Sorry to hear the unpleasant moment.
I will take the transistors (Q1-Q6 etc) out and test them.
Think of that they were fed reverse voltage in pulse for quite a few cycles....
The caps wouldn't be too happy either they are polarized.
Edit: just saw the image, this is a DC adapter, it will be something else.
Suggestion remains to check the transistors.
I will take the transistors (Q1-Q6 etc) out and test them.
Think of that they were fed reverse voltage in pulse for quite a few cycles....
The caps wouldn't be too happy either they are polarized.
Edit: just saw the image, this is a DC adapter, it will be something else.
Suggestion remains to check the transistors.
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Just for clarity, the first adapter was 24VAC, the adapter pictured in my last post was what I bought to use instead of the Triad adapter, because it had the same barrel size as the adapter in NP's BOM...should be getting DC now but makes the oscillations strange...
If you can't tell yet this is my first pre-amp build...
If you can't tell yet this is my first pre-amp build...
The switch on the right is the power switch (on/off).
Your picture of the power supply is not in focus so I cannot read the current capacity. Please repost a focused picture. A properly functioning ACP+ draws about 300mA. The recommended power supply is specified to supply 500mA.
The cycling of the voltages is a sign that the current capacity of the power supply is exceeded. This could be because transistors and/or capacitors on the board were shorted by the first power supply.
You have replaced C6 and C7 but the other capacitors may have failed also.
As Fred suggested, pull the transistors and test them, and the capacitors too.
Your picture of the power supply is not in focus so I cannot read the current capacity. Please repost a focused picture. A properly functioning ACP+ draws about 300mA. The recommended power supply is specified to supply 500mA.
The cycling of the voltages is a sign that the current capacity of the power supply is exceeded. This could be because transistors and/or capacitors on the board were shorted by the first power supply.
You have replaced C6 and C7 but the other capacitors may have failed also.
As Fred suggested, pull the transistors and test them, and the capacitors too.
LOL, should never read the forums while cooking dinner, I thought your 2nd post was part of the first 😱
The torched R18 suggested C6 was shorted. So, all the current probably went down via this route especially the R19 spot didn't look burnt. You had a R4 reading. That is a good sign. The reading is kind of low, go ahead to sold another 100R parallel to the existing R4. The chance is good that you will hear some music after that!!!
The torched R18 suggested C6 was shorted. So, all the current probably went down via this route especially the R19 spot didn't look burnt. You had a R4 reading. That is a good sign. The reading is kind of low, go ahead to sold another 100R parallel to the existing R4. The chance is good that you will hear some music after that!!!
Just for clarity, the first adapter was 24VAC, the adapter pictured in my last post was what I bought to use instead of the Triad adapter, because it had the same barrel size as the adapter in NP's BOM...should be getting DC now but makes the oscillations strange...
If you can't tell yet this is my first pre-amp build...
Ben, apologies, below is a clearer pic. Looks to be 600mA so not much more than 500, but possibly too much?
Fred, R4s are socketed so I could just substitute for now? I did so because I was seeing the discussion on everyone's varying R4 value and had a wide range in values with my J113s, as well, so I thought I'd play it safe...(welp)
Will follow Fred's advice and pull and check transistors and caps...will report my findings.
Fred, R4s are socketed so I could just substitute for now? I did so because I was seeing the discussion on everyone's varying R4 value and had a wide range in values with my J113s, as well, so I thought I'd play it safe...(welp)
Will follow Fred's advice and pull and check transistors and caps...will report my findings.
Attachments
600mA is not a problem. That is the capacity of the power supply. The power supply will only supply what the amplifier requires, up to a maximum of 600mA. A properly functioning ACP+ draws about 300mA.
I have been on the hunt for a decent Headphone Amp and came across this. Naturally Mr.Pass needs no introduction and such, but am curious how the ACP+ compares to entry level headphone amps like say the JDS Atom etc... I mean, I assume this smashes the Atom? Pun aside, I am genuinely curious the level of performance and wonder if anyone has links to anythorough reviews/comparisons?
Or should I just build one? LOL
Or should I just build one? LOL
There's a million and a half completely subjective ways to look at this... but I'll bite.
We love our ACP+. It sounds just as great over headphones as it does plugged into an amp. While I haven't done a comparison to another super popular HPA—"the wizard's assistant's" WHAMMY. I have built 4 of them—and spent a lot of time listening to it. Here's the thing about comparisons of any nature audio-related. It's supremely personal. The only way I would know what I think I like is to build everything I am able to and try as many things as I am capable of. Here's what I think I know about HPAs. Each headphone I have sounds different from another. Each DAC I use as an interface between my source and the amp sounds different. Each opamp I roll inside WHAMMY, in this case, sounds different. This also assumes I have a hi-res audio file—AND—if I am using my iPhone as a source for say, Tidal, I'm not double-DACing—for me it meant hunting down a lighting to USB cable in a single cable—Apple's adapter has a DAC in it!
To THE point—BUILD IT—and you will know what you know in that moment—and then build something else (Mark Johnson's Noir for instance, or Whammy) and let more fun begin. Worst case with ACP+—you have a fantastic preamp. And if you build it with the groundplane—a work of art, in my opinion, worthy of any museum on the planet....Makes me smile just looking at it.
We love our ACP+. It sounds just as great over headphones as it does plugged into an amp. While I haven't done a comparison to another super popular HPA—"the wizard's assistant's" WHAMMY. I have built 4 of them—and spent a lot of time listening to it. Here's the thing about comparisons of any nature audio-related. It's supremely personal. The only way I would know what I think I like is to build everything I am able to and try as many things as I am capable of. Here's what I think I know about HPAs. Each headphone I have sounds different from another. Each DAC I use as an interface between my source and the amp sounds different. Each opamp I roll inside WHAMMY, in this case, sounds different. This also assumes I have a hi-res audio file—AND—if I am using my iPhone as a source for say, Tidal, I'm not double-DACing—for me it meant hunting down a lighting to USB cable in a single cable—Apple's adapter has a DAC in it!
To THE point—BUILD IT—and you will know what you know in that moment—and then build something else (Mark Johnson's Noir for instance, or Whammy) and let more fun begin. Worst case with ACP+—you have a fantastic preamp. And if you build it with the groundplane—a work of art, in my opinion, worthy of any museum on the planet....Makes me smile just looking at it.
Thanks for the thought out response.
I am tempted to build something over buying. The ACP+ looks like it would probably best some of the ~$100 amps out there. The WHAMMY and NOIR came up in my preliminary searches as well. I presume based on your reply that they are a progression/improvement in what you hear over the ACP+, yes?
The worst thing about the Pass designs is they're all so tempting!!!
I am tempted to build something over buying. The ACP+ looks like it would probably best some of the ~$100 amps out there. The WHAMMY and NOIR came up in my preliminary searches as well. I presume based on your reply that they are a progression/improvement in what you hear over the ACP+, yes?
The worst thing about the Pass designs is they're all so tempting!!!
You're terrible 6L6... Always tell me what I wanna hear, and everything my wallet doesn't LOL
You could think of it in the context of ... 6L6 just saved me over $800 by not buying a $1k retail product. 😀
My wife uses that logic on me when she buys things on sale...
Me: Why did you pay $100 for another pair of shoes?
Her: But I saved $X.
Flip the roles, sub in amplifier for shoes.... voila.
Edited to add - the ACP+ is absolutely fabulous. Build it. 🙂
My wife uses that logic on me when she buys things on sale...
Me: Why did you pay $100 for another pair of shoes?
Her: But I saved $X.
Flip the roles, sub in amplifier for shoes.... voila.
Edited to add - the ACP+ is absolutely fabulous. Build it. 🙂
Jokes on you... I'm so cheap, spending $1000 isn't anything I can remember even doing anytime since I paid $3500 for my car... but it has a Harman Kardon stereo at least LOL.
Yeah, I will likely pull trigger. I noticed the matched components needed are out of stock at present though, so I will continue to sift through this thread. Is the kit considerably cheaper than the WHAMMY once parts are attained? I have only skimmed the BOM, but noticed the WHAMMY kit is $189 on the store, tho also OOS presently.
Yeah, I will likely pull trigger. I noticed the matched components needed are out of stock at present though, so I will continue to sift through this thread. Is the kit considerably cheaper than the WHAMMY once parts are attained? I have only skimmed the BOM, but noticed the WHAMMY kit is $189 on the store, tho also OOS presently.
To fuel the fire—but add a tinge of practicality—build ACP+ (GP version—it's in stock—our ACP+ is the one pictured on the store site in "Work of art" mode), build Noir as the kit (not in stock)—since both of these have a "chassis" solution ready to go. Later build a Whammy when the DIY store chassis is available (soon!!! I'm told). Chassis often more than doubles the total project cost...purely looking at the currency. Otherwise—totally accurate to say you built a $1000 class A HPA for ~$200 (or well under). I've also heard the Starving Student II HPA is great—it's on my list....Love tubes.
I see the boards are in stock. The LSJ74 in the schematic shows 4 and presumed they were intended to be matched. Is that not correct? If the case, it appears the store is OOS on the matched quads from what I can see.
Enclosures don't worry me as I've mounted plenty of components into enclosures and have a bunch of quality enclosures. The GP is definitely beautiful and may give it a show before installing in a chassis.
It's always been my instinct in a stereo circuit that matching improves results, but science may indicate differently. Is it safe to assume that if there is no mention of matching in the PDF that it's not as critical as selecting quality components with close tolerances?
Enclosures don't worry me as I've mounted plenty of components into enclosures and have a bunch of quality enclosures. The GP is definitely beautiful and may give it a show before installing in a chassis.
It's always been my instinct in a stereo circuit that matching improves results, but science may indicate differently. Is it safe to assume that if there is no mention of matching in the PDF that it's not as critical as selecting quality components with close tolerances?
Thanks. Presumed they needed to be matched. Hope the store gets stock, added myself to notification list.
Hello Friends!
I was trying to create a project in Mouser to get idea of what is required. The BOM lists all electrolytic capacitors as 25V, but the incredible build guide (as always!) by 6L6 has a picture of a more 'mixed' bag of capacitors:
- 50v 1000uF PS filter caps
- 16v 3300uF C4
- 50v 10uF C1
- 25v 1000uF Audio Grade C3
So, my question is, is 25v only critical on C3? Are these mixed values actually BETTER than having all at 25v, for example?
Thanks for any feedback.
I was trying to create a project in Mouser to get idea of what is required. The BOM lists all electrolytic capacitors as 25V, but the incredible build guide (as always!) by 6L6 has a picture of a more 'mixed' bag of capacitors:
- 50v 1000uF PS filter caps
- 16v 3300uF C4
- 50v 10uF C1
- 25v 1000uF Audio Grade C3
So, my question is, is 25v only critical on C3? Are these mixed values actually BETTER than having all at 25v, for example?
Thanks for any feedback.
I think I spent somewhere between $200 and $300 on my ACP+. Keep in mind that the matched quad of LSJ74 is $50, so just those and the boards will be $80 plus shipping and tax. I think the rest of the parts could be had for less $100 total, however it's not possible to source everything from one place, so you'll end up paying shipping from several vendors. I also ordered spares of almost everything as this is one of my first projects and I don't have any extra parts on hand.
I measured my preamp and it's using the the BOM listed 24 VDC walwart. The caps sees the following (Vdc):
C6=23.8V, C7=23.41V, and C8 and C9 are 23.4V and 23.2V respectively.
C2 sees about 21.7V, C3 is about 10.8V, and C4 is about 6V.
On mine, I use 35V rating for C6 to C9, C1, C2 ,and C3. 25V for C4. All are about 12mm diameter. So far, so good. The caps does not extend towards the ring (circle) mark on the board
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