VOLT+D class D amp , dual mono 2x 60W

[Chinquapin]

I have been enjoying this amp for around a week now. It is truly wonderful. I found an improvement in the sound buy using a 24v 5a ps. Engineer friend expressed some concern with overheating. I have had no problems so far, but have been using this ps for only a few days. Was using a 19v 230w HP ps before. The voltage jump brought great improvement.

[Chinquapin]

I’m a tube guy, so I’m not familiar with digital amps and their clipping characteristics. With the 19v ps at high volumes, certain sharp transients produced a cracking sound. Wasn’t sure what it was initially because of the very detailed sound this amp has. Dropping the volume a bit got rid of that. With 24v, the sound seemed more relaxed at all volume levels. My speakers are an easy load for any amp. They are comprised of two transmission line enclosures—one big and one small. The small one is a quarter wave t-line with a Jordan JX-92 fullrange, and the large t-line has a Peerless 8 inch woofer. Little one sits on top of the big. Using a series crossover—one coil, one cap— the impedance does not drop below 4-5 ohms at any frequency. I have good frequency response in the low 20Hz range. 

    Amplification I’m using in reference is a custom modded pair of Altec-Lansing 1570B tube monoblocks extensively reworked by Tom Tutay of Transition Audio Design In Ft Walton Beach, FL. Google Arthur Salvatore’s comments about this amp. A class AB amp and a real sweetheart of an audio device running around 170wrms of push-pull triode power. Two 811 transmitter vacuum tubes are the output devices. One 12AT7 input, one 6SN7 phase inverter, two EL34s drive the plates on the 811s. These amps have the same air and detail in subsonic frequencies that they have at all other frequencies. Best sub-woofer amp I’ve heard, and the best sounding amp in general. 

     The Allo Volt+D shares many of the same sound characteristics including the solidity and detail of the lowest frequencies. I was truly gobsmacked when I first heard it. The only areas where the 1570s are superior, is in the depth of the stereo image, and the cost—the 1570s are valued at $10K. If the Volt+D had 150-200wpc, I don’t believe that there would be any difference except that the Allo is perhaps a bit more detailed overall.

     I leave the Volt+D muted without an input signal when I’m not listening. This is with a 24vdc 5a ps. So far, no problems. Any thoughts or comments? Source for this system includes a Fulla Schiit using a Allo battery pack for power, or a Scott Nixon Tube Dac+. Speakers are from Ronnie Thackeray at Carolina Audio. carolinaaudio.com  Scott-Nixon.com. Hey Allo—-if this amp is as good as it seems to be, you better make a bunch of them. 

[Chinquapin]

On 12/8/2018 at 10:02 AM, Chinquapin said:

I have been enjoying this amp for around a week now. It is truly wonderful. I found an improvement in the sound buy using a 24v 5a ps. Engineer friend expressed some concern with overheating. I have had no problems so far, but have been using this ps for only a few days. Was using a 19v 230w HP ps before. The voltage jump brought great improvement.

 

[Chinquapin]

Hi Allo. I’m looking to build or buy an optimal power supply for my 

Volt+D. 24 volts seems to improve the sound so I’ll start there. What does your amp want to see interms of power. A linear power supply , or a low noise switching supply?

[Chinquapin]

103.68w if you use Allo’s formula. My speakers are five ohms. Amp stays on continuously. No wisp of smoke yet. Am sending one of these V+D amps to Mr Tutay for further inspection(and a nice Christmas surprise!). No change in SQ. Could not be more pleased. Considering 90% efficiency on the number above.

[Chinquapin]

7 hours ago, pjmcos said:

 

with your setup, the amp may give 72 W of power. Will the device be safe for a longer period of time? 

See above.

[Chinquapin]

3 hours ago, HiFiJeff said:

Hello. I currently have the Volt+ but am thinking about upgrading to the Volt+D. Any reason to upgrade? Sound quality better? I have super efficient speakers. ZU Audio Omens at 97db. 

Hi Jeff. I haven’t heard the Volt+, but I have had experience with the Breeze 3116 amps. Changing from the early series to the D2 version runs parallel to what Allo did with  the V+D—-added an op-amp to the input and doubled up on the chips. With the greater power, I heard an improvement in dynamics, and depth of image. I feel fairly sure that the V+D would have similar improvements over the V+. My speakers run at 88dB/w@1meter, and I am happy with this amount of power. By the way, the V+D is a much better sounding amp than the Breeze D2. Zu would jump with the V+D.

[Chinquapin]

1 hour ago, allo.com said:

Working on a 2/100W 8Ohm. 3 months around

Brilliant! 

[Chinquapin]

Hi KR,

I have been using a 24vdc 5a power supply branded Alitov purchased from Amazon for $20. Sounds marvelous. I really don’t believe you need to spend the money on linear power. Like you, my analog instincts had me thinking linear power. I had a 24v AGM truck battery in mind. A lot of expense and bother, that. So, in the interest of hearing this thing quickly—Amazon. I gifted one of these amps and power supplies to Tom Tutay at Transition Audio Design and he said that the Alitov was very quiet. He loves this amp too. He took it to Tom Norton—columnist for Stereophile who was rather shocked as well. Tom Norton now owns a V+D as well as another gentleman that was present that evening. I have two of Tutay’s Altec 1570B monoblocks that have not been on since the Allo went on line. I am using a tube line stage from TAD. DAC from Scott Nixon. Speakers from Carolina Audio and Ronnie Thackeray. V+D would work well for horns. I would go Allo high and low. Shockingly good bass out of this amp.

[Chinquapin]

4 hours ago, KingRex said:

I'm still wondering what power supplies people are using for best results.  I would seem a good $1,000 Linear with 24 volt and a minimum of 5 amps, maybe more like 7 would be best.  But that is a lot of cash.  There are plenty of inexpensive 24 volt 10 amp DC supplies for $40 something on Ebay.  Does the quality of the PS affect the sound as much as they do with digital equipment such as DAC and Servers?  Am I really going to hear it.  As a full range amp I assume so but I would like to hear from others.  In my case, in the final configuration I am hoping to use these in a biamp situation and they will run the woofers and my tube amp will run the horn or mi/high driver.  They are interchangeable in my speakers.

Go cheap Alitov 24vdc 5a ps from Amazon or similar @ $20. Quiet stable power. Use two V+Ds, or wait and get 4 of the upcoming mono blocks. Exciting stuff!

[Chinquapin]

3 hours ago, KingRex said:

I did some reading.  I think I saw where a linear PS did not sound as good as a switch mode.  I'm not sure if the linear was 12 volt vs 19 for the SM.  I would have to dig around more.   One thing I worry about is a big hunk of junk noisy SM PS such as found in computers is now going to be in my audio power chain.  That is all sorts of high frequency noise.  I don't know how much other think about this, but I have done as much as possible to minimize the impact of these devices in my house.  With this amp I would be looking at adding one right back in.  Kind of repeating my self, but to minimize the occurrence of ground loups I would have to power the amp in the same circuit my Preamp, DAC and Server are powered from.  Selection of this type of device kind of matters.  It should be built with filters on its front end to eliminate contamination to other equipment.  

 

I went back and read the review in DIY Audio.  He indeed used a 24Volt linear PS and did not like it.

 

I also thought hard about a computer PS and remembered that 6 or so months back I was getting my server updated.  I plugged my laptop into my audio PS to stream and immediately heard a very unpleasant bbzzzzzzz.  Very noticeable.  I unplugged the laptop PS and it went away.  I put the laptop PS in another circuit of general power in the room and I did not notice the noise so much any more.

 

If I were to use this amp, I would think I would need a dedicated PS to my rack for only amps.  It's possible to do, but I also spend a lot of time optimizing power to audio systems.  I generally bring a single circuit unless a customer wants more.  2 or more is more difficult as ground loups become an issue. 

Not all switching PS are junk. The Alitov I’m using was measured by Transition Audio to be very stable @24v. Don’t recall the noise figures, but Tom said that it was very quiet. He also said that he did not feel the need to design and build a different PS. Sounds like you had some sort of ground loop with your laptop. My absolute reference PS here might be a 24vdc glass’s mat truck battery, or 2 12v car batteries in series. Maybe I’ll try hooking this up some day—to see if linear power truly makes a difference. For now, the $20 Alitov works very well. There are other simple mods that improve this amp’s ability to be driven by more devices—or work well with long signal cables, but that’s another topic I will discuss later.

[Chinquapin]

I typically use Mundorf Silver foil and V-caps in combination as coupling caps. Tom put a switchable electrolytic in my head phone amp. Not sure what the 1570s have for coupling . Black gates are visible on top-along with Tom's choice of caps. Probably should PM about this since it is off topic. Have had Tom remove the attemuator from both of my V+Ds. Have also replaced the wire from the board to the teminals. Amp has about 60K ohms input impedance without the pot. Easier load for most things and the amp sounds better, too. Hard to decide to what to do with tube amps with the advent of really good digital amplification. Would find it really hard to part with my 1570s though.......

[Chinquapin]

6-10 days to Virginia. There.is a dealer in Florida. Only $20 to ship and arrival time is less.

[Chinquapin]

It will be a pleasant surprise.

[Chinquapin]

Just visited Chicago Electronic Distributors web site and they list 25 in stock. Allo main web site also shows them in stock.

[Chinquapin]

My thoughts exactly.

[Chinquapin]

On 3/8/2019 at 11:26 PM, KingRex said:

Initial impression.  Absolutely stunning.  Have to listen more.  My wife said its the best sound we ever had from our system. 

Now, give it 24vdc 

[Chinquapin]

Volt +D has a capacitance multiplier. I’m running 5 ohm speakers with 89dB/watt/meter efficiency in a room that’s 14x28/8. I’m very happy with the power level. However, when Allo announced a “100watt/8ohms amp due soon”, I knew I would purchase one of those too.

[Chinquapin]

Allo let the cat out of the bag about the new amp. I get the impression that it will be stereo, not monoblocks. No idea on the price. Estimated timeframe ?2-3 months?. You should buy the V+D. For horns, this should be enough power. Really considering selling my Transition Audio Design Altec 1570B monoblocks. 170 watts of triode push pull power. V+D keeps up with it. Never heard deeper or tighter or more detailed bass. You are in for a shock.  

     V+D needs to have the stepped attenuator removed to make it a better load for conventional line stages. With the 10k pot you get about 8.7k ohms as a load. Take the pot out and you get 60k ohm input impedance—an ideal load for a line stage that has high output impedance, or if you have long cables to drive. Not difficult to remove the pot.

[Chinquapin]

Most definitely. Sorry I didn’t mention that before. 24vdc is mandatory to get the full potential of this amp.  Alitov 24v 5a switching PS from Amazon is what I use. Tom at Transition Audio Design has one of these amps and this PS—said the PS is very quiet and stable—all for $20. LED lighting systems use switching PS like this.

[Chinquapin]

Yes, that’s right. Without the pot, you get 60k ohm impedance, which is perfect.

[Chinquapin]

Congrats! Yes there is a break in  time of at least four days. I leave mine on all the time. Now look to remove the pot . Picture shows the bottom of the circuit board. The outer two pair are twisted together, and the center pair just get snipped off. This gives you an input impedance of 60k ohms-perfect load for anything. Best and enjoy. Please let me know what you think.

[Chinquapin]

6 minutes ago, Chinquapin said:

Congrats! Yes there is a break in  time of at least four days. I leave mine on all the time. Now look to remove the pot . Picture shows the bottom of the circuit board. The outer two pair are twisted together, and the center pair just get snipped off. This gives you an input impedance of 60k ohms-perfect load for anything. Best and enjoy. Please let me know what you think.

A little solder is necessary as well.😀

[Chinquapin]

9 hours ago, HiFiJeff said:

 

What happens if you don't solder it? 

It would most likely work, but the connection would not be as positive. Leave the leads a little longer and it’s a very easy job. Bend out of the way, and you’re done. I have to repeat that this mod is for people that plan to use a line stage with its own volume control feeding the Allo.

[Chinquapin]

32 minutes ago, SMen said:

Regarding power supply, being in the UK I went for (I believe) similar 24v 5amp power supply from Amazon to the one Chinquapin recommended after seeing what he wrote.

AC 100-240V To DC 24V 5A 5.5x2.1mm DC Output Jack Power Supply Converter Adapter for Led Light Strips

and I was very surprised. I am just getting more 'information', low level detail, sound staging. Duets are more 'in their own space'. More impact from percussion at lower volumes. I am using 88 db kefs - 6ohm.

I wonder if Allo will bring out a power supply with the mono blocks, or if they feel that with their CM this type of supply is enough.

I missed out on their discontinued one, but I was confused as to its actual voltage because it was measured at 23v I think but described as 21? Cant remember.

My comparison is with their standard 19v supply. The 24v seems well made, and is described as being well protected etc. It is double the size - see photo.

So pleased that you have discovered the full potential of this amp. Yes, the 

Alitov seems decent enough. My analog Spidey Sense tells me to build a better PS, but my ears and practical sensibilities say no to that. Still.... I do have two of the same 12v car batteries.....digital amps don’t seem to be as critical about their diet—PS above seems OK— as I find most of them are. Nice not to need to spend big bucks to get optimum results. Not sure what Allo night supply with the new amp, but I’m not worried. If it wants 24v, I’ll use a cheap switching PS like “Alitov”, or the one above.