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Deleted member 148505
Yes it doesn't require an input buffer specially if it's directly connected to a low impedance < 1Kohm source like DAC output, use 10K audio pot or add buffer if you want to add some volume control.
It requires 2Vrms on SE input 4Vrms on Balanced input.
Production version (March 19, 2021) has a 1.3X gain
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Deleted member 148505
Latest update: efforts to add air and details - degrades the smoothness of highs. So I settled with not so airy sound but will have smoother highs (default non-PFFB)
Increasing AVDD cap from 22uF to 100uF slightly improves the highs.
Better GVDD decoupling also improves the highs.
TPA3251 has a noticeable thickness on lower midrange (best for mids in a triamp system), TPA3255 has better high registers.
Increasing AVDD cap from 22uF to 100uF slightly improves the highs.
Better GVDD decoupling also improves the highs.
TPA3251 has a noticeable thickness on lower midrange (best for mids in a triamp system), TPA3255 has better high registers.
So, if I have a DAC (for example SMSL 10TH SANSKRIT MK2 AK4493) with adjustable output and 2V output level, I don't need anything between the power amplifier and the source?
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Deleted member 148505
Yes, if the DAC already has a built in volume control, you don't need a buffer.
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Deleted member 148505
Greetings JLesterP!
My sister-in-law originally hails from the Philippines - Tuguegarao if I remember correctly.
Your TPA3255 modules sound most interesting. I'm not in a position to buy yet, but hopefully we could could come to an arrangement when my brother and his wife next visit the Philippines - hopefully in 2022.
My sister-in-law originally hails from the Philippines - Tuguegarao if I remember correctly.
Your TPA3255 modules sound most interesting. I'm not in a position to buy yet, but hopefully we could could come to an arrangement when my brother and his wife next visit the Philippines - hopefully in 2022.
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Deleted member 148505
Nice!
Covid cases here is still surging this month. Hopefully vaccination will be successful and we can travel freely by 2022.
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Deleted member 148505
Update for TICore260BTL mods.
- Best opamp feedback cap value is around 47pF to 56pF.
- Input coupling caps: RFS-50V4R7MF3#5 or RFS-25V100MF3#5, I already tried MKS2B044701K00KSSD, but these silmic ii's are still better.
- Dual supply opamp buffers will clear up the sound (needs external adapter, I will create pcb soon)
- Disabled PFFB will provide better mids.
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Deleted member 148505
Just dual opamps like opa1656 / lme49860 since I already have existing circuits / layout, using Opa1637 will add time to the development, and you already created one
Also TPA3251 has a better midrange. TPA3255 has better highs.
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Deleted member 148505
Ripple and noise looks good, however fosc is around 70kHz only, it would have been better if fosc is around 100kHz.
No mods for production version Sylph-D200, all goodies are there already. Just disable the PFFB to get the best sound.
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May be MKS should be good in my case because the opa1637 allow nulling dc biais across the caps with Vcom input tuning.
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Deleted member 148505
Hmm I already checked Vcom input tuning, you still need to place additional coupling caps there, so the effect will be cancelled.
You can set Vocm to 1/2 AVDD, remove input coupling caps, then use MKS caps in OPA1637 circuit.
You can set Vocm to 1/2 AVDD, remove input coupling caps, then use MKS caps in OPA1637 circuit.
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Thanks Lester. In that case, do you recommend changing to SE-450 model, which has Fosc of 100k, but a higher ripple of 200mv p-p?
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Deleted member 148505
When I peeked on the scope output of my Mean Well LRS-350, its ripple is actually low, and on par with with my connex LLC supply. The 200mV p-p is the 65kHz fosc switching noise.
Not sure, just get the overall better switching supply. I have no problems with the LRS-350. I already connected the LRS-350 in reverse twice and its OCP worked, no smoke in either my module or power supply. (don't try with other power supplies or other tpa3255 modules).
Not sure, just get the overall better switching supply. I have no problems with the LRS-350. I already connected the LRS-350 in reverse twice and its OCP worked, no smoke in either my module or power supply. (don't try with other power supplies or other tpa3255 modules).
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Deleted member 148505
If the switching frequency is at or near the LC-filter's resonant frequency, the noise might get amplified specially at open load.
Looks like 70kHz is safe with our 10uH + 1uF LC filter.
