saheb11123
Active Member
Good to see a lot of testing, and if you plan to use the lm3886, you wont need the speaker protection, and around 10000uf is enough per channel.
Custom Audio Amplifier Experiment
- Thread starter eapen
- Start date
saheb11123
Active Member
I had bought the Peerless speakers, LM3886 amplifier board & power supply board (shown earlier) through diyaudiocart. The power supply board was enhanced by replacing the 4,700uf x4 capacitors with 10,000uf ones.
Also picked up:
1)Low pass frequency filter by Wintek. It is a fourth order filter using 3x TL072 op-amps with cut-off frequency at 110Hz.
2) speaker protection circuit by Lumin using uPC1237 which protects the speaker against amplifier output DC, over load & short circuit.
Tested the C1237 speaker protection circuit with a 0-12v power supply. Switches on the speaker after 4 sec delay after power on. An extra connection goes into the transformer AC section to switch off the relay immediately during power off suppressing pop off noise.
Try to replace TL072 with Ne5532/34 at the minimum cause tl072's are very bad not recomended for audio applications.
Yes. After I test it out first, have the TL072 ICs removed & then install 8 pin DIP sockets in place. Since its a sub-woofer filter HF noise should not pose a problem. The test would be to determine which IC set would be sonically superior in bass ie; give more LF performance.
As a note the Wintek Low-pass board does not provide for cut-off frequency adjustment. The preset is only for gain.
Op-amps in mind
NE5532 (not NE5534 since pin out is different)
LM4562 or latest LME49860
An op-amp shoot-out :
NwAvGuy: Op Amp Measurements
As a note the Wintek Low-pass board does not provide for cut-off frequency adjustment. The preset is only for gain.
Op-amps in mind
NE5532 (not NE5534 since pin out is different)
LM4562 or latest LME49860
An op-amp shoot-out :
NwAvGuy: Op Amp Measurements
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Coming back to the 350W Indo Power amplifier (Class AB) the final output stage consists of power transistors. I decided on Power transistors based amplifier since according to some audiophiles it gives better low frequency response than Mosfets.
Instead of Toshiba 3x 2SA1943 PNP & 2SC5200 NPN pairs , I opted for ON Semiconductor 3x NJW0302G PNP & NJW0281G NPN pairs. The driver transistors are 2x A940 & 1x C2073
When I received the board, on inspection I was surprised to find that each transistor branch is not entirely NPN or PNP unlike Darlington complementary designs.
Instead of Toshiba 3x 2SA1943 PNP & 2SC5200 NPN pairs , I opted for ON Semiconductor 3x NJW0302G PNP & NJW0281G NPN pairs. The driver transistors are 2x A940 & 1x C2073
When I received the board, on inspection I was surprised to find that each transistor branch is not entirely NPN or PNP unlike Darlington complementary designs.
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On discussion with the vendor I came to realise that the circuit is JBL 'T-circuit' inspired design.
Refer: Leach amp The Leach Amp - Output Stage
The above topology of pairing NPN with PNP is called Sziklai pair in contrast to Darlington pair which is either pairing NPN or PNP.
Darlington pair : Darlington transistor - Wikipedia, the free encyclopedia
Sziklai pair : Sziklai pair - Wikipedia, the free encyclopedia
Refer: Leach amp The Leach Amp - Output Stage
The above topology of pairing NPN with PNP is called Sziklai pair in contrast to Darlington pair which is either pairing NPN or PNP.
Darlington pair : Darlington transistor - Wikipedia, the free encyclopedia
Sziklai pair : Sziklai pair - Wikipedia, the free encyclopedia
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Further probing of the circuit dawned on me that the output stage of the 350w amplifier is termed ' Compound complementary ' different from the usual ' Darlington complementary '.
Refer: Amplifiers: Output stage
On the initial fingertip testing for 5 minutes I am surprised how efficient this 350w Class AB design is in terms of heat dissipation. Continuous running with the fingertip at the input for 5 minutes & the heatsink is only slightly getting warm. In comparison for the earlier IRS2092 IRFB4227 Class-D amplifier with a similar fingertip test the heatsink would be hot to touch within a minute's time !
Also there is no loud thud , pop noise when you switch ON / OFF this amp. Just a slight tick sound which in my personal opinion is good in reducing current surges through the speaker.
Refer: Amplifiers: Output stage
On the initial fingertip testing for 5 minutes I am surprised how efficient this 350w Class AB design is in terms of heat dissipation. Continuous running with the fingertip at the input for 5 minutes & the heatsink is only slightly getting warm. In comparison for the earlier IRS2092 IRFB4227 Class-D amplifier with a similar fingertip test the heatsink would be hot to touch within a minute's time !
Also there is no loud thud , pop noise when you switch ON / OFF this amp. Just a slight tick sound which in my personal opinion is good in reducing current surges through the speaker.
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In the month of February 2015 ordered a MINI X-8H Plus Android TV box.
NEO X8-H Plus - Android TV Box - MINIX
The main reasons to decide on it was it has H.265 / HEVC Hardware Decoding Support & SPDIF optical TOSLINK out. However an external 5.1 Dolby Analog Audio Decoder is required to connect to an analog 5.1 home theater audio setup.
Additional got a mini wireless remote with QWERTY keyboard & touch pad -Rii type since using the stock remote (& with gyro) was proving difficult to browse to the menus.
TV is Micromax 50" Full HD 1080p 60Hz. Movies stored & played through an external 1TB Seagate HDD. Watching ripped Blue-ray 1080p movies in the external hard drive without any pixelation is indeed exhilarating.
Having no 'Smart TV' feature was another reason for going for this box. Have directly connected RJ45 cable from MINIX box to the Airtel router instead of Wifi connection for watching streaming songs on Youtube. Regardless of availing an 8MBPS broadband plan, HD content does play seamlessly albeit sometimes with a slight initial buffering delay.
NEO X8-H Plus - Android TV Box - MINIX
The main reasons to decide on it was it has H.265 / HEVC Hardware Decoding Support & SPDIF optical TOSLINK out. However an external 5.1 Dolby Analog Audio Decoder is required to connect to an analog 5.1 home theater audio setup.
Additional got a mini wireless remote with QWERTY keyboard & touch pad -Rii type since using the stock remote (& with gyro) was proving difficult to browse to the menus.
TV is Micromax 50" Full HD 1080p 60Hz. Movies stored & played through an external 1TB Seagate HDD. Watching ripped Blue-ray 1080p movies in the external hard drive without any pixelation is indeed exhilarating.
Having no 'Smart TV' feature was another reason for going for this box. Have directly connected RJ45 cable from MINIX box to the Airtel router instead of Wifi connection for watching streaming songs on Youtube. Regardless of availing an 8MBPS broadband plan, HD content does play seamlessly albeit sometimes with a slight initial buffering delay.
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Am contemplating building a 5.1 audio system. The inputs would be coax/optical SPDIF decoded to 5.1 analogue using an after-market digital Dolby decoder.
For controlling analogue audio - Bass, Treble & 5.1 speaker -front, center, rear & subwoofer volume I came across a custom made 5.1 audio channel remote controller by Imranics , Tamilnadu.
Imranics - 5.1 remote kit
I bought their TX103 kit which controls only 5.1 analog audio input -
It utilises PT2322 6-Channel Audio Processor IC. Though it doesn't have LCD display to indicate selected parameters (particular LCD version was not in stock), the remote button presses are indicated by flashing LED.
For controlling analogue audio - Bass, Treble & 5.1 speaker -front, center, rear & subwoofer volume I came across a custom made 5.1 audio channel remote controller by Imranics , Tamilnadu.
Imranics - 5.1 remote kit
I bought their TX103 kit which controls only 5.1 analog audio input -
It utilises PT2322 6-Channel Audio Processor IC. Though it doesn't have LCD display to indicate selected parameters (particular LCD version was not in stock), the remote button presses are indicated by flashing LED.
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Testing one of the recent mini Class-D amplifiers, TPA3116D2 - the second version of Texas Instruments TPA3116 audio chipamp. It it highly rated in terms of music reproduction
SMPS power supply is 19v 3.5A & speakers 10w 8? x2.
SMPS power supply is 19v 3.5A & speakers 10w 8? x2.
goldyrathore
Active Member
Did you source the TPA3116D2 locally? Pls share details
Finished soldering components the earlier mentioned Class-AB E305 FET Differential amplifier board.
Parts list & circuit:
The input stage consists of low-noise FET transistors 2SJ103 & 2SK246. The final stage is Darlington Complementary.
Bare PCB:
Assembled & testing with 28v-0-28v 2A transformer & 400w 4? subwoofer.
Parts list & circuit:
The input stage consists of low-noise FET transistors 2SJ103 & 2SK246. The final stage is Darlington Complementary.
Bare PCB:
Assembled & testing with 28v-0-28v 2A transformer & 400w 4? subwoofer.
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Amplifier is rated 250w 4? which is lower than than the connected load. The architecture is also known as Diamond Differential amplifier.
Output stage replacement transistors are NJW0302 & NJW0281. Rest all transistors are the same as per the the parts list. Driver transistors are 2SC5171 & 2SA1930. FET transistors 2SJ103 & 2SK246 were not available locally hence had to import them.
At 28v -0- 28v AC =~ +39v -0- -39v DC (after rectification) 2A even with lowest forward biasing set with the variable resistor, the heatsink is running hot. I guess the size of the heat sink is inadequate. Increase the biasing of the driver transistors the heatsink will become quite hot. This characteristic would fit this amp's description in a conjugate Class AB-A model.
The 400w speaker excursion is quite good due to the input stage at the above mentioned VA. However, the current draw for this design is so much that the transformer core also becomes too hot within few minutes.
Output stage replacement transistors are NJW0302 & NJW0281. Rest all transistors are the same as per the the parts list. Driver transistors are 2SC5171 & 2SA1930. FET transistors 2SJ103 & 2SK246 were not available locally hence had to import them.
At 28v -0- 28v AC =~ +39v -0- -39v DC (after rectification) 2A even with lowest forward biasing set with the variable resistor, the heatsink is running hot. I guess the size of the heat sink is inadequate. Increase the biasing of the driver transistors the heatsink will become quite hot. This characteristic would fit this amp's description in a conjugate Class AB-A model.
The 400w speaker excursion is quite good due to the input stage at the above mentioned VA. However, the current draw for this design is so much that the transformer core also becomes too hot within few minutes.
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Got another mono Class D amplifier. This one uses IRS2092 & IRFI4019 mosfet. The amplifier is listed as 200w output into 4? load with input operating voltage between +-30V to +-60V
Made by Yuan Jing (YJ) audio, China - http://www.yuan-jing.com/irs2092-class-d-mono-amplifier-board-200w
Connected Peerless sub. Tried with 2 power supplies first 28-0-28 2A & then 40-0-40 6A. It is quite stable & doesn't heat up much (both heatsink & inductor coil) as compared to the first Class D IRS2092 & IRFB4227 mosfet board I tried.
However, from the speaker excursion I guess this amp would not drive more than 100w into 4?. There is only a slight increase in the cone movement with the large increase in VA.
Made by Yuan Jing (YJ) audio, China - http://www.yuan-jing.com/irs2092-class-d-mono-amplifier-board-200w
Connected Peerless sub. Tried with 2 power supplies first 28-0-28 2A & then 40-0-40 6A. It is quite stable & doesn't heat up much (both heatsink & inductor coil) as compared to the first Class D IRS2092 & IRFB4227 mosfet board I tried.
However, from the speaker excursion I guess this amp would not drive more than 100w into 4?. There is only a slight increase in the cone movement with the large increase in VA.
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Fantastic
Well-Known Member
Eapen, a question slightly off topic. How long does it take for customs clearance in Bangalore ? I guess you must be checking the parcel on the tracking web site. Either Indiapost.com (Ips web tracking) or 17track.com .
In some places it can take over a month after reaching the customs office.
Was the duty reasonable ( or free! ) and not over 40 % of the cost ? To me this appears to be different for different cities !
In some places it can take over a month after reaching the customs office.
Was the duty reasonable ( or free! ) and not over 40 % of the cost ? To me this appears to be different for different cities !
Usually 15 days. However, I have had Customs clearance delayed more than 30 days. Bulk of the imported items from China are received at Kolkata port first & then forwarded to Sub Foreign Post Office, Bangalore. Mostly the delay happens when the item comes under the detention of Customs. To receive the Customs intimation letter by post sometimes takes more than 15 days ! The double whammy here is if you do not reply within 15 days on receipt of the letter, the Custom have the authority to send it back or discard/auction it !
Yes duty is between 30-40% depending nature of the item. Large or heavy parcels >100gms usually come under scrutiny. Occasionally I have been charged duty for smaller items - depends on your luck.
Yes duty is between 30-40% depending nature of the item. Large or heavy parcels >100gms usually come under scrutiny. Occasionally I have been charged duty for smaller items - depends on your luck.
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Am planning to build a budget 2-way bookshelf speaker using Peerless S16NI 6.5" woofer (India), Dainty TW202 Tweeter (China) & Sony BT212 replica passive crossover .
Dianty TW202 is also sold in Russia as Alphard TW202 http://en.alphardaudio.ru/shops/77/872-alphard-tw202.html
Dianty TW202 is also sold in Russia as Alphard TW202 http://en.alphardaudio.ru/shops/77/872-alphard-tw202.html
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saheb11123
Active Member
Waiting to see the build.
The BT212 circuit is advertised as center channel speaker crossover - for a home theater setup.
I tried different combinations of components to get the music quality right. The Peerless 6.5" does suppress frequency response from mid towards high as compared to a Salora 10w oval TV speaker (which I have shown previously while testing TPA3116 amp)
Finally I ended up removing 2 components from the crossover PCB :
I had the wrong notion that the brown disc was a ceramic capacitor. Actually it is a MOV (metal oxide varistor) to protect the tweeter against surges.
I tried different combinations of components to get the music quality right. The Peerless 6.5" does suppress frequency response from mid towards high as compared to a Salora 10w oval TV speaker (which I have shown previously while testing TPA3116 amp)
Finally I ended up removing 2 components from the crossover PCB :
I had the wrong notion that the brown disc was a ceramic capacitor. Actually it is a MOV (metal oxide varistor) to protect the tweeter against surges.
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Below is the original crossover circuit I simulated to a diagram :
C1 - 220uf electrolytic non-polar capacitor
C2 & C3 - 1.5uf box film capacitor
L1 - inductor coil
V1 - 065 varistor
For the woofer circuit C1 was blocking lower bass < 100Hz hence removed & bypassed it.
Regarding the tweeter circuit V1 varistor was slightly muting the upper treble response therefore removed it & decided to use the 4.7uf non-polar capacitor which came soldered standard on Dainty tweeters in series with parallel 2x 1.5uf capacitors in the crossover. With this combination the harsh treble around 7kHz is reduced without affecting higher kHz levels. Basically capacitors in series reduces total capacitance.
C1 - 220uf electrolytic non-polar capacitor
C2 & C3 - 1.5uf box film capacitor
L1 - inductor coil
V1 - 065 varistor
For the woofer circuit C1 was blocking lower bass < 100Hz hence removed & bypassed it.
Regarding the tweeter circuit V1 varistor was slightly muting the upper treble response therefore removed it & decided to use the 4.7uf non-polar capacitor which came soldered standard on Dainty tweeters in series with parallel 2x 1.5uf capacitors in the crossover. With this combination the harsh treble around 7kHz is reduced without affecting higher kHz levels. Basically capacitors in series reduces total capacitance.
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