$6 TDA7297 Chip Amp

rhing · « **Reply #100 on:** 6 Jan 2014, 02:29 am »

Any chance the speaker cables may have shorted? It can easily happen when strictly relying on those terminal blocks for bare wire connections.

Folsom · « **Reply #101 on:** 6 Jan 2014, 02:31 am »

Eating my words.

S Clark · « **Reply #102 on:** 6 Jan 2014, 04:04 am »

I put the TDA7297 amp on more efficient speakers tonight. Also, I had changed the caps to Panasonics and Sprague orange drops. Much deeper and cleaner bass. Listening thru vintage speakers (Design Acoustics D12's)

and a Sony Walkman cd player... and it sounded actually very good. Not ready to sell my main rig type good, but I could live with this.

Folsom · « **Reply #103 on:** 6 Jan 2014, 04:13 am »

Clark what do you have powering it?

I have no idea what orange drops sound like, but I can tell you for the money my muse es tactic will blow your socks off. It makes my black gates sound like harsh toys.

S Clark · « **Reply #104 on:** 6 Jan 2014, 05:13 am »

I'm using a 26 Ah battery- will power it for at least 12 hours that I know of. Keep a charger on it over night and it never goes dead. Now, what exactly is a "muse es tactic"?

Folsom · « **Reply #105 on:** 6 Jan 2014, 05:19 am »

Nichicon Muse ES. Two 1uf's in opposite orientations, for each input cap. I was just refering to what I did in my build guide. I don't know how I could be more impressed.

Did you pull the diode?

I'm just buggin you because at some point I think you might view it as a contender for your main amp (well depending on speakers)

S Clark · « **Reply #106 on:** 6 Jan 2014, 05:41 am »

Quote from: Salis Audio on 6 Jan 2014, 05:19 am

Did you pull the diode?

I'm just buggin you because at some point I think you might view it as a contender for your main amp (well depending on speakers)

The diode is the next thing to go.
Somehow I doubt if it is going to replace my Moscode 401HR. I need those 200 wpc to control the back EMF on my LS9 speakers. Nearly everyone that owns them has come to the same conclusion.
Here is a picture of a pair at RMAF.

Oh, the orange drops are decent polypropylenes.

Folsom · « **Reply #107 on:** 6 Jan 2014, 06:30 am »

Hm, yeah maybe a bit shy on power

shadowlight · « **Reply #108 on:** 6 Jan 2014, 02:15 pm »

Quote from: rhing on 6 Jan 2014, 02:29 am

Any chance the speaker cables may have shorted? It can easily happen when strictly relying on those terminal blocks for bare wire connections.

That is possible. Will not get a chance to work on the amps until the weekend. Will let everyone know what the outcome is

rhing · « **Reply #109 on:** 6 Jan 2014, 03:59 pm »

Quote from: S Clark on 6 Jan 2014, 05:41 am

The diode is the next thing to go.
Somehow I doubt if it is going to replace my Moscode 401HR. I need those 200 wpc to control the back EMF on my LS9 speakers. Nearly everyone that owns them has come to the same conclusion.

Oh, the orange drops are decent polypropylenes.

Nice LS9 linear arrays with ribbon tweeters. Dannie Richie is a great, and under-appreciated speaker designer. I was at that RMAF, but missed hearing the LS9's, there was so much to see and hear. I wish I did, because linear arrays are great speakers when done right. It's the reason why so many excellent pro audio set-ups use them.

The TDA7297 will never give you enough current to power those speakers. I'd be interested in how good the little amp sounds with those "mod" DA geodesic speakers.

shadowlight · « **Reply #110 on:** 7 Jan 2014, 01:03 am »

Pictures of the amp that is not working due to the wima cap (the one closest to the heat sink) that is not properly connected (one side is flapping loose. Will have to desolder and try it again. I thinking I have everything else connected correctly but could definitely use a second look from someone else.

Folsom · « **Reply #111 on:** 7 Jan 2014, 02:30 am »

Your incoming wires for signal are connected to nothing. Please look at this, and rewire to these holes for R(ight) , L(eft), and G(round)

S Clark · « **Reply #112 on:** 7 Jan 2014, 05:47 am »

Quote from: rhing on 6 Jan 2014, 03:59 pm

Nice LS9 linear arrays with ribbon tweeters. Dannie Richie is a great, and under-appreciated speaker designer. I was at that RMAF, but missed hearing the LS9's, there was so much to see and hear. I wish I did, because linear arrays are great speakers when done right. It's the reason why so many excellent pro audio set-ups use them.

The TDA7297 will never give you enough current to power those speakers. I'd be interested in how good the little amp sounds with those "mod" DA geodesic speakers.

Those old Design Acoustics have never sounded this good on any of the old stuff that used to drive them. They are fairly efficient (about 92dB) and the TDA7297 fills a big room with plenty to spare. Orchestral music has clean mids, pretty good instrument separation, pretty good soundstage, and very clean bass (the better caps make a difference). These usually do HT duty, but for several days its been set up for music. I really could sell about $10k worth of gear, keep this little amp and those old speakers and be pretty darned happy with my listening.
The TDA is a better amp that all the mid fi stuff that used to power those speakers - a 60wpc Sherwood 7900 receiver, a Marantz 1060 integrated, a Soundcraftsmen amp/Sansui pre, and lastly a Karma Hardon AV receiver. Oh, I forgot the Pioneer 1010 receiver. None is close in terms of clarity. Now, it isn't in the same league as my modded Moscode 401HR with a Dodd pre. Doesn't have the soundstage depth, not as clear, but its musical... and is 1/1000th the cost. Well, after an extra $8 worth of caps, I guess it's only 1/500th the cost. Don't want to be accused of hyperbole.

Folsom · « **Reply #113 on:** 7 Jan 2014, 11:01 am »

Clark, if I sent you 4 Nichicon caps would you give them a go?

Also I wonder how a lithium battery that's lower impedence would sound.

I am meaning to put a B1 buffer in front of this amp. It seems sensitive to impedence matching since it's leading and trailing detail goes up with volume (hence some imaging and timbre).

shadowlight · « **Reply #114 on:** 7 Jan 2014, 01:48 pm »

Quote from: Salis Audio on 7 Jan 2014, 02:30 am

It's not the wima cap. It has nothing to do with it, BUT you should replace it with stock one. The Wima is way too big. It might lower the gain of the amplifier significantly.

Your incoming wires for signal are connected to nothing. Please look at this, and rewire to these holes for R(ight) , L(eft), and G(round)

Salis,

Will rewire the left and right with ground. What am I suppose to do for the other 4 holes which are left of the R/L connection? I am also getting a replacement volume pot and wiring changes do I need to make to get it working with the new pot.

mboxler · « **Reply #115 on:** 7 Jan 2014, 02:26 pm »

Quote from: shadowlight on 7 Jan 2014, 01:48 pm

Salis,

Will rewire the left and right with ground. What am I suppose to do for the other 4 holes which are left of the R/L connection? I am also getting a replacement volume pot and wiring changes do I need to make to get it working with the new pot.

Actually, your wiring looks good as is, as long as you wire the new pot to the the six holes where the old pot was pulled. If you follow the traces on the bottom of the board, you will see that there are connections from the input wires you installed and the holes for the removed pot. The signal passes thru the pot to the coupling caps/amp. That's why you are getting no sound.

Hope that helps.

Mike

shadowlight · « **Reply #116 on:** 7 Jan 2014, 02:46 pm »

Quote from: mboxler on 7 Jan 2014, 02:26 pm

Actually, your wiring looks good as is, as long as you wire the new pot to the the six holes where the old pot was pulled. If you follow the traces on the bottom of the board, you will see that there are connections from the input wires you installed and the holes for the removed pot. The signal passes thru the pot to the coupling caps/amp. That's why you are getting no sound.

Hope that helps.

Mike

Thanks Mike. I guess I better order the new pot soon.

mboxler · « **Reply #117 on:** 7 Jan 2014, 02:59 pm »

Quote from: shadowlight on 7 Jan 2014, 02:46 pm

Thanks Mike. I guess I better order the new pot soon.

Or...wire as Salis suggested, and then you would need a preamp, or someway to lower the input signal.

Cheers

Mike

S Clark · « **Reply #118 on:** 7 Jan 2014, 03:20 pm »

Quote from: Salis Audio on 7 Jan 2014, 11:01 am

Clark, if I sent you 4 Nichicon caps would you give them a go?

Also I wonder how a lithium battery that's lower impedence would sound.

I am meaning to put a B1 buffer in front of this amp. It seems sensitive to impedence matching since it's leading and trailing detail goes up with volume (hence some imaging and timbre).

Sure, I'll give them a try. Don't know about lithium, but I know that batteries need to be decent size. I can hear some breakup with a 7ah battery that I don't hear with the 26ah. I need to call Gary Dodd today anyway to check up on him. I may ask him what he thinks about lithium batteries. He probably has more practical experience with battery powered audio than anyone around.
Scott

Folsom · « **Reply #119 on:** 7 Jan 2014, 04:13 pm »

I thought 7ah would be plenty, maybe it needs some more power caps? I was going to make a duel amp for a friend with 10ah lithium LFP (RWA uses them). But if more power caps isn't sufficient then I am going to have to rethink it.

I use multiple 1kufish caps at enough charge that I can unplug the amp from one SMPS and into another without music stopping, roughly 2 seconds maybe. More importantly they won't let the voltage drop during critical times. The stock cap size has the juice, but capacitors voltage drop quick; too quick. We are talking differences of perhaps mv, but it matters.