chip amps: Almost everything you ever wanted to know

[rhing]

Thanks for posting the link. The music sounded so good, I must have been distracted. The great thing about the TPA3110D2 amp is that it will run on the same power supplies that work with the TDA7297. I've included the Sure Electronics manual for this amplifier.

320-329-Parts-Express-Brochure, Sure Electronics TPA3110D2.pdf

Edited December 13, 2013 by rhing

[rhing]

I had a holiday audio get together at my home yesterday comparing the TDA7297 chip amp to my restored and EFB-modified Dynakit Stereo 35 6BQ5/EL84 push-pull amp. Actually, it was a comparison between the TDA7297 and the combination of my Audio Research LS7 tube line stage and Dynakit Stereo 35. I ran the TDA7297 as an integrated amp. I kind of had my Stereo 35 and TDA7297 amps tucked away behind the Klispch Forte II speaker on the right hand side.

My friend John has been applying some system set-up tips from Jim Smith's "Get Better Sound" (Quarter Note Press) to speaker placement and room treatments, so he brought over his book and we played around with speaker placement and throwing large, thick beach towels over my LCD TV and glass-top coffee table in my living room. These tweaks made profound improvements, and I encourage anyone who cares about great sound quality to invest in this book.

My friends and I enjoyed quite a few nice LPs:

• Paul Motian Trio, Le Voyage, ECM
• Kenny Drew, Freddie Hubbard, Hank Mobley et al, Undercurrent, Blue Note (Music Matters reissue)
• Tina Brooks, True Blue, Blue Note (Music Matters reissue)
• Muddy Waters, Folk Singer, Chess (Classic Recordings reissue)
• Pink Floyd, Wish You Were Here, EMI (reissue)

Not surprisingly, the vacuum tube amp combination won out, but not by much. The tube amps were slightly more detailed and created a slightly more three dimensional presentation. My friends liked the ability to hear the better defined separation of performers in the soundstage. Interestingly, the tube amps had a more forward presentation than the TDA7297.

My friends knew nothing about the TD7297 chip amp before the get together, so they were quite astonished by the small size of the amp and the big sounds they heard from it. They all agreed that the TDA7297 has a warm tube-like presentation, impressive dynamic response and a well defined low end. The imaging was bit more diffused compared to the tube amps. It is analogous to using a diffuser in film.

I told my friends that I have the Sure Electronics TPA3110D2 Class D amp from Parts Express on its way, and that we would have to have another amp shoot-out soon. Anyway, everyone really liked the TDA7297 and I get the feeling that my friends will placing orders on eBay soon.

[DizRotus]

Rich-

As indicated above in post #188, I've ordered two more chip amps. I plan to install one of my 7 chip amps (probably one of the TDA 7297 amps) inside the "iPod Dock on steroids" I built. For now, I've eliminated the pot. The volume is controlled by the input device, whether smart phone, iPad, etc. using Bluetooth, or by the phono preamp with vinyl.

I'd like the opinions of you and others on the following:

-Should I include a volume pot;

- If yes, suggestions and sources;

- Should I include a balance control with chip amps; and

- If yes, suggestions and sources.

Clearly, 7 chip amps is too many. I'm inclined to let go of one or more of the following:

- Lepai TA2020;

- SMSL SA-S1; and/or

- SMSL SA-50

If anyone wants to make an offer, send a PM.

Edited December 15, 2013 by DizRotus

[rhing]

I would only put a balance pot on the amp if you absolutely need it. I refurbished a Dynaco SCA-35 and kept all the tone and balance controls. As it turned out, I didn't need them, and all these pots are lossy components that suck a bit of life out of the music. If you only plan to use the amp as a power amp, then try it out first as a power amp and add a volume pot or stepped attenuator as needed. With my TDA7297 amp used with my line stage preamp, I just turn the Alps Blue Velvet all the way up (0kohms) and it works fine, but I am sure the good quality of the Alps pot keeps any signal loss to a minimum.

As soon as my TPA3110D2 amp comes in, I will wire it up as a power amp and use my ARC LS7 line stage to control volume. I am really interested to see if this Class D amp has the headroom of the TDA7297. The TDA7297 casts a really large soundstage that rivaled my tube amps.

Edited December 16, 2013 by rhing

[DizRotus]

The herd has been thinned.

At the suggestion of daleS., I donated the Lepai TA2020 and the SMSL SA-S1 to an auction on the Audio Karma site to benefit Veterans and their families.

If you want to bid on the amps, or other great stuff, while supporting veterans, go to http://www.audiokarma.org/forums/forumdisplay.php?f=174

I neglected to mention that while on the AK site I purchased a plate amp to power my inbound Anarchy Tapped Horn subs (see https://community.klipsch.com/index.php?/topic/138019-25hz-tapped-horn/). That means a net reduction in ampness of a mere 1. Oh well . . . . .

[rhing]

After listening to this amp, I have to say I am very impressed with this Sure TPA3110D2 amp board. I have to qualify this statement with the fact that I connected this amp to my Audio Research LS7 vacuum tube line stage preamp, since I do not have any spare 50kohm volume pots except the cheap stock volume pots that came with my two TDA7297 amps. I used the Audio Research preamp to handle volume control duties. At this point, I cannot make a direct apples-to-apples comparison between the Sure Class D amp and the TDA7297 Class A/B amp, but I will say that the combination I have been listening to sounds better, overall, than the TDA7297 in stock or modified form.

• More detailed or articulate
• Deeper and cleaner bass--less boomy
• Higher frequency extension
• More natural tonality
• Soundstage is comparable with a large, deep soundstage
• Greater dynamic range

I feel like I'm splitting hairs with this, but I do hear the difference with careful listening with music material that I am very familiar with. Using my Alan Parson's "Sound Check 2" test CD which has a series of 1/2 octave tones from 20Hz up to 20kHz, I could verify that the bass response is lower with the TPA3110D2 than with the TDA7297. With the TPA3110D2, I could hear down to 31.5Hz in my room. I don't hear this with the TDA7297. In fact, the bass seems to roll off around 45Hz. What the TDA7297 does do is it seems to have a stronger bass output between 80 and 120Hz, which can give the impression that the bass is stronger.

I still have to sort this out, but I do hear some low level background noise with the TPA3110D2. The noise disappears when I engage the MUTE on my LS7, which indicates that the output filter-less TPA3110D2 amp may be emitting some RFI that's affecting my preamp. I never hear this noise, or any for that matter, from the TDA7297 or my Dynakit Stereo 35 tube amp. If this is something that cannot be reduced/eliminated, then an amp module such as the Yuan Jing TPA3116D2 2.0 amp might be a better solution since it does have the LC output filter to minimize RFI.

I still have more testing and listening to do, but the Texas Instruments Class D-proponents are probably onto something really good with these Class D amps. The TPA3110D2, TPA3116D2, TPA3122D2 and other TI Class D amps are representative of newer Class D technology than the Tripath Class D technology, which hasn't been refined since Tripath went out of business.

[DizRotus]

Rich,

You're like a drug dealer. First the hook then the ramp up.

I'm more eager now than ever to receive the Sure TA2024 and the Sure TPA3110 inbound from eBay. You influenced me into buying the Sures to supplement the TDA72972 which you persuaded me to get .

Unfortunately, there are more projects than time. I just received two Anarchy tapped horn kits (see: https://community.klipsch.com/index.php?/topic/138019-25hz-tapped-horn/). After I steal time to complete those, I'll play with the Sure amps and compare them to my TDA7297s.

Edited December 21, 2013 by DizRotus

[Thaddeus Smith]

I have a Sure TA2024 board and volume pot inbound from China as well.

[rhing]

Rich,

You're like a drug dealer. First the hook then the ramp up.

I'm more eager now than ever to receive the Sure TA2024 and the Sure TPA3110 inbound from eBay. You influenced me into buying the Sures to supplement the TDA72972 which you persuaded me to get .

Unfortunately, there are more projects than time. I just received two Anarchy tapped horn kits (see: https://community.klipsch.com/index.php?/topic/138019-25hz-tapped-horn/). After I steal time to complete those, I'll play with the Sure amps and compare them to my TDA7297s.

Guilty as charged. The Sure TPA3110D2 is a nice amp, but it does seem to induce noise with my ARC LS7 tube line stage. I will have to trouble shoot the system and determine the source, but I suspect it is the TPA3110 amp since it doesn't have an LC output filter.

BTW, nice horn kits. Please share your listening results.

Edited December 22, 2013 by rhing

[DizRotus]

My Sure TA2024 ordered 12/12 arrived today. I'm eager to play with it and share my impressions. Alas, too many projects and not enough time.

http://s928.photobucket.com/user/neildisney/slideshow/TA2024

[Thaddeus Smith]

Ordered mine on the 17th and it's in Illinois as of yesterday.

[rhing]

Okay guys, I was able to sort out a solution to significantly reducing the noise. I wired 33kohm resistors between the signal input and signal ground on each channel. Now that I am able to listen to this amp, I have to say I am impressed with this amp driving my Forte II's. I will probably have to sell my TDA7297 and SMSL SA-S1 amplifiers. This little amp is the real deal. Before you think about buying the Sure TPA3110D2 amp, consider the Yuan Jing TPA3116D2 Class D amp. This amp is based on the newer, more powerful Texas Instruments TPA3116D2 amp and it has output filters to minimize RFI from the switching amp chip circuit.

In hindsight, I wish I bought the Yuan Jing board, but I'm happy with this little guy for now. One thing is certain, this amp clearly outperforms any Tripath amp I've owned. It is absolutely void of any glare and tilted treble synonymous with Class D amps, and it has a serious low end and large soundstage. If anything, it is smoother and more transparent than the TDA7297 chip amp and Tripath TA2020 or TA2024 amps I've owned. I'm listening to Patricia Barber's "Cafe Blue," and the kick drum is presented in full note-form and thumping the floor. The tonality and detail are something to behold. The real kicker is that I don't have to mod this amp other than add those resistors or a 50kohm volume pot at the inputs. This amp sounds great out of the box.

[NBPK402]

So how would these compare sonically to my Denon 4520 avr driving LaScalas? Would this be an upgrade in sound or just in efficiency?

[rhing]

So how would these compare sonically to my Denon 4520 avr driving LaScalas? Would this be an upgrade in sound or just in efficiency?

Very good question. I have no reference for how the Denon 4520 performs, but being a Denon product I am sure it sounds good. Right now, the only commercially available amplifier using the Texas Instruments TPA31xx series Class D amplifiers is the TBI Millenia:

http://www.tbisound.com/dsp_products_millenia.asp

You can read the reviews linked to their Web site. These amps all have the similar Texas Instruments house sound, which based on my experience thus far, is very impressive.

Here are a couple links to the diyAudio.com forum threads discussing these amps:

http://www.diyaudio.com/forums/class-d/217903-ti-tpa3100d2-amazing-class-d-amp.html

http://www.diyaudio.com/forums/class-d/237086-tpa3116d2-amp.html

These amps are reasonably priced, so conducting your own experiment is pretty easy as long as you know how to stick wires into screw-down terminal blocks. As I mentioned earlier, the Yuan Jing amps available on eBay are probably the best choice for most. It offers higher power and it can be used with longer speaker cable lengths than the Sure Electronics TPA3110D2 amp.

I've been listening to some really well recorded RCA Living Stereo SACDs of orchestral music, and it really is impressive how this little amp seems to have incredible drive and headroom for reproducing complex passages. To my ears, I feel like I have a KT88 push-pull tube amp connected to my Audio Research LS7 Tube line stage preamp. With the higher efficiency of the La Scalas, an amp like this would play louder.

[NBPK402]

So how would these compare sonically to my Denon 4520 avr driving LaScalas? Would this be an upgrade in sound or just in efficiency?

Very good question. I have no reference for how the Denon 4520 performs, but being a Denon product I am sure it sounds good. Right now, the only commercially available amplifier using the Texas Instruments TPA31xx series Class D amplifiers is the TBI Millenia:

http://www.tbisound.com/dsp_products_millenia.asp

You can read the reviews linked to their Web site. These amps all have the similar Texas Instruments house sound, which based on my experience thus far, is very impressive.

Here are a couple links to the diyAudio.com forum threads discussing these amps:

http://www.diyaudio.com/forums/class-d/217903-ti-tpa3100d2-amazing-class-d-amp.html

http://www.diyaudio.com/forums/class-d/237086-tpa3116d2-amp.html

These amps are reasonably priced, so conducting your own experiment is pretty easy as long as you know how to stick wires into screw-down terminal blocks. As I mentioned earlier, the Yuan Jing amps available on eBay are probably the best choice for most. It offers higher power and it can be used with longer speaker cable lengths than the Sure Electronics TPA3110D2 amp.

I've been listening to some really well recorded RCA Living Stereo SACDs of orchestral music, and it really is impressive how this little amp seems to have incredible drive and headroom for reproducing complex passages. To my ears, I feel like I have a KT88 push-pull tube amp connected to my Audio Research LS7 Tube line stage preamp. With the higher efficiency of the La Scalas, an amp like this would play louder.

Thanks for the info... Where abouts are you in the Bay Area (let me know via PM if you don't want to post it)? I am in Concord.

[rhing]

I've been experimenting with the Sure Electronics TPA31110D2 Class D amp module I bought from Parts Express for $10. Here's what I've done to date:

1. Removed both stock 220uF / 25V power supply capacitors and replaced them with two (2) Panasonic FM 1,500uF / 25V low ESR electrolytic capacitors.
2. Moved the Vampire CM1F RCA connectors closer to the amplifier signal inputs at the front of the board to shorten the signal path.
3. Installed a Panasonic EVJ 50kohm audio taper dual gang volume potentiometer between the RCA connectors for volume control to use as a standalone amplifier.

Using this as a power amp with my Audio Research LS7 tube line stage preamp, or as an integrated amp, this is a very transparent amp. I can hear things that I do not normally hear with my modified TDA7297 chip amp or my SMSL SA-S1 T-amp. With the upgraded power supply caps, the sound quality improved in terms of:

• Bass response
• Richer tonality
• Greater dynamic range-headroom
• Reduced noise
• Greater separation of performers

I still hear a little background noise when I use this amp with the LS7 as a power amp, but when used alone, it is dead quiet like the TDA7297 chip amp. Even though this amp is rated around 5-8 watts with distortion less than 0.1-0.5%, it can easily drive my Klipsch Forte IIs. I've listened to a variety of music including rock, classical and jazz. I could see where the Texas Instruments Class D amp would make a great studio monitor amp for its accuracy. The tonality is very good and the amp has some warmth. I really see no other need for additional modifications at this point.

[DizRotus]

OUCH!

I fried a Sure TA2024 installed in my DIY boombox when I initially applied power. I suspect a dead short in the "RioRand LM2596 DC-DC Buck Converter Step Down Module Power Supply Output 1.23V-30" purchased from Amazon. The step-down is needed to reduce the 12v needed by the amp to 5V needed by the Harman Kardon Bluetooth adapter. Everything worked fine prior to being actually anchored to the boombox. I suspect the short was created when attaching the step-down. I should have used the DVM to check for shorts prior to flipping the switch. The amp and step-down are now toast. The h/k B'tooth adapter survived.

The good news is the cost to replace the amp is minimal. Also, while online ordering a replacement, I noticed that Sure makes a B'tooth adapter that also uses 12v, thus eliminating the need for a step-down. I've been impressed with the Sure amps, so I ordered a B'tooth adapter.

Edited January 7, 2014 by DizRotus

[rhing]

Sorry to hear about your Sure TA2024 amp.

Here are some photos of my completed Sure Electronics TPA3110D2 Class D amp. I ended up with another Panasonic FC 1800uF / 25V electrolytic cap on the power supply inputs on the board. This improved the sound in terms of deeper, tighter bass, a larger, deeper soundstage and a warmer sound.

The chassis is just about 3/4" wider than my iPhone 5 and the same length. Since it has slots to accommodate 3" wide boards like the Sure amp, I didn't even need to use stand-offs to mount it. I really like the sound of this amp a lot.

I used my Alan Parsons' "Sound Check 2" test CD to measure the frequency response from my Klipsch Forte IIs to compare the TPA3110D2 and TDA7297. The TPA3110D2 goes down to 31.5Hz, while the TDA7297 rolls off at around 40Hz.

[DizRotus]

Very cool. Where is the power input on your amp above? What are you using to power it?

I'll be ordering some more Panasonic caps for the power supplies of my Sure amps.

[rhing]

The Switchcraft 722A 2.1mm x 5.5mm DC power connector is located just below the power switch. From the connector, I run the "+" wire up to one lead of the NKK SPST power switch. Another wire is soldered to the other power switch terminal and twisted with the black Ground (or 0V DC) wire from the DC power connector and fed to the amp board where I have an additional Panasonic FM 2200uF / 25V cap soldered at the power input thru-holes--J8 in this instance.

I'm using the same modified Power One MAP110-S148 SMPS I have used for my T-amps and TDA-7297 amp. I had replaced all the second stage filter caps with 7X Panasonic FM 2200uF / 25V electrolytic caps and fabricated a DC power cable:

2X Kimber Kable TCSS 19AWG wires twisted as a pair

Polyethylene spiral cut tubing slid over the twisted pair

Polyester expandable sledging slid over the spiral cut tubing

Switchcraft DC power connectors added

This SMPS voltage output can be adjusted between 11 and 13.4V DC. I just have it set to 12V DC right now. This beats any of those brick supplies that came with my T-amps. I would like to build a nice, quiet high current regulated linear power supply, but that's a project that is beyond my DIY skills. I'm considering an Astron RS-12A regulated linear power supply, which is used for CB radios.

Handmade Electronics sells the Kimber Kable TCSS for just over $1.00/ft. I use this wire to connect the amp to the speaker binding posts as well. If you know how to make a tri-braid, you can even make your own Kimber Kable PBJ interconnects with the TCSS wire (2X - Ground, 1X - Signal), one of the best interconnects for the money.

Edited January 11, 2014 by rhing