Maybe I was a bit premature in judging the small cheap TD7297, I went in and removed the cheap pot to bypass it and the sound improved dramatically - I would say as good as the larger lunch money amp now, perhaps maybe better since the SMT components for resistors and caps allow a tight layout for less noise pickup. I wish it had a standard 3.5mm jack though. The heatsink runs warmer than its bigger brother though - just less ability to dissipate but not too hot to touch at 12v.
I converted the amp to mono bridged by using two 4.7k as bypass leads for the pot and then tying to common and then tied outputs together. Works great for a small TABAQ speaker.
Hi folks, new to the 7297 bandwagon here. I've just received the module, blue PCB that is common on evilBay. I'm interested in replacing simple parts with better quality ones, for starter is the caps. I see one 2200uF 25V and one 10uF 25V. I have access to 2200uF 50V and 15uF 50V Nippon ChemiCon, and 10uF 50V Panasonic. Please advise what difference in sound can I get by going bigger in voltage, also what will happen if I switch 10uF with 15uF? Thanks.
Until you upgrade to my PCB boards, here's a good little way to do up the board. You may have to make adjustments for your board if it's different.
Thanks for the link, I've read that thread but unfortunately I live so far away from Mouser/Digikey and have limited access to the parts listed in that thread. What I can get is what I've mentioned in my post above, and I'd like to know what differences I can expect. Thanks again!
The pictures are not good enough to judge for certain, but I do have some safety concerns. This is for your kid?
Its waiting the iec socket and me to get time off to install it be for I give it to her
Thanks for this guide, I've read it and found that my board is one with reversed speaker polarity marker.
I'm ordering another one of the same board, to run A/B and see how different components affect the sound.
AC DC 12V TDA7297 2 15W Digital Audio Dual Channel Amplifier Module Board Kit | eBay
I have the following items in my cart at a local components supplier:
220nF 100V
15uF 50V Nippon Chemi-Con FL 105C
2200uF 50V Nippon Chemi-Con KY 105C
1uF 250V MKP Audiophiler
AC DC 12V TDA7297 2 15W Digital Audio Dual Channel Amplifier Module Board Kit | eBay
I have the following items in my cart at a local components supplier:
220nF 100V
15uF 50V Nippon Chemi-Con FL 105C
2200uF 50V Nippon Chemi-Con KY 105C
1uF 250V MKP Audiophiler
This is the stock board:
This is the upgrade I'm planning to do:
Replacing the elco with Nippon Chemicons
Removing the diode and put jumper wire in its place
Removing the small cap (not sure if it's ceramic or tantalum capacitor) with MKP, capacity is 100nF if I understand correctly
Not sure about the mylar caps, looks like what I have locally is the same quality as what's on board, so prolly just leave it there.
Any suggestions? Thanks, really excited now.
This is the upgrade I'm planning to do:
Replacing the elco with Nippon Chemicons
Removing the diode and put jumper wire in its place
Removing the small cap (not sure if it's ceramic or tantalum capacitor) with MKP, capacity is 100nF if I understand correctly
Not sure about the mylar caps, looks like what I have locally is the same quality as what's on board, so prolly just leave it there.
Any suggestions? Thanks, really excited now.
Folsom Mods
I followed the mods by Destroyer OS (aka Folsom) suggested as much as possible. I did not buy any new parts but scrounged all this from my existing or salvaged parts bin. I am using an ENEC 1uF X2 MKP 305V cap bypassed with a 1800pF 250V axial MKP film cap which I also used for its long legs. Panasonic FM 560uF 35V (top) and ECA-1VM471 470uF 35V (bottom), Nichicon 100uF 25V in place of the the little 10uF electrolytic (what is that for? Are you saying it's not needed?). I replaced the 22nF ceramic bypass with a Milspec AVX 104 100V box film cap. I got rid of the pot, but decided to keep the power jack and 3.5mm jack for convenience. Got rid of the diode. Swapped the terminal blocks for higher quality (green) ones.
So it sounds pretty nice - I think the bass is more decisive and mids have more clarity.
Top view:
Bottom side:
Detail of ENEC 1uF and 1800pF bypass cap, and new terminal blocks:
I followed the mods by Destroyer OS (aka Folsom) suggested as much as possible. I did not buy any new parts but scrounged all this from my existing or salvaged parts bin. I am using an ENEC 1uF X2 MKP 305V cap bypassed with a 1800pF 250V axial MKP film cap which I also used for its long legs. Panasonic FM 560uF 35V (top) and ECA-1VM471 470uF 35V (bottom), Nichicon 100uF 25V in place of the the little 10uF electrolytic (what is that for? Are you saying it's not needed?). I replaced the 22nF ceramic bypass with a Milspec AVX 104 100V box film cap. I got rid of the pot, but decided to keep the power jack and 3.5mm jack for convenience. Got rid of the diode. Swapped the terminal blocks for higher quality (green) ones.
So it sounds pretty nice - I think the bass is more decisive and mids have more clarity.
Top view:
Bottom side:
Detail of ENEC 1uF and 1800pF bypass cap, and new terminal blocks:
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The small film cap is very bad for sound. You can literally hear the ringing stop if you remove it. (you can just wiggle it till it's off) The treble will be much easier to listen to without it.
The 10uf is needed to keep the mute/standby from turning on. It's not very important in terms of quality at all.
1uf input caps are a little small. If you want good bass under 100hz, down to 20hz, you'll need to up it to something like 1.5uf.
The 10uf is needed to keep the mute/standby from turning on. It's not very important in terms of quality at all.
1uf input caps are a little small. If you want good bass under 100hz, down to 20hz, you'll need to up it to something like 1.5uf.
Ok I can take the 0.22nF film cap off - I thought it was to provide a close-to-chip power supply bypass? Why would a chip on the power supply cause ringing? Anyhow, the 10uF was replaced with a nice 100uF which I will swap back as I will reserve the nicer cap for something else. Regarding the main input caps, your recommendation was a 1uF MKP - are you saying that was incorrect? I have a Panasonic brown 3.3uF 250V MKP I could have used. Although none of my speakers go down to 20Hz except a FLH bass horn which I am not using this amp for. Maybe it's fine for 40Hz?
I believe I changed it to 1.5uf. The corner frequency says 1uf is good, but listening shows truncated base with only 1uf.
The .22nf cap rings with the capacitance that comes before it most likely, not the chip. What I'm saying is it's not just a minor argument about best practices, but rather that it's very audible and bad.
100uf on the mute/standby is causing no harm. There wasn't a reason to change it before, nor one now.
Okay I can definitely hear the ringing. Am now in the process of listening and getting myself familiar with its qualities, so I know what each component changes did. First on the list is removing the small cap and diode. In your build guide v.2 you still put jumper wire, is that not needed in my case? If you'd kindly elaborate, I'd be most thankful.
I have ordered another one from the same seller, looking to compare the difference between stock vs modded.
In my board above, input cap is 0.22uF marked by 224 right? Is it correct to replace it with MKP type capacitor? I can get Wima, Ero, and some Chinese/Taiwanese brands, voltage ranging from 50 to 250V. I noticed some have long legs, while others have short legs like xrk971 above has. What does different voltage capacity does in this case?
Thanks for your kind explanation, as you can tell I'm a noob but I'm enjoying the learning process.