Posted "NuClassD" amp design: 50W hybrid class-D / Korg Nutube

pmillett · 29th October 2018, 12:18 AM

I finally got to documenting the design of the 50 watt hybrid amp design I've been playing with for some time. It uses the Korg Nutube as a gain stage in front of a Monolithic Power MP7770 self-oscillating class-D amp chip (as well as a few JFETs).

You can find details here: NuClassD 50W Nutube hybrid amp

Pete

dtaylo3 · 29th October 2018, 01:43 AM

Very nice!!! Kudos once again. How do you think this new hybrid might sound compared to your Nutube buffer (which I purchased but have yet to solder up) leading into a Hypex amp? I currently have multiple Hypex amps, but miss the sound of my old EL34 that has been in sick bay for a few years. So I purchased your buffer. I may have to purchases this one as well in order to compare the two.

pinkfloyd4ever · 1st November 2018, 09:35 PM

Man Pete! This sounds awesome, but I already have too many projects in the cue! Looks like I'm going to have to add another.

Just wanted to take the opportunity to thank you for all your great designs and for sharing them with the DIY community. I really enjoyed building and listening to your SSMH and a couple versions of the Millet Hybrid Maxed, one of which I'm listening to as I type.

Cheers!

HiGHFLYiN9s · 2nd November 2018, 08:31 PM

I'm very excited to get mine built Pete, love the idea of a super efficient tube amp

512-P6KE30A was all sold out at Mouser, assuming this is a good sub? 625-P6KE30A-E3

Also, are 2% resistors okay, or do they need to be 1% on the amp boards?

TIA.

Vunce · 3rd November 2018, 01:29 AM

Hello Pete,

I went to the webstore and orders won't be processed until late
November

HiGHFLYiN9s · 5th November 2018, 10:24 PM

Looks like he'll be back on the 23rd.

pmillett · 6th November 2018, 10:07 AM

Quote:

Originally Posted by Vunce

Hello Pete,

I went to the webstore and orders won't be processed until late
November

Yeah, sorry about that - in Japan for a week then Europe for two, so I shut down the store until I get back.

pmillett · 6th November 2018, 10:08 AM

Quote:

Originally Posted by HiGHFLYiN9s

I'm very excited to get mine built Pete, love the idea of a super efficient tube amp

512-P6KE30A was all sold out at Mouser, assuming this is a good sub? 625-P6KE30A-E3

Also, are 2% resistors okay, or do they need to be 1% on the amp boards?

TIA.

2% resistors are OK, as is the TVS substitute.

Pete

Vunce · 6th November 2018, 09:32 PM

Quote:

Originally Posted by pmillett

........so I shut down the store until I get back.

No problem Pete, have a great journey.
Does the board need any additional heatsinking?

pmillett · 6th November 2018, 11:39 PM

Not for normal music applications. If you run a 50W sine wave, though, it will hit a thermal limit and shut down after some time.

I haven't tried adding any external heatsinks.

Pete

29th October 2018, 12:18 AM	#1
pmillett diyAudio Member Join Date: May 2005 Location: Near Fort Collins, CO	Posted "NuClassD" amp design: 50W hybrid class-D / Korg Nutube I finally got to documenting the design of the 50 watt hybrid amp design I've been playing with for some time. It uses the Korg Nutube as a gain stage in front of a Monolithic Power MP7770 self-oscillating class-D amp chip (as well as a few JFETs). You can find details here: NuClassD 50W Nutube hybrid amp Pete

2nd November 2018, 08:31 PM	#4
HiGHFLYiN9s diyAudio Member Join Date: Jun 2010 Location: East Coast, USA	I'm very excited to get mine built Pete, love the idea of a super efficient tube amp 512-P6KE30A was all sold out at Mouser, assuming this is a good sub? 625-P6KE30A-E3 Also, are 2% resistors okay, or do they need to be 1% on the amp boards? TIA. __________________ My DIY Electronics Blog: DIYAudioBlog.com

5th November 2018, 10:24 PM	#6
HiGHFLYiN9s diyAudio Member Join Date: Jun 2010 Location: East Coast, USA	Looks like he'll be back on the 23rd. __________________ My DIY Electronics Blog: DIYAudioBlog.com

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29th October 2018, 01:43 AM	#2
dtaylo3 diyAudio Member Join Date: Nov 2004 Location: coloradao usa	Very nice!!! Kudos once again. How do you think this new hybrid might sound compared to your Nutube buffer (which I purchased but have yet to solder up) leading into a Hypex amp? I currently have multiple Hypex amps, but miss the sound of my old EL34 that has been in sick bay for a few years. So I purchased your buffer. I may have to purchases this one as well in order to compare the two.

1st November 2018, 09:35 PM	#3
pinkfloyd4ever diyAudio Member Join Date: Apr 2008 Location: St. Louis, MO	Man Pete! This sounds awesome, but I already have too many projects in the cue! Looks like I'm going to have to add another. Just wanted to take the opportunity to thank you for all your great designs and for sharing them with the DIY community. I really enjoyed building and listening to your SSMH and a couple versions of the Millet Hybrid Maxed, one of which I'm listening to as I type. Cheers!

3rd November 2018, 01:29 AM	#5
Vunce diyAudio Member Join Date: Jan 2014 Location: LI, NY	Hello Pete, I went to the webstore and orders won't be processed until late November

6th November 2018, 11:39 PM	#10
pmillett diyAudio Member Join Date: May 2005 Location: Near Fort Collins, CO	Not for normal music applications. If you run a 50W sine wave, though, it will hit a thermal limit and shut down after some time. I haven't tried adding any external heatsinks. Pete

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