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JLE TPA3255 Build and Modifications
JLE TPA3255 Build and Modifications
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Old 5th June 2021, 06:48 PM   #281
avivz is offline avivz  Israel
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Quote:
Originally Posted by JLesterP View Post
For non-PFFB, there is no problem if there is no load connected.
For PFFB I would be cautious on running it without load. (Specially if there is a source connected, and has a music output)
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Hi Leser,

TI PFFB application report mentions "open load" stability. Does your PFFB design tested for open load conditions?

If not, what would be a minimum resistor I can use as a pilot load (in case I want to swich ams during operation)?

Thanks,
Aviv.
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Old 6th June 2021, 05:10 PM   #282
JLesterP is offline JLesterP  Philippines
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JLE TPA3255 Build and Modifications
Hi Aviv,

Sylph-D200 PFFB is not yet tested in open loads, I'll test it in month's time. You need a minimum of 20ohms to tame the output filter LC resonance.
You can skip the dummy load resistor if you can mute the amp (header pins 3 and 4) or short the inputs before and during removal of speakers.

Regards,
Lester
Quote:
Originally Posted by avivz View Post
Hi Leser,

TI PFFB application report mentions "open load" stability. Does your PFFB design tested for open load conditions?

If not, what would be a minimum resistor I can use as a pilot load (in case I want to swich ams during operation)?

Thanks,
Aviv.
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Old 8th June 2021, 02:23 PM   #283
avivz is offline avivz  Israel
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By minimum of 20 Ohm i assume you mean 20 Ohm or lower value right?
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Old 8th June 2021, 02:31 PM   #284
JLesterP is offline JLesterP  Philippines
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Quote:
Originally Posted by avivz View Post
By minimum of 20 Ohm i assume you mean 20 Ohm or lower value right?
Yes correct, <= 20 ohms
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Old 13th June 2021, 12:24 PM   #285
JLesterP is offline JLesterP  Philippines
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Interesting listening comparison between Purifi Eigentakt vs AHB2. The reviewer reported that the Eigentakt has a stronger midbass / low-midrange.

Benchmark AHB2 / Class D Purifi Eigentakt / Mark Levinson 333 - Listening impression & Conclusion | Audio Science Review (ASR) Forum

Reminds me my PFFB vs non-PFFB comparison of my module.

With my latest build, PFFB sound has a strong bass, and the highs are slightly finer. Using Motu M4 balanced source, there's no constrained sound at all (probably because there's a lot of bass) but the vocals are behind the soundstage. (so probably the lower-midrange is weaker)

Non-PFFB has stronger midbass/low midrange (120hz-300hz), and vocals are more forward sounding.
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Old 13th June 2021, 12:35 PM   #286
JLesterP is offline JLesterP  Philippines
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I prefer non-PFFB because it is more natural sounding. Then there's TPA3251 which has a stronger midrange than TPA3255. But on TPA3251, there's a coloration on the sound on mid-highs that I can't describe. When I quickly change the amp to a TPA3255 module, the sound is definitely more neutral and cleaner. So with compromises weighed-in, I prefer the TPA3255 for its pure sound.
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Old 13th June 2021, 06:57 PM   #287
douede is offline douede  France
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Quote:
Originally Posted by JLesterP View Post
I prefer non-PFFB because it is more natural sounding...on TPA3251, there's a coloration on the sound on mid-highs that I can't describe. When I quickly change the amp to a TPA3255 module, the sound is definitely more neutral and cleaner. So with compromises weighed-in, I prefer the TPA3255 for its pure sound.
Hi Lester, thank's a lot for sharing this TPA3251/3255 comparision.
Are the differences heard with as similar as possible PCB/components, assessing sounding differences of the chips (not their implementation) ?
I too prefer no PFFB (and open loop), for its "natural/free" rather than "processed/controled" sounding.
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Old 14th June 2021, 04:22 AM   #288
JLesterP is offline JLesterP  Philippines
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Quote:
Originally Posted by douede View Post
Hi Lester, thank's a lot for sharing this TPA3251/3255 comparision.
Are the differences heard with as similar as possible PCB/components, assessing sounding differences of the chips (not their implementation) ?
I too prefer no PFFB (and open loop), for its "natural/free" rather than "processed/controled" sounding.
Yes I compared it using identical board and parts. TPA3251 has a more organic sound, same transparency and air but has less refinement compared to a module with TPA3255 IC.

In an ABX test, TPA3251 might win outright, but on longer listening sessions you will also like the TPA3255.
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Old 14th June 2021, 02:30 PM   #289
SinGun is offline SinGun  Russian Federation
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Click the image to open in full size.Click the image to open in full size.

Last edited by SinGun; 14th June 2021 at 02:32 PM.
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Old 14th June 2021, 03:17 PM   #290
JLesterP is offline JLesterP  Philippines
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Hi SinGun,

Attached corrections.

Sylph-D200 uses:

Elna Silmic II input coupling caps
United Chemi-con KZN series PVDD caps.
Nichicon / Rubycon on housekeeping supplies.

Sylph-D200 also has bulk capacitors on GVDD_AB and GVDD_CD supplies. I think I'm the first to implement it in any TPA325X modules.

Also added ICE 1D23A-100M as an option for output inductors.

Regards,
Lester
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File Type: jpg IMG_0454+_1_.jpg (490.6 KB, 64 views)
File Type: jpg 137608a430958ce4b2879334c40e1a9d.jpg (82.4 KB, 65 views)
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Last edited by JLesterP; 14th June 2021 at 03:29 PM.
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