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Holton NXL800 Power Amp Build


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2 minutes ago, Tubularbells said:

 

Yep truly scrambled Sir Egg.

 

Im not lying when I say its affected my mental health greatly (yeah first world problems and all that but it truly has taken quite a toll and has almost made me want to give up on HiFi altogether and just return to my boombox from the 80's and just enjoy the tunes rather than the system as I did then......

 

I understand totally.

3 minutes ago, knight2001dts said:

Sounds like you and Anthony have pretty much exhausted all options, and both have tried to resolve without success....

Is it time to call this project quits, return the modules for a refund, and put it down to a system incompatibility issue?

 

Build something else?  Re-kindle that audio flame?

 

Turf it out, our hobby shouldn't be this painful

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50 minutes ago, Tubularbells said:

So ive just sent Anthony a message asking for further assistance, Im sure hes getting tired of this as am I so not sure where to from here im afraid ?

 

 

Haven't followed the entire thread Doug but the little bit I've read I'm pretty sure you've gone above and beyond the call of duty when it  comes to bending over to a manufacturer and trying everything they've recommended.

 

It's time to call it it quits and seek recompense from Anthony and Anthony if your reading this then you'd be aware of the damage that this thread has done to your brand, it's not a good look. No one's the winner here and perhaps you could do the right thing for Doug in private away from this open stage that we're all watching and just shaking our collective heads at thinking that it's gone too far.

 

It's a shame and as the Eggmiester has said above, no one should be at a point where the problem affects their personal well being.

 

I had a long chat with you at Marc's first show at Albert Park and at no point did we discuss how long to keep someone suffering via faulty kit.

 

The ball is in your court I believe.

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15 minutes ago, Tubularbells said:

 

I'm not lying when I say its affected my mental health greatly (yeah first world problems and all that but it truly has taken quite a toll and has almost made me want to give up on HiFi altogether and just return to my boombox from the 80's and just enjoy the tunes rather than the system as I did then......

 

 

If it's any consolation, Doug ... I've also been in a nightmare state from building an amplifier (actually, a pair of stereo amps).  :(  And yes, I also have thought that I will never ever again build an amplifier.

 

I started to build these Class A amps in Dec 2019 - I hope I will shortly be able to get to a successful conclusion ... because, with the changes on the go, I have exhausted all possible reasons why the amps don't work!

 

The amps are a Class A design on diyAudio.  The amps were designed (in LTSpice) for an 8 ohm load - and quite a few people have successfully built them; they say they sound really, really good!  :)  I, however, wanted to build the 4 ohm version (to power the mids & rbbons on my Maggies) - and, although the designer had produced a schematic with various component value changes to cope with a 4 ohm load ... no-one had actually built one.  :(  So I was the first.

 

I first experienced some instability ... which blew up one of the power supplies.  :(  After an amp component value change - to supposedly solve this instability, I 'finished' putting them together about June last year.  I was able to fire up the 1st one on my test bench and measured it to clipping, at various loads from 4 ohms to 2 ohms.  But with the 2nd one ... I could get it to work when the rear panel was open (laying backwards) - but as soon as I bolted the panel closed ... the amp started to oscillate.  BTW, the amp boards were bolted vertically, to the back panel - all I can think of is that when closing the back panel ... all the various wires going to and from the amp PCB were placed in close contact ... causing instability?

 

7 months later, I have now re-organised the layout of my amps to be able to mount the amp boards horizontally on the bottom panel of the case - I'm hoping this will remove the previous instability when the back panel was closed.  The next few days will reveal this.  :)

 

Andy

 

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18 hours ago, knight2001dts said:

Sounds like you and Anthony have pretty much exhausted all options, and both have tried to resolve without success....

Is it time to call this project quits, return the modules for a refund, and put it down to a system incompatibility issue?

 

Build something else?  Re-kindle that audio flame?

Admittedly I'm in the middle of a DIY build where I need to send the amplifier back to the vendor over a transformer issue that will require replacement but I've learned that at some point you have to cut your losses and move forward in a way that enables you to rest easy at night. 

 

You can always get your money back for parts but what isn't returnable is the hours that you spend undertaking these builds. That being said the decision to go down the route of a DIY build is a personal choice. 

 

I personally think that this isn't all doom and gloom. It's a perfect opportunity for Anthony to come to a mutually beneficial arrangement with Doug. You can win plenty of people over doing this. 

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1 minute ago, ghost4man said:

Admittedly I'm in the middle of a DIY build where I need to send the amplifier back to the vendor over a transformer issue that will require replacement but I've learned that at some point you have to cut your losses and move forward in a way that enables you to rest easy at night. 

 

You can always get your money back for parts but what isn't returnable is the hours that you spend undertaking these builds. That being said the decision to go down the route of a DIY build is a personal choice. 

 

I personally think that this isn't all doom and gloom. It's a perfect opportunity for Anthony to come to a mutually beneficial arrangement with Doug. You can win plenty of people over doing this. 

Why can't he / you just change the transformer ? its not hard. 

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2 minutes ago, Melon_Head said:

I would be willing to have a look at it, if you wanted to have a fresh pair of eyes and brains see where the problem might be.

 

Do we have a circuit diagram for this amp?

Even one without component values would be useful.

Anthony won't give that out..

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1 minute ago, Melon_Head said:

I would be willing to have a look at it, if you wanted to have a fresh pair of eyes and brains see where the problem might be.

 

Do we have a circuit diagram for this amp?

Even one without component values would be useful.

The problem is not with the amplifier circuit per se, it is with the actual dual die output devices.

I will be contacting Profusion and see if they still produce the Z version of the dual die devices, as these are the ones that have the built in Gate resistors.

The current version have two separate silicon dies mounted on a TO247 package, and the Gates are connected together within the package, but the die's do not have inbuilt Gate resistors.

This is what is causing the oscillation burst at low power under load.

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21 minutes ago, Aussieamps said:

The problem is not with the amplifier circuit per se, it is with the actual dual die output devices.

I will be contacting Profusion and see if they still produce the Z version of the dual die devices, as these are the ones that have the built in Gate resistors.

The current version have two separate silicon dies mounted on a TO247 package, and the Gates are connected together within the package, but the die's do not have inbuilt Gate resistors.

This is what is causing the oscillation burst at low power under load.

Awesome work Anthony, glad to see you watching this and willing to work with the end user ! Class A perfect support !

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25 minutes ago, Aussieamps said:

The problem is not with the amplifier circuit per se, it is with the actual dual die output devices.

I will be contacting Profusion and see if they still produce the Z version of the dual die devices, as these are the ones that have the built in Gate resistors.

The current version have two separate silicon dies mounted on a TO247 package, and the Gates are connected together within the package, but the die's do not have inbuilt Gate resistors.

This is what is causing the oscillation burst at low power under load.

 

I don't believe there is a problem with the circuit.

In addition to the known issue surrounding oscillation of double die lateral mosfets, there might also be other possible faulty components or bad solder joints or just weirdness.

 

Having a very basic circuit diagram would be useful for fault finding.

 

I am starting to believe there could be another fault at play here.

 

I would like to observe it first hand.

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3 hours ago, Aussieamps said:

The problem is not with the amplifier circuit per se, it is with the actual dual die output devices.

I will be contacting Profusion and see if they still produce the Z version of the dual die devices, as these are the ones that have the built in Gate resistors.

The current version have two separate silicon dies mounted on a TO247 package, and the Gates are connected together within the package, but the die's do not have inbuilt Gate resistors.

This is what is causing the oscillation burst at low power under load.

 

So are they building and shipping out faulty boards ?

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Anthony

 

Any chance in the future you would do a new/different design with all through-hole components that people assemble themselves?

 

Kind of think a big part of the problem is the fact, even though it is diy, using pcbs with surface mount components is not so easy to DIY  repair or modify.

 

The way it is now, every time a customer has an issue they are relying on you to fix the problem rather than the community.  Most of these problems could be solved by the community, which would take the heat off you and your business.

 

 

 

 

 

 

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8 minutes ago, Aussieamps said:

I have not survived over 20 years in the DIY Audio industry by shipping faulty product. 

Well let me just say that this entire thread is damaging your brand Anthony, I find it hard to believe you've let it go on this long.

Wouldn't it just be simpler to do all of this back and forth in private rather than in the centre of a group of people who could be potential customers of yours in the future perhaps.

Doesn't really matter now where the fault lies it just needs to be remedied with just replacing everything or refund and apologies or whatever you think is a fair thing. Doug probably doesn't need to shave now as he'd of pulled his beard off during this awful experience.

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4 hours ago, Luc said:

Wouldn't it just be simpler to do all of this back and forth in private rather than in the centre of a group of people

 

I agree entirely. AussieAmps asked me to close the thread this morning, and I'm told has indeed offered a full refund already.

I reached out to the OP to see if he would agree that closing this thread now is the best way forward, but as yet, no response.

I see no good coming from this thread and if anything changes in the future, the OP can start a new one.

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