Fitting a more powerful amplifier stage inside LIO

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Vinnie R.

Happy New Year to everyone!  :beer:

2017 was an excellent year filled with many audio shows, new LIO customers, new modules… and plenty of R&D on my end towards new things to come in 2018!

Well, not every idea makes it to production.  As many of you know, a LIO MOSFET AMP 2.0 module (more powerful version) was something that I was working on in 2017.  After prototyping/testing a couple of iterations, it looks like it is just not in the cards – at least not without a fairly substantial LIO redesign.

The 3 main issues that I have been facing with fitting more power inside LIO are:

1) Limited space.

Besides the speaker output stage, LIO was designed to accommodate many other modules such as a dac, phonostage, discrete resistor or autoformer volume control, tubestages, headphone amp stage, as well as analog inputs an outputs.  Even though it is very well laid-out, the size of the enclosure is only so big and there is too much of a space for a larger, more powerful amplifier stage.

2) Heat.

Even with fitting more power into the limited space, I have performed some heat testing and have not been comfortable enough with the added internal heat with a more powerful Class AB output stage.  I was trying to be very optimistic and wanted to march forward, but when evaluating worst case heat scenarios that must factor in the added heat of the DAC 2.0, the tubestage (6922 based or DHT PRE), and the heat from the linear voltage regulators on the power supply board, there is too great a chance that it would end up get too hot inside (especially with customers with 4-ohm speakers and pushing it around 100 wpc) and this could lead to reliability issues down the road that would not be fun for any of us.
 
3) Voltage.

There is also the issue of needing higher voltage rails for higher output wattage, so a different internal power supply design is required. 

It tried to get around this in an earlier iteration of AMP 2.0 that used an even higher current output stage (1-ohm drive ability) followed by an output autoformer to step up the output power (trading current for more voltage).  The problem with this (besides the heat mentioned above) is that in order to obtain a flat response down to 20Hz and at full power (e.g. 100 watts), a large autoformer is required.  The problem of limited space then becomes the issue.  The autoformer that I had prototyped did fit inside LIO and sounded excellent, but under 40Hz and at close to full output power, it was having saturation issues.  A larger one was needed per channel and I decided if it cannot fit inside of LIO, then it really isn’t a LIO module after all...


So what if you need more power, but really want to move forward with LIO?

As things stand right now, *if* you require more power (i.e., you find that you need to be able to play louder without running into clipping), there are still good options to consider:

1) Use more efficient speakers.  Speakers with a higher sensitivity means you need fewer watts to reach desired SPL (Sound Pressure Level), so it is like having a more powerful amplifier.

2) Sit closer to your speakers.  Mid-field and near-field listening requires far less power to achieve higher SPL than far-field listening.

Halving the distance between you and the speaker (e.g. going from 12 feet away to 6 feet away), it is equivalent to increasing the speaker’s sensitivity rating by 6dB (which is also equivalent to having an amplifier with 4x the power).

E.g. Let's say you have an amplifier pushing 25 watts per channel into your speakers that are located 12 feet away. If you move them (or your chair) so they are now 6 feet away, this is the equivalent (in terms of max SPL output) of leaving them at 12 feet away, but using a 100wpc amp instead of a 25wpc amp.

Or you can look at it the other way around.  Let's say you have a 25wpc amp and your speakers are 6 feet away.  If you move them (or your chair) so they are now 12 feet away, you would need a 100wpc amplifier to obtain the same max SPL at the new distance that is twice as far away.  So it follows an inverse-square-law.

There are other benefits to mid-field and nearfield listening (e.g. taking more of the room acoustics out of the sonic picture), but that is another topic.

3) Use LIO as a preamp (of course with dac, phonostage, and headphone stage options) to feed a higher power external amplifier of your choice.  LIO makes for a phenomenal sounding active preamp, no matter if you are using the RVC + Tubestage, AVC/Tubestage, or DHT PRE.   The LIO DAC 1.0 & 2.0, Phonostage, and HPA options are also superb, as many of you already know from owning them and comparing to stiff competition…  8)

You can also use your LIO Intregrated Amp as a preamp and simply switch off just the power amp output stage via the “AMP” button on the front panel.  Maybe right now you want to try a more powerful external amplifier option, but later on you might want your LIO back as an integrated if your room or speakers change.   

Output Power (along with somewhat related topics such as volume setting and gain) can sometimes be confusing.  You might find this post helpful for more insight into the question of "how do I know if I need more power?"
http://www.audiocircle.com/index.php?topic=150938.msg1614483#msg1614483

That is all on this topic that I have for now, but I'm always working on new ideas and hope to have a lot more info to share by Spring 2018.  :shh:

Thanks for your understanding and continued support! 

Vinnie
« Last Edit: 30 Dec 2017, 04:31 pm by Vinnie R. »

jwes

Re: Fitting a more powerful amplifier stage inside LIO
« Reply #1 on: 30 Dec 2017, 05:28 pm »
Thanks Vinnie!  Makes a lot of sense.  Even you have to abide by the laws of physics at some point   :)

Looking forward to how awesome the DAC 2.0 / DHT LIO is going to be!.  My RWA Isabella DAC/Pre is still great and that's now light years old.  Also will be fun to see how the high current amp in the LIO works with the existing speakers.

mirekti

  • Jr. Member
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Re: Fitting a more powerful amplifier stage inside LIO
« Reply #2 on: 11 Jan 2018, 08:57 pm »
What about VR120? Isn't that a good option for those who need more power or you have plans on upgrading it perhaps?
I do agree that of all options, near field listening is the best one as it addresses many issues.

Vinnie R.

Re: Fitting a more powerful amplifier stage inside LIO
« Reply #3 on: 12 Jan 2018, 12:37 am »
What about VR120? Isn't that a good option for those who need more power or you have plans on upgrading it perhaps?

Hi Mirekti,

I do have plans... things are in the works.  Just can't go into them at this point.  I should be able to start discussing
more this Spring.

There is still much to be done!  :hyper:

Vinnie

AmpDesigner333

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Re: Fitting a more powerful amplifier stage inside LIO
« Reply #4 on: 12 Jan 2018, 05:09 am »
Vinni,

How much room do you have?  How much power do you need?  Thanks, and Hope all is well.

-Tommy O
« Last Edit: 12 Jan 2018, 07:46 am by AmpDesigner333 »

radarnyc

Re: Fitting a more powerful amplifier stage inside LIO
« Reply #5 on: 14 Jan 2018, 09:02 pm »
Another consideration is that 4ohm speakers will play louder. I picked up a pair of inefficient (85db) 4ohm speakers; Elac UF5. I’ll be using these in a HT setup but I first put them on the LIO and was really blown away at what they did with the LIO in light of their $800 pricetag. Great sound stage and plenty loud at 10’ away and a LIO volume of 42. I’m very tempted to bring my LIO to an Elac dealer and hear it with the new Adante ($5000).

Tyson

Re: Fitting a more powerful amplifier stage inside LIO
« Reply #6 on: 14 Jan 2018, 10:54 pm »
Another consideration is that 4ohm speakers will play louder. I picked up a pair of inefficient (85db) 4ohm speakers; Elac UF5. I’ll be using these in a HT setup but I first put them on the LIO and was really blown away at what they did with the LIO in light of their $800 pricetag. Great sound stage and plenty loud at 10’ away and a LIO volume of 42. I’m very tempted to bring my LIO to an Elac dealer and hear it with the new Adante ($5000).

The Adante is freaking amazing - you should definitely go hear it. 

David C

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Re: Fitting a more powerful amplifier stage inside LIO
« Reply #7 on: 15 Jan 2018, 03:24 am »
My 26 yo son (lives in Denver) and I thought that the Elac Adante speakers were BY FAR the very best for the money at RMAF 2017. Andrew was in the room and gave a very good intro. If I had to buy new speakers , for the money, these were the money

I currently run PMC PB1i’s