My experience with Class-D Amplifiers (Part 1 & 2)

A couple of points may also be prudent to keep in mind.

1. Lyrita is, at best, a hobby of Viren. Though he is a fine gentleman, he does not have any intention to go mainstream.
2. For people like Cadence, Rethm and Acoustic Portrait, India and Indian consumers were never in their mind. Their target were always the western and developed world - mostly the US and at best UK.

And, all these players are single outlet players. So unless you are in the city where they operate, getting their products serviced will always be a hassle. Retailers and distributors are passive at best. They are just interested in selling their products, if and when someone asks for it. There is no active selling and promotion. What I also find surprising is the complete lack of adopting newer technologies. Even companies such as NAD, Parasound and others have moved to new technologies quickly. But then, as I said before, it all boils down to numbers. If the number of products you expect to sell is small, your development, production, and selling costs will stay high.
 
.... Continued from Part 1 of 2.....

Final Serious Listening
After fooling around with the system for a few days, I had roughly 20 hours of music played on the system. In my mind, that was enough breaking in. In any case, I was never one to believe in the breaking in philosophy.

I now had the option of listening to some music, both streamed to the Lepai and played from the iPod.

Breathless. Shankar Mahadevan. Saregama. Wave files.
I once mentally counted how many times I had listened to The Wall. After mentally counting 500, I gave up. I may not have listened to Breathless that many times, but I know every nuance of the song. I know exactly when a particular instrument will take centre stage, when Shankar’s voice modulation will change, or when the ‘ting’ of a triangle would sound. When I streamed Breathless to the Lepai, I was astounded with the details the system threw at me. Every instrument sounded just right and Shankar’s voice sounded tighter as if he was holding the mike closer to his throat. I immediately played the song from the iPod, and I listened to a larger and deeper sound stage. The only troubling sound was that maybe Shankar’s higher pitches were a mite exaggerated, as was his ‘ufff’ as he breathes in at the end of the song. But what delighted me was the complete background silence as he breathes out a large gulp of air. When the electronic organs gave way to the drums, the sound stage became deeper and stronger, though there was no change in Shankar’s voice.

Afreen Afreen. Rahat Fateh Ali Khan, Momina Mustehsan, Coke Studio, Season 9, Ep 2. MP3 – 320kbps.
Afreen Afreen was written in the 1990s by Javed Akthar and composed by Nusrat Fateh Ali Khan. Though Nusrat did sing the Ghazal well, the video tried to bring in overtones of sex through Lisa Ray.

In 2016, Faakhir Mehmood took the song and literally rewrote it to be sung by Rahat Fateh Ali Khan and Momina Mustehsan in the Coke Studio Season 9. This rendering took the song to a different level making it a true Ghazal that takes away the sex and makes the appreciation of beauty, well just that.

Rahat, I would say, has excelled himself in this song. You must watch the video to see the look of sublime pleasure in his face as he sings. Pushing his throat to the extreme, he delivers notes I can never dream of singing myself. There is a nary a second of wavering or vibration in his voice. The notes are sung accurately. At 4:49, when he renders ‘Mehajabeen, Mehajabeen’ with a distinct variation, one of the accompanying artist smiles and nods his head in appreciation. In reality, Rahat outperforms Momina flat out. But she is happy to smile and enjoy the song.

Unfortunately, Coke Studio has released only an MP3 of this beautiful number, though at 320kbps. I do wish they would release a lossless version.

By this time, I had moved the speakers to some 5 feet from the Lepai on both sides. I now had nearly double the sound stage. I had also placed the speakers at a slightly elevated level.

I closed my eyes and started Afreen Afreen played from the iPod. I wanted to see how much of the video scenes and sound stage I had seen so many times I could visualize. Lepai did not disappoint me. I am sure a more expensive amp will stitch a larger soundstage and more precise locations of the instruments. But to hear Lepai doing that was heartening. At 4:49, I could sense the artist in my mind smiling and nodding. That was the kind of recall the Lepai was able to bring. The Guitar twangs were clearly audible, and the sound of the ghungroo was as pleasant as could be. Again, the drums could have been better, but that, I am sure is an issue with MP3. But the most important part of the song – the majestic vocals of Rahat was perfect.

Concerto for Sitar & Orchestra. Ravi Shankar and London Symphony Orchestra conducted by Andre Previn. Wave files. 633kbps, 44.1kHz
I can wax eloquent about this album, but let me give you a bit of history. Ravi Shankar was commissioned by the London Symphony Orchestra (LSO) in 1971 to compose a number that could have Indian instruments and the Western Symphony playing together. This was done after his experiments with Philip Glass and Yehudi Menuhin gained popularity. Unfortunately, RS knew little about Western Music. Even then, produced by Christopher Bishop, the album peaked at #6 in Billboards Classical LP’s chart in 1972.

The four movements are powered by Ravi Shankar introducing the ragas Khamaj, Sindhi Bahairavi, Adana, and Man Khamaj with the LSO both accompanying him, and at times, taking over in a crescendo of bongos, brass and strings. This is roughly 40 minutes of sheer bliss. The four movements take on a different shape as Previn brings energy and rhythm to the numbers. Sometimes Andre’s and LSO’s presence become so strong that RS quietly moves to the background. At places where the woodwinds and strings first repeat the sitar’s movements and later take over, it is as of you are waiting for them to do so.

Some 10 odd years later in 1981, Ravi Shankar collaborated with Jose Luis Greco and Zubin Mehta to bring a different version of the concert. Called ‘Raga Mala’, the concert had Mehta’s typical large presence. Instead of starting with the alap as is common with Hindustani music, Mehta jumps in with orchestral thunder and goes on to pile 21 different Ragas with dazzling notes from trumpet, clarinet, cello, and harp. Ravi comes in nearly 2:22 minutes after the start of the number but joins in with energy and vitality that makes you nod with happiness.

The teasing interplay between the sitar and trumpet is even more pronounced with Mehta leading the London Philharmonic Orchestra. The interaction between these two instruments is so perfect you would think they are made for each other.

To properly hear these numbers, I switched on the AC, waited for 30 odd minutes, switched off the AC and then played the numbers.

I increased the Lepai’s volume to roughly 12 ‘o'clock position to get the soundstage I desired. This is not an issue with the amp as I know the recordings have very low gain. I did not want to push the iPod to full volume but kept it at 75%. I reckon I must have been pumping some 45-50 watts per channel to the speakers. At that position, the Lepai rendered both numbers with a precision that gladdened my heart. The trumpets moved forward and backwards on the stage and the position of Shankar’s sitar was dead centre. The tiny cymbals were audible coming from the back of the stage on the left. Usually, the roll of drums gets muffled as one large sound, but here I could visualize the sticks hitting the drums. The strings were soothing instead of being harsh. What I liked most was the clarity with which the amp rendered the low octaves of Shankar’s Sitar. I was able to hear the vibration of the Sitar’s string even at very low octaves, something that Shankar renders beautifully in these albums.

In the beginning, there is absolute silence when a cello starts the album with gentle pulls on the strings. Then the violins take over in crescendos that are joined by trumpets and drums. The Lepai placed the cello far to the left and below the speakers. Yes, below the speakers. That was the kind of soundstage rendering that the Lepai is capable of.

The Very Best of Jim Reeves. Jim Reeves. Sony Music. Wave Files 16/44.
Though Jim Reeves is more popular with Christmas songs, he has sung many romantic songs between 1960 and 1972. Gaining popularity with ‘He Will Have to Go’, Jim sang several songs you can listen to many times including, ‘Distant Drums’, ‘Roses Are Red’, ‘I love You Because’, ‘Bimbo’.

The Lepai played Jim’s songs with a dark background that made you enjoy Jim’s unique voice. When Jim hums or croons, there is just no vibration in his throat. This is something I realized when I was listening to Distant Drums through the Lepai. And the drums were actually far away. Again Lepai rendered depth that I never expected it to.

Hotel California 24/192. Eagles. Asylum/Warner Music Group. Wave Files 24/192.
What can I say about this album? If you are a music lover and haven't heard this song several times, you have wasted your life.

With the Lepai, the first 50 seconds of introduction was sheer bliss. The guitars seemed to tease you and tell you, ‘just wait till the main song starts’. The introduction of the drums in the last few seconds seemed to herald the arrival of Don Henley’s voice.

Around 3:53 when Don sings, ‘they still can’t kill the beast’, the immediate roll of drums was simply superb.

The last two odd minutes was a sublime mixture of guitar, drums, cymbals and other instruments. With the Lepai, the high pitches of the guitar as well as the cymbals stopped short of hurting your ears and added to the magic of the song.

Take Five. The Dave Brubeck Quartet – Time Out. Columbia Records. Wave Files. 96/1504
A long time ago when I visited the US, a client of mine gifted me this album as a CD. Till today it has been one of my most cherished albums along with an expensive Jazz At The Pawnshop that I paid through my nose to get. I have multiple digital copies of this album, and this particular version has been extracted at 96kHz and 1504 kbps.

Though nearly 5:26 long, I am always left with a sad feeling as to why the song could not have been longer.

As the trumpet plays in the beginning, with the Lepai, you can actually hear the ‘air’ that audiophiles so crave for.

Around 2:20, the drums take over with a gentle background note repeated on the piano. I increased the volume to 12 ‘o'clock position to understand if the Lepai could handle the drums properly. Oh, boy, did it? It threw the sound of drums into my face with aplomb clearly separating the various notes and playing the roll of the drum sticks.

Other Notes and Conclusion
The Lepai is certainly worth the trouble I took to get it. It seems to marry extremely well with the Aperion speakers. My wife and I have been using it regularly for nearly a year now, listening to all kinds of music. We have subscribed to both Amazon Prime as well as Gaana. I have a large collection of FLAC and other files that I have ripped.

Lepai’s Bluetooth works quite well. It, of course, prefers to be paired with an aptX capable Bluetooth signal but handles 4.0 and other versions quite well. Just remember not to transmit more than one BT signal at a time. When you are using one device, you must remember to disconnect all other devices.

After prolonged playing, the Lepai unit does feel warm to the touch. But that is nothing to worry about. I have played it for up to 5 hours at a stretch, using it to play music in the background as I work.

Paired with the right speakers, the Lepai LP1601 amplifier is a worthwhile addition to any music lover’s music room. Just remember to use a 32-36 volts external power supply and you will be rewarded with wonderful music for hours together without any ear fatigue. The Lepai is not worried about the genre of the music you throw at it. Hindi or Tamil film music, slokas, jazz, serious rock, even classical numbers – it handles all of them with ease creating the soundstage required. It is, in my opinion, quite transparent and does not add any of its own twists to the music. And that, for a sub 100$ amp, is a great achievement.

Addendum
The Lepai 1601 and Aperion Audio speakers have been steadily improving the sound they deliver. Whatever I play, the sound is pleasant, and just right. The sound stage is good and the voices and instruments placed correctly. Most important, I can use the system for hours together without worrying about electricity and other costs.

I have, in the recent past, assembled a player consisting of a Raspberry Pi 3B, an Allo Boss DAC, and an Allo Isolator. Connected to the LP1601, the sound is just perfect. The sound stage is larger, the voices and drums tighter, and the background absolutely black. The Allo Isolator is critical in killing all noises between the RPi and Allo Boss DAC. I will write a review of this later.

All told, I spent 100$ on the LP1601, and roughly another 100$ on the player. For roughly 200$ I have an audio system that can seriously challenge any system costing 5 times or more.

Equipment Used
  • Amplifier: Lepai 1601 from Parts Express. Roughly US$100. (https://www.parts-express.com/lepai...fier-with-bluetooth-and-power-supply--310-303). External 32V, 3.0A.
  • Speakers: Aperion Audio Intimus 532 LR Bookshelf speakers. Only newer models are available now. (https://www.aperionaudio.com)
  • Speaker Cables: Val den Hul’s Tvvin.
  • Players (1): iPod 5th Generation, iPad Air
  • Players (2): Raspberry Pi 3B with 1 GB RAM, Allo Boss DAC v1.2, Allo Isolator v1.2, 5V 2A external power adaptors. (https://www.fabtolab.com).
  • Connector Cables: (1) Acoustic Research Performance Series audio cable. (2) Custom made audio cable using Belden cable and Neutrik connectors.
  • Sources: Ripped files of various types including FLAC, Wave, M4A, ALAC, and MP3.
View attachment 47550

View attachment 47551

View attachment 47552
So good to know @venkatcr about your experiences. I have been using hypex ncore. And I have to share here that speaker driver control/low distortion is up there with anything else I have heard. Bass, understandably, is incredible. But then I think It's worth cautioning everyone here that the weakest link is a system are the speakers. Great amps will make marginal difference if everything else from source to speakers aren't up there. Amps, unless they are poorly made, have really few things to do - high S/N ratio over 110-120 db, adequate wattage for headroom, be linear, have low THD, and have high damping factor (cone control). If they do these well, I really doubt anyone can hear differences between amps in blind AB/ABX testing. Moving from passive to active speakers are likely to produce the biggest difference in listening experience, and then comes the amp.
 
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.... Continued from Part 1 of 2.....

Final Serious Listening
After fooling around with the system for a few days, I had roughly 20 hours of music played on the system. In my mind, that was enough breaking in. In any case, I was never one to believe in the breaking in philosophy.

I now had the option of listening to some music, both streamed to the Lepai and played from the iPod.

Breathless. Shankar Mahadevan. Saregama. Wave files.
I once mentally counted how many times I had listened to The Wall. After mentally counting 500, I gave up. I may not have listened to Breathless that many times, but I know every nuance of the song. I know exactly when a particular instrument will take centre stage, when Shankar’s voice modulation will change, or when the ‘ting’ of a triangle would sound. When I streamed Breathless to the Lepai, I was astounded with the details the system threw at me. Every instrument sounded just right and Shankar’s voice sounded tighter as if he was holding the mike closer to his throat. I immediately played the song from the iPod, and I listened to a larger and deeper sound stage. The only troubling sound was that maybe Shankar’s higher pitches were a mite exaggerated, as was his ‘ufff’ as he breathes in at the end of the song. But what delighted me was the complete background silence as he breathes out a large gulp of air. When the electronic organs gave way to the drums, the sound stage became deeper and stronger, though there was no change in Shankar’s voice.

Afreen Afreen. Rahat Fateh Ali Khan, Momina Mustehsan, Coke Studio, Season 9, Ep 2. MP3 – 320kbps.
Afreen Afreen was written in the 1990s by Javed Akthar and composed by Nusrat Fateh Ali Khan. Though Nusrat did sing the Ghazal well, the video tried to bring in overtones of sex through Lisa Ray.

In 2016, Faakhir Mehmood took the song and literally rewrote it to be sung by Rahat Fateh Ali Khan and Momina Mustehsan in the Coke Studio Season 9. This rendering took the song to a different level making it a true Ghazal that takes away the sex and makes the appreciation of beauty, well just that.

Rahat, I would say, has excelled himself in this song. You must watch the video to see the look of sublime pleasure in his face as he sings. Pushing his throat to the extreme, he delivers notes I can never dream of singing myself. There is a nary a second of wavering or vibration in his voice. The notes are sung accurately. At 4:49, when he renders ‘Mehajabeen, Mehajabeen’ with a distinct variation, one of the accompanying artist smiles and nods his head in appreciation. In reality, Rahat outperforms Momina flat out. But she is happy to smile and enjoy the song.

Unfortunately, Coke Studio has released only an MP3 of this beautiful number, though at 320kbps. I do wish they would release a lossless version.

By this time, I had moved the speakers to some 5 feet from the Lepai on both sides. I now had nearly double the sound stage. I had also placed the speakers at a slightly elevated level.

I closed my eyes and started Afreen Afreen played from the iPod. I wanted to see how much of the video scenes and sound stage I had seen so many times I could visualize. Lepai did not disappoint me. I am sure a more expensive amp will stitch a larger soundstage and more precise locations of the instruments. But to hear Lepai doing that was heartening. At 4:49, I could sense the artist in my mind smiling and nodding. That was the kind of recall the Lepai was able to bring. The Guitar twangs were clearly audible, and the sound of the ghungroo was as pleasant as could be. Again, the drums could have been better, but that, I am sure is an issue with MP3. But the most important part of the song – the majestic vocals of Rahat was perfect.

Concerto for Sitar & Orchestra. Ravi Shankar and London Symphony Orchestra conducted by Andre Previn. Wave files. 633kbps, 44.1kHz
I can wax eloquent about this album, but let me give you a bit of history. Ravi Shankar was commissioned by the London Symphony Orchestra (LSO) in 1971 to compose a number that could have Indian instruments and the Western Symphony playing together. This was done after his experiments with Philip Glass and Yehudi Menuhin gained popularity. Unfortunately, RS knew little about Western Music. Even then, produced by Christopher Bishop, the album peaked at #6 in Billboards Classical LP’s chart in 1972.

The four movements are powered by Ravi Shankar introducing the ragas Khamaj, Sindhi Bahairavi, Adana, and Man Khamaj with the LSO both accompanying him, and at times, taking over in a crescendo of bongos, brass and strings. This is roughly 40 minutes of sheer bliss. The four movements take on a different shape as Previn brings energy and rhythm to the numbers. Sometimes Andre’s and LSO’s presence become so strong that RS quietly moves to the background. At places where the woodwinds and strings first repeat the sitar’s movements and later take over, it is as of you are waiting for them to do so.

Some 10 odd years later in 1981, Ravi Shankar collaborated with Jose Luis Greco and Zubin Mehta to bring a different version of the concert. Called ‘Raga Mala’, the concert had Mehta’s typical large presence. Instead of starting with the alap as is common with Hindustani music, Mehta jumps in with orchestral thunder and goes on to pile 21 different Ragas with dazzling notes from trumpet, clarinet, cello, and harp. Ravi comes in nearly 2:22 minutes after the start of the number but joins in with energy and vitality that makes you nod with happiness.

The teasing interplay between the sitar and trumpet is even more pronounced with Mehta leading the London Philharmonic Orchestra. The interaction between these two instruments is so perfect you would think they are made for each other.

To properly hear these numbers, I switched on the AC, waited for 30 odd minutes, switched off the AC and then played the numbers.

I increased the Lepai’s volume to roughly 12 ‘o'clock position to get the soundstage I desired. This is not an issue with the amp as I know the recordings have very low gain. I did not want to push the iPod to full volume but kept it at 75%. I reckon I must have been pumping some 45-50 watts per channel to the speakers. At that position, the Lepai rendered both numbers with a precision that gladdened my heart. The trumpets moved forward and backwards on the stage and the position of Shankar’s sitar was dead centre. The tiny cymbals were audible coming from the back of the stage on the left. Usually, the roll of drums gets muffled as one large sound, but here I could visualize the sticks hitting the drums. The strings were soothing instead of being harsh. What I liked most was the clarity with which the amp rendered the low octaves of Shankar’s Sitar. I was able to hear the vibration of the Sitar’s string even at very low octaves, something that Shankar renders beautifully in these albums.

In the beginning, there is absolute silence when a cello starts the album with gentle pulls on the strings. Then the violins take over in crescendos that are joined by trumpets and drums. The Lepai placed the cello far to the left and below the speakers. Yes, below the speakers. That was the kind of soundstage rendering that the Lepai is capable of.

The Very Best of Jim Reeves. Jim Reeves. Sony Music. Wave Files 16/44.
Though Jim Reeves is more popular with Christmas songs, he has sung many romantic songs between 1960 and 1972. Gaining popularity with ‘He Will Have to Go’, Jim sang several songs you can listen to many times including, ‘Distant Drums’, ‘Roses Are Red’, ‘I love You Because’, ‘Bimbo’.

The Lepai played Jim’s songs with a dark background that made you enjoy Jim’s unique voice. When Jim hums or croons, there is just no vibration in his throat. This is something I realized when I was listening to Distant Drums through the Lepai. And the drums were actually far away. Again Lepai rendered depth that I never expected it to.

Hotel California 24/192. Eagles. Asylum/Warner Music Group. Wave Files 24/192.
What can I say about this album? If you are a music lover and haven't heard this song several times, you have wasted your life.

With the Lepai, the first 50 seconds of introduction was sheer bliss. The guitars seemed to tease you and tell you, ‘just wait till the main song starts’. The introduction of the drums in the last few seconds seemed to herald the arrival of Don Henley’s voice.

Around 3:53 when Don sings, ‘they still can’t kill the beast’, the immediate roll of drums was simply superb.

The last two odd minutes was a sublime mixture of guitar, drums, cymbals and other instruments. With the Lepai, the high pitches of the guitar as well as the cymbals stopped short of hurting your ears and added to the magic of the song.

Take Five. The Dave Brubeck Quartet – Time Out. Columbia Records. Wave Files. 96/1504
A long time ago when I visited the US, a client of mine gifted me this album as a CD. Till today it has been one of my most cherished albums along with an expensive Jazz At The Pawnshop that I paid through my nose to get. I have multiple digital copies of this album, and this particular version has been extracted at 96kHz and 1504 kbps.

Though nearly 5:26 long, I am always left with a sad feeling as to why the song could not have been longer.

As the trumpet plays in the beginning, with the Lepai, you can actually hear the ‘air’ that audiophiles so crave for.

Around 2:20, the drums take over with a gentle background note repeated on the piano. I increased the volume to 12 ‘o'clock position to understand if the Lepai could handle the drums properly. Oh, boy, did it? It threw the sound of drums into my face with aplomb clearly separating the various notes and playing the roll of the drum sticks.

Other Notes and Conclusion
The Lepai is certainly worth the trouble I took to get it. It seems to marry extremely well with the Aperion speakers. My wife and I have been using it regularly for nearly a year now, listening to all kinds of music. We have subscribed to both Amazon Prime as well as Gaana. I have a large collection of FLAC and other files that I have ripped.

Lepai’s Bluetooth works quite well. It, of course, prefers to be paired with an aptX capable Bluetooth signal but handles 4.0 and other versions quite well. Just remember not to transmit more than one BT signal at a time. When you are using one device, you must remember to disconnect all other devices.

After prolonged playing, the Lepai unit does feel warm to the touch. But that is nothing to worry about. I have played it for up to 5 hours at a stretch, using it to play music in the background as I work.

Paired with the right speakers, the Lepai LP1601 amplifier is a worthwhile addition to any music lover’s music room. Just remember to use a 32-36 volts external power supply and you will be rewarded with wonderful music for hours together without any ear fatigue. The Lepai is not worried about the genre of the music you throw at it. Hindi or Tamil film music, slokas, jazz, serious rock, even classical numbers – it handles all of them with ease creating the soundstage required. It is, in my opinion, quite transparent and does not add any of its own twists to the music. And that, for a sub 100$ amp, is a great achievement.

Addendum
The Lepai 1601 and Aperion Audio speakers have been steadily improving the sound they deliver. Whatever I play, the sound is pleasant, and just right. The sound stage is good and the voices and instruments placed correctly. Most important, I can use the system for hours together without worrying about electricity and other costs.

I have, in the recent past, assembled a player consisting of a Raspberry Pi 3B, an Allo Boss DAC, and an Allo Isolator. Connected to the LP1601, the sound is just perfect. The sound stage is larger, the voices and drums tighter, and the background absolutely black. The Allo Isolator is critical in killing all noises between the RPi and Allo Boss DAC. I will write a review of this later.

All told, I spent 100$ on the LP1601, and roughly another 100$ on the player. For roughly 200$ I have an audio system that can seriously challenge any system costing 5 times or more.

Equipment Used
  • Amplifier: Lepai 1601 from Parts Express. Roughly US$100. (https://www.parts-express.com/lepai...fier-with-bluetooth-and-power-supply--310-303). External 32V, 3.0A.
  • Speakers: Aperion Audio Intimus 532 LR Bookshelf speakers. Only newer models are available now. (https://www.aperionaudio.com)
  • Speaker Cables: Val den Hul’s Tvvin.
  • Players (1): iPod 5th Generation, iPad Air
  • Players (2): Raspberry Pi 3B with 1 GB RAM, Allo Boss DAC v1.2, Allo Isolator v1.2, 5V 2A external power adaptors. (https://www.fabtolab.com).
  • Connector Cables: (1) Acoustic Research Performance Series audio cable. (2) Custom made audio cable using Belden cable and Neutrik connectors.
  • Sources: Ripped files of various types including FLAC, Wave, M4A, ALAC, and MP3.
View attachment 47550

View attachment 47551

View attachment 47552
What a Brilliant write up.... You should definitely try the NKOTB - The " AIYIMA A07"(Amazon.in stocks it) from Aiyima Audio as you are keen about Class D Amps...they have even brought out a BT version of it - AIYIMA A07 PRO with a lot of upgraded components that you will be able to relate better with. (upgraded component details available on the website)...These amps are priced around $80 and since you already have the 36V PS from the lepai ,you could run it off the box.
 
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