Allo Volt+ D Amplifier Review

[sonci99]

Are you planning on any new amp based on more powerful chip like the TPA3255?

 

[johan]

Yes I am. Different price point , diff specs. It wont be ready for a few months

 

[mhardy6647]

18wpc is completely inadequate for high fidelity reproduction.

Depending upon the sensitivity and load characterstics of one's loudspeakers.

 

[tomtoo]

I call it a toy because it's a simple class D chip amp solution PCB in a perspex case with absolutely no effort whatsoever to make it remotely attractive. It runs on a surplus laptop supply. It has a cheap knob, one input, one pair of speakers, no facilities or features and is no more powerful than most portable blue-tooth speakers sold at big box stores.

I'd be proud of it when I was 12 years old.

That doesn't mean it isn't fun. I have fun with filterless 2W class D amplifiers that run on a USB charger too. I do. But let's be adults and put it into perspective.

Asthetics are personal taste. Yes i prever accuphase from this point of view but i hate mcintosh. Do I call mcintoshs now toys? It uses a class d chip. Cool why not?
Is it a high class audiophile PA amp?
NO! But it's not a toy. It's well engineered and it works well in its specifications. You can say it would not fit you. Thats ok, but call it a toy is imo not fair.
P.S Dont know whats wrong with me today, yesterday i called 8 inch woofers toy speakers. Peace bro!

 

[Jdunk54nl]

Sure, with efficient speakers (like yours), not many watts can be an awful lot of fun, but let's face it, most people are running 85-87dB SPL@1M/W speakers these days. They need more, undistorted power than the little Allo can do, unless you take the TPA right up to the V+ limit of around 30V.

18wpc is completely inadequate for high fidelity reproduction. A capacitance multiplier does not provide additional power either. It provides power supply/noise/ripple rejection.

But why is 18wpc not enough, especially if it is used as a desktop amp at roughly 1m?
I know my listening levels (and most peoples) are not normally over 90db for extended periods of time. My office levels are usually much lower than that.

So if you have 85db sensitive speakers and are within that 1m for desktop use, you should have extra power on hand.

1w for 85db/87db
2w of 88db/90db
4w for 91db/93db
8w for 94db/96db
16w for 97db/99db
32w for 100db/102db (requires better power supply)

I’m pretty confident that most will be more than satisfied with 97db/99db extended listening capabilities if they have 85db/87db sensitive speakers. This isn’t bass reproduction, 97/99db mid to high frequency reproduction is loud!

This also can be increased (as shown above) by getting a better power supply and/or more sensitive speakers and/or lower impedance speakers.

I don’t think I’d use it for HT, but I’m definitely thinking about picking it up for my office where the speakers are well within 1m. Sure the case isn’t my favorite, but I could just hide the amp if I really wanted to.

Edit* I just tested my listening level using REW and my calibrated microphone (also verified with decibel x iphone app) and I was about 70db with it peaking at 75db for louder listening, and 65db-70db for more comfortable office listening. This was with subwoofer turned off.

So that means I would need ~ 0.125w on 85db sensitive speakers to listen at loud listening for me.

0.5w for 82db
0.25w for 79db
0.125w for 76db

 

[amirm]

No amps are not supposed to clip at max power (unless signal feed is above specs)

Adding to this, I make sure that there is no clipping as I increase output power for SNR measurements at "full power."

 

[Bruce Morgen]

Yes I am. Different price point , diff specs. It wont be ready for a few months

Looking forward to it. I already have an Aiyima A07 that I'm very happy with, but I'm interested to see how much better you folks can do with the (IMO wonderful) TPA3255. I already have a 48VDC 10A SMPS, so I'm good to go whenever you are!

 

[restorer-john]

I take it you have used a 31v power supply with the Volt +D? Lots of questions about this from owners on another forum. Allo.com only sells a 19v for the Volt+D and that's what they recommend.

From the manufacturer:

None of this is rocket science. The IC performs generally better at high voltages, up to the limit in the TI datasheet. As Po is V²/R, every volt counts...

They use a 19V regulated SMPS because they are made by the millions in China and can be sold as an add-on to the amp for only $18 extra. But you are getting way less than half the power the chip is capable of.

 

[Girafenaine]

Hello,

Thank you @amirm for this review about a great little amp. I bought it a few months ago and it is indeed detailed and quick and gives a pleasant and true-to-life sound in my home setup, with a Sanskrit DAC. I found it more interesting than a SMSL AD18, which is heftier and appealing, but did not show as many details and tones. And thank you @johan for having made it ! I personnaly like the case that shows the inner well done job with pots and chips.

I use it with the "recommended" 19V PSU. Thanks to the measurements and Johan's statement in this thread, I understand I could try 24V and even 31V (yet the allo.com site tells "24V max", which is strange since Johan is OK for 31V). What changes could be awaited with a bigger voltage : the sound should be louder ? Or rather some frequencies should be heftier, especially in the lows, where speakers impedance is lower ?

I made a quick listening test (on a single track) with a 24V PSU and did not hear any volume increase, coming from the 19V PSU. That's why I would like to understand more about voltage effect.

 

[johan]

Voltage increase will give you a volume increase (more power) but the difference between 24V and 19V is marginal and unless you are using test tools you wont necessary hear (remember) the difference .

We advise 24V max since thats the normal PSU voltage available , we dont want anyone to fry the AMP (but we will update the page)

 

[Poultrygeist]

Is the new high power Volt based on the TPA3255 and when can we buy one?

 

[johan]

Yes I am working on it , it will take some time to be ready

 

[Bruce Morgen]

Yes I am working on it , it will take some time to be ready

I know cosmetics are not a major concern for you folks, but a non-transparent case would be a welcome option.

 

[Poultrygeist]

I'm a fan of the transparent futuristic Volt amps.

Adding a metal case will escalate the price.

 

[restorer-john]

I'm a fan of the transparent futuristic Volt amps.

That's a good photograph.

 

[johan]

I know cosmetics are not a major concern for you folks, but a non-transparent case would be a welcome option.

In order to use the casing as a heat sink we will have a metal case

 

[tomtoo]

Just thought about a complete change.
Get ride of that complete power cleaning stage. Add for that a 24v li-ion accu. Would make a littel clean and portabel amp.

 

[Girafenaine]

Voltage increase will give you a volume increase (more power) but the difference between 24V and 19V is marginal and unless you are using test tools you wont necessary hear (remember) the difference .

We advise 24V max since thats the normal PSU voltage available , we dont want anyone to fry the AMP (but we will update the page)

Hello @johan,

Thanks for your answer. OK for 24V as "normal PSU", much easier to find than 28 or 30V.

I understand that the volume increase won't be noticed when you increase input voltage from 19 to 24V. I wonder if there are quicker and heftier low freq thanks to the ability to give more current to the speakers. Or any other interest ?

Thank you for your work on this little amp. This review show that you have done a very good job to take the best from this TPA3118D2. The measurements are the best for this price point, even if measurements don't describe the whole music. The result is an excellent quality price ratio which one could not find with other brands. Nice ! I understand that some people are eager to see your next amp... For me this Volt+D is what I need for next years.

Girafenaine

 

[lobo]

Voltage increase will give you a volume increase (more power) but the difference between 24V and 19V is marginal and unless you are using test tools you wont necessary hear (remember) the difference .

We advise 24V max since thats the normal PSU voltage available , we dont want anyone to fry the AMP (but we will update the page)

Hi, newbie here. Bought the volt a couple weeks ago and forgot to order the psu. I've been using a 12V 5.4A psu. The volume is more than enough. Any impact in sq or other besides volume? Thanks in advance.

 

[Bruce Morgen]

In order to use the casing as a heat sink we will have a metal case

Thank you, Johan.