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Holton - DIY Kit for Stereo HPA-NXV800L R4 Amplifier


ghost4man

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On 26/02/2020 at 11:15 PM, ghost4man said:

Hi fellow travellers,

 

Just wanted to add some clarity on how the build is progressing given I have received some very flattering PM's.

Okay, I just want to confirm that the amplifier has been started up without - fingers crossed - any issues.

It has NOT been connected to any speaker so I cannot make any comment regarding performance.

 

You do not need insulating washers etc to fix the FETs to the side heat sinks.

I went for 2 mm ceramic spacers and went for the pricier versions given what they are meant to do. As always there are good and bad.

 

What I am hoping to do is subject the amplifier to some rigorous testing to see what the data yields and report back.

I use Jaycar sticky sili-pads. Can be hard to line-up everything for the tighten down but I think they work. 

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11 hours ago, Aussieamps said:

END Game: What I am willing to do is to order you another power transformer with updated primary and secondary voltages that will hopefuly over come the apparent issues with your local AC mains , I will require that you send the transformer you have to me in exchange.

Given the current situation in Australia (COVID-19) I have no desire or time to continue this conversation in a public forum, please contact me via email so we can arrange the exchange.

 

I hope this helps you?

I do think this is now a technical issue for discussion between the buyer and the supplier, best suited to private communication. This is not a Holton/Aussie Amps manufacturer's sub-forum.

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3 minutes ago, Marc said:

I do think this is now a technical issue for discussion between the buyer and the supplier, best suited to private communication. This is not a Holton/Aussie Amps manufacturer's sub-forum.

Hi Marc


More than happy to take those technical issues and resolving in private.

 

I would however like to keep the thread open as I have had a number of people PM me along the way. Some in fact went down the route of purchasing their own modules like I did as a result of the thread.

 

Its inevitable that things happen along the way.

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Agreed, which is why the thread hasn't been closed. You can work through technical issues directly with the manufacturer - and then post your progress here. 

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  • 2 weeks later...

Hi guys, 

 

Just a quick update. 

 

Obviously have had a number of people PMing me asking what is happening with the build. 

 

Given the circumstances behind COVID-19 I made a purposeful decision to limit posting given the fact that there are far bigger problems in the world at this minute. 

 

We will be building a sturdy box so the amplifier can be sent back to Anthony as we reached the point where we did everything we could but the limitations of the transformer and the ongoing concern with the Volt One regulator could not be successfully addressed. 

 

To that end I thank Anthony for his offer. 

 

I have also been able to communicate with a former SNA member who many of you - Trevor/Zaphod - who will put the amplifier through its paces and report back. Please note regardless of the current situation I was going to do that anyway as I wanted a clean bill of health. I think any DIY build which includes electricity needs or should have this done. Who wants to start a fire in your own home because of faulty equipment. 

 

Ozzie 

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  • 1 month later...
  • 4 months later...

The death of my father and COVID during the last few months put a lot of things on the back burner.

Managed to get a colleague to put the amp on the bench and confirmed a number of suspicions that I have had - that is that the amp is performing way way under expectations. On the way to getting a box built and off the amp goes to Anthony. 

Its clear the power output is nowhere near the mark. Looking at the figures its almost as if this amp is performing like the 300/500 wpc series. A lot of information gathered in these tests.

 

HOLTON 8 OHMS.PNG

HOLTON 4 OHMS.PNG

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G'Day Mate

I grew up on the Central Coast, so nice to see someone on this forum from that location.

 

What rail voltages do you have feeding the amp?

When you load the amp to 300W what are the rail voltages at that point?

 

What is the power you were expecting to achieve?

 

Have you had a chance to listen to the amp?

 

Edited by Melon_Head
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Well even though it seems power is way down than expected, however in terms of SPL at the speakers, there is very little difference between 300W and 500W, so the amp should still sound quite good, and it does perform well into 4 Ohms (scaling into lower impedance loads looks very good) which is probably more important for Maggies than just absolute power.

 

If you really want to fix it, we can probably get to the bottom of it and get it operating correctly.

Were you able to get a replacement transformer with higher output on the secondaries or are you still using the same one?

Edited by Melon_Head
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1 hour ago, Melon_Head said:

Well even though it seems power is way down than expected, however in terms of SPL at the speakers, there is very little difference between 300W and 500W, so the amp should still sound quite good, and it does perform well into 4 Ohms (scaling into lower impedance loads looks very good) which is probably more important for Maggies than just absolute power.

 

If you really want to fix it, we can probably get to the bottom of it and get it operating correctly.

Were you able to get a replacement transformer with higher output on the secondaries or are you still using the same one?

Unfortunately the limiting factor isnt just in the transformer.

The intention is for Anthony to source an appropriately sized transformer. This test was completed with the existing transformer. These results were not unexpected. 

A very good test nonetheless. Maggies do test the resilience of any amplifier particularly into the lower impedance. Current is the critical factor for any maggie.

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1 hour ago, Melon_Head said:

 

Can you reveal more?

 

What are the secondary voltages and the VA rating of the transformer you have now?

 

 

3.0KVA core

1 x 240vac primary winding

1 x electrostatic shield between primary and secondary windings

4 x 60vac secondary windings each winding @ 12 Amps

4 x 70vac secondary windings each winding @ 400ma

 

Im using the same amp modules and I went with the  same secondary voltages (60v) as you did instead of the recommended 65v for precisely the reasons Mr. Holton outlined in the previous page and I quote.

 

"The reason from memory and it was I think a couple of years ago, I speced the transformer to 60 volts is with the volt one approximately 800 watts into 4 ohms could be achieved, also given your amplifier was going to be driving 2 ohm loads or lower I reasoned for better reliability reasons that a 60 volts AC supply would help with lower output stage dissipation."

 

Although I don't have the very amp demanding Maggies my Sovereigns being a 7 driver speaker are still pretty demanding being a nominal 4 ohm load (dropping to 3.2 ohms) so imo both you and I don't specifically require ultimate voltage drive and instead are more interested in an amps current capability to deliver into low impedances and as such it is my personal belief chasing outright power into 8 ohms  is not the way to go.

 

Take a look at any ME amps and you'll also notice there running lower voltage rails and even there range topping ME1500 is only rated at 220w/8 and that has a 5kv tranny and 300,000uF of storage! I realise they fudge the 8 ohm in order for it to appear to double into 4 but still it highlights that the important bits for high current capability are a big transformer (and you have that covered), massive storage supply (yours is pretty good being 105,600uF but a potential bolt in upgrade could be to use the new Holton power supply boards as you can go a bit higher to 160,000uF) and output devices capable of delivering current (which you are also good having 8 x 250w/16A per channel)

 

 

Get your Volt One working properly and give the amp a listen as you might be surprised. Yeah it might not put out exactly what it says on the tin but your already close with your 600w/4 and the published 800w/4 is probably only about 0.5db louder and i'll bet your amp would bet better @2 ohm loads.

 

 

 

 

 

 

Edited by Tubularbells
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6 hours ago, Melon_Head said:

 

... in terms of SPL at the speakers, there is very little difference between 300W and 500W,

 

 

Shirley that is a completely irrelevant statement, MH - few people, if any, have their 300w amps delivering maximum power ... let alone a 500w amp.

 

What the extra power gives you ... is more headroom, to deal with transients.

 

Andy

 

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4 hours ago, andyr said:

 

Shirley that is a completely irrelevant statement, MH - few people, if any, have their 300w amps delivering maximum power ... let alone a 500w amp.

 

What the extra power gives you ... is more headroom, to deal with transients.

 

Andy

 

True, but a transient not greater than 2dB more than the transient capability at 330W.

Unless he plays music with ear protection I doubt he will ever be clipping this amp, even at 330W.

I was just trying to cheer the guy up.

The glass is much better than half full in reality here.

 

If Ozzie has 40V transients, then going from a 73V rail to a 90V rail will be virtually meaningless and possibly even detrimental to transient response if the Transformer and power supply aren't suitably scaled. It's not as simple as more voltage equals more dynamic capability especially driving a speaker like the one he has.

So what I said is actually entirely relevant.

 

Edit: Since you called me Shirley, will it be ok that I refer to you as Sharon from now on.

LMAO

Edited by Melon_Head
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5 hours ago, Tubularbells said:

 

 

3.0KVA core

1 x 240vac primary winding

1 x electrostatic shield between primary and secondary windings

4 x 60vac secondary windings each winding @ 12 Amps

4 x 70vac secondary windings each winding @ 400ma

 

Im using the same amp modules and I went with the  same secondary voltages (60v) as you did instead of the recommended 65v for precisely the reasons Mr. Holton outlined in the previous page and I quote.

 

"The reason from memory and it was I think a couple of years ago, I speced the transformer to 60 volts is with the volt one approximately 800 watts into 4 ohms could be achieved, also given your amplifier was going to be driving 2 ohm loads or lower I reasoned for better reliability reasons that a 60 volts AC supply would help with lower output stage dissipation."

 

Although I don't have the very amp demanding Maggies my Sovereigns being a 7 driver speaker are still pretty demanding being a nominal 4 ohm load (dropping to 3.2 ohms) so imo both you and I don't specifically require ultimate voltage drive and instead are more interested in an amps current capability to deliver into low impedances and as such it is my personal belief chasing outright power into 8 ohms  is not the way to go.

 

 

 

More agreement here.

 

It would be a much better investment of his time and money doing those things.

 

To maintain the same current ability he will also need to go higher in VA rating if he increases the secondary voltages.

 

Then I see his caps are only rated to 100V so he can't go much higher with his secondary voltages anyway.

 

Knowing what measured voltage is coming out of his secondaries at idle and at full power would be useful.

 

The bridge rectifiers might even be partly responsible if the IV curve is not that great.

Also what is the regulation spec for this transformer?

 

Or does he have some kind of bizzare mains power issue giving him 220V or less,

Edited by Melon_Head
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5 hours ago, Tubularbells said:

 

 

3.0KVA core

1 x 240vac primary winding

1 x electrostatic shield between primary and secondary windings

4 x 60vac secondary windings each winding @ 12 Amps

4 x 70vac secondary windings each winding @ 400ma

 

 

 

60V gives 84V unloaded and unregulated voltages, in a perfect world 440W max

 

There will be losses due to diode forward voltage drop (could be higher than expected depending on diodes) and possibly the amp won't swing all the way to the rail (maybe 1V or 2V loss there).

 

Let's call it 80V after losses.

Then to regulate properly (assuming he wants to use a regulated supply) you probably want to allow 10%, so another 8V to 9V loss.

After regulation maybe 72V which is around the 320W figure.

 

Assuming he is using a regulated supply, the power he is getting is actually not unexpected at all.

 

More clarification is required to know if there is actually a problem here or was it a just a misunderstanding at the time of purchasing and specifying what he wanted.

 

I think he has an incredibly awesome amp, I would be very happy having those driving Maggies.

 

Edit: Does Anthony's regulated supply regulate both the output stage and front end voltage gain stage?

That would change things a bit if it was just the front end voltage gain stages.

Edited by Melon_Head
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On 19/03/2020 at 11:33 AM, Guest jakeyb77 said:

I didn’t go that route. Mark has built his own power supply into mine so haven’t encountered this 

Just catching up on some of the post but not all. My PS maybe underwhelming compared with above. With jakeyb77’s PS I use a 1KV Tranni. But for my other two 300/500W Holtons only 625VA Tranni with 80,000uf of 100V cheapo caps. Hearing aid PS compared to others posted BUT with 90db efficient 8ohm speakers I knew I’d only be tapping about 20W of power from an amp capable of 500W peaks. What I do get is deep well controlled bass and utter transparence. For me and my intended use, even up loud, it’s plenty with minimum cost and complications.

 

2551056E-9D2B-4D4C-ABA8-8655F63F4D09.jpeg

C2CCEEAE-6CA0-43D4-8BDF-B8B658D31073.jpeg

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  • 4 weeks later...
On 12/09/2020 at 11:29 AM, Melon_Head said:

 

60V gives 84V unloaded and unregulated voltages, in a perfect world 440W max

 

There will be losses due to diode forward voltage drop (could be higher than expected depending on diodes) and possibly the amp won't swing all the way to the rail (maybe 1V or 2V loss there).

 

Let's call it 80V after losses.

Then to regulate properly (assuming he wants to use a regulated supply) you probably want to allow 10%, so another 8V to 9V loss.

After regulation maybe 72V which is around the 320W figure.

 

Assuming he is using a regulated supply, the power he is getting is actually not unexpected at all.

 

More clarification is required to know if there is actually a problem here or was it a just a misunderstanding at the time of purchasing and specifying what he wanted.

 

I think he has an incredibly awesome amp, I would be very happy having those driving Maggies.

 

Edit: Does Anthony's regulated supply regulate both the output stage and front end voltage gain stage?

That would change things a bit if it was just the front end voltage gain stages.

This is all well and good but is missing a very important detail - the advertised specifications promote 500 wpc into 8 ohms and 800 wpc into 4 ohms with unconditional stability into a 2 ohm load 

Anyone embarking on such a build would expect nothing less than the stated output figures particularly when an overstated transformer is thrown into the mix. There are a number of issues at hand which need to be addressed hence why the amp is making a trip down south. 

 

Unfortunately a number of things in my personal life has resulted in things slowing down at this stage. I imagine many people have been affected in one way or another during this COVID pandemic. I'm endeavouring to get a box built for shipping shortly. 

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