What size monoblocks should I build for my Q Acoustics 5020 Bookshelf Speakers?

[hokeyWB]

Hi there!

I bought myself a pair of Q Acoustics 5020 Bookshelf Speakers for Christmas and I freaking LOVE them... but I feel that my SMSL AD18 amp isn't prob doing them justice.... so I ordered a Schiit Saga 2 pre-amp and I want to build a couple of Monoblocks.

The speakers have a recommended power range of 25 to 100 watts per channel but im assuming that I don't want to build 100 watt amps... I should build something bigger to allow for overhead and so that the poor monoblocks arent working too hard. I also think that maybe 2000 watts is overkill... which doesn't bother me one bit... but I expect it might damage stuff... so im looking for the right-sized amps... any advice?

Thanks in advance!

 

[Clmrt]

Build or buy?

Visit:

Crown Audio - Professional Power Amplifiers | English (US)

www.crownaudio.com

"Amplifier Power Required"

 

[anome]

eigentakt eval

 

[hokeyWB]

Thanks everyone! According to the calculator, I just do need 100w amps.

 

[hokeyWB]

eigentakt eva

Looks great, I will review in detail!

 

[kemmler3D]

Hi there!

I bought myself a pair of Q Acoustics 5020 Bookshelf Speakers for Christmas and I freaking LOVE them... but I feel that my SMSL AD18 amp isn't prob doing them justice.... so I ordered a Schiit Saga 2 pre-amp and I want to build a couple of Monoblocks.

The speakers have a recommended power range of 25 to 100 watts per channel but im assuming that I don't want to build 100 watt amps... I should build something bigger to allow for overhead and so that the poor monoblocks arent working too hard. I also think that maybe 2000 watts is overkill... which doesn't bother me one bit... but I expect it might damage stuff... so im looking for the right-sized amps... any advice?

Thanks in advance!

Normally I try to talk people out of upgrading amps, because it's usually not necessary, but the AD18 seems bad enough that the problems are pretty plausibly audible and it doesn't have much power to begin with.

If you are dead set on building monoblocks, go for it, although in 2024 it's more of a personal satisfaction thing than performance thing. A couple Fosi V3 Monos will give you 100-200 clean watts without stressing your wallet much.


You can only pump so much power into a speaker before the voice coil smacks into something. So I think it's reasonable to go for 200w in an amp if you want extra headroom, but take care not to turn it up all the way. More than that is probably beyond overkill for these speakers.

 

[hokeyWB]

Build or buy?

Visit:

Crown Audio - Professional Power Amplifiers | English (US)

www.crownaudio.com

"Amplifier Power Required"

I'm going to build them. I'm poor.
Thanks for the link; super helpful!

 

[kemmler3D]

I'm going to build them. I'm poor.

Purifi builds are top of the heap but not the most gentle on budgets... check this out also: https://www.audiosciencereview.com/...dio-tpa3255-260-2-29a-amplifier-review.50208/ https://www.audiophonics.fr/en/ampl...GQpIwqZvnJWMHdTZ8R3v_-e9KuTslnmEYXeWmIookqnzq for comparable performance at a bit less price.


Not to dampen DIY enthusiasm too much, but you may find that after PSU and cases that DIY is actually more expensive than retail. I think the best way to get an amp for a good price is to search the secondhand market.

I got NCore 500w monoblocks for $300 each a while back! And my brother just found a Beomaster 1600 receiver for $120 at the thrift shop. Deals are out there...

 

[hokeyWB]

Normally I try to talk people out of upgrading amps, because it's usually not necessary, but the AD18 seems bad enough that the problems are pretty plausibly audible and it doesn't have much power to begin with.

If you are dead set on building monoblocks, go for it, although in 2024 it's more of a personal satisfaction thing than performance thing. A couple Fosi V3 Monos will give you 100-200 clean watts without stressing your wallet much.


You can only pump so much power into a speaker before the voice coil smacks into something. So I think it's reasonable to go for 200w in an amp if you want extra headroom, but take care not to turn it up all the way. More than that is probably beyond overkill for these speakers.

You don't think I would get 'better' quality from building something... say ICEpower based, rather than picking up Fosi's?
I saw something yesterday that said the first component I should spend serious money on is the DAC.. and I only have a Schiit Modi so maybe my priorities are wrong.

 

[hokeyWB]

Purifi builds are top of the heap but not the most gentle on budgets... check this out also: https://www.audiosciencereview.com/...dio-tpa3255-260-2-29a-amplifier-review.50208/ https://www.audiophonics.fr/en/ampl...GQpIwqZvnJWMHdTZ8R3v_-e9KuTslnmEYXeWmIookqnzq for comparable performance at a bit less price.


Not to dampen DIY enthusiasm too much, but you may find that after PSU and cases that DIY is actually more expensive than retail. I think the best way to get an amp for a good price is to search the secondhand market.

I got NCore monoblocks for $300 each a while back! And my brother just found a Beomaster 1600 receiver for $120 at the thrift shop. Deals are out there...

Interesting... and great reviews... thanks, I'll check it out!
Ill check out my local marketplaces for deals. I don't have the Facebook though, and that is where everyone seems to go :-(

 

[Chrispy]

Why increase expense with monoblocs?

 

[kemmler3D]

You don't think I would get 'better' quality from building something... say ICEpower based, rather than picking up Fosi's?

Measurably better, yes. Audibly better - not really. Fosi stuff is cheap but not incompetently designed. Rule of thumb is that artifacts below -60dB are hard to hear, below -80dB they are extremely, extremely hard to hear, most people can't.

I saw something yesterday that said the first component I should spend serious money on is the DAC.. and I only have a Schiit Modi so maybe my priorities are wrong.

Bottom line: There is a lot (A LOT) of audio nonsense out there on the web. The first and last component you should spend serious money on is speakers. In 2024 nothing else above a very low standard has audible problems you can fix by spending 2, 5, or 10x more. The subtle gains in quality people talk about are 99.99% illusions.

e: to @Chrispy's point the benefits of monoblocks from 30+ years ago have mostly been obviated by improved engineering in normal stereo amps. Audible crosstalk or inadequate power supplies in stereo amps are quite rare today.

In 2024 the main reasons to get monoblocks:

Sounds cool to say
Shorter speaker cables

 

[DVDdoug]

The speakers have a recommended power range of 25 to 100 watts per channel

Manufacturer's shouldn't give a range like that... 25W is pretty meaningless. If you want to know how little power you can get away with you need to know the sensitivity of the speakers and how loud you want to listen. The manufacturer doesn't know if 25W is going to be loud enough for you! And there's really no way to get a firm answer because loudness is complicated... It depends on the short-term average and the frequency content, etc. And whether an amp clips or not depends on the peaks (which don't correlate well with loudness).

I should build something bigger to allow for overhead

The idea is that a 100W speaker should be safe with a 100W amplifier playing normal program material that's not clipping on the peaks. But that's complicated too because speakers are blown from short-term average power and the dynamics (peak to average ratio) of the music and other program material varies.

If you push an amp into clipping the peaks don't increase but the average power into the speaker increases. You can fry a 100W speaker with an over-driven 100 amp, or with constant 100W test tones. And the tweeter can't take as much power as the tweeter.

There's a popular myth that a higher powered amplifier with "headroom" is safer than a clipped amplifier but a higher-powered amplifier worse and you can fry the speaker either way. And you're more likely to play it safe and turn-down a lower powered amplifier if you hear clipping,

But if you are "reasonable" you probably won't be using all of the available power and you probably won't burn-out your speakers in any case. Speakers are usually blown at loud parties, especially if a drunk person or teenager has access to the volume control. Or you might blow a speaker "testing it' to see how loud it will go (or with high-power test tones).

 

[hokeyWB]

Manufacturer's shouldn't give a range like that... 25W is pretty meaningless. If you want to know how little power you can get away with you need to know the sensitivity of the speakers and how loud you want to listen. The manufacturer doesn't know if 25W is going to be loud enough for you! And there's really no way to get a firm answer because loudness is complicated... It depends on the short-term average and the frequency content, etc. And whether an amp clips or not depends on the peaks (which don't correlate well with loudness).



The idea is that a 100W speaker should be safe with a 100W amplifier playing normal program material that's not clipping on the peaks. But that's complicated too because speakers are blown from short-term average power and the dynamics (peak to average ratio) of the music and other program material varies.

If you push an amp into clipping the peaks don't increase but the average power into the speaker increases. You can fry a 100W speaker with an over-driven 100 amp, or with constant 100W test tones. And the tweeter can't take as much power as the tweeter.

There's a popular myth that a higher powered amplifier with "headroom" is safer than a clipped amplifier but a higher-powered amplifier worse and you can fry the speaker either way. And you're more likely to play it safe and turn-down a lower powered amplifier if you hear clipping,

But if you are "reasonable" you probably won't be using all of the available power and you probably won't burn-out your speakers in any case. Speakers are usually blown at loud parties, especially if a drunk person or teenager has access to the volume control. Or you might blow a speaker "testing it' to see how loud it will go (or with high-power test tones).

I move my gear to a locked room and put out my 80's boombox... luckily people think retro is cool and don't ask me where the good speaker are.

 

[David James]

I'd buy something like the Fosi v3. if you really insist on diy, you might consider a lm3886 chip amp. they can be built inexpensively assuming you can scavenge a transformer. They sound fantastic assuming you can get it built correctly. Many people have difficulty eliminating noise. My experience is that this is a great path for learning and personal gratification, but these days with the low cost options available, not the easiest or cheapest way to get good sound. Might as well start with the quick and cheap approach like the Fosi, and if you don't like it then sell it and move on.

 

[Roland68]

I'm going to build them. I'm poor.
Thanks for the link; super helpful!

You don't save any money these days if you build your own amplifier, it's usually much more expensive.
The second, even more important point is that it will be very difficult to build something equivalent to the Fosi V3 stereo amplifier and you will exceed the approx. €/$ 80-90 including power supply many times over.

Wanting to save money is the worst motivation for building something yourself these days, at least when it comes to power amplifiers.