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SylphAudio's High-Performance Amplifier Modules (2024 and Beyond)

daniboun

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@SylphAudio
It seems to me that you are announcing around 106db to 108db Sinad @5W/4R for the FB100 with a gain of 14db (5V/V). It is finally very close to the 3E Audio 260-2-29A (TPA3255) module with a gain of 16.5db (stock = 20.5db) which displays more than 105dd Sinad@5W/4R.
What would be the major benefit of moving from a TPA3255 module to a much less powerful TPA3251 module?


PSU set @34V/10A

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SylphAudio

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It seems to me that you are announcing around 106db to 108db Sinad @5W/4R for the FB100 with a gain of 14db (5V/V). It is finally very close to the 3E Audio 260-2-29A (TPA3255) module with a gain of 16.5db (stock = 20.5db) which displays more than 105dd Sinad@5W/4R.
What would be the major benefit of moving from a TPA3255 module to a much less powerful TPA3251 module?


PSU set @34V/10A

index.php
Hmm measurement looks dubious to me; it might be the case where REW is showing an overly optimistic measurement. I saw some similar post in Cosmos discord channel where a DAC has been measured with a 3dB higher SINAD measurement than the published AP measurement.

Window title should have been included on the screenshot as well to show what the settings are. It's very easy to manipulate REW measurements. Even using a 4.5ohm load vs a 4 load, will drastically improve the measurements.

If the PFFB ratio has been increased which resulted to lowered gain, then I will believe in that screenshot.

However, if he just lowered the preamp gain, then, it would not improve the overall measurements, it will just lower the noise floor.
If the measurements have greatly improved after the preamp gain has been slightly lowered (like 4db), then there is something wrong with the preamp design.

I have recently experimented with my FB360 using 36V and a 52V DC supply; and using a lower voltage supply only reduced the noise floor by 1.5dB. The harmonics were slightly different, but the overall THD more or less remained the same.

What would be the major benefit of moving from a TPA3255 module to a much less powerful TPA3251 module?
The major benefit would be the output power. Using a 51V supply, the 3e stereo version only reaches 144W at the knee of clipping. If you reduce its power supply to 34V, then I believe the clipping point will decrease to around 60W at 4ohm (probably even lower, you can observe the clipping point when the red clipping indicator is faintly pulsing).

The FB100 can get 100W @4ohm using a 38V supply. (I think the 3e stereo's clipping point will be around 80W with 38V supply). The PFFB design of TPA325x will alter the clipping point profile, that's why I've abandoned designing a stereo single chip TPA3255 PFFB. This isn't the case for non-PFFB TPA325x designs, where it should have the same clipping point when given a specific voltage supply (assuming all else are equal).

Not promoting the TPA3251, but it has a slightly clearer midrange, and finer highs. What's good about TPA3255 though is that it has a fatter midrange sound, making it suitable as a bass/mid amp for a bi-amp system.

This guy used our D100 for powering the highs, and D400 for bass/mid biamp system.

-Lester

1703153335283.png
 
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daniboun

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Hmm measurement looks dubious to me; it might be the case where REW is showing an overly optimistic measurement. I saw some similar post in Cosmos discord channel where a DAC has been measured with a 3dB higher SINAD measurement than the published AP measurement.

Window title should have been included on the screenshot as well to show what the settings are. It's very easy to manipulate REW measurements.

If the PFFB ratio has been increased which resulted to lowered gain, then I will believe in that screenshot.

The measurements were shared by @S=klogW
I don't think the results were truncated... you can also look at the measurements with the stock gain here:


Major benefit would be the output power, using 51V supply, the 3e stereo version only gets 144W at the knee of clipping. If you reduce its power supply to 34V, then you will only get more or less 60W to 70W at 4ohm. FB100 can get 100W @4ohm using a 38V supply.

Looking forward to see measurements from Amir )

Here the right graph in BTL, my bad @3eaudio :

1703158091730.png
 
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SylphAudio

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The measurements were shared by @S=klogW
I don't think the results were truncated... you can also look at the measurements with the stock gain here:
Maybe he should submit his modified module for AP measurements for true evaluation.
I saw 3e posted a 108dB SINAD at 5w 4ohm (on DIYAudio) when he changed some PFFB parts values. I believe his measurements, though with a deeper PFFB, the TPA3255 clipping point will further reduce. So, I think he will go to TPA3251 route as well if he designs a 108dB TPA325x stereo single IC amp.

That's what I achieved with the FB100, deepening the PFFB further without the clipping point penalty. (FB100 PFFB is deeper than PA5, it's not just a lower gain PA5 lol)
If you lower the preamp gain of PA5, you'll just get a lower noise floor PA5 (up to a point). If you increase the PFFB ratio of a TPA325x amp, that's where you get better results.

Looking forward to see measurements from Amir )
If you can achieve 100W@4R with a 38V @ THD+N 1% ( I guess with a LRS-200-36 or LOF350-20B36-C PSU) = better than the original TI spec
That's why I avoid posting rew measurements until it's been verified by a gold standard AP measurement.
 
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daniboun

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Maybe he should submit his modified module for AP measurements for true evaluation.
I saw 3e posted a 108dB SINAD at 5w 4ohm (on DIYAudio) when he changed some PFFB parts values. I believe his measurements, though with a deeper PFFB, the TPA3255 clipping point will further reduce. So, I think he will go to TPA3251 route as well if he designs a 108dB TPA325x amp.

That's what I achieved with the FB100, deepening the PFFB further without the clipping point penalty. (FB100 PFFB is deeper than PA5, it's not just a lower gain PA5 lol)

That's why I avoid posting rew measurements until it's been verified by a gold standard AP measurement.

Thank you in any case for this feedback) I would be delighted to see a new TPA325X module on the market with some SOTA performance))
We know that the Topping PA5 II has a max power of 71W@4R (38V/3.2A PSU) which is a good point of comparison)
Wait for the review now yeah
 
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SylphAudio

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If you can achieve 100W@4R with a 38V PSU @ THD+N 1% ( I guess with a LRS-200-36 or LOF350-20B36-C PSU) = better than the original TI spec
I think you're looking at the wrong section of the datasheet, you published the graph of SE section, so you should be interpreting its 2 ohm graph since it sees 2ohm load when being used on a 4 ohm BTL configuration.

Here's the graph of output power vs supply voltage for BTL output configuration. Non-PFFB BTL output designs can get 140W / 4ohm @1% THD+N, with a 36V supply

1703157418474.png

1703157492417.png



When you add a PFFB network, it alters the clipping point of the amp. (Assuming that the preamp still has the steam to drive the amp to clipping point)
So, a better PFFB design should get a higher clipping point. (where the ideal value is getting the same clipping point as a non-PFFB TPA325x)
 
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daniboun

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I think you're looking at the wrong section of the datasheet, you published the graph of SE section, so you should be interpreting its 2 ohm graph since it sees 2ohm load when being used on a 4 ohm BTL configuration.

Here's the graph of output power vs supply voltage for BTL output configuration. Non-PFFB BTL output designs can get 140W / 4ohm @1% THD+N, with a 36V supply

View attachment 335938
View attachment 335939


My bad just saw the mistake ) going to correct thanks

also found the THD+N @10% grah in BTL



1703157829543.png
 

daniboun

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Forgot to ask )

Do you plan to ship FB100 and FB360 to Audiophonics, if so: when?
 

GNK

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I'm sure you've priced it through a reasonable process, but I personally hope it to be USD 149.99.
Many countries charge customs duties over USD150 and in my country $150 and $150.1 is a price difference of $27.12.
 
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SylphAudio

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I'm sure you've priced it through a reasonable process, but I personally hope it to be USD 149.99.
Many countries charge customs duties over USD150 and in my country $150 and $150.1 is a price difference of $27.12.
Ok thanks for the suggestion!
 

daniboun

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FB360 test with LOF550-20B48-C and 20800uF output capacitance.

Unless I'm wrong... the Sylph Audio modules just like the 3E Audio modules have a good PSRR, right ?The LOF550-20B48-C has a pretty good ripple and is regulated furthermore...

Do you have measurements that show difference between stock PSU vs PSU with extra caps ?
I would have rather thought that the use of extra caps at the PSU output made sense with unregulated power supplies....


1703332887970.png
 

daniboun

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I'm sure you've priced it through a reasonable process, but I personally hope it to be USD 149.99.
Many countries charge customs duties over USD150 and in my country $150 and $150.1 is a price difference of $27.12.

Regarding this point, I think we need to study competitive prices. In any case, the 3E Audio 480-1-29A are offered @129 euros taxes included in Europe
Depending on the promised measurements, it will be necessary to find the right price compromise, otherwise; people may be put off....


As far as I am concerned, I would be the first to buy one of these FB360s if the price seems consistent with the competition) :)
$166 would amount to selling them in Europe at around: €150 + 20% taxes + reseller margin + shipping costs = more or less 220€ (70% more expensive than 3E Audio)....
 
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SylphAudio

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Do you have measurements that show difference between stock PSU vs PSU with extra caps ?
I would have rather thought that the use of extra caps at the PSU output made sense with unregulated power supplies....
Just testing out if the power supply will still work properly given the load capacitance.
Those extra caps are not required at all since TPA325x are commonly configured as BTL and PBTLs.

Bus pumping is aggravated on class-D amplifiers with single ended outputs. One of the mitigation techniques include placing large bus capacitors to absorb the energy backflow from the load to the power supply. If the energy backflows, then it will "pump up" the supply rail voltage (if the supply can't regulate it properly).
Like our upcoming SE800 amplifier, it has a single ended output, which requires an external 6800uF per rail to avoid bus pumping.

By having the class-d on BTL (full bridge) configuration, it will balance out the energy flow, so it's a non-issue on BTL amps. So, large caps are not required for TPA325x amps.

Regarding this point, I think we need to study competitive prices. In any case, the 3E Audio 480-1-29A are offered @129 euros taxes included in Europe
Depending on the promised measurements, it will be necessary to find the right price compromise, otherwise; people may be put off....
We don't want to be severely limited by costs in designing an amp board. Price is actually just right given that we can only produce in very limited quantities. If we design it to compete on price, the product will just become a throwaway board because of low quality design choices.

One of the design choices is a bigger PCB, which enables our modules to operate with a cooler idle operation, as the heat is dissipated evenly throughout the board. It might not look like it, but we carefully thought of the design choices in our amps ;). Section with one of the highest temp on idle is the preamp that's why we've included a heat spreader.

Though we also do consider that a DIY build should have an equal or slightly lower price than the commercial alternatives. But with better build quality, design choices, etc...
 
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312elements

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Just testing out if the power supply will still work properly given the load capacitance.
Those extra caps are not required at all since TPA325x are commonly configured as BTL and PBTLs.

Bus pumping is aggravated on class-D amplifiers with single ended outputs. One of the mitigation techniques include placing large bus capacitors to absorb the energy backflow from the load to the power supply. If the energy backflows, then it will "pump up" the supply rail voltage (if the supply can't regulate it properly).
Like our upcoming SE800 amplifier, it has a single ended output, which requires an external 6800uF per rail to avoid bus pumping.

By having the class-d on BTL (full bridge) configuration, it will balance out the energy flow, so it's a non-issue on BTL amps.


We don't want to be severely limited by costs in designing an amp board. Price is actually just right given that we can only produce in very limited quantities. If we design it to compete on price, the product will just become a throwaway board because of low quality design choices.

One of the design choices is a bigger PCB, which enables our modules to operate with a cooler idle operation, as the heat is dissipated evenly throughout the board. It might not look like it, but we carefully thought of the design choices in our amps ;). Section with one of the highest temp on idle is the preamp that's why we've included a heat spreader.

Though we also do consider that a DIY build should have an equal or slightly lower price than the commercial alternatives. But with better build quality, design choices, etc...
I support your attitude to not allow a price point to interfere with quality. Without getting into a debate over whether op-amps matter, I notice that some of your boards are dip8 equipped and some aren’t. Is there any rhyme or reason to that?
 
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SylphAudio

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I notice that some of your boards are dip8 equipped and some aren’t. Is there any rhyme or reason to that?
D100 and D400M have shallower PFFB, meaning less gain is required in the preamp stage to recover the lost gain due to PFFB. So, an onboard single-stage DIP package preamp can do the job. User replaceable opamp is nice to have, which can alter the sound flavor of the amp.

FB100 and FB360 have deeper PFFB, which requires an onboard preamp with a higher gain.
If you increase the gain of a single-stage DIP preamp, it will reach a point where the preamp's performance is lower than the PFFB amplifier itself.

So, a two-stage cascaded opamps setup is needed to improve the performance of a preamp with a high gain. SMT layout is needed for space constraints and performance benefits.
 
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daniboun

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We don't want to be severely limited by costs in designing an amp board. Price is actually just right given that we can only produce in very limited quantities. If we design it to compete on price, the product will just become a throwaway board because of low quality design choices.

One of the design choices is a bigger PCB, which enables our modules to operate with a cooler idle operation, as the heat is dissipated evenly throughout the board. It might not look like it, but we carefully thought of the design choices in our amps ;). Section with one of the highest temp on idle is the preamp that's why we've included a heat spreader.

Though we also do consider that a DIY build should have an equal or slightly lower price than the commercial alternatives. But with better build quality, design choices, etc...
I know that 3E audio is designing a new module. I am looking forward to see Sylph Audio measurements )
Concerning the quality/price debate we all know that the Sylph Audio and 3E Audio modules play in the same league. These are reliable and efficient modules and having owned both I know what I am talking about.))It is proof that we can produce good products at controlled prices without compromising on quality.
 

daniboun

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