i was even born and Heard stories about its beat thumping and how powerful it used to be while the actual amplifier was SCR1080 (which I'm trying to restore).
As you said each boxes total impedance stays 8ohm, isnt it better that i replace the two 10uf with 1uf, and the 820ohm with 82ohms just like this one? Or should i go for the first circuit (pcb one).

Why - is the second circuit in some way supposedly better?.

At a completely vague 'guess' I would imagine the 820 resistors are for setting the gain of the amplifier, and 82 ohms would give higher gain.

Using 8 ohm speakers will half your power, but also half the stress on the amplifier, making it more reliable and using much less power. A transistor amplifier isn't designed to feed it's rated impedance, it's designed to feed anything higher than that - and the minimum rating is where you're likely to blow the amp if you go below it.

 

[TieBravo]

Why - is the second circuit in some way supposedly better?.

At a completely vague 'guess' I would imagine the 820 resistors are for setting the gain of the amplifier, and 82 ohms would give higher gain.

Using 8 ohm speakers will half your power, but also half the stress on the amplifier, making it more reliable and using much less power. A transistor amplifier isn't designed to feed it's rated impedance, it's designed to feed anything higher than that - and the minimum rating is where you're likely to blow the amp if you go below it.

Here, tried it, and the bass response without even Baxandall's circuit is enough to crack my windows.

4.18 MB file on MEGA

mega.nz

 

[Nigel Goodwin]

Here, tried it, and the bass response without even Baxandall's circuit is enough to crack my windows.

4.18 MB file on MEGA

mega.nz

You mean it's louder, the output from a phone is quite low, due to restrictions to help prevent causing deafness - so the extra gain will certainly help as you don't have a preamp between them.