I have two of these amps, and I liked the first one so much that I decided to get a nice anodized Aluminum case for it. I bought this Context Engineering case from a local Fry's Electronics (a chain of electronics superstores that are the size of a department store). I swapped out the eBay-bought 21-step SMD resistor stepped attenuator, and installed an Alps Blue Velvet volume pot. I really like this amp a lot and it will serve well as an alternative to my tube amps.
Here are a couple photos of my second unit in prototype mode. I was going to leave it stock for a while, but without the upgraded 2,200uF / 25V Panasonic FM cap in the power supply path, it really lacked a nice low end and deep soundstage. I put that cap in and also upgraded the input caps with a pair of 1uF / 50V Black Gate N non-polar caps I had in my spare parts bin. I installed the SMD resistor stepped attenuator on the board. This photo doesn't show it, but it almost looks the same as the stock volume pot. This amp sounds great too, and eventually, I'll probably stick this in a nicer enclosure as well.
Both of these amps sound great with my turntable and Audio Research PH5 phono stage. This next weekend, I'm going to have some audio friends come over and compare these amps to my Audio Research LS7 line stage amp and Dynakit Stereo 35 power amp combination.
Next up is an evaluation of the TI TPA3116D2 Class D board.
Here are a couple photos of my second unit in prototype mode. I was going to leave it stock for a while, but without the upgraded 2,200uF / 25V Panasonic FM cap in the power supply path, it really lacked a nice low end and deep soundstage. I put that cap in and also upgraded the input caps with a pair of 1uF / 50V Black Gate N non-polar caps I had in my spare parts bin. I installed the SMD resistor stepped attenuator on the board. This photo doesn't show it, but it almost looks the same as the stock volume pot. This amp sounds great too, and eventually, I'll probably stick this in a nicer enclosure as well.
Both of these amps sound great with my turntable and Audio Research PH5 phono stage. This next weekend, I'm going to have some audio friends come over and compare these amps to my Audio Research LS7 line stage amp and Dynakit Stereo 35 power amp combination.
Next up is an evaluation of the TI TPA3116D2 Class D board.
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Very nice! Thanks for posting this. It's great to see pics of how others are using these boards.
A couple of quick questions for you.
Is the Alps pot out-performing the 21-step SMD resistor stepped attenuator?
What Value is the Alps?
To my ears, the Alps Blue Velvet 100k log-tapered volume pot is equal to the 50k log-tapered, 21-step SMD resistor attenuator in terms of transparency and balance. I happened to have this Alps volume pot on-hand for a Dynaco tube amp project where I didn't need it after all. For the TDA7297 as an integrated amp, I wanted the ability to more finely adjust volume when feeding audio directly from my ARC PH5 phono stage or Sony ES SACD/CD player. The 50k SMD stepped attenuator seems to only give me about 2-3 positions before it gets too loud, so that's why I tried the 100k pot.
At the same time, I wanted a transparent volume pot to allow me to use this as a power amp when feeding audio from my ARC LS7 line stage for more tube magic. Here's a photo of the amp connected to my LS7 with the volume pot turned all the way up. Sounds great!
Try the Sure TPA3110D2 from PE for $10. You can upgrade power supply caps and run it from 19v brick. Sounds great to my ears - just a less powerful version of the 3116. I am listening to it totally stock and really enjoying it. There are some sound clips with it and a mini Karlsonator speaker here: http://www.diyaudio.com/forums/attachments/full-range/386726d1386621099-mini-karlsonator-0-53x-dual-tc9fds-karlsonator-04x-clip5.zip
Very nice anodized aluminum box BTW.
There is a kit version here:
TDA7297 Audio Amplifier Board Amplifier 2X15W With Wima Capacitor | eBay
I've ordered two of these to replace the one I fried (which was the assembled version with the wima capacitors)... hopefully at least one of them will survive this time...
TDA7297 Audio Amplifier Board Amplifier 2X15W With Wima Capacitor | eBay
I've ordered two of these to replace the one I fried (which was the assembled version with the wima capacitors)... hopefully at least one of them will survive this time...
Just for the record these do not like 20VDC at all. I just let the magic smoke out.
I seriously considered one of those kits, but it looks like the heat sink sits right over the two board mounting holes in the back end of the board. Other than that little quirk, the kit looks like a winner.
Thanks for the recommendation. KJA 2013 and wushuliu also recommended that I check out the Sure TPA3110D2 amp as well as the Yuan Jing TPA3116D2 2.0 amp. I had a Sure TA2024 board years ago that I experimented with, and I really disliked working with boards using SMD components, because the SMD pads started to fall off with multiple heats from trying different parts. I know these boards are pretty cheap and I can always get more if I screw one up, but I hate wasting boards and trying to do repair surgery in case a pad goes. I wish someone had an all thru-hole TPA31xx board. Jerry's Electronics has a TPA3122D2 15W amp board for thru-hole components, but I do not know if that Class D amp is comparable to the TPA31110D2 or the TPA3116D2 amps, which everyone seems to be impressed with. Will an SMPS with 12V DC nominal output be adequate for the TI Class D amps?
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Good looking little box you have there rhing. Is that a Dual 122x series turntable I see there in your rig? I have a near mint 1229 that works as perfect today as it did back in the Summer of 1972 when it was new. 41 yrs old and still going strong. Actually, it's not in service at the moment due to a recent move and me trying to finish my man-cave.
This is a great hobby!
redjr,
The turntable is an obscure Kenwood PC-400U belt/idler wheel drive turntable that was made in the late-1960's. It's basically Trio Electronics' (Kenwood's parent company) clone of the Thorens TD124 minus the eddy current braking system. Most Japanese electronics from the late-1960's seemed to make it to the US through servicemen who bought hi fi gear while serving in Asia. A friend who bought it through eBay received it from a seller who didn't package it well, so it sustained damage to the dust cover by the time he received it. My friend was so sour about the deal, he told me I could take it and work with it to see what I could do with it. The first area that needed attention was the platter bearing assembly, so I dismantled it, and polished the spindle and thrust bearing to a mirror finish. Next, I fabricated a new Delrin thrust bearing plate to replace the completely shot original Polyurethane plate. I went to the nearest Yamaha/Honda motorsports dealer for high performance Molybdenum grease and applied it to the bearing assembly. After that, I dismantled the stock Jelco SA-100 tonearm and polished the pivot bearing cups and points and re-wired the arm with Cardas phono wire and added a little damping material. It took me a while to figure out how to balance the tonearm with no manual available. This turntable is a rare find, so it's not like I could consult a lot of people through Web forums for help. Another friend gave me a Talisman Alchemist IIB high output moving coil cartridge to replace the Shure MM cartridge. My friends and I have had turntable shoot outs with this turntable, a rebuilt Bogen Lenco L75, an Empire belt driven TT, a Thorens TD124 and a Sota Sapphire. Everyone loves the dynamic response, drive, huge soundstage and detail that this TT produces. The icing on the cake was finding a matching Kenwood dust cover for $20 through eBay.
I would love to get my hands on a reasonably-priced Dual 1229 or Dual 1019 TT to refurbish. I used to own a Linn Sondek LP12 with an Ittok II arm and Grado Signature MM cartridge, and it was a great belt drive TT, but I've converted to the idler wheel drive camp. My uncles who were audiophiles owned McIntosh amps, Fisher amps, AR loudspeakers and Dual turntables. I have very fond memories listening to their stereos with those German turntables.
The turntable is an obscure Kenwood PC-400U belt/idler wheel drive turntable that was made in the late-1960's. It's basically Trio Electronics' (Kenwood's parent company) clone of the Thorens TD124 minus the eddy current braking system. Most Japanese electronics from the late-1960's seemed to make it to the US through servicemen who bought hi fi gear while serving in Asia. A friend who bought it through eBay received it from a seller who didn't package it well, so it sustained damage to the dust cover by the time he received it. My friend was so sour about the deal, he told me I could take it and work with it to see what I could do with it. The first area that needed attention was the platter bearing assembly, so I dismantled it, and polished the spindle and thrust bearing to a mirror finish. Next, I fabricated a new Delrin thrust bearing plate to replace the completely shot original Polyurethane plate. I went to the nearest Yamaha/Honda motorsports dealer for high performance Molybdenum grease and applied it to the bearing assembly. After that, I dismantled the stock Jelco SA-100 tonearm and polished the pivot bearing cups and points and re-wired the arm with Cardas phono wire and added a little damping material. It took me a while to figure out how to balance the tonearm with no manual available. This turntable is a rare find, so it's not like I could consult a lot of people through Web forums for help. Another friend gave me a Talisman Alchemist IIB high output moving coil cartridge to replace the Shure MM cartridge. My friends and I have had turntable shoot outs with this turntable, a rebuilt Bogen Lenco L75, an Empire belt driven TT, a Thorens TD124 and a Sota Sapphire. Everyone loves the dynamic response, drive, huge soundstage and detail that this TT produces. The icing on the cake was finding a matching Kenwood dust cover for $20 through eBay.
I would love to get my hands on a reasonably-priced Dual 1229 or Dual 1019 TT to refurbish. I used to own a Linn Sondek LP12 with an Ittok II arm and Grado Signature MM cartridge, and it was a great belt drive TT, but I've converted to the idler wheel drive camp. My uncles who were audiophiles owned McIntosh amps, Fisher amps, AR loudspeakers and Dual turntables. I have very fond memories listening to their stereos with those German turntables.
Thanks for the history. It's always nice to hear the story behind how we all came by some of our gear, and what we've done to restore/rebuild certain pieces. Good stuff.
- RickBTW - I have an old Dual in a box down in my basement. Not exactly sure of the model #. I picked it up on eBay a couple years ago and it's been boxed up ever since. I don't think it was a 1229, but close enough in model numbers that I picked it up for spare parts. Not sure how well/if at all it functions. It's your's for shipping costs only. I'll check when I get home tonight for the exact model and PM you.
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I just found a cheap replacement pot, in case anyone is interested. Not as good quality as the other ones discussed here, but should work as an inexpensive ($1.68) replacement of the non functional original. It would be the Bourns PDB182-K430K-503A available from digikey.
If you have the simple LM338 or the high end "tracking pre-regulator" LM338 pair, I'd suggest to find out what voltage (below 16v) that the little amplifier likes best (per subjective sound quality for reasons of practicality).
First thing to try would be 14.8vdc (same voltage as a car with the engine running).
Every Class AB chip amplifier has a voltage "sweet spot" and it would be very interesting to know what voltage that is for this chip. So, what voltage are you running at?
First thing to try would be 14.8vdc (same voltage as a car with the engine running).
Every Class AB chip amplifier has a voltage "sweet spot" and it would be very interesting to know what voltage that is for this chip. So, what voltage are you running at?
I'm using an inexpensive Chinese built LM338 adjustable PS with the fan removed and pegged at 18vdc with super glue.
The amp's tiny heatsink remains just above room temp. connected to my big old 15Ohm speakers at a serious listening level.
I'm guessing that inefficient sealed box jobs will give different results?
I'm also running a little $8 fm module, mentioned on this thread, from the LM338 PS. Super quiet reception, so unlike the all the D-amps I have tried and ditched.
Here are my limited results so far using my 8 ohm nominal impedance, 98dB sensitive Klipsch Forte II three-way floorstanding speakers:
1. Sonic Impact T-Amp SMPS (12VDC/2A), brick-type:
My plan is to build or purchase a regulated linear power supply like an LM338 regulated type with adjustable output around 12VDC for comparison.
I've been posting on other forums like the Klipsch forum, and others have reported good results with SLA batteries.
1. Sonic Impact T-Amp SMPS (12VDC/2A), brick-type:
- Thin sounding
- Weaker bass
- Less definition/detail
- Shallower soundstage
- Blurred imaging
- Slightly richer, fuller sound, especially in midrange
- Bass is audible, but lacks punch or definition
- Shallow soundstage
- Slightly improved imaging, but difficult to accurately locate performers in space
- Rich, full sound with good tonality
- Strong, punchy bass
- Deep soundstage
- Good imaging with better defined location of performers
- Slightly better than Option 2, but with better bass response
- Soundstage was shallower compared to Option 3
My plan is to build or purchase a regulated linear power supply like an LM338 regulated type with adjustable output around 12VDC for comparison.
I've been posting on other forums like the Klipsch forum, and others have reported good results with SLA batteries.
I think we are discussing the tda7297?
I have purchased various d-amps recently and have been very disappointed because they all produced EMI and I'm loath to give up on FM radio just now.
The 2 very simple looking non d-amp boards I have purchased, tda7297 and TDA7294, do not produce EMI and sound better (to me) than the D-amps.
Besides the D-amps use in battery powered equipment, are there other advantages to this technology?
Yes, exactly. I just tried all these SMPS from my T-amps with the TDA7297 and listed my results above. To date, I would agree that the TDA7297 sounds better than the Tripath-powered Class D amps (T-amps) I've tried so far, and that also includes a Virtue Audio Two TK2050-based amp.
I've ordered a Sure Electronics TPA3110D2 amp from Parts Express and I will compare that to the TDA7297 and my vacuum tube amp system.
I've ordered a Sure Electronics TPA3110D2 amp from Parts Express and I will compare that to the TDA7297 and my vacuum tube amp system.
What the heck? I paid $4.50 !!!!
Ok, I have been reading this thread and after I received the amp boards, I decide to chime in....
I bought two boards from another seller that was not mentioned in this thread. But I paid only $4.5 each. The package came from China so it took almost 3 weeks to arrive.
I ordered two and have only tried one board and listening to it while I'm typing this. It was really hard to believe this board can deliver such good sound. It does sound tube like and no where makes you think this is a class AB chip amp.
The volume pot is L/R balanced. I don't notice any side weaker or stronger than the other. Everything is stock now and the power supply is a small uA723 regulated linear supply set to 13VDC. The amp is quiet, not hearing any noise when there is no input signal.
After I tested it out on the bench, most importantly to measure the output DC (15mV/7mV, L/R), I moved it to the living room have it now driving my Tannoy 611 MKII floor. Lots of volume to spare and very enjoying to listen to.
The other board has a kind of problem. The PCB is supposed to be single sided, meaning the component side should have no copper trace. But the PCB has manufacturing defect. There is a large area of copper remains on the component side (see pics). I don't want things to short-out so I haven't test it yet. But I will just put it on test bench using the lowest DC voltage to try out later. If it works, I probably will de-solder some components and drill out some copper so it will not cause a short circuit....
By the way, what are those .22uF input caps. Are they worth keeping ? or better replace them ?
But "What the heck? I paid $4.50 !!!!"
Ok, I have been reading this thread and after I received the amp boards, I decide to chime in....
I bought two boards from another seller that was not mentioned in this thread. But I paid only $4.5 each. The package came from China so it took almost 3 weeks to arrive.
I ordered two and have only tried one board and listening to it while I'm typing this. It was really hard to believe this board can deliver such good sound. It does sound tube like and no where makes you think this is a class AB chip amp.
The volume pot is L/R balanced. I don't notice any side weaker or stronger than the other. Everything is stock now and the power supply is a small uA723 regulated linear supply set to 13VDC. The amp is quiet, not hearing any noise when there is no input signal.
After I tested it out on the bench, most importantly to measure the output DC (15mV/7mV, L/R), I moved it to the living room have it now driving my Tannoy 611 MKII floor. Lots of volume to spare and very enjoying to listen to.
The other board has a kind of problem. The PCB is supposed to be single sided, meaning the component side should have no copper trace. But the PCB has manufacturing defect. There is a large area of copper remains on the component side (see pics). I don't want things to short-out so I haven't test it yet. But I will just put it on test bench using the lowest DC voltage to try out later. If it works, I probably will de-solder some components and drill out some copper so it will not cause a short circuit....
By the way, what are those .22uF input caps. Are they worth keeping ? or better replace them ?
But "What the heck? I paid $4.50 !!!!"
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You're doing great! It's fun isn't it!
Those .22 are the input caps and they can be changed.
The other board's ok, that's just the paint/varnish coming off the copper. Just put electrical tape over it and you're good to go!
So what you should do is keep one stock, compare to get a baseline and then start your mods one at a time and listen for any difference. It's a blast, you'll love it! I commend your jump-right-in DIY style!
You can see my upgrade path starting here and going for 3 pages with descriptions of all components
http://www.diyaudio.com/forums/class-d/231988-what-heck-its-less-than-lunch-16.html#post3706119
Upgraded:
Step atten, sm 24 pos 10k
Silmic II 2.2/100V input caps
FC 2200uF/25V ps cap
100nF, 100V X7R ps cap
increased C4 mute cap
Schottky on the bottom. (That's what she said!)
Those .22 are the input caps and they can be changed.
The other board's ok, that's just the paint/varnish coming off the copper. Just put electrical tape over it and you're good to go!
So what you should do is keep one stock, compare to get a baseline and then start your mods one at a time and listen for any difference. It's a blast, you'll love it! I commend your jump-right-in DIY style!
You can see my upgrade path starting here and going for 3 pages with descriptions of all components
http://www.diyaudio.com/forums/class-d/231988-what-heck-its-less-than-lunch-16.html#post3706119
Upgraded:
Step atten, sm 24 pos 10k
Silmic II 2.2/100V input caps
FC 2200uF/25V ps cap
100nF, 100V X7R ps cap
increased C4 mute cap
Schottky on the bottom. (That's what she said!)
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Great idea of keeping one stock and mod the other one for comparison! I did read your upgrades before I started posting.
I was just asking what type of stock input cap on the amp if anybody recognize them. I definitely will try PP film type input caps. But as of stock form, the amp sounds very good. The bass department is definitely better than class D/T.
I'll eventually mount the amp on a permanent chassis. I'm wondering if the metal part on the chip is ground ? or do I need insulation if I'm going to mount it to the chassis directly (using the chassis as the heat sink)?
I can't believe the datasheet says TV as the application. It's a waste for that ! I think of using 2 amps to drive the four speakers in my car taking the signal from the Lineout RCA of the head unit. I don't think a regular head unit can sound this good.
*How did this discussion falls under Class-D forum ?
I was just asking what type of stock input cap on the amp if anybody recognize them. I definitely will try PP film type input caps. But as of stock form, the amp sounds very good. The bass department is definitely better than class D/T.
I'll eventually mount the amp on a permanent chassis. I'm wondering if the metal part on the chip is ground ? or do I need insulation if I'm going to mount it to the chassis directly (using the chassis as the heat sink)?
I can't believe the datasheet says TV as the application. It's a waste for that ! I think of using 2 amps to drive the four speakers in my car taking the signal from the Lineout RCA of the head unit. I don't think a regular head unit can sound this good.
*How did this discussion falls under Class-D forum ?
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