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Class D Switching Power Amplifiers and Power D/A conversion

Orderd a 2-chip TPA3116... Mistake?
Orderd a 2-chip TPA3116... Mistake?
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Old 13th January 2018, 04:30 PM   #11
sguyader is offline sguyader
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Thanks everybody. I've been able to cancel my order and get a refund.
Now I have to think about what to do with my speaker. I still want it to be small and transportable (one speaker with a mid-range drive and a tweeter) yet powerful enough so Incan hear myself on stage (it will be a stage monitor for acoustic misc, but with drummer)
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Old 15th January 2018, 06:20 AM   #12
Eva is offline Eva  Spain
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Learning requires mistake.

Audibility of portable gear at stage or street requires some power. Maximum power output is dictated by supply voltage and load impedance. Advertisements can result misleading if the root rule is not known.

BTL power ceiling equals V^/(2*r) where "V" is supply voltage and "r" is load impedance. For a 19V (single ended) supply and 4ohm load power ceiling is 45W.

More power can be obtained by boosting the 19V from the power adapter, or adding a 2nd power adapter in series. 38V is about the limit for TDA7498, for 100W/8r, per channel (in active filter 2-way operation, "4 ohm nominal" speaker driver impedance plot may be high enough for being driven by TDA7498 without shutdown or damage).

Example boost (step-up) DC-DC regulator board from ebay:
DC-DC 6-35V to 6-55V 10A 200W Boost Converter Charger Step-up Power Module | eBay
That kind of boost regulators, combined with some pass/protect diodes, and switches, and over-discharge protection circuit, allow wall-plug and battery operation.

The other issue is: what to do with 2 channels? Driving a 2-way system is a technically superior approach, which also implies technically superior implementation. There are 2 requirements to fulfill.

1- A reliable (not leaking LF into HF due to clipping) and accurate (tweaked for uniform on-axis or off-axis response) frequency division circuit, taking signal from guitar and conditioning it for amplifier channels.

2- Protection, including a gain reduction circuit based in clipping indication from amplifier (problem: if the chip does not include clip indication, another circuit is required to detect clipping), and a DC protection system for both channels (like pre-made boards, but not just pop-suppression delay boards). I don't recommend a capacitor in series with the tweeter as a protection, unless phase shift is accounted for. Simple 2-way does not sound good with too many "filter orders" in tweeter response, due to phase incoherence.
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Last edited by Eva; 15th January 2018 at 06:22 AM.
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Old 15th January 2018, 01:52 PM   #13
sguyader is offline sguyader
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Quote:
Originally Posted by Eva View Post
Learning requires mistake.

Audibility of portable gear at stage or street requires some power. Maximum power output is dictated by supply voltage and load impedance. Advertisements can result misleading if the root rule is not known.

BTL power ceiling equals V^/(2*r) where "V" is supply voltage and "r" is load impedance. For a 19V (single ended) supply and 4ohm load power ceiling is 45W.

More power can be obtained by boosting the 19V from the power adapter, or adding a 2nd power adapter in series. 38V is about the limit for TDA7498, for 100W/8r, per channel (in active filter 2-way operation, "4 ohm nominal" speaker driver impedance plot may be high enough for being driven by TDA7498 without shutdown or damage).

Example boost (step-up) DC-DC regulator board from ebay:
DC-DC 6-35V to 6-55V 10A 200W Boost Converter Charger Step-up Power Module | eBay
That kind of boost regulators, combined with some pass/protect diodes, and switches, and over-discharge protection circuit, allow wall-plug and battery operation.
Thanks Eva. What do you think of this one: 6A Boost Converter DC-DC 10-32V to 12-35V Step Up

Quote:
Originally Posted by Eva View Post
The other issue is: what to do with 2 channels? Driving a 2-way system is a technically superior approach, which also implies technically superior implementation. There are 2 requirements to fulfill.

1- A reliable (not leaking LF into HF due to clipping) and accurate (tweaked for uniform on-axis or off-axis response) frequency division circuit, taking signal from guitar and conditioning it for amplifier channels.

2- Protection, including a gain reduction circuit based in clipping indication from amplifier (problem: if the chip does not include clip indication, another circuit is required to detect clipping), and a DC protection system for both channels (like pre-made boards, but not just pop-suppression delay boards). I don't recommend a capacitor in series with the tweeter as a protection, unless phase shift is accounted for. Simple 2-way does not sound good with too many "filter orders" in tweeter response, due to phase incoherence.
In fact I was thinking to try one of the boxed amps (Breeze/Nobsound) which include an NE5532-based preamp module (Nobsound Mini Dual TPA3116 Digital Power Amplifier HiFi Stereo Audio Amp 2.0 Channel 100W2 DIY with NE5532 Pre-level OP Amp).
I just bought a pair of used Pioneer bookshelf 2-way speakers, which I think are light enough to be portable. This way I could connect each speaker channel to one speaker, and be done with it. For just 20 the speakers, if I blow them when testing it's won't be a great loss.
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Old 16th January 2018, 11:54 AM   #14
Eva is offline Eva  Spain
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The 2 modules you propose are suitable for 24V peak output and 4 ohm speakers (72W/ch). The solution I proposed was for 39V peak output on 8 ohm speakers (95W/ch).

Note that, for stereo operation, at low frequencies, peak supply current as high as 2*24V/4r=12A or 2*39V/8r=9.75A can be demanded. This is the main criteria for sizing the boost converter. The 6A unit covers only 50% requirement, acceptable for, say, >100hz, operation (considering the little bulk capacitor bank included in the dual TPA3116 module).

EDIT: Input impedance of the amplifier module is not listed. NE5532 is an op-amp intended for low signal impedances, input impedance could be a few kohm only. Circuit modification could be needed for optimum musical instrument use.
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Last edited by Eva; 16th January 2018 at 12:03 PM.
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Old 16th January 2018, 06:42 PM   #15
sguyader is offline sguyader
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The guitar will go through an effect board which gives a 2 kOhms output impedance (-10 dBU line out). It is said to have unity gain. Is that enoughj to go directly into a TPA3116 amp, or does it need to go into a preamp before?
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Old 18th January 2018, 12:11 PM   #16
sguyader is offline sguyader
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Quote:
Originally Posted by Eva View Post
The 2 modules you propose are suitable for 24V peak output and 4 ohm speakers (72W/ch). The solution I proposed was for 39V peak output on 8 ohm speakers (95W/ch).

Note that, for stereo operation, at low frequencies, peak supply current as high as 2*24V/4r=12A or 2*39V/8r=9.75A can be demanded. This is the main criteria for sizing the boost converter. The 6A unit covers only 50% requirement, acceptable for, say, >100hz, operation (considering the little bulk capacitor bank included in the dual TPA3116 module).

EDIT: Input impedance of the amplifier module is not listed. NE5532 is an op-amp intended for low signal impedances, input impedance could be a few kohm only. Circuit modification could be needed for optimum musical instrument use.
What do you think of this boost converter:
1 PC DC DC 600 W EN 10 60 V Out 12 80 V Boost Converter Step up Module Voiture Portable Alimentation dans Alimentation a decoupage de Amelioration de l'habitat sur AliExpress.com | Alibaba Group
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