# Allo Volt+ Speaker Amplifier (tpa3118)



## AudioNoob

If there is a standout amongst assembled Tripath/Class-D boards, it has to be the Volt+. Volt and the Rpi focused audio ecosystem it belongs seem to be a hobby project of Allo, an otherwise telecom manufacturer in India.

With a little diy (if you don't buy it preassembled), it would be the perfect amp to power bookshelf speakers from your DAC/Headphone Amp Line out for shared listening sessions. It is no frills, doesn't need warm up, and is generally not finicky.

**Largely building on the TI reference design for the TPA3118, even including the AM avoidance dipswitch, Allo uses Würth inductors and a generous spread of Film Caps and 1% resistors on an amp circuit designed to maximize fidelity. The choice of short and symmetrical paths over all else is evident in the the quirky I/O layout with jacks flanking three sides of the board, with the volume pot ending next to the input.

Beyond the core of the amp, In addition to the the usual bootstrap snubbers and an anti-pop filter, *_The Volt+ includes a capacitance multiplier that works to reduce the ripple from switching supplies to negligible levels. *_ Essentially it uses a capacitor as a small power buffer to eliminate fluctuations from the PSU.

For the ones wanting to go over the top for an amp in this price range, and since this is head-fi, Allo offers a Stepped Attenuator (available pre-built as well as separately) to further the already excellent THD performance another notch. Speaking of THD, ALLO measures their amps at various load levels and provides extensive reports downloadable on their website, something you will definitely not find on other manufacturers’ at this price level.

Anyhow, most of this can be found on their brochures and website, but I wanted to highlight the significant differences between the ALLO, and say, a SMSL or a Lepai T amp. I'm not comparing to various other tpa311* boards because I don't have any at hand, but it's basically like getting an upgraded board with a built in power filter. On to what it translates to in practical terms:

Firstly, the VOLT+, *should be infinitely more dependable thanks to the higher end components used throughout the board.* You should expect to get a well functioning amp with well matched channels and low ESR/leakage. I’d rather pay the $10-15 extra up front and not enter the cheapo capacitor lottery, or worry about channel imbalances and non-linearity of improperly used smd components down the line.

In comparing it to other amps such as the Q5 Pro, the Origain AD250, the SA36a-pro and the Pro-ject MaiA, the Volt consistently takes things a tiny step further, even in cases where all the amps are more than good enough to enjoy without pause. *The most notable difference is the low-end reproduction, the volt+ acing through flabby, roaring bass passages with impeccable control*, especially notable with smaller bookshelves already limited in their low end reproduction capabilities. *Transients are another point where I can consistently pick the Volt+ out in blind comparisons, the decays of high hats lasting a moment longer, breath following vocals crystalizing in a shimmer* before disappearing completely.

Having said the above, the volt+ is definitely neutral in its reproduction. The AD250 for example, though using the same chipset and despite other forgivings, has a warm, and as far as these adjectives are useful, more musical sound singature. Essentially though, this is mostly the coloration afforded by certain distortions which I feel are better left to slight, controlled EQ adjustments, for every source and speaker combination is going to behave differently.

*Putting it all together, the VOLT+ is a no brainer if you value sound quality above the convenience of having a mini-receiver, or if you have a focused system with a single input and no need for a sub out.* Besides slipping it into your headphone dac+amp setup, you could pair the VOLT with the ALLO Boss + Rasberry Pi, and for under $100, have yourself a network receiver that can see you through a few speaker upgrades as it should handle most things you throw at it under $500-750 as well as anything else.

I tried the volt+ with a higher end industrial SMPS but could not hear a difference from the one provided by Allo. I do not have a suitable linear PSU at hand, but I feel that the capacitance multiplier is working well to nullify weaknesses inherent to switching supplies.

The seperately available power supply is 19V, but you can go up to 26V if you need to drive less sensitive speakers, and to drive them loudly. However, the chipset really does better staying under 25W(8ohm) per channel or so, and below 24V. Save for some crazy bookshelves, I can’t see the point in stressing the voltage as paired with the Dali Zensor Picos, far from a sensitivity champion at 84db, the volt provided more than ample power with the 19V supply, going louder than I could bear shortly past the one o’clock mark. Also bear in mind that defining a useful volume range where you don't quickly out your hearing, you will have more control over the volume as there is no way to set it between steps in a stepped attenuator setup. Furthermore, stepping up to 24V yields audible change in SNR in all the tpa 311* amps that I have, all reproducing lower ranges with more control around the 19-21V level. Lastly, If you do decide to go 24V and intend to use it for long hours, I would suggest adding a wide/tall heatsink.

*Where the amp falls short in comparison is convenience, and to be clear, this is not a place where the volt even bothers to try, a bit apples and oranges, comparing stereo receivers to stereo amplifiers. With something like the Q5(or the AD18), you can trade in a notch in sound quality to have multiple inputs, a built in DAC, subwoofer out, and a remote to controlling the whole setup from the cradle of your couch.* I would not count on any of the others to last more than a couple years, but if your priority is to build it into your home entertainment system with budget speakers, I could see priorities balancing out in going with another solution.

I had the Volt+ prebuilt by Allo with a stepped attenuator. It comes in a case made from laser cut acrylic with a relatively large footprint due to the pillar/stacking design they scaled up from their raspberry pi cases. As I mentioned before, there is not much to note in the interface as this is a one input one output box with only a volume pot for control. As it is a stepped attenuator, the knob clicks the assembly into position to route the signal through a fixed set of resistors*, the nature of the setup makes such devices harder to turn and the volt+ would really benefit from a larger/duckbill knob to facilitate this.*

*I had a couple issues with the assembly of my prebuilt unit.* One issue that I had with my build was that the speaker posts were reversed, forcing you to cross the wires in the back with the left speaker posts on stage right, and the right speaker stage left. When I opened up the unit to reverse them (the speaker posts are screwed, not soldered), one of the solder points on the board failed, immediately followed by the paired cable when I tried moving the first one to see what happened. Turns out the cabling used -even at the high level stage- is a super dinky, few tinned strands in a thick jacket sort of affair. To top this, all the said cables were zip tied together, along with the DC input, running parallel below the board, with a potential for crosstalk and noise. Finally, the soldering of the cables from case mounted components to the board was a little sloppy, one signal cable almost touching the hole for the signal cable of the other channel. **Given all this, I would recommend getting the regular volt+ and building your own case, or upgrading the cabling on the allo one. Allo responded to my comment, noting that they will look into upgrading the cabling.

*It is an easy recommendation if you know what you need and find the absent conveniences an unnecessary surplus. The unyielding performance and dependability of the amp –the issues with the built version nonwithstanding– more than deserves the inconvenience even if you have to DIY some additions.*

*disclaimer, allo provided the amp, though I owe them nothing in exchange and told them from the get go that I would post an honest, if not critical, review.

https://www.allo.com/sparky/volt-plus-stepped-attenuator.html


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## Cho Worsh (Jul 19, 2022)

AudioNoob said:


> If there is a standout amongst assembled Tripath/Class-D boards, it has to be the Volt+. Volt and the Rpi focused audio ecosystem it belongs seem to be a hobby project of Allo, an otherwise telecom manufacturer in India.
> 
> With a little diy (if you don't buy it preassembled), it would be the perfect amp to power bookshelf speakers from your DAC/Headphone Amp Line out for shared listening sessions. It is no frills, doesn't need warm up, and is generally not finicky.
> 
> ...


EDITED: I used this for a while and it is not bad. But eventually it failed on me and I moved on to something else.


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## Marshmellow

Cho Worsh said:


> Volt + D (US$129) is worth a try.



Does Allo Volt+ D have reversed binding posts or some other problems?


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## Cho Worsh (Nov 6, 2019)

Marshmellow said:


> Does Allo Volt+ D have reversed binding posts or some other problems?


No, the binding posts were not reversed and overall workmanship is very good. 
No issues. 
You just have to handle the amp with care to make sure you don't squeeze it between your fingers too hard which could crack the fragile acrylic case.


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## Marshmellow

@Cho Worsh Which power supply do you use with it? I want to use a good power supply with it.


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## Cho Worsh (Nov 6, 2019)

Marshmellow said:


> @Cho Worsh Which power supply do you use with it? I want to use a good power supply with it.


(Revised 11.5.19) Decided to just use the 19V supply that came with the amp instead of this cheap 24V that I bought and did not like and returned to amazon for a refund: 
https://www.amazon.com/gp/product/B01GC6VS8I/ref=ox_sc_act_title_1?smid=AA0YO4F2UD50F&psc=1


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## Marshmellow

Cho Worsh said:


> For now, I am using this one which is 24 volt 5 amp. It was recommended in another forum on another website:
> https://www.amazon.com/gp/product/B01GC6VS8I/ref=ox_sc_act_title_1?smid=AA0YO4F2UD50F&psc=1
> It costs less than $20 and is a switching power supply. I haven't checked but eBay may have some merchants that would build a 24V 5A linear power supply for you if you want to go "all out".



As far as I know, you want a heatsink with a 24V power adapter. At 19V, a heatsink is not needed.


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## Cho Worsh

Marshmellow said:


> As far as I know, you want a heatsink with a 24V power adapter. At 19V, a heatsink is not needed.


Yes, ideally a heatsink would help to avoid possible overheating. 

The 19V power supply that comes with the amp has a crap ac cord and US wall plug adapter so I substituted a larger gauge figure 8 ac cord from a cd player with a US plug on it when I used the 19V power supply. 

In case you have not seen it, go to audiophilestyle website for a discussion of power supplies and other things about the Allo Volt + D: https://audiophilestyle.com/forums/topic/41484-voltd-class-d-amp-dual-mono-2x-60w/#comments


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## Marshmellow

Cho Worsh said:


> The 19V power supply that comes with the amp has a crap ac cord and US wall plug adapter so I substituted a larger gauge figure 8 ac cord from a cd player with a US plug on it when I used the 19V power supply.



If I wanted a 24V power supply, I would make a power supply out of Mean Well LRS-200-24 industrial SMPS.


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## Cho Worsh

Marshmellow said:


> If I wanted a 24V power supply, I would make a power supply out of Mean Well LRS-200-24 industrial SMPS.


Right. Does it have a quiet internal cooling fan?  Some of the SMPS have very small fans that spin very fast and make a lot of noise which disturb listening.


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## Marshmellow (Nov 4, 2019)

Cho Worsh said:


> Right. Does it have a quiet internal cooling fan?  Some of the SMPS have very small fans that spin very fast and make a lot of noise which disturb listening.



LRS-200-24 doesn't have a fan. SMPS usually requires a fan if it can consume more power than 250W. LRS-200-24 consumes 200W at maximum. Mean Well LRS-xxx-xx industrial SMPS turns its fan on and off, depending on the temperature.


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## Cho Worsh (Nov 8, 2019)

Marshmellow said:


> LRS-200-24 doesn't have a fan. SMPS usually requires a fan if it can consume more power than 250W. LRS-200-24 consumes 200W at maximum. Mean Well LRS-xxx-xx industrial SMPS turns its fan on and off, depending on the temperature.


Great. I avoid fans whenever possible. They may be quiet when you first get them and then get louder and louder the older they get. 

I will probably get a LRS-200-24 for another 24V head-fi amp I use sometimes. Thanks for the tip. 

I am listening to the Volt+D right at this moment.  It has over 300 hours running time on it now and seems to sound a lot better than when it was brand new.  Or, maybe I have just grown accustomed to its sound.   Volt+D is impressive.


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## Marshmellow

Cho Worsh said:


> I am listening to the Volt+D right at this moment. It has over 300 hours running time on it now and seems to sound a lot better than when it was brand new.



I purchased a chinese no-name TPA3255 amplifier and a chinese 32V 5A power adapter from aliexpress.com. They seem to sound fine. Although the potentiometer has channel imbalance at very low volume levels, since input gain is low, I can avoid channel imbalance with ease.
How would you compare my chinese no-name TPA3255 amplifier with Allo Volt+ D?


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## Cho Worsh (Nov 8, 2019)

Marshmellow said:


> I purchased a chinese no-name TPA3255 amplifier and a chinese 32V 5A power adapter from aliexpress.com. They seem to sound fine. Although the potentiometer has channel imbalance at very low volume levels, since input gain is low, I can avoid channel imbalance with ease.
> How would you compare my chinese no-name TPA3255 amplifier with Allo Volt+ D?


Wow, I don't know. I have no experience with TPA3255.


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## Marshmellow

Cho Worsh said:


> The Volt+D sounds too boring to use as headphone amp



Allo Volt+ D is a speaker amp. It is not suitable as a headphone amp.


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## Cho Worsh

Marshmellow said:


> Allo Volt+ D is a speaker amp. It is not suitable as a headphone amp.


I understand Allo is coming out with a more powerful amp (maybe mono blocks) soon. Have you heard anything about that?


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## Marshmellow (Nov 4, 2019)

Cho Worsh said:


> I understand Allo is coming out with a more powerful amp (maybe mono blocks) soon. Have you heard anything about that?



The rumor is that allo will release a TPA3255 amplifier at the beginning of next year. Perhaps, I will buy allo's TPA3255 amplfier next year.


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## Cho Worsh

Cho Worsh said:


> Wow, I don't know. I have no experience with TPA3255.





Marshmellow said:


> I purchased a chinese no-name TPA3255 amplifier and a chinese 32V 5A power adapter from aliexpress.com. They seem to sound fine. Although the potentiometer has channel imbalance at very low volume levels, since input gain is low, I can avoid channel imbalance with ease.
> How would you compare my chinese no-name TPA3255 amplifier with Allo Volt+ D?


Would you give me the url link to the chinese TPA3255 amp and 32V 5A power adapter that you purchased from aliexpress.com?  I may buy one to try. Thanks!


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## Marshmellow

Cho Worsh said:


> Would you give me the url link to the chinese TPA3255 amp and 32V 5A power adapter that you purchased from aliexpress.com?  I may buy one to try. Thanks!



AIYIMA AC100V-240V 32V 5A adapter (Model 3205000)
Chinese generic no-name TPA3255 Amplifier
This is exactly what I ordered.


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## Cho Worsh

Marshmellow said:


> AIYIMA AC100V-240V 32V 5A adapter (Model 3205000)
> Chinese generic no-name TPA3255 Amplifier
> This is exactly what I ordered.


Many thanks!


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## Marshmellow

Cho Worsh said:


> Many thanks!



I discovered that the amp or the power supply has white noise. But, it is not perceptible beyond 1 feet.


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## Cho Worsh

Marshmellow said:


> I discovered that the amp or the power supply has white noise. But, it is not perceptible beyond 1 feet.


thanks for letting me know
i will wait until next year to see if Allo comes out with a TPA 3255 amp
apparently, Allo thinks they may be able to make a 3255 amp that sounds close to the same as a Hypex NC200 module amp


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## Marshmellow (Nov 15, 2019)

Cho Worsh said:


> apparently, Allo thinks they may be able to make a 3255 amp that sounds close to the same as a Hypex NC200 module amp



How do you know what they think? How good and expensive is Hypex NC200 module amp? How expensive are allo tpa3255 amp and its power supply going to be?

By the way, my chinese generic TPA3255 amp is ok for the price. White noise from a generic TPA3255 amp and a generic TPA3251 amp is imperceptible at 12cm away with ambient noise. Both amps work with a 32V 5A adapter.


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## Cho Worsh

Marshmellow said:


> How do you know what they think? How good and expensive is Hypex NC200 module amp? How expensive are allo tpa3255 amp and its power supply going to be?
> 
> By the way, my chinese generic TPA3255 amp is ok for the price. White noise from a generic TPA3255 amp and a generic TPA3251 amp is imperceptible at 10cm away with ambient noise. Both amps work with a 32V 5A adapter.


i saw a discussion online of tpa 3255 amps in general where someone said Allo thought they could make 3255 sound as good as NC400 amp (NC200 was a typo, sorry) but can't find it now and no price was mentioned. 
audio science reviewed a DIY NC400 module based DIY amp https://www.audiosciencereview.com/...and-measurements-of-hypex-nc400-diy-amp.5907/
the review lists the cost of the parts
for now, I will stick with my volt + d


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## Marshmellow (Nov 16, 2019)

Cho Worsh said:


> for now, I will stick with my volt + d



A bigger problem with a generic chinese amp is channel imbalance in input gain.
My generic TPA3251 amp and my generic TPA3255 amp have ~1dB of channel imbalance in input gain. This small channel imbalance in input gain can be heard in music and is more apparent in white noise at idle state.
However, even SMSL AD18 has 1.1dB of channel imbalance according to audio science review.


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## Cho Worsh

Marshmellow said:


> A bigger problem with a generic chinese amp is channel imbalance in input gain.
> My generic TPA3251 amp and my generic TPA3255 amp have ~1dB of channel imbalance in input gain. This small channel imbalance in input gain can be heard in music and is more apparent in white noise at idle state.
> However, even SMSL AD18 has 1.1dB of channel imbalance according to audio science review.


I had a similar channel imbalance issue with the SMSL SA50 amp that I tried for a while. 
Are you into head-fi amps at all or just speaker amps? I recently bought SMSL's new THX AAA 888 headphone amp and like it a lot.


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## Marshmellow (Nov 17, 2019)

Cho Worsh said:


> Are you into head-fi amps at all or just speaker amps?



I'm not looking into headphone amps, yet because my headphones display no apparent malfunction with an onboard soundcard.
First, I'd like to get rid of apparent malfunctions such as channel imbalance. White noise is not yet an audible concern.

Today, I discovered that there is channel imbalance in my ears. By swapping the left and right sides of my headphones, I discovered that higher frequencies are substantially quieter in my left ear. Massive channel imbalance in the past was caused by massive amounts of wet earwax in my left ear canal. But, I've cleaned both of my ear canals recently.


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## Marshmellow

@Cho Worsh It turns out that the channel imbalance was caused by residual water in my left ear. My left ear tends to trap water and earwax after a shower. I have earwax removed from my both ears once or twice each year.
After I took a shower, I took measures to remove water from my left ear. After removing water from my left ear, higher frequencies have the same volume in my both ears.
There is no apparent channel imbalance in my amp, my onboard soundcoard, and my ears.
Although my TPA3255 amplifier has channel imbalance in white noise, white noise is not really audible beyond 10~12cm away. My listening position is 60cm away.

Now, I can recommend the combination of a generic TPA3251/TPA3255 amplifier and an onboard soundcard for poor men who want reasonable sound quality at a reasonable price.
You can upgrade later.


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