Class A SS: Journey for a budget champion for LCD-X

Coming back to this, if you want a DIY amp for the 650, the answer is Crack. It's one of those classic synergies.

 

Agreed, one of the best pairings. I have been there done that though. I'm kind of done with the tube/tube amp chapters in my journey, and have sold off such gear and tubes completely now. No more tube nervosa life!

 

Trust me, OPAMP nervosa is no better.

 

So what amps will feed both tube and opamp rolling nervosa?

 

https://www.elekit.co.jp/en/product/TU-HP01

Edit: And not to forget the old SOHA: https://headwizememorial.wordpress.com/2018/03/19/a-simple-tube-opamp-hybrid-amplifier/

 

Agreed. That is exactly where I am now..............

 

Thanks for all the great feedback and experiences!

In one short day, things have escalated quickly for me. I sold my Lyr 3, returned the GLmk2, and when returning the ACP+ to the local owner, we naturally got into discussing my fondness for the sound it produced, my comparisons with it, and my challenges sorting out the steps of possibly getting myself into one of these.

To my surprise, he offered to sell me his ACP+, given that I was pretty passionate about this thing and he felt it would be going to someone who’d appreciate it. So I will absolutely be buying it from him very soon!

A must do, however, is getting this thing into a proper chassis. I’ve got little ones and our office doesn’t have a lockable door, and despite my close eye and teaching them (the 3 year old at least), I want this amp and my kids to be safe.

So with that, I have a couple chassis options in mind (prefab), and LOTS of questions for doing it right. That said, I’m incredibly stoked!

 

Ok, so now I'm starting to compile my laundry list of DIY questions, starting with the chassis. Since I can't seem to get the admins of DIYAudio to respond to my requests to un-ban me as spam, I'm hoping I can get some assistance here with you all!

Due to the pre-drilled holes and almost identical layout/component placement vs. the ACP+ design, I wanted to use the DIYAudio B1K Tiode chassis for the ACP+. From what I can tell, the only hole I would need to drill is one for the 1/4" phone jack. I think I can handle that. Link: https://diyaudiostore.com/products/b1-korg-chassis

Questions:

1. Comparing the ACP+ board dimensions with the B1K chassis, they seem to align (albeit a little tight with little room to spare).
   • The B1K chassis internal dimensions are 210mm (W) x 170mm (D) x 40mm (H)
   • The ACP+ PCBs exterior dimensions are 203mm (W) x 165mm (D)
   • The height, I assume, would clear the PCB with relevant capacitor heights. HOWEVER, I need to consider the added dimensions of the SMPS kit that the original owner added. This might be a problem.
   • Question: is there any concern with the wire leads fitting in the tight margins around the PCB? Are there any other considerations I need to keep in mind with this tight fitment?
2. Based on the ACP+ design and wire leads needed, what gauge wire should I use respectively? Would 18awg for the power-related leads and ~22awg for the signal-related leads be appropriate? Likewise, I was considering Mogami W2514 Hi-Fi Hook-up Wire for this purpose. Fair choice? https://www.performanceaudio.com/products/mogami-w2514-hi-fi-red-hook-up-wire-by-the-foot
3. The power adapter that comes with the ACP+ is a Triad WSU240-0500 wall wart, 24VDC, with a 2.5mm barrel connector. This means I need to be sure that the power connector mounted to the chassis is 24VDC rated and has an internal connector diameter of 2.5mm, correct?
4. When mounting the PCB to the bottom panel of the chassis, do I need to have any sort of isolation layer added, or are standoffs needed between there, or anything else to consider?
5. Is it recommended to do a lot of practicing with de-soldering and soldering with some cheap parts first? Are there any absolute dos and don'ts I need to keep in mind?
6. How would the LED light be mounted to the front panel? Is there a glue that is commonly used, or is there another preferred method?

I'm sure I'm going to have a lot more questions, and likely run into some other barriers as I move along, but wanted to at least get a starting point. Thanks!

 

If you haven't done it in a while, or you feel so-so about soldering skills, this is always good practice to do! Especially if you're working with little space or a tight chasis.

 

Horizontally it'd be a tight fit, but might work - but I'd be more worried about the vertical alignment of everything. Because the switches and I/Os of the B1 are off the board, the holes in its front & rear case panels have been drilled so everything's nicely centred vertically. However on the assembled ACP+, because the source switch and volume pot shaft are directly soldered to the board, they're at different elevations. I'd guess that the elevations of the RCA jacks at the rear of the board are different again.

On a quick keyword search of the DIYA thread I didn't find confirmation that anybody has used that case. When you get your access problems sorted, it'd be worth asking specifically.

Because the ground plane board is included in your ACP+ assembly, your case options can include plastic (or just plastic front & rear panels), which is easier to drill. Have a look at Hammond's site for some ideas. Short standoffs or washers under the ground plane will be fine. You could use a bigger case so the power supply filter would fit, or you could put the filter in its own case something like this (with 2.5mm power jacks for I/O).

For the LED, look for 'panel mount' in supplier's catologues. I presume the kit one is 3V; here's an example.

 

I've already come to the conclusion that the B1K chassis will be too tight. So instead I'm looking at the DIYAudio Store Galaxy kits, specifically the taller 1GX283 model (2U/80mm (H) x 230mm (W) x 230mm (D)), which shouldn't take that much larger of a footprint, but provide plenty of space to fit everything in there (and my idea is to stack the SMPS filter where the existing power connector is above the PCB via a standoff).

https://diyaudiostore.com/collections/chassis/products/galaxy?variant=46622963040535

After scouring that forum, I've come to the same conclusion. That said, a number of folks have used the 1U Galaxy case with success, but they also didn't have the added SMPS filter, so that eliminates that as a useful option.

I've toyed back and forth with the idea of something "simpler" like a repurposed wood box, or some other pre-fab'd option, that wouldn't require special tools/bits to modify. And maybe I will as a starting point. The grounding plane already being included certainly makes that a feasible and quick option. That said, I do want something "proper" for sitting at my listening seat, and a metal enclosure just ticks all the boxes for me.

Ideally, in using the Galaxy 2U chassis, I would "fly wire lead" the RCAs for sure, and swap the existing PCB-mounted power connector for a panel mount option (and wire the PCB > SMPS > panel mount jack). From there, the question remains whether I do the same for the switches, volume pot, phone jack, and LED (so I can panel mount them as I wish), or try to figure out how to align the PCB-mounted components as they exist and mark for holes to drill so they simply pass through (and use standoffs to raise the whole board to the desired height of the front faceplate).

I'm not going to rush through any of this, but still have some burning questions on how some of these things get properly panel-mounted.

I've seen several chassis designs where a 1mm hole was drilled into the front faceplate as a simple light passthrough, but it's been difficult to clearly see how those LEDs have been held in place behind the faceplate. In most cases, I don't see any sort of panel mounting hardware. Similarly, I'm trying to figure out how that works for the switches that exist on the unit I'll have (the housing ahead of the toggle appears smooth, with no threading to use a lock nut). These mysteries escape me lol.

 

Quick question: looking to ideally use this style of power connector, as it's design would be more flush mounted than basically every other panel mount power connector I've seen: https://www.digikey.com/en/products...AlgDsA5iAC+JALRNoIdJGz5iZSiAYBmWCBJhEsOiwkmgA

However, the spec shows it is rated at 48VDC and 6 Amps. The ACP+ uses a 24V wall wart power supply, and the original PCB mounted connector was rated at 24VDC and 5 Amps. Is the connector I'm hoping to use OK? Or must I only use a panel mount connector rated at 24VDC?

 

It's really the amp rating that concerns you unless you get way up in high voltage. Should be alright!

 

Rated voltage means that's the max voltage it has UL approval for. Anything below is fine.

 

LED mounting: drill hole same diameter as LED. Put LED in hole. Dab silicone on back of LED to hold it in hole.

 

F*ing THANK YOU! That makes so much sense. Can the same be applied to the power and input selection switches that don’t have any threads?

 

Nope. Unlike the LED, you'll be handling those - they need to be secure.

 

Ok, so the simple solution is just to get new panel mount switches that are threaded - make this easier on myself rather then trying to fit a square peg in a round hole.

 

Yup.

 

Have you heard the Liquid Gold X @HeyWaj10 ? It’s pure class A and has amazing synergy with Audeze’s for the price.