Holton - DIY Kit for Stereo HPA-NXV800L R4 Amplifier

[ThirdDrawerDown]

Congratulations Peter!

 

As for the LEDs, it wouldn't be hifi if there wasn't a heap of LED lights to turn night into day in the lounge room.

 

I am seriously thinking of putting an amp in the bathroom just so I can see at night without turning on the bright overhead light.

[andyr]

On 18/02/2020 at 4:26 PM, Tubularbells said:

Ceramic isolators? Wow things have changed since my time with mica spacers and thermal paste. Later came the silicone version but ceramic? never heard of that before.

 

Aluminium oxide, TB.    But I think you still use the white thermal paste.

 

Andy

 

[ghost4man]

23 hours ago, jakeyb77 said:

Oh and look at that big shiny beast torroid!!! 

Toroidy from Poland. 

 

25 kg of 3.0Kva beastiness by itself. 

[Guest jakeyb77]

23 minutes ago, ghost4man said:

Toroidy from Poland. 

 

25 kg of 3.0Kva beastiness by itself. 

Love it. I’m having the 300W version built at the moment with a 1Kva puny one

 

Your amp is a beast. 

[gonefishing999]

@ThirdDrawerDown Hi Murray thanks, I still have a couple of small projects I'm catching up on then

I will be doing your Maggies with aluminum foil, will let you know when it starts.

Ozzie and Murray have been very patient me.

 

Peter

[ghost4man]

14 hours ago, jakeyb77 said:

Love it. I’m having the 300W version built at the moment with a 1Kva puny one

 

Your amp is a beast. 

Mate,

Dont be disheartened, Having a 1 KVa transformer these days is a rarity. Many a so called hi end amplifier does not have that.

[ghost4man]

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.

[ghost4man]

Okay things that need to be done and will be done before I move forward:

On the to do list and already done list -

 

1. Coupling capacitors to install on the input stage

2. Speaker protection modules - Audio solid state relay (HPA - SS Relay one) to install.

3. There is a fuse on the high current power supply boards but does not appear to be one on the high voltage regulator boards therefore I am going to have 

1 amp inline fuses be added for peace of mind.

4. Rewired the mains input plug to the mains controller board using 3-core 15 amp flex.

5. Added a mains earth strap from the mains controller board to the chassis.

6. The Bias has been correctly set to 5mV across the source resistors however the pot is extremely small and very easy to bugger up. Perhaps as a recommendation a

10 turn pot with a decent set screw would have been better for us folk with older eyes.

 

Concern list -

 

Only one but before I do anything it needs to be addressed. The high voltage Regulator for the pre-driver stages does not regulate properly when set to its recommended voltage of +/- 92V. In this case the minimum dropout voltage is not met and the indicator LED's do not illuminate to indicate that the regulator is operating correctly. Because of this it has been reduced in voltage from +/-92V down to +/-85 voltages to make it regulate at the cost of a reduced power output. According to the manual in order to achieve the stated output figures the minimum is +/- 92V. In the absence of any direct measurement one would anticipate that the stated figures of 500 wpc into 4 ohms would not or rather should not be achievable given where we are at with the regulator board if it is not regulating properly.

 

I'll communicate with Anthony to see what he makes of this but in the meantime plenty of good little jobs to attend to.

 

Huge thanks again to the extremely tech savvy gentlemen who have been helping out.

[ghost4man]

Current status and feedback -

 

We thought that the possibility existed for the voltage regulator to not be specific for my current requirements given that essentially speaking there are 4 different voltage ranges and mine was not performing to expectation - perhaps the wrong one was sent.

After some testing and re-testing the minimum voltage was in fact 50 VDC which one could surmise is the correct voltage range for this setup. The upper limit is 110 VDC. However, there is a problem.. To get the maximum power output you need to +/- 92 V which is consistent with the manual.

 

The maximum level attained here is +/- 83 which poses a big problem in terms of power output. Beyond this figure the voltage is no longer regulated. 

 

Consequently the current output figures are as follows -

 

335 wpc into 8 ohms (approx)

575 wpc into 4 ohms (approx)

 

Given the power output ratings for the modules this is way under what one would expect - 500 wpc/8 ohms and 800 wpc/4 ohms.

[ghost4man]

Two ongoing and competing problems  which has left me at a standstill - transformer(recent discovery that it was not "specked" properly) and voltage regulator which would limit the availability to the rail voltage due to inability to set above +/- 83 VDC when the bare minimum to get anywhere near the stated output figures needs to be at least +/- 92.

[Guest jakeyb77]

So you have to wait for a new transformer? 
 

[ghost4man]

2 minutes ago, jakeyb77 said:

So you have to wait for a new transformer? 
 

Transformer part of the problem. So even if the transformer was sufficiently powerful enough the voltage regulator is for now not playing ball.

This is a good lesson in watching dominoes fall one after the other. You need a transformer that can supply enough voltage on your power rails. The regulator which 

very simply regulates the voltage needs to be set at a certain level to meet the demands required on the rails. 

We realised that the voltage regulator was the right one because of the minimum voltage which coincided with what is required for these modules. The capacitors on your power supply need to be correctly rated given the incoming voltage. Same with the FETs. They are all interlinked.

So the issue here isn't just exclusive to the transformer.

[ghost4man]

Ongoing concerns continue with the Volt One regulator. 

 

Anthony Holton has recommended a mod by way of a parallel addition of a 100k resistor across the existing 22k one to raise the voltage with the vire to ultimately raise the output. 

 

The primary concern that I have at present is the need for the mod in the first place. By rights the Volt One according to the numbers should be achieving the necessary voltages to achieve the stated output figures. 

 

At the minute this is way off the mark. 

 

More to come.. 

[ghost4man]

According to Anthony after having run some numbers the Volt One regulator with its current configuration should be capable of 97 volts output with 

the right input voltage and higher voltage rated input caps. Additionally with 98 volts dc input from 70 VAC windings 90 volts output shouldnt be a problem.

My problem however is two fold. The transformer windings weren't rated accordingly to achieve this but the big issue at the minute is that the regulator is nowhere 

near the ball park in terms of desired performance. Above 85 volts and it simply does not regulate properly. A classic case of what you think and hope will occur but no

cigar.

Will be interesting what the outcome of this mod will yield.

[Guest jakeyb77]

I thought the boards and the power regulator and relays were all plug and play? 

[Guest jakeyb77]

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

[stereo coffee]

16 minutes ago, ghost4man said:

According to Anthony after having run some numbers the Volt One regulator with its current configuration should be capable of 97 volts output with 

the right input voltage and higher voltage rated input caps. Additionally with 98 volts dc input from 70 VAC windings 90 volts output shouldnt be a problem.

My problem however is two fold. The transformer windings weren't rated accordingly to achieve this but the big issue at the minute is that the regulator is nowhere 

near the ball park in terms of desired performance. Above 85 volts and it simply does not regulate properly. A classic case of what you think and hope will occur but no

cigar.

Will be interesting what the outcome of this mod will yield.

70v AC agrees ( /.707 ) with conventional diode full wave rectification, to achieve 99.00 V DC  , caps should be +120V ( 150v better )

Is there a schematic ? 

 

(Most band gap regulators are good with Vin - Vout differential of 3v  http://www.ti.com/lit/ds/symlink/lm117.pdf

see Reference Voltage page 7.  The Holton though,  might be based on a different design requiring higher differential voltage. ) 

[ghost4man]

37 minutes ago, jakeyb77 said:

I thought the boards and the power regulator and relays were all plug and play? 

Your first port of call is to ensure that you have a transformer that is properly rated. If that doesn't happen then your output will never achieve what you want. 

 

The voltage regulator isn't regulating accordingly. So what you say about plug and play is correct to a certain degree but you still have to set the regulator. In this case +/-92VDC. 

 

Its falling way short of this mark which is evident in the leds switching off. Thats for both regulators as well so its not isolated to one only. 

[ghost4man]

33 minutes ago, stereo coffee said:

70v AC agrees ( /.707 ) with conventional diode full wave rectification, to achieve 99.00 V DC  , caps should be +120V ( 150v better )

Is there a schematic ? 

 

(Most band gap regulators are good with Vin - Vout differential of 3v  http://www.ti.com/lit/ds/symlink/lm117.pdf

see Reference Voltage page 7.  The Holton though,  might be based on a different design requiring higher differential voltage. ) 

Correct mate. 

 

In this particular instance the caps are +100V so sailing very close to the wind. 

 

Bear in mind as well that your FETS have to be rated accordingly as well. Good points mate. 

[Aussieamps]

Hi Guys

 

If the on board LEDs on the Volt One regulator board turn off it only means one thing, that the main raw supply voltage has been reached. (With a +-85v regulated output)

As the Volt One has an approximate 6 volt input output differential this would mean the raw supply voltage is approximately 91 volts, which is much lower than it should be given

the raw AC voltage should be approxiamtely 70vac - 0 - 70vac, the input DC supply would be approximately 98vdc per supply rail.

The onboard MOSFETs are rated at 200VDC and the input rectifiers are rated at 600Vdc, while the 100v rating for the caps is close it is still ok as all good quality caps are conservatively rated with a +20-30% long term surge rating.

Given the info here I would be looking at what is happening with the RAW supply voltage. This can be checked by measuring across power ground and RAW supply input.

The contact points for each raw supply is the grid array of gold plated through holes around each power mosfet or the metal tabs on the surface mounted mosfet.

 

I hope this helps?

 

 

Edited March 19, 2020 by Aussieamps

[ghost4man]

Okay so the suggested mod was undertaken with the following result - 

 

With the mods the power output seems to be down at 48.5Vrms before clipping which is equivalent to 294 watts into 8 ohms. Also max regulated output voltage has reduced to +/-85.5V no signal and +/-81V at full power before clipping the regulators are not even regulating properly. 

 

Testing suspended due to such poor results. On this basis it is apparent that the mod does not yield the desired result. In fact the complete opposite seems to be the case. 

 

Mod to be reversed. 

 

Edited March 19, 2020 by ghost4man

[ghost4man]

Just to clarify the following results came to light - 

 

Volt one measurements with recommended mods.

 

AC input 70 Vrms

Unregulated DC = +/- 93V

Max Regulated output = +/- 86V

 

How is this supposed to help with a main B+ supply from a recommended 60 Vrms transformer yielding a supply rail of only +/-83V no load.  In any event irrespective of the voltage range on the FETS and the caps these will not be pushed anywhere nesr their threshold for reasons already stated.. 

 

Raw supply voltage measurement is only confirming the existing problems and as such it appears that this build is nowhere near what is to be expected in terms of power output. The VOTLAGE regulator is at this stage yielding highly undesirable results notwithstanding the issue with the main B + from the transformer. 

 

What voltages should we see on the main B+ supply rails to the power stage and the regulator output in order to achieve 500/800 wpc and how to balance that against a transformer that was spec'd to 60VRMS. 

 

That is the question that needs to be asked. 

[Aussieamps]

13 hours ago, ghost4man said:

Just to clarify the following results came to light - 

 

Volt one measurements with recommended mods.

 

AC input 70 Vrms

Unregulated DC = +/- 93V

Max Regulated output = +/- 86V

 

How is this supposed to help with a main B+ supply from a recommended 60 Vrms transformer yielding a supply rail of only +/-83V no load.  In any event irrespective of the voltage range on the FETS and the caps these will not be pushed anywhere nesr their threshold for reasons already stated.. 

 

Raw supply voltage measurement is only confirming the existing problems and as such it appears that this build is nowhere near what is to be expected in terms of power output. The VOTLAGE regulator is at this stage yielding highly undesirable results notwithstanding the issue with the main B + from the transformer. 

 

What voltages should we see on the main B+ supply rails to the power stage and the regulator output in order to achieve 500/800 wpc and how to balance that against a transformer that was spec'd to 60VRMS. 

 

That is the question that needs to be asked. 

The mod does not work because the raw input voltage into the Volt one is not enough to allow the Volt One to adjust correctly to the needed output voltage.

70 volts AC will and should result in having a raw DC voltage of approximately 98vdc been feed into the Volt One regulator. The math is as follows, 70 volts AC X 1.414 is 98.98, however in real life it is more like 98 volts.

If you are not getting the 98 volts as a raw supply then you need to look as to why this is not happening.

My first suggestion is to see why the Volt One  RAW supply is only 92 volts, possible cause it is been overloaded, the protection poly switches on the Volt One are rated at around 200ma trigger, so anything above this the poly switch will trigger and become a large value resistor in which case it will drop excessive voltage across it.

The input stage/driver stage should not need anything like this amount of current.

 

The reason the Volt One will increase the output voltage swing and therefore the power output is the extra voltage present on the input driver stage helps to over come the several volt losses in the input/driver stage, this will then allow 3 to 4 more volts to be applied to the load, even 83 volts dc on the output stage stills allows this to happen.

its one of the reasons in the installation manual I supplied to you that I suggest the input stage supply rails are adjusted to at least 5 volts above the main unload output stage supply.

 

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 reliabliity reasons that a 60 volts AC supply would help with lower output stage dissippation. I hope you can see I have not tried to disceive you but to try and give you the best amp that could be supplied with this DIY module.

 

Look into why only 92 volts  raw supply is there, if needed unload the Volt One so it is not connected to the amplifier modules, and test the module again.

If you have excessive loading after reconnection to the modules, you will need to find out why this is happening, remember I did not build your amplifier and I am not present actual to see and do some test actual, so the more information you can feed me the better. That way I can help you the most.

 

 

 

Edited March 19, 2020 by Aussieamps

[ghost4man]

12 hours ago, Aussieamps said:

The mod does not work because the raw input voltage into the Volt one is not enough to allow the Volt One to adjust correctly to the needed output voltage.

70 volts AC will and should result in having a raw DC voltage of approximately 98vdc been feed into the Volt One regulator. The math is as follows, 70 volts AC X 1.414 is 98.98, however in real life it is more like 98 volts.

If you are not getting the 98 volts as a raw supply then you need to look as to why this is not happening.

My first suggestion is to see why the Volt One  RAW supply is only 92 volts, possible cause it is been overloaded, the protection poly switches on the Volt One are rated at around 200ma trigger, so anything above this the poly switch will trigger and become a large value resistor in which case it will drop excessive voltage across it.

The input stage/driver stage should not need anything like this amount of current.

 

The reason the Volt One will increase the output voltage swing and therefore the power output is the extra voltage present on the input driver stage helps to over come the several volt losses in the input/driver stage, this will then allow 3 to 4 more volts to be applied to the load, even 83 volts dc on the output stage stills allows this to happen.

its one of the reasons in the installation manual I supplied to you that I suggest the input stage supply rails are adjusted to at least 5 volts above the main unload output stage supply.

 

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 reliabliity reasons that a 60 volts AC supply would help with lower output stage dissippation. I hope you can see I have not tried to disceive you but to try and give you the best amp that could be supplied with this DIY module.

 

Look into why only 92 volts  raw supply is there, if needed unload the Volt One so it is not connected to the amplifier modules, and test the module again.

If you have excessive loading after reconnection to the modules, you will need to find out why this is happening, remember I did not build your amplifier and I am not present actual to see and do some test actual, so the more information you can feed me the better. That way I can help you the most.

 

 

 

I have a big concern related to the above which I will post later and which highlights one of my biggest disappointments thus far. It relates to the advertised claims of the modules which quite simply cannot be met and what is currently being reflected right now. 

 

For now - 

No cigar for the polyswitch. There is virtually no voltage drop across them. The voltage across the caps and there is some ripple as expected. For example the positive rail measures as follows:-

 

Maximum voltage = 96V

Minimum voltage = 93.6V

Average Voltage = 95.2V

 

Some voltage drop across the diodes as expected.but the assumption of clean sinusoidal mains is questionable and would be viewed by many as being incorrect..Most mains supplies are truncated and the peaks are clipped so instead of the expected peak of 99V we are only getting 96V which is already a drop of 3 Volts.This would apply to the main B+ supply as well so the supply rails are under spec because of mains clipping.

 

With a 6V dropout voltage the maximum regulated output voltage is 93.6 - 6 = 87.6 and is indeed what we are measuring! 

 

 

 

[Aussieamps]

3 hours ago, ghost4man said:

I have a big concern related to the above which I will post later and which highlights one of my biggest disappointments thus far. It relates to the advertised claims of the modules which quite simply cannot be met and what is currently being reflected right now. 

 

For now - 

No cigar for the polyswitch. There is virtually no voltage drop across them. The voltage across the caps and there is some ripple as expected. For example the positive rail measures as follows:-

 

Maximum voltage = 96V

Minimum voltage = 93.6V

Average Voltage = 95.2V

 

Some voltage drop across the diodes as expected.but the assumption of clean sinusoidal mains is questionable and would be viewed by many as being incorrect..Most mains supplies are truncated and the peaks are clipped so instead of the expected peak of 99V we are only getting 96V which is already a drop of 3 Volts.This would apply to the main B+ supply as well so the supply rails are under spec because of mains clipping.

 

With a 6V dropout voltage the maximum regulated output voltage is 93.6 - 6 = 87.6 and is indeed what we are measuring! 

 

 

 

If mains clipping is happening then can you tell me what the measured primary AC mains input is please, loaded and unloaded ?

As this would explain why the needed voltage are not there.

All specifications for the power transfomer were at the time (11/07/2017 from ) are rated for at least 240vac been feed into the primary winding, to achieve the specified output voltages.

See copy of email dated 11/07/2017

Hi Ozzie

Here are the transformer details as requested so you can use the Volt One regulator.

2.5KVA core

1 x 240vac primary winding

1 x electrostatic shield between primary and secondary windings

4 x 60vac secondary windings each winding @ 10 Amps

4 x 70vac secondary windings each winding @ 350ma

 

 

Primary winding exit point 12 o'clock

2 x 70vac winding exit point at 9 o'clock

2 x 70vac winding exit point at 3 o'clock

2 x 60vac winding exit point at 9 o'clock

2 x 60vac winding exit point at 3 o'clock

All primary and secondary external windings wires to be 300mm flexible leads

 

 

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?

 

 

 

Edited March 20, 2020 by Aussieamps