[Build] CAPI HPA500, 500 Series Headphone Amplifier, Official Support Thread

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jsteiger

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Hey folks!

Since my new HPA500 Headphone amplifier kit is shipping, I started the official support thread.

Full details and automated checkout can be had here:
https://capi-gear.com/catalog/product_info.php?cPath=22_117_225&products_id=614

The build guide is following my newish Pictorial Build Guide format. All BOMs, support docs and the build pictorial can be found here:
https://capi-gear.com/catalog/Build_HPA500_Rev_A.php

Since this is the official support thread, please post all questions, components and/or build problems here. I will do my best to help you get things sorted. This is the place to handle issues, not with a direct email. Thanks for understanding.

And heres a pic of the beauty with my giant knob  ;D
HPA500-front.jpg


And before someone asks...The HPA500's Left input source is the rack slot's input. The HPA500's Right input source is accessed by using a XLR Female to Female Coupler plugged into the rack slot's output. This gold plated contact XLR adapter is included with the HPA500 Entire Bundle.

Cheers, Jeff
 

forgotteng

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Ok Jeff. I got mine build and I am having numerous problems. First of all when on button is engaged I get nothing including LED. When on button is disengaged I hear at very low volume a distorted signal.  The volume knob has no effect as I turn it. The mono LED only works when The on button is engaged. The On LED doesn't light at all. I'm sure I went wrong somewhere. Any obvious thoughts?
 

RuudNL

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What a coincidence! This week I created my own 500-rack headphone amplifier.
My version offers a selection for the right channel input between 'aux in' (some racks have it) or 'main out' as input.
It also features a 'left only', 'right only' and 'stereo reverse' switch.
 

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jsteiger

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forgotteng said:
Ok Jeff. I got mine build and I am having numerous problems. First of all when on button is engaged I get nothing including LED. When on button is disengaged I hear at very low volume a distorted signal.  The volume knob has no effect as I turn it. The mono LED only works when The on button is engaged. The On LED doesn't light at all. I'm sure I went wrong somewhere. Any obvious thoughts?
The Mono LED only illuminates when the On pushbutton is depressed by design so that is correct.

As for the On LED, could it be backwards or maybe one of the leads is too long and shorting to the ground plane behind it?

As for the other issues, I guess we'll have to look at some build pics of your unit. Its a pretty simple one and honesty this is the first build problem we are getting into.
 

forgotteng

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jsteiger said:
The Mono LED only illuminates when the On pushbutton is depressed by design so that is correct.

As for the On LED, could it be backwards or maybe one of the leads is too long and shorting to the ground plane behind it?

As for the other issues, I guess we'll have to look at some build pics of your unit. Its a pretty simple one and honesty this is the first build problem we are getting into.

Oh I'm sure the mistake is on my end Jeff. Here is a pic. I can send more if it helps.
 

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jsteiger

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forgotteng said:
Oh I'm sure the mistake is on my end Jeff. Here is a pic. I can send more if it helps.
At first glance the headers from the Alps PCB look to be shorting where they are solder at the top of the main PCB. Lots of flux lurking about there too.
 

forgotteng

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jsteiger said:
At first glance the headers from the Alps PCB look to be shorting where they are solder at the top of the main PCB. Lots of flux lurking about there too.

It certainly seems the problem lies in the Alps PCB. I cleaned that up and now there is no distortion but the volume pot has no signal until you reach 3 oclock than it is a low signal. But only at 3 oclock. Do I need to resolder the whole ALPS PCB Assembly? What's the best way to go about that. Thanks again for your patience with the noobs.
 

jsteiger

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forgotteng said:
It certainly seems the problem lies in the Alps PCB. I cleaned that up and now there is no distortion but the volume pot has no signal until you reach 3 oclock than it is a low signal. But only at 3 oclock. Do I need to resolder the whole ALPS PCB Assembly? What's the best way to go about that. Thanks again for your patience with the noobs.
Sounds like it could be a cold solder joint on the Alps PCB. At this point, you will need to break down the assembly. I would gently pry the black shrouds off of the header pins on the bottom of the Alps PCB. This will give you clear access to the pins so you can resolder them from the bottom of the Alps PCB since the access between the 2 boards is now gone.
 

forgotteng

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jsteiger said:
Sounds like it could be a cold solder joint on the Alps PCB. At this point, you will need to break down the assembly. I would gently pry the black shrouds off of the header pins on the bottom of the Alps PCB. This will give you clear access to the pins so you can resolder them from the bottom of the Alps PCB since the access between the 2 boards is now gone.

Well I was able to remove the PCB but the pin holes were compromised. Is there a way to purchase the volume PCB, the volume pot, and the black shrouds and pins? I'll have to try round 2.
 

jsteiger

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forgotteng said:
Well I was able to remove the PCB but the pin holes were compromised. Is there a way to purchase the volume PCB, the volume pot, and the black shrouds and pins? I'll have to try round 2.
I would recommend trying to desolder the Alps pot. Those are the most expensive part of the whole kit. Send me an email thru the store and well get you hooked up.
 

TubeMonkey

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Hey Jeff!

Great project!  Was able to put this together in around an hour and twenty minutes with only the BOM as reference. Sounds great!!!! I'm going to stick this in the penthouse of my console as my main Cue/headphone control room situation. 

The only bit of advice I might have for beginners is that these boards use non-polarized electrolytics (the green ones) they are noted by BP on the cap (bi-polar) as well as in the BOM and the orientation doesn't matter as it does with traditional electrolytics. (they can be placed in either direction like ceramic caps and resistors)

Also take a look at the ALPS assembly diagram... I didn't and soldered the molex pins to the main board.... then had to de-solder and place them correctly on the sub-board once I got near the end and figured out how the assemblies went together.

ALSO BIG KNOB  ;D


-E.B.

EDIT: I missed that there is already an entire build guide with pictures..... which explains both of these point clearly
 

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kante1603

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Kit received yesterday and built in about two relaxing hours.Works really nice,sounds good,is affordable and is so easy to do.A no-brainer.
Another great little helper in my racks-preferably on slot number eleven  8)
Massive thanks to Jeff for another great piece of gear!


Best regards,


Udo.
 

jsteiger

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kante1603 said:
Kit received yesterday and built in about two relaxing hours.Works really nice,sounds good,is affordable and is so easy to do.A no-brainer.
Another great little helper in my racks-preferably on slot number eleven  8)
Massive thanks to Jeff for another great piece of gear!

Best regards,

Udo.
Thanks for the kind words! Its a fun little build and a great sounding, useful module...perfect for the vacant #11 slots  :)
 

rockprocess

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I've just built mine up and am having trouble with it.  Upon firing it up, the right side is working great,  just static on the left side that faded to silence.  I haven't been able to get any sound out of the left side since then.  I've tried swapping the opamps and chopsticking the unit with it in an extension test jig.  I'm using an API lunchbox and tried different slots.

Any ideas what to check or maybe a schematic?
 

jsteiger

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rockprocess said:
I've just built mine up and am having trouble with it.  Upon firing it up, the right side is working great,  just static on the left side that faded to silence.  I haven't been able to get any sound out of the left side since then.  I've tried swapping the opamps and chopsticking the unit with it in an extension test jig.  I'm using an API lunchbox and tried different slots.

Any ideas what to check or maybe a schematic?
Could be many things including a bad solder joint. Can you post a pic of the top so I can dbl check component placement?
 
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