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Online paulca

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Audio amp recommendations!
« on: July 15, 2019, 09:38:50 am »
tldr; So I need suggestions for a new amp for my TV/Media centre in the living room.  BlueTooth, USB DAC, Optical in, 2x80W RMS, probably Class D, £200 budget.

I currently have a close-to 20 year old Sony integrated HiFi, or what's left of it, the amp and tuner block.  It's 80W RMS, 160W PMPO with 5 way speakers (3 angled 'surround' tweeters, 1 front focus tweeter, 1 6" mid/bass driver and port).  This amp/speakers combo, explaining it's age, has always impressed me and worked flawlessly.  It will rattle windows and shake floors, but still sounds crisp at 3am watching NetFlix at mouse squeak volume.  It's also completely silent when idle, even at 75% volume.

I got a new TV, LG HDR 4K 55" and it has no analogue audio output, only digital optical.  Connecting the amp to the headphone jack on the source and there is a noticeable delay on the TV picture, which is normal for digital TVs.  However it's irritating.

So I need a new amp.

I'm thinking of a modern mini-amp with USB DAC, Bluetooth, Optical Input and 80W per channel RMS output.  Given the power requirements and the wish for it being small/compact a class D sounds appropriate.  The power output is less important to me, my days of having the neighbours knock the door while rattling windows are over.

I an NOT an Audio-Phool!  If you want to tell me I need 256kbit/s DAC and spend £3000 on the amp, save your typing.

My budget is £200.  I will be keeping the Sony speakers as my daughter has yet to manage to stick her fingers through a driver yet.

On a quick google, I found this:
https://www.amazon.co.uk/Sabaj-Bluetooth-Optical-Digital-Amplifier/dp/B01N10PF4B/ref=sr_1_3?keywords=digital+optical+audio+amplifier+80W&qid=1563181244&s=gateway&sr=8-3

It seems to meet my requirements, reviews seem encouraging.  It's a completely unknown brand to me, but they seem very proud of their design and components used.  Optimistically it could be a gem of a find from an unknown brand that turns out really good.  Pessimistically it could turn out to be rubbish.

I thought I would ask here to see if anyone can give me suggestions for alternatives.

Note, I'm in the UK if it matters and it's Amazon Prime day, so they have a sale on :)
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Offline dzseki

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Re: Audio amp recommendations!
« Reply #1 on: July 15, 2019, 10:41:47 am »
Amplifiers like shown in your link,want to stand out by listing the used components to impress users, but in reality they only worth as much as they sell for, also you have to consider your chance if it will work out of the box or not.
In your shoes I'd go to the nearest electronics store and would pick one brand name amplifier you like the most. You have to pay for the name of course, but they at least usualy live up to it. But also don't have high hopes, nothing you buy today will last as much as your old Sony.
Just my 2 pence.
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Online paulca

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Re: Audio amp recommendations!
« Reply #2 on: July 15, 2019, 10:55:43 am »
In your shoes I'd go to the nearest electronics store and would pick one brand name amplifier you like the most. You have to pay for the name of course, but they at least usualy live up to it.

I checked Richer Sounds but the only things they have are large full HiFi separates power amplifiers with dozens of features I don't ever need, like Phono and CD inputs.  They did have one single class D mini-amp, but only 25W and it was £130.

I'll check a few more places.
« Last Edit: July 15, 2019, 10:57:40 am by paulca »
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Online paulca

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Re: Audio amp recommendations!
« Reply #3 on: July 15, 2019, 11:06:20 am »
Actually on Richer Sounds when I upped my price range to £300 I started finding mini-amps with less than half the power and half the features with brand names like Denon.
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Offline dzseki

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Re: Audio amp recommendations!
« Reply #4 on: July 15, 2019, 11:33:52 am »
In your shoes I'd go to the nearest electronics store and would pick one brand name amplifier you like the most. You have to pay for the name of course, but they at least usualy live up to it.

I checked Richer Sounds but the only things they have are large full HiFi separates power amplifiers with dozens of features I don't ever need, like Phono and CD inputs.  They did have one single class D mini-amp, but only 25W and it was £130.

I'll check a few more places.

You have to be realistic, the Sabaj amplifier you linked will only deliver half of its rated power, if you are lucky. They state 2x80W output, and an STA326 amplifier IC, if you look up the datasheet it looks like that it is indeed capable of delivering that power, yes, with 10% distortion and 36V supply voltage. The Sabaj has 19V supply voltage as seen on picture. The datasheet states 50W with 21V supply (not 19V!) @10% distortion and 4 Ohm speaker, at 1% distortion power goes down to 40W at 4 Ohm.
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Online paulca

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Re: Audio amp recommendations!
« Reply #5 on: July 15, 2019, 12:04:34 pm »
Yes, I found other reviews that claimed to measure the output power at 17W before it started to clip with 8 Ohm speakers.

I found a Denon equivalent, but it was £299 and only 25W per channel into 4 Ohms.  I haven't measured my speaker resistance.

That said, I'm not really sure I need more than 25W per channel these days.

The thing I loved about the Sony was it was paired perfectly with it's speakers, you could put the volume to 100% and play whatever your liked and it wouldn't clip.  It would wind back the bass a little or engage a limiter when you pushed it, but I used to happily leave it on 100% volume at parties with a DJ in the next room feeding it.  Actually people found the sound to be better than the actual hired DJ speaker rig in the main room.  The point is I could trust it to self manage and I do believe it's output power is 80W per channel RMS.

It did used to have an optical input.  I swear.  However the Mandela effect has now removed that as soon as I needed it.  All I can think was that the optical input was on the CD module which has since been binned.
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Offline klunkerbus

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Re: Audio amp recommendations!
« Reply #6 on: July 15, 2019, 12:08:46 pm »
One thought would be to try a optical to analog converter.  They're really inexpensive.  If nothing else, I'd try that as a temporary solution until I figured out what I wanted to do for a new amp or new amp/speakers.
 
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Online paulca

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Re: Audio amp recommendations!
« Reply #7 on: July 15, 2019, 12:27:29 pm »
One thought would be to try a optical to analog converter.  They're really inexpensive.  If nothing else, I'd try that as a temporary solution until I figured out what I wanted to do for a new amp or new amp/speakers.

Funny enough I came to the same conclusion a moment ago.

https://www.amazon.co.uk/SGEYR-Converter-Control-Digital-Coaxial-BLACK/dp/B07HL2QFKR/ref=sr_1_2_sspa?keywords=Digital+Optical+to+RCA&qid=1563193459&s=gateway&sr=8-2-spons&psc=1

But I might do a bit of shopping around.  Any DAC will introduce delay itself, but hopefully that should not be more than 10ms or so.  But I'd like to find one of these that actually publishes it's input latency.
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Online paulca

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Re: Audio amp recommendations!
« Reply #8 on: July 15, 2019, 12:41:01 pm »
Normal HiFi optical is just S/PDIF isn't it?

Something like this is what I need:
https://www.thomann.de/gb/swissonic_converter_da_24_192.htm
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Offline SiliconWizard

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Re: Audio amp recommendations!
« Reply #9 on: July 15, 2019, 01:00:47 pm »
Just wondering...

Bluetooth: this small amp is proudly equipped with a 24-bit, 96kHz DAC, but does Bluetooth audio transmit 24-bit, 96kHz audio to begin with? I may not be up to date with Bluetooth 4.2, but I doubt it goes above 16-bit, 48kHz... not to say it's not adequate for your needs. Maybe you're never going to use Bluetooth either, in that case, nevermind. I guess you should be OK with the optical input.

2x80W what? This is one the most confusing figures that are given for audio amplifiers. Is that W RMS? I doubt it.

Looking at the STA326, which this amp revolves around, the datasheet also states 2x80W (so they just copied that). I didn't see clearly what those W were in the datasheet, but I suspect those are NOT RMS. Not a huge problem per se, you probably don't need 2x80W RMS of power for a TV system... but I definitely hate those figures when looking at power amp's specs...

Also note that the STA326 IC is obsolete: https://www.st.com/content/st_com/en/search.html#q=STA326-t=products-page=1
Not that you should necessarily care as a simple end-user, but it probably says something about this amp's design and may have been produced with old stock only (or maybe even fake chips)...
 

Online paulca

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Re: Audio amp recommendations!
« Reply #10 on: July 15, 2019, 01:20:29 pm »
2x80W what? This is one the most confusing figures that are given for audio amplifiers. Is that W RMS? I doubt it.

Yea, I know the power output lottery :)  For a while PC speaker systems were being sold with figures like 1000W PMPO, but the power supply for the amplifier consumed something like 3W.  So all I can think they were quoting was instantaneous peak power for a single pulse.

This is why I like to find amplifiers that properly quote a range of power outputs for various Ohms and RMS versus PMPO etc.  Even then it's still a lottery unless you are buying a brand name where people WILL return amps for not meeting spec.  And those kind of brands costs 10 times more than cheap brands.
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Online NiHaoMike

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Re: Audio amp recommendations!
« Reply #11 on: July 15, 2019, 02:54:51 pm »
But I might do a bit of shopping around.  Any DAC will introduce delay itself, but hopefully that should not be more than 10ms or so.  But I'd like to find one of these that actually publishes it's input latency.
The cheap DACs without DSP will have a very low latency, far less than 1ms.
Bluetooth: this small amp is proudly equipped with a 24-bit, 96kHz DAC, but does Bluetooth audio transmit 24-bit, 96kHz audio to begin with? I may not be up to date with Bluetooth 4.2, but I doubt it goes above 16-bit, 48kHz.
There are proprietary implementations that will do 24bit 96kHz, for example Nvidia's implementation for the Shield TV and Qualcomm's AptX. I agree the Bluetooth standard should have added a standard provision for HD audio as soon as the bandwidth became high enough for that.
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Online paulca

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Re: Audio amp recommendations!
« Reply #12 on: July 15, 2019, 03:02:50 pm »
So i went for a cheap, but not cheapest DAC box.  The reviews seemed okay with several people mentioning running it along with their TV built-in speakers and not having issues, so it can't have much of any lag.

It also has a volume control as quite a few without had reviews complaining about excessively low output levels, although mostly there were people trying to drive headphones direct from the output.

Also a nice feature is that it's powered from USB, so can be powered off the TV USB socket.  I might even get lucky and the TV powers down it's USB power when shutdown to standby.
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Online blueskull

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Re: Audio amp recommendations!
« Reply #13 on: July 15, 2019, 05:40:00 pm »
256kb/s=128kb/s/ch=8ksps*16bit/ch=telephone quality.

I think you meant 256ksps (commonly misspelled as 256kHz).

Also FYI, 256ksps is not a common sample rate. It goes like 44.1ksps or 48ksps times 1/2/4, so 44.1ksps (common CD), 88.2sps (only used by Japanese), 176.4ksps (rare), 48ksps (SACD, DVD), 96ksps (old studio standard) and 192ksps (current studio standard).

Being a two-decade audio DIY fan, I would like to correct a common misconception. Many say high sample rate is BS as human ears can't hear them. I say that's wrong.

Human years indeed can't hear anything above 20kHz, mostly 16kHz. But low pass filters need a transition band. If your converter runs at 44.1ksps, your stop band is 22.05kHz to prevent aliasing, and your pass band is 20kHz, so you only have a very narrow transition band (2.05kHz/48ksps=4.27%).

If you sample at 192ksps, your transition band can be extremely wide, so it's easier to design filters, thus you can use more ideal filters (elliptic, for instance) rather than more aggressive but less phase flat filters (butterworth, for instance).

Even though nowadays DACs are internally interpolated, the digital interpolation filter is still not ideal. To keep power, pre-ringing and delay low, filters usually have only a few taps (rarely above 64), thus transition band still limits the performance.

If your DAC takes in pre-filtered 192ksps data, its internal filter will have a much easier job to do, thus you have higher quality audio without having to suffer from artifacts caused by real time DSP.
 

Offline BrianHG

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Re: Audio amp recommendations!
« Reply #14 on: July 15, 2019, 06:02:15 pm »

Being a two-decade audio DIY fan, I would like to correct a common misconception. Many say high sample rate is BS as human ears can't hear them. I say that's wrong.

Human years indeed can't hear anything above 20kHz, mostly 16kHz. But low pass filters need a transition band. If your converter runs at 44.1ksps, your stop band is 22.05kHz to prevent aliasing, and your pass band is 20kHz, so you only have a very narrow transition band (2.05kHz/48ksps=4.27%).

For most audio, you are using software interpreted over sampling synthesize a perfect analog 20Khz reconstruction filter, vastly simplifying the output stage filter and creating a stop-band attenuation which you'll never be able to reproduce with any single or even multi-stage RLC opamp filters.  In this case, I agree with you.

In other words, go for the higher oversampling DAC since it will run circles around any archaic 1:1 DAC with an analog filter design especially even so when listening simple 44.1k audio.


Side note about modern recordings:
      A properly produced 44.1k CD, without the pitiful modern over-volume with heavy limiting techniques (this includes the modern bullshit remasters of old albums), do exceed most of our speakers capabilities to reproduce, or our ears ability to hear.  If you have albums sounding better recorded in HD audio, it may sound better usually because the HD audio release is mastered without these BS heavy limiting techniques.  It's easy enough to prove when taking such a HD audio source and do a simple digitally down-sampling to CD 44.1k.  That copy will most likely outperform the official studio CD release of the same song.
« Last Edit: July 15, 2019, 06:09:02 pm by BrianHG »
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Offline MosherIV

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Re: Audio amp recommendations!
« Reply #15 on: July 15, 2019, 07:29:29 pm »
Hi. I am late to the conversation. I had a similar problem, when my old Panasonic TV died, i was left with no surround sound with the new TV.
New AV receivers were hideously expensive and I did not need a 10 channel amp.

I turned to ebay. I managed to pick up a decent Yamaha AV Amp for less than £50.

I would suggest you look at AV Amps as well. They have multiple opticle inputs and being a full blown amplifier, it is going to have very good audio quality. People are upgrading and the old AV Amps go for very little because people do not want them.

I turned off the internal speakers in the TV.
 

Online paulca

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Re: Audio amp recommendations!
« Reply #16 on: July 16, 2019, 08:05:28 am »
I went for an adaptor for now, thanks for that advice.

On AV amps, the new ones are expensive and finding an old one on ebay s/h is a bit of mine field.  I looked through about a dozen and only found one that had optical AND still had a working remote control.

However it did get me to thinking.  I had kind of excluded a proper dolby surround system out of hand, but this is because I have been renting a flat for 10 years.  Now I own my house, so routing cables around the place and drilling holes to mount surround speakers etc. is my business.

So I might continue to research this possibility now.

On higher bitrates/ksps/kHz and bit depth.  On a hearing test I top out at around 12-14Khz, so, no, I don't care.
« Last Edit: July 16, 2019, 08:07:11 am by paulca »
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Offline rdl

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Re: Audio amp recommendations!
« Reply #17 on: July 16, 2019, 09:09:55 pm »
I used an old Creek 4330R and an AudioQuest Dragonfly I bought used for $45 for many years. I replaced the Creek with a Pioneer A20 recently because it needs some repair and I don't know when I'll have time for that. I've never had a need for Bluetooth anything.
 

Online paulca

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Re: Audio amp recommendations!
« Reply #18 on: July 17, 2019, 06:59:48 am »
Well the adapter arrived.  Joys of Amazon Prime next day delivery.  Also I checked a few better places and there are fairly decent AV amps for £200-300, £400-500 with a full set of 5.1 speakers.  Just need to research things a little more and consider budgeting.

On the adaptor the downside is that the optical out is basically a line out, so the TV volume control has no effect on it.  Thus, I need two remotes again.  I realise I could fix this by using a custom programmable remote with the volume programmed to the HiFi and the rest the TV.
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Current Open Projects:  3 Channel Audio mixer with DAC, BT, pre-amps and h/phone amp, WS281x LED controller Version 2 5V/5A w/Atmega328, FY6600 Power supply, 5A DC Load (Still!)
 


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