$175 Class D amp--120 wpc

rajacat · « **Reply #3380 on:** 9 Jul 2012, 07:37 pm »

Do you have one of the higher powered classdamps too? If so, is this mini amp comparable in sound quality? I'm just looking for a general impression of the difference. I realize you're still going through break-in.
Did you try 12V power or just use 24V battery power?
BTW, what kind of speakers are you using?

Thanks,

Roy

TrungT · « **Reply #3381 on:** 9 Jul 2012, 07:57 pm »

I do have CDA-254 and will bring to a friend setup soon.
Mac Mini , DIY CAT SL1 , Pendragon

rajacat · « **Reply #3382 on:** 15 Jul 2012, 12:21 am »

I just ordered one of the mini amps.

For $55 why not? I really like using batteries to eliminate AC noise issues. If it doesn't work out, I'll have a serviceable backup amp. All of the other amps have much more power than I need.

I'll be using a sealed 12V 9.0 Ah battery that is buffered with multiple caps . If this little amp meets my requirements I'll bridge it and order another one. I might experiment with lithium batteries too, to hear if they affect SQ.

....Roy

enal · « **Reply #3383 on:** 15 Jul 2012, 09:39 pm »

I just put my CDA1000 kit forsale in the swap section if anyone is interested...Still new in the box it came in from CDA.

TrungT · « **Reply #3384 on:** 15 Jul 2012, 09:49 pm »

6"X6"X4" Electrical box (Free)

praedet · « **Reply #3385 on:** 15 Jul 2012, 10:54 pm »

So you are running it on 24V Trung?

TrungT · « **Reply #3386 on:** 15 Jul 2012, 11:17 pm »

^^^^^
Yes, DC DC converter 12v to 24v

rajacat · « **Reply #3387 on:** 15 Jul 2012, 11:21 pm »

Did you try it with with a 12V battery, no converter?

TrungT · « **Reply #3388 on:** 15 Jul 2012, 11:28 pm »

^^^^^
Yes, I think 24V give more everything.

rajacat · « **Reply #3389 on:** 15 Jul 2012, 11:45 pm »

Hmm...I might try a couple of 12V batteries in series. I also use battery power for my Bolder SB3 and use a 12V to 5V converter. Works well.

How's is the SQ compared to your larger amp?

praedet · « **Reply #3390 on:** 16 Jul 2012, 12:47 am »

Hmmm, in the good old cheap/cheerful ideas, I might have to figure out creating a cheap integrated to include using this DAC with this new amp and some type of cheap preamp that can run on 12V as well and accept a few inputs...

Ideas?

wushuliu · « **Reply #3391 on:** 16 Jul 2012, 01:01 am »

Quote from: TrungT on 15 Jul 2012, 11:28 pm

^^^^^
Yes, I think 24V give more everything.

argh. give more of what?! you're holding back bro! how's it sound?!!!

TrungT · « **Reply #3392 on:** 16 Jul 2012, 02:23 am »

I'm still have one more week to "burn-in" the Mundorf caps.
I can't get the best perform of the speakers.
Only what I can heard now.

A2snider · « **Reply #3393 on:** 22 Jul 2012, 08:09 am »

Where do you find inexpensive chassies for one of these amps?

TrungT · « **Reply #3394 on:** 22 Jul 2012, 01:26 pm »

Good place for some nice chassis with a good price:
http://www.sanjosescientific.com/servlet/the-PRINTED-CIRCUIT-BOARD-ENCLOSURES--PCB-BOXES/Categories

justd · « **Reply #3395 on:** 28 Jul 2012, 11:35 am »

I am having humm issues with the amps.

I wanted to know.

The transformer has a ground coming out which goes in to the mains. But there is not ground which goes in to the power supply. Then there is a ground which goes from the power supply to the amp board. So how do the amp and the power supply get grounded?

mboxler · « **Reply #3396 on:** 28 Jul 2012, 01:06 pm »

Quote from: justd on 28 Jul 2012, 11:35 am

I am having humm issues with the amps.

I wanted to know.

The transformer has a ground coming out which goes in to the mains. But there is not ground which goes in to the power supply. Then there is a ground which goes from the power supply to the amp board. So how do the amp and the power supply get grounded?

Hi justd...

Is the hum coming from your amp or your speakers (and what amp/speakers are you using)? Does it go away when you disconnect the inputs?

To quote Tom...

As far as grounding, don’t overdo it. Just put the transformer ground wire to the chassis and the ground from the IEC to chassis ground… that’s all. The mistake many make is trying to ground everything… this only causes problems.

I ran a short wire from IEC earth to the chassis

The ground wire from the transformer...I just crimped/soldered a spade to it and attached it under one of the PS standoffs. Nothing else. Anyone else need to do more???

Mike

justd · « **Reply #3397 on:** 29 Jul 2012, 05:46 am »

Thanks Mboxler,

The hum is coming from the speakers. I am using Mirage speaker OMD 15, OMD 5, OMD C1. Yes it does go away if i remove the interconnects.

I am using a UMC-1 as the pre-amp and processor. I have tried lifting ground on all the equipments and it is not helping at all. in fact the problem is very peculiar. There is very little hum (almost inaudible) when everything is connected. But as soon as i play the source, and the hum volume increases. The volume of this hum is the same irrespective to the volume on the UMC-1. When i pause the source the and the music stops... the humm stops after a 2 seconds.

So it seems to me that a 50hz, signal is superimposing itself on the interconnects between the umc-1 and the amp boards. Or may be the amps are grounding themselves through the interconnects via the UMC-1 since the amps do not have a ground available to them.

Quote from: mboxler on 28 Jul 2012, 01:06 pm

To quote Tom...

As far as grounding, don’t overdo it. Just put the transformer ground wire to the chassis and the ground from the IEC to chassis ground… that’s all. The mistake many make is trying to ground everything… this only causes problems.

I ran a short wire from IEC earth to the chassis

Mike

Whats is IEC? is it the power supply board? i actually do not have a body as such for the amp. And i have not grounded it. May be i should do that.

In fact i am running all my equipment on an online ups now. So i am getting clean power.

justd · « **Reply #3398 on:** 29 Jul 2012, 08:02 am »

I have two transformers feeding the two power supply boards. I just checked the larger transformer is giving me a slight buzz/hum

mboxler · « **Reply #3399 on:** 29 Jul 2012, 01:26 pm »

Sorry...I now recognize your setup from a previous post.

IEC International Electrotechnical Commission is the IEC connector. It's the power inlet for your power cord. Grounding the mains earth to the chassis is a SAFETY procedure. I can't see your power cord connection.

Same problem with different source?

I remember a few of us were concerned about the rca-to-speaker configuration. Do you have chassis mount speaker binding posts that you could attach to the amp to answer that question? Just run wires from the amp, over the top of the chassis, to the posts, then hook your speakers to those. That would rule out the rca to speaker question.

Again, I'd attach the transformer ground wire to a separate bolt/nut on the chassis.

Good Luck!

Mike