Another ACA build coming up

[Subbu68]

The biggest benefit, IMO, will come from a tightly regulated PS. Look up the Tungsten Audio mods for ACA on DIYA.

Saw that thread Kieth. I haven't read through properly.

PS is in my head already. A 400VA, 2 x 24V so it may be moded for future F5 or something. Have to find the budget though . Maybe I can cut down costs if i got the components in India when I visit next

 

[Subbu68]

Since you are using 24 volt supply, I guess DC balance should be 12 volts.

Yes it is 12V. You can see it on the DMM above.

 

[Kannan]

Yes it is 12V. You can see it on the DMM above.

missed that post.

 

[rajan-]

Get the second one going soon, you will want both of them to be burned-in around similar hours as your end goal is to use them as Bridge monoblocks.

What you might notice is that bridged ACA monoblocks sound greater than the sum of two amps would suggest.

You can try this with your IFI Nano feeding both ACA in Bridged mono config, and after that go back to IFI feeding only one single ACA in regular stereo mode.

That was the aha moment for me. I was quite happy with a single ACA until I tried bridged monoblocks.

I couldn't / wouldn't go back to a single one after that experiment.

All these with the SMPS PS that came along with the kit. I am already thinking abt a proper PS for these babies.

for example, at very volumes, delicate touches on a drum hi-hat sounds muddled or hardly inspiring in a regular stereo mode, while the same music became extremely REAL in the bridged mode,

That level of performance convinced me to build a dual mono Pre Amp as well, until then, my Whammy HP Amp was doing yeoman duty as preamp. I just had to up the game on the pre side.

 

[Subbu68]

Get the second one going soon, you will want both of them to be burned-in around similar hours as your end goal is to use them as Bridge monoblocks.

What you might notice is that bridged ACA monoblocks sound greater than the sum of two amps would suggest.

You can try this with your IFI Nano feeding both ACA in Bridged mono config, and after that go back to IFI feeding only one single ACA in regular stereo mode.

That's exactly I am planning to do. Unit 2 is nearly ready. After the final DC balance it'd run in stereo mode with iFi Nano. Then set up in bridge mode.

I am also planning a short video with same input in stereo mode and bridge mode for the benefit of future aspirants.

 

[Subbu68]

ACA Unit 2 completed. Took on board the suggestion by @rajan- to the extent possible for now. Further improvement later

Now for powering up and DC balance before burning in. Then the bridge mode with Unit 1 for one channel and Unit 2 for the other. Unit 1 had blue LEDs and Unit 2 red ones to differentiate

 

[keith_correa]

I am also planning a short video with same input in stereo mode and bridge mode for the benefit of future aspirants.

You need to match the output levels too else it's an apples to mangoes [because it's the season ] comparison.

 

[Subbu68]

You need to match the output levels too else it's an apples to mangoes [because it's the season ] comparison.

It'd be apple to mango . Stereo would've the harmonics that I believe would be cancelled with bridged connection?!!

Maybe match the dB at the listening position with the preamp would do? It's going to be 15+15W in bridge against 8+8W on stereo mode to a 99dB Klipsch Heresy IIIs.

 

[keith_correa]

Maybe match the dB at the listening position with the preamp would do?

Yes!

 

[Subbu68]

First impressions

YT Music on PC > iFi Audio iDSD Nano USB DAC > ACA in bridged mono > Klipsch Heresy IIIs

crystal clear voices and highs, solid bass. Klipsch lacks bass (raised from floor and away from wall in contrast to it's design) so not so deep, still "feelable". Imaging is super - limited again by Klipsch. Voice centered, ensemble can be picked.

My daughter has very picky ears. She just said "Wow, crystal clear.

Hope to park the audio quest for now

 

[sachu888]

Here is my build https://audiokarma.org/forums/index.php?threads/another-amp-camp-build.602303/

Regards
Sachin

 

[Subbu68]

@rajan- We have British 3 pin sockets (BS 1363A) and plugs in UAE. for regular sockets around the house. Plugs are fused with replaceable fuses and a maximum rating of 13A.

I got the Meanwell adaptors with EU plugs that are the closest we can use with adaptors in UAE. Still I've to cut off the plugs and change to BS plug with fuses. Though the adaptor has in-built protection against shorts, the wire remains without protection so a fuse would make it safer and prevent the circuit MCB from tripping for a fault on the adaptor. From data sheet of these adaptors on diyaudiostore website they say 0.7A and a 3A fuse should do the job.

Do you have in-built fuses in the plugs in Australia? Did your plugs come with any fuse inside? If so what is the rating?

 

[Subbu68]

Here is my build https://audiokarma.org/forums/index.php?threads/another-amp-camp-build.602303/

Regards
Sachin

I think I saw this too when searching about ACA. You too inspired me to build this.

The Red and Black chassis- Ford Mustang GT!!

Your chassis looks simple to assemble than the ACA kit. Oh, it is a pain to put the covers though they look simple. Holes do not align due to the way the heatsink is fitted. Covers fit to the frame on the heatsink and if the heatsink are not properly aligned with front and rear panel you are lost.

 

[rajan-]

Stereo would've the harmonics that I believe would be cancelled with bridged connection?!!

Nope, with Bridged mono, the Amps will NOT cancel the harmonics. This information is very easy to miss.
You Get all the benefits of a single amp stereo mode in Bridged mono mode.

It is In Balanced Mono mode, it WILL cancel the Harmonics, that is when you use Balanced Connectors.

@rajan- We have British 3 pin sockets (BS 1363A) and plugs in UAE. for regular sockets around the house. Plugs are fused with replaceable fuses and a maximum rating of 13A.


Do you have in-built fuses in the plugs in Australia? Did your plugs come with any fuse inside? If so what is the rating?

Nope, Aussie plugs does not have fuses built-in.
The meanwells are 24V , 5Amps, So a 5A fuse will be a safe option ?

 

[Subbu68]

Nope, with Bridged mono, the Amps will NOT cancel the harmonics.

Nope, Aussie plugs does not have fuses built-in.
The meanwells are 24V , 5Amps, So a 5A fuse will be a safe option ?

Oh, yes for it.

The bridged mono is superb. As the amps got warm clarity was oozing. I can only imagine how a Pass made amp costing $$$ would sound.

Meanwells are 24V and 5A at the output. They draw 0.7A on mains side. My calcs are about the same. 120W output, 0.89 efficiency, 0.93 power factor. Input is 120/(0.89x0.93) = 145VA. Input current is 145VA/230V = 0.64A.

Can't say primary and secondary sides as there is no transformer.

The data sheet is in diyaudiostore web page for ACA under Kits. Since they have inbuilt protection for output or internal short circuit as per that sheet, we need to protect only the mains chord. A mechanical damage can result in shorts and the MCB for the whole circuit of your room will trip. If it does not trip the wire will get heated and can catch fire and further collateral damage.

Fuses should be rated higher than the maximum current. Or they'll blow for a slight overload. Ideally there the fuse curve should be coordinated with the load overload capability curve. We do not have that curve for Meanwells.

In this case the aim is to prevent damage to wire. So a 3A should do it. I will try with it or up the rating.

Aussie system is 230V, 50Hz, isn't it? I guessed they followed the British for equipment specifications too.

 

[keith_correa]

Stereo would've the harmonics that I believe would be cancelled with bridged connection?!!

It is In Balanced Mono mode, it WILL cancel the Harmonics, that is when you use Balanced Connectors.

Exactly, what harmonics are we talking about there? Induced by what?

 

[Subbu68]

Exactly, what harmonics are we talking about there? Induced by what?

The second harmonics from the design that gives the tubey sound..

 

[Subbu68]

Exactly, what harmonics are we talking about there? Induced by what?

The second harmonics from the design that gives the tubey sound

Nope, Aussie plugs does not have fuses built-in.

The BS plugs we have in UAE. You can see the fuse inside. It's 5A. Couldn't get 3A. EU plug cut off.

 

[rajan-]

Exactly, what harmonics are we talking about there? Induced by what?

In single amp mode as well as in Bridged monoblock operation, the ACA works in Single ended Class-A

PassDiy

In Balanced mono operation, the ACA. it removes most of the second order harmonics, (rather the tubey sound)

https://cdn.shopify.com/s/files/1/1006/5046/files/ACA_Monoblock_Operation_RevA.pdf

the ability to change the sound character so easily and at this price point is one of the main attraction of Amp Camp amps.

 

[rajan-]

Oh, yes for it.

The bridged mono is superb. As the amps got warm clarity was oozing. I can only imagine how a Pass made amp costing $$$ would sound.

you are still on the ifi nano feeding the bridged ACA ?

I am curious to know how the Elekit Tube pre-amp feeding the ACA will sound.