ICEPower Amplifier Build

[Diyengineer]

Hello,

I'm starting a new amplifier build based on two ICEpower 700AS1 modules for a two channel build.

Initial stages of this build were discussed in another thread because I was intending a hybrid build but through discussion this amp will not have a tube stage. So I started a thread just for this build as the hybrid no longer applies.

The ICEpower modules have been on order for a week or so but other items have come in (i.e. xlr/RCA jacks, binding posts, & Lundahl transformers) so I can start working on the build and laying everything out. Chassis will be a Hifi 2000 and should be ordered this week.

I started by laying out the back panel with the inputs and speaker outs.

Then I started a PCB for an "Input Module" which I would like some input on as I am new to PCB layout. There will be two different boards, one with Lundahl LL1545A transformers and one without. I will try both and see which one I like best.

The input board will span the back of the chassis and mount directly to the XLR jacks with some additional standoff's as well. The RCA and input select switches will be connected to the board via short wires. The XLR housing will be grounded via mechanical connection to the chassis. There are connections for an input select switch to ground pin 15 of the LL1545A when using unbalanced. And I put a spot for a X2 cap and resistor filter to use if needed to isolate signal ground from the chassis. I can connect the chassis to either side to isolate it or not. The orange traces are top layer and blue are bottom layer.


I've attached my PCB layout and the datasheet for the LL1545A with my connections I'm using labeled with arrows on the second sheet. Any input on the PCB is appreciated.

Thank you

 

[Diyengineer]

A little closer to starting the build. Modules, connectors, transformers, and wire are now in. Just waiting on the chassis and PCB’s. I hope within the next week or so.

 

[Turbowatch2]

Nice plan!

 

[Kay Pirinha]

I guess there's no demand for a class X2 capacitor in the ground loop breaker.
Best regards!

 

[Diyengineer]

Since I wasn’t sure if it would be needed or not, I left a spot for it on the board but can omit it.

 

[levistubby]

For ease of soldering, wouldn't it be better to have all the XLR pads on the top of the board? That would need some wire links for the cross overs of course.

Mounting the XLRs from inside the case, which is what I guess you intend, looks neater but needs the holes to be very neatly/accurately cut.

 

[Diyengineer]

My intention is to have the board mount directly to the XLR pins on the back panel of the amp. Then use two additional PCB standoffs. The plated through holes in the PCB for the XLR pins are a little oversized. We’ll see how it fits.

 

[Dadbeh]

what does the input transformer do? is it about impedence matching or about somehow isolation? I am asking because i have seen this amp used as a power amp with no input stage and i also have seen it being used with a buffer as an input stsge but i have never seen that before and it is very interesting to me.

 

[Diyengineer]

Hi,

I’m going to try the amp with and without the Lundahl’s first, then with them and use what sounds best. My though was to use them for isolation. Based on some research and the help in these forums, they can be good for ground isolation and have been used successfully in some commercial amplifier designs.

Currently I did the PCB for 1:1 wiring and we’ll see how that goes.

Pcb’s are on the way, just need the chassis now.

 

[Turbowatch2]

The input transformers do a few things:
First, they insulate the ground of the amp from any pre-stage.
Second you drive the amp balanced, independent off RCA or XLR per amp.
The transformer may add a touch of it´s own sound. Most consider it to become a bit softer.

The downside, the source needs to be able to deliver quite some current. A passive pre amp is not the best driver, usually.

Good audio transformers, like these, are quite expensive.

 

[Diyengineer]

Boards came in so I and was able to populate them. Looks good so far.

Chassis will be delivered Thursday, then assembly can start.

 

[Kay Pirinha]

Since I wasn’t sure if it would be needed or not, I left a spot for it on the board but can omit it.

I meant that you don't need a capacitor of class X2 at that spot. Any other foil cap of appropriate value will do. But class X2 surely won't hurt .

Best regards!

 

[Diyengineer]

Chassis came in and looks really good. Worth the wait to have all the milling and printing done by them at the factory. All of the connectors fit nicely.

 

[Diyengineer]

Amp is just about done, all wired and tested. Dead silent using both balanced and unbalanced inputs. Just waiting on some feet and some dampening material for the upper and lower covers. Sound is very good.

 

[e_fortier]

Very nice work, congrats!

Just wondering, why did you choose such a big enclosure w heatsinks (you don’t seem to be using them) Maybe I’m missing something.

Enjoy it, I also enjoy my IcePower stuff.

BR
Eric

 

[Diyengineer]

This amp was originally going to have a tube buffer, that’s why I went for a 4U for the extra space. Sometime after ordering the chassis, I decided on the input transformers instead. As for the heat sinks, the Icepower manual stated mounting the modules upside down to additional heatsinks as optional for increased dissipation. I haven’t yet but will if needed.