[Folsom]

The TPA31xx amps have differential inputs, positive and negative, per channel. Referring to the Texas Instruments data sheet, I am using a single 3.3 cap on each input to establish a cut-off frequency of 1.6Hz for 26dB gain.

Can you post a photo of your setup? Like Poultrygeist mentioned, something must be amiss for you to experience RFI.

I thought you meant two so you can use one in reverse orientation (can be beneficial).

[rhing]

I installed a set of the 10uH Coilcraft SER2915L-103KL nductors in my Yuan Jing blue amp, and I have to say the improvement was noticeable from the start. It's like a veil has been lifted and the amp has reached another level of transparency. It's difficult for me to make an apples-to-apples comparison to the Bourns 10uH inductors I've previously tried, since that amp was shipped off elsewhere. I will say that the current amp has a big, full bodied sound, and I haven't even upgraded the input caps yet.



These are some bulky inductors and I took my time planning how I was going to fit these on the Yuan Jing amp and in what order I was going to install them. I am please with how it looks even though it does look a bit different. Once this amp gets placed into an enclosure, I'll forget about it.







One thing is sure, upgrading the inductors adds a higher degree of clarity and transparency to this amp. It's almost like I don't have anything between my phono stage and line stage and my speakers except gain.

The S.M.S.L. SA-36 Pro TPA3118D2 is on it's way. It's cleared the San Francisco USPS sorting center, so I should receive it this Tuesday or Wednesday. I am looking forward to comparing these amps. The S.M.S.L. could be the big surprise.

[Markvdv]

Wow Rhing, special admiration for the soldering of these coils, i think you kept DCR intact (ultralow) by keeping contact beautifull level and minimum solderthickness. I believe 1mm solderthickness could increase DCR 4times, thats how low these DCR ratings of this coil are. Now handle with extreme care not to have the weight pull off the pcbtraces, or do they look heavier then they are?

Very interested in your opinion about the SMSL. I ordered a 3116 board with remotecontrol and display, which could be worst on market SQ wise. And once again not from ebay, so keeping my fingers crossed:)

[rhing]

Thanks. The Coilcraft inductors are on the board very solidly. For the two inner inductors, I did my best to insure the leads were bent to make the best possible contact with the solder pads. I even applied some masking tape to my needle nose pliers to protect the joint surface from getting scratched when I bent the leads. I use Cardas quad-eutectic solder, which has served me well over many projects. To solder these on properly, you really need a good 40 watt iron with a narrow neck and a small chisel tip to be able to get into the tight spaces without scorching adjacent components and rapidly heat up the joint. The Copper coils in the inductors work like a heat sink, so you need to be able to transfer heat quickly before the coils start to conduct heat away from the solder joint. Once the coils were secured, I re-touched the joints one at a time to get them nice and shiny--I hate cold solder joints.

I think I read somewhere that eBay seller hiamplifier is willing to sell the Yuan Jing blue amp boards without the stock inductors. This would be a good deal if you want to add your own. For that matter, it would be great if hiamplifier is willing to sell completely blank boards.

This is the best I've heard these TPA3116 amps sound. I have to go off memory on how the Bourns inductors sound, and I am clearly hearing more of the music. The amp is very tonally balanced from top to bottom. In fact, the bass is more defined and the treble is sweet and less forward. The soundstage is deep with a focused imaged. I thought the TDK and Panasonic OSCON caps really made a huge improvement, and these inductors have taken this amp to another level of performance. If I stopped now with the mods, I would be pleased, but I think installing the 3.3uF Wima MKP10 film caps on the inputs will be another improvement. For now, I'm in vinyl heaven spinning LP after LP.

[Folsom]

How about boards with chips n sinks... I don't have any desire to solder the itty bitty chip leads; especiaally since there's no mods to be had hear, the heatsink is adequate too. May as well have the couple non-signal smd parts too.

[matt_garman]

What do you think about putting a glob of epoxy like JB Weld over each of the inductor solder contacts to further reinforce the connection?  Might be overkill, but for example, if you ever shipped it (listening tour version 2?) it might need safeguarding against ham-handed shippers.  (I'm sure we've all seen the videos of UPS/FedEx employees caught in the act, making that scene in Ace Ventura a little less comedic, and more like documentary).

Or maybe you could JB weld "flanges" to the bottom of the PCB, effectively increasing the width of the PCB, given those inductors something to "rest" on, and relieve the torque on the solder joint.

<shrug>  Just throwing out random ideas.

[rhing]

That's not a bad idea. I think I'd rather go with a non-conductive adhesive to avoid the possibility of connecting the inductor housings to the ground plane. A few dabs of Silicone adhesive or hot melt adhesive should be sufficient since these inductors are solidly on the pads.

[Markvdv]

Blue and black boards only have one per input. Which is all you need for single ended input. Balanced requires two.

I thought you meant two so you can use one in reverse orientation (can be beneficial).

They have 2 input caps per channel like all 311x pcb's, unfortunately they are not identical but differ in physical size, like the SMSL amp. Might be contributing to pop.

[Markvdv]

hiamplifier is selling board without components, just not the YJ board:)

looks so easy, soldering a chip like tpa

http://www.youtube.com/watch?v=5uiroWBkdFY

[Folsom]

If you read the paper on the 3116 boards it specifically says that the ground from single ended signal goes straight to ground. Furthermore there's only one pin on the blue and black board for ground. That's why they use cheaper caps, there's no signal.

I don't care if it is "easy" to solder SMD stuff, I don't like to, and it's zero effort for them, and it takes a youtube video for me (by comparison, been doing it before youtube videos).

[Markvdv]

If you read the paper on the 3116 boards it specifically says that the ground from single ended signal goes straight to ground. Furthermore there's only one pin on the blue and black board for ground. I'm pretty sure I followed the traces and it's just one signal through one cap to the chip.

LINN and RINN, in single ended operation are connected to ground via a capacitor, but there's no signal.

There's no reason to change them. They are grounded out, and the caps is probably just to prevent DC.

I don't care if it is "easy" to solder SMD stuff, I don't like to, and it's zero effort for them, and it takes a youtube video for me (by comparison, been doing it before youtube videos).

There is no changing 2 caps but changing 4 caps

Literally:
To use the TPA31xxD2 family
with a single-ended source, ac ground the negative input through a capacitor equal in value to the input capacitor
on positive and apply the audio source to either input. In a single-ended input application, the unused input
should be ac grounded at the audio source instead of at the device input for best noise performance. For good
transient performance, the impedance seen at each of the two differential inputs should be the same.
The impedance seen at the inputs should be limited to an RC time constant of 1 ms or less if possible. This is to
allow the input dc blocking capacitors to become completely charged during the 10 ms power-up time. If the input
capacitors are not allowed to completely charge, there will be some additional sensitivity to component matching
which can result in pop if the input components are not well matched.

[rhing]

I think I read somewhere that eBay seller hiamplifier is willing to sell the Yuan Jing blue amp boards without the stock inductors. This would be a good deal if you want to add your own. For that matter, it would be great if hiamplifier is willing to sell completely blank boards.

I stand corrected. A buddy of mine had contacted Yuan Jing and asked if they would sell the blue amp board without the inductors. They were willing to do so if my friend bought two boards.

[Folsom]

Thanks Kant. You could have just said LINN and RINN need matched impedance grounding caps to the signal input capacitors.

[fredgarvin]

These amps sure seem to have a lot of veils being lifted. How many layers of veils can a amp have and still be considered a good amp? 

[wushuliu]

These amps sure seem to have a lot of veils being lifted. How many layers of veils can a amp have and still be considered a good amp? 

I think there's another layer yet. At least no one can say were biased because we paid $$$$$ so of course we think its amazing etc.

@ rhing: I'm thinking that rc filter off the avcc pin tweak mentioned at diyAudio may be worth investigating. Maybe that's what the TBI secret RX filter is related to.

And I'd be willing to pitch in a little money for a full modded version for a tour if someone else builds. I no longer have the time.

[rhing]

@ rhing: I'm thinking that rc filter off the avcc pin tweak mentioned at diyAudio may be worth investigating. Maybe that's what the TBI secret RX filter is related to.

And I'd be willing to pitch in a little money for a full modded version for a tour if someone else builds. I no longer have the time.

I read about that AVCC pin tweak on diyAudio.com too. I might post on the Texas Instruments forum to see if they might comment on that.

I would be willing to donate my time to building another amp. In fact, I would donate the second YJ blue amp I have that is stock with the exception of the 470uF/35V Panasonic FM caps in the power supply decoupling positions. I would only be willing to do this if enough people are interested and can supply the other parts. Otherwise, I'll spend my time and money on other projects.

[shadowlight]

I read about that AVCC pin tweak on diyAudio.com too. I might post on the Texas Instruments forum to see if they might comment on that.

I would be willing to donate my time to building another amp. In fact, I would donate the second YJ blue amp I have that is stock with the exception of the 470uF/35V Panasonic FM caps in the power supply decoupling positions. I would only be willing to do this if enough people are interested and can supply the other parts. Otherwise, I'll spend my time and money on other projects.

Check your PM.

[rhing]

More toys in the attic...

I just received the S.M.S.L. SA-36A Pro TPA3118 today and hooked it up in my system. Even though it came with a 12VDC/3.8A brick-type SMPS, I connected it to my upgraded Astron RS-12A regulated linear power supply. I will listen to it more and report on the sound quality and how it compares to my other TPA31xx amps:

• Yuan Jing TPA3116D2 2.0 blue amp, near stock (only swapped in 470uF/35V Panasonic FM caps in for stock 1,000uF/25V Nichicon PW power supply decoupling caps)
• Modified Yuan Jing TPA3116D2 2.0 blue amp
• Modified Sure Electronics TPA3110D2 amp

As with my S.M.S.L. SA-S1 TA2020 T-amp, which I sold to a friend, this is a very attractive amp inside a nice Aluminum enclosure. I haven't opened up the hood yet. Just playing music and letting the amp settle in before I do some critical listening this evening (I want to catch the NBA playoffs too).

[Folsom]

I think hot glue would be better than jb weld, for securing inductors. Versions of it have been used in electronics for decades.

[gregfisk]

More toys in the attic...

I just received the S.M.S.L. SA-36A Pro TPA3118 today and hooked it up in my system. Even though it came with a 12VDC/3.8A brick-type SMPS, I connected it to my upgraded Astron RS-12A regulated linear power supply. I will listen to it more and report on the sound quality and how it compares to my other TPA31xx amps:

• Yuan Jing TPA3116D2 2.0 blue amp, near stock (only swapped in 470uF/35V Panasonic FM caps in for stock 1,000uF/25V Nichicon PW power supply decoupling caps)
• Modified Yuan Jing TPA3116D2 2.0 blue amp
• Modified Sure Electronics TPA3110D2 amp

As with my S.M.S.L. SA-S1 TA2020 T-amp, which I sold to a friend, this is a very attractive amp inside a nice Aluminum enclosure. I haven't opened up the hood yet. Just playing music and letting the amp settle in before I do some critical listening this evening (I want to catch the NBA playoffs too).

I'm looking forward to your comparison with your other amps. I purchased the same amp a couple of weeks ago and had a short listen with it before shipping it off with my daughter and a Pure i20 dock. I was very impressed for the money and it sounded much better in her small carpeted living room than in my place.

I got mine with the 24v supply, any reason you opted for the 12v instead?

Greg