rhing

Hi Mike, The battery should work fine. Here's a simple calculation you can use for the battery charge life: Power [watt] = Voltage [Volt] x Current [Amp], or P = V x I => Current [Amp] = Power [watt] / Voltage [Volt], => Current [Amp] = 15W / 12V = 1.25A and => Time[h] = Capacity[Ah] / Current[Amp] => Time[h] = 18Ah / 1.25A = 18h This is an approximation at best assuming no losses occur and that the amp is driven at 15W, which we know is not the case. As for the turn-on/turn-off thump, I haven't put a power switch in place between the amp and SMPS. When I plug in the amp, there is no thump. When I unplug the amp, I hear a small thump, but nothing that is objectionably loud or cause for damage. I actually leave the amp on for several days, and I haven't had any problems yet. Please share your listening impressions.

I'd like to know if you can hear the difference between the Wima and Panasonic caps with this amp. The Panasonics are no longer manufactured, so if the Wima's work fine, that would be great for others who want to try the amp. According to a description of your car starter battery unit, it is capable of providing "900 peak amps and 225 cranking amps of jump starting power." Is the amp chip smoking or getting warm when you have it connected to the amp? I am curious what sound quality differences you hear when you use this battery. That could very well be a very good power supply for this amp, especially for those of us who are on a dirty utility grid. I'm not sure what speakers you use in your home, but please share what kind of bass response you get from the TDA7297 amp, especially when you are possibly feeding 225-900A through the amp.

Google "Jim McShane Tubes" and you'll find his Web site. He's a great guy and very responsive. I only get my tubes from him now.

I think so, but opinions may vary. To my ears, the Panasonic caps are warmer and reproduce fuller notes, but I'm probably splitting hairs here. A friend of mine restored a Dynaco Stereo 35 power amp that duplicated my own Stereo 35 rebuild, except he used Polyester caps where I used the Panasonic ECQP Polypropylene caps. We did blindfolded listening tests comparing each other's Stereo 35's, and my amp came out on top when we auditioned different types of music--same tracks with each amp. This was an experiment among three listeners. Afterwards, he bought the same Panasonic ECQP caps from Jim McShane, and he's a happy man now. You can try the Sprague 716P Orange Drops, which are similar, but my personal preference are the Panasonic ECQP's.

Hi Neil, I like your experimental setup. I like the raw amp look. The TDA7297 seems to like 12V plus current. My modified SMPS, which I used with my SMSL SA-S1 T-amp puts out 12V and 4-5A. An audio buddy of mine who lives in the South purchased a Mean Well RS-100-12 SMPS that outs out 12V and around 7A. I have to take his word that he gets deep bass and plenty of slam. Like me, he owns a pair of Klipsch Forte II's. I tried my little black box SMPS that came with my Sonic Impact Gen 2 T-amp (Model 5065) that puts out 12V and 2A, the recommended power from the TDA7297 amp module manufacturer. It sounds okay, but it is anemic compared to my higher current modified SMPS: weakened bass, thinner sound and less detail. To get the most out of this amp, I would recommend something like the Astron RS-7A regulated linear power supply or the Pyramid PS9KX 13.8 VDC 5A regulated linear power supply. I'll probably get the Astron from a local marine radio and electronics dealer. I'm not sure what photo you are referring to, but I posted a photo of my amp with the Panasonic 0.22uF / 400V ECQP Polypropylene film and foil caps (the largish rust-colored epoxy coated caps). You can only get these from Jim McShane, a well known vacuum tube dealer. He's the only person I know that has NOS inventory of these caps. They cost $3.50 each, and a little extra if you want Jim McShane to match them. The more recent photo of my TDA7297 amp shows the Mundorf Supreme 0.22uF / 1200V metallized Polypropylene film caps. These caps are awesome, and I'm glad my buddy turned me onto them. The Panasonic ECQP caps are a tremendous value, but these Mundorf Supremes are definitely higher end audio caps. Mundorf makes even more expensive Supreme caps that use Silver and Silver/Gold. For your boombox needs, try the Wima MKP2 caps. They're good value and they work well. I used them in my rebuild and modification of my Dynaco SCA-35 tube integrated amp, and they worked very well in the phono stage and amplifier driver stage as coupling caps. They're compact, inexpensive and they look neat. My Audio Research LS7 line stage and PH5 phono stage preamps have a bunch of the little red Wima MKP caps in the power supply as bypass filter caps.

I'm glad you're enjoying the TDA7297. I don't know the significance of FM or FC. Both are excellent and can be used. The FM caps have a bit lower Equivalent Series Resistance (ESR) compared to the FC caps. This is preferable for power supply filtering. Both are rated for long life. I just happened to have some Panasonic FM caps on hand for modifying power supplies in Sony Playstations for CD playback. There is only one Panasonic FM cap that has the 2,200uF / 25V rating. This will fit right on the board, and is more than adequate for the application. An investment in a better power supply would go a lot further than going for a slightly larger cap. I'm not sure about the Panasonic ECQ-E Polyester film caps for the input coupling caps. I'm just not a fan of Polyester caps for audio signals. You can try them and see if you like them. I recommend the Wima MKP2 metallized Polypropylene caps (Mouser PN 505-MKP20.22/250/5). They should fit on the board without any problems.

You can mount the power supply cap off board, but keep it as close as possible to the DC input, and keep the polarity correct. I wish some of these Chinese manufacturers would make these boards a bit larger to accommodate upgrades and mods. Oh well. I can tell you that vinyl sounds good through this amp. You might as well let the amp burn in before you get your phono preamp. If you want to keep the amp compact for your portable system, you can use compact box-type capacitors like Wima MKP2 0.22uF / 250V metallized Polypropylene film caps from Mouser. Just make shire you get the caps with the 5mm lead spacing. These will fit on the board. I got the Mundorf Supreme caps, because I want really high quality caps, but the Wimas will sound much better than the stock Polyester caps.

Nice portable system there. The TDA7297 ought to work in that rig very nicely. I'd like to make a portable system using some highly efficient single drivers. I have a pair of small speakers using Fostex FX120 drivers and I'm thinking of designing some new bass reflex enclosures that will house a small amp like the TDA7297 to make the stereo pair more portable. Here's a photo showing these speakers sitting on top of my Forte II's driven by the TDA7297. It sounds very nice. I just met one of my son's classmate's dad, and he has a pair of Klipschorns that I would like to try with this amp. The Klipschorns are not portable, but they'll make the most of this flea-powered amp's first watt. For the power supply filter cap (the 2,200uF / 25V electrolytic), you can add higher capacitance if you want. You need to consider the size (diameter and height) and the voltage rating. The board you ordered may or may not accommodate a cap with a diameter larger than the stock cap, which is 12.5mm diameter. You have to consider the height of the capacitor based on the enclosure you want to place the amplifier in. As for the capacitor's voltage rating, use a cap with 25V up to 50V rating. Anything larger is unnecessary. I happened to use a Panasonic FM cap from Mouser Electronics since these caps are suitable for this type of application. Panasonic FC caps are also good choices.

If you intend to upgrade or modify this amp, use caution to not overheat the board while de-soldering and soldering. Some of these printed circuit boards aren't the best quality for re-working. The thru-holes and eyelets are less than 1mm diameter, so you have to be careful about capacitor leads properly fitting into the thru-holes. I received my 0.22uF Mundorf Supreme caps the other day and installed them in the TDA7297 amp the same evening. Using the Panasonic Polypropylene film and foil caps made a vast improvement in sound quality over the cheap stock Polyester film caps. Switching to the Mundorfs wasn't a quantum leap like the last change, but it was more a refinement of sound. Where the Panasonic caps addressed tonality, the Mundorfs maintained the warmth and rich tonality, but added a large degree of transparency. The timbre detail coming through along with a more focused image give more life to the music. My friend who recommended that I try the Mundorfs best describes these caps as having an organic presentation. Some may call it more life-like. I've gone through many capacitors in my DIY projects: Auricaps, Sonicaps, Sprague Orange Drops, Wimas, Obbligatos, Illinois Capacitor MPWs and the Panasonics, and these Mundorfs are very impressive. I have Sonicaps in my Klipsch Forte II crossovers that I purchased from Bob Crites as part of his crossover cap upgrade kit, but I might have to replace these with some Mundorf Supreme caps. The TDA7297, in stock form, is better than the SMSL SA-S1 TA2020 T-amp, but these cap upgrades really take this amp to a higher level of performance. The circuit is so simple, it only takes changing these three caps.

The plug should work fine. Try it out and enjoy.

The DTA-1 power supply should work. Can you share the specs that are usually written on the bottom of the unit?

And I see the link is to the B version which compared to the A version already has the power supply DC adapter in place. That's correct. I have the A version with the screw down terminals for the DC input. They're saving everyone time by including the DC power connector on the B version board now. They still offer the A version board. Just search for "TDA7297f" on eBay, and you'll find it. This amp seems to like more current. Using my modified SMPS, when I adjust the output voltage to 12V vs. 13.4V, the output current increases and the soundstage is a bit larger. My friend uses a Mean Well RS-100-12 SMPS with his TDA7297 amp, and when he dials the voltage down to 12V DC with a slightly higher output current, he gets a richer sound from this little amp. If you can use a power supply with 12+V DC and 5+A output, I think the results are very impressive. DizRotus, you should have received some tracking information from homemart.usa. My amp came within a week. I live in California, and my friend lives in Huntsville, AL, and he got his before I did. I'm still waiting on my 0.22uF Mundorf Supreme film caps and stepped attenuator. Once I get those, I'll post photos and listening impressions. I think I'll buy another TDA7297 to use as a baseline to gauge the effects of any component upgrades I make.

It sounds like a great presentation. It is truly amazing what Gustav Holst composed before the age of space flight. His use of the bass section to characterize the gravity of each planet is really incredible. Wish I could have been there.

The recommended power supply should be capable of providing 12V DC and 2A. I use a modified 110 watt Switch Mode Power Supply (SMPS) that has a regulated 12-13V DC and 3-4A output. The amp can actually be driven with anything from 12 to 16V DC. If you can find a laptop power supply or an LED monitor power supply that fits this range, that should be good for starters. These are usually SMPS and should work well. If you are a DIY audio person -- especially with working safely with power supplies -- I would recommend the Mean Well RS-100-12 SMPS. You will need to put this in an enclosure and also add the following: Power switch IEC inlet DC power cable With the right power supply, this amp will provide more bass and musical body than the Dayton DTA-1 amp. From what I know, the Dayton DTA-1 is basically the same as the original Sonic Impact T-amp using the Tripath TA2024 Class D chip. I have a Sonic Impact Gen 2 T-amp, which I have modified, and it still doesn't sound as good as the TDA7297 amp in stock form. I have since replaced the stock Polyester input coupling caps with Panasonic Propylene film and foil caps, and the sound quality has reached a new level. I have some Mundorf Supreme film caps and an SMD resistor-based stepped attenuator on the way. I have high expectations for taking this amp even further. I've even connected this little amp to my Audio Research PH5 phono stage, and I've obtained great results. This is a very musical amp, and it's so inexpensive. It doesn't beat my Audio Research LS7 and restored and modified Dynakit Stereo 35, but it's able to hold its own.

It is a slippery slope indeed. The low costs of these fine low power amps makes it a fun adventure to experiment and improve the audio chain with a low budget. The TDA7297 amp is a stereo amp. The amp I purchased has a 1/8" stereo jack. I bypassed this by soldering hook-up wire between my RCA connectors and the PCB where the stereo jack is mounted. I also recently replaced the 2,200uF/25V power supply cap with a better 2,200uF/25V Panasonic FM electrolytic cap that has further improved dynamic response and bass extension. I might replace the cheap Polyester film caps at the inputs with better Polypropylene film caps. By the way, besides the TDA7297 chip, the only other passive components in the signal path are the two input caps. The other handful of components are tied into the Mute and Standby circuits of the chip along with the two caps in the power supply. This amp is almost like a straight wire with gain. I don't want to give the impression this amp trounces the SMSL T-amp, because they do sound similar and they are both very good in their own right. What's impressive though is that this amp is only $6 and has a very low parts count making upgrades easy and affordable. On top of that, the sound is more immediate and perhaps less colored, because the circuit is so minimalist. With good, efficient speakers like Klipsch speakers a very nice amplification system can be built on a shoestring budget.

At the recommendation of some people on the diyAudio.com Class D amplifier forums, I decided to purchase a TDA7297 Class AB chip amp from an auction seller, Homemart.USA. The amp only cost $4.99 plus $1.00 shipping from Hong Kong. Several people claimed that this amp sounds better than the SMSL SA-S1 TA2020 Tripath Class D (i.e., Class T) amp. I've wasted $6 on bad lunches before, so I figured what could I lose. Within a week, the amp module came in a padded envelope from Hong Kong. It was wrapped in Saran Wrap and bubble wrap. The amp has a 2" x 2" footprint. The heat sink, which is the largest component on the printed circuit board is a bit less than 2" high. This amp is tiny. I wired it up in a makeshift test bed with 5-way binding posts and good quality RCA connectors. I hooked up my Klipsch Forte IIs, my Sony SACD/CD player and powered up the amp with the same modified power supply I used with my SMSL T-amp. I've been listening to music the last two evenings using this tiny amp, and I am amazed that this amp really does sound better than the SMSL amp. It digs deeper in the bass and sounds clearer than the SMSL amp. The tonality is balanced, the timbral detail is nice, and the amp has plenty of headroom despite its low power spec. I've listened to rock, classical and jazz, and I am impressed with the size of the soundstage and well defined imaging. The funny thing is the data sheet from STM, the chip's manufacturer, states that applications for this chip include televisions and portable audio.

I've found with using my SMSL SA-S1 with my Audio Research PH5 tube phono stage, I get a lot of the magic of tube audio. It still doesn't match the sound when I go with all tubes, but it does sound very nice with a bit of the holographic quality that tube amps provide. I listened to other Class D amps based on B&O's Ice Power, and Hypex amp modules, and they were okay, but not really as involving as Tripath-based Class D amps I've heard. One of the better Class D amps I've heard was a Lab Gruppem pro audio amplifier based on their Class TD technology. I have no idea what chip technology Lab Gruppen amps are based on, but it had similar sound qualities of Tripath Class D amps--clear sound and nice harmonic content without the high frequency artifacts that other Class D amps have. It's too bad Lab Gruppen doesn't make consumer audio amplifiers.

Jerry Bloomfield of Falcon Acoustics still runs a fine operation. I helped my non-DIY friend recap his KEF Reference 101 monitors using tested and matched Alcap electrolytic caps (same as OEM caps) from Falcon Acoustics, and the results were fantastic. With his revamped Conrad-Johnson MV75-A1 75 watt amplifier, my friend's system sounds great. I do like the British speakers, but my preference is for the Klipsch Heritage series speakers with upgraded crossovers and internal wiring. With T-amps and tube amps, they just sound magical to me.

What speakers are you using with these amplifiers?

Here is a link to the Paul Hynes regulator module for building a higher performance power supply for the SMSL SA-S1 T-amp. http://diyparadise.com/shop/index.php?main_page=product_info&cPath=3&products_id=110 With a nice high toroid power transformer, this should really enhance headroom and overall sound quality.

Hi Neil, That's interesting that you don't hear a difference between the SMSL SA-50 and SA-S1 amps in terms of sound quality except volume. With the mods you have planned for the Lepai amps, do you expect the results to sound better than the SMSL SA-S1? With these amps or the Lepai TA2020 amps, I believe improvements can be made with using better power supplies. I'm looking into the Paul Hynes power supply regulator module from DIYParadise or the regulated power supply kit from Welborne Labs. The Paul Hynes solution is more expensive since I would need to get a power transformer and enclosure, but I have read positive reviews with using his module with Tripath TA-2020 amps. The Welborne Labs offering looks attractive, but I've read some spotty reviews about Welborne Labs' service.

Compared to some of the cheap wire and thin PCB traces, good wire can make a noticeable improvement. The cap in the link is 1F = 1,000,000uF. That would explain part of the price. The rest is just profit margin based on marketing hype.

Compared to some of the cheap wire and thin PCB traces, good wire can make a noticeable improvement. The cap in the link is 1F = 1,000,000uF. That would explain part of the price. The rest is just profit margin based on marketing hype.

Which is as big as the whole amp. Love it! I read that one guy was using one of these in his T-amp power supply and getting much improved bass. http://www.monstercable.com/mpc/productPageMPC.asp?pin=2950&section=two Maybe the car audio guys are onto something.

Siemens MKL = metallized lacquer film Siemens KS = Polystyrene film Very nice indeed. I haven't read too much about these Siemens caps on the American audio forums, but your choices make a lot of sense. I may have to check out eBay and search some of these out, especially the Siemens KS Polystyrene caps. Next to Teflon, Polystyrene is a good cap material choice for audio, especially in cool running Class D amps where there is no problem with heat affecting the Polystyrene caps. The BHC slit foil electrolytic cap is very high end too. These caps are used in vintage Naim and Rotel amp power supplies. When you removed the volume pot, did you replace the pot with 10k or 20k resistors? Thank you very much for sharing your upgrades on the SMSL SA-50 amp.