MCH-K38 - a giant killer!

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triumph

Re: MCH-K38 - a giant killer!
« Reply #260 on: 1 Oct 2016, 11:59 am »
Just got the MCH-K38 home and been listening for two hours.... but it's evening and I can't even try pushing it a little!

What I like so far is the presentation.  Even at low volume, which my old Yamaha couldn't do.  All the details would get sucked out at low volume with the Yamaha amp.  The MCH brings it all back, even at such low volume. 

Can't wait for tomorrow!  :)

Eisener Bart

Re: MCH-K38 - a giant killer!
« Reply #261 on: 1 Oct 2016, 05:21 pm »

What I like so far is the presentation.  Even at low volume, which my old Yamaha couldn't do. 

it's familiar feature of NuPrime PowerAmps. i had same effect with STA-9.

zwizardofoz

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Re: MCH-K38 - a giant killer!
« Reply #262 on: 19 Oct 2016, 08:48 am »
I have just received the K38 from my local distributor for a period of testing with the www.LinkwitzLab.com LX521 Reference (ASP) and LXmini/Studio with MiniDSP 4x10HD setups so will report back how it sounds and any issues with the rather low input gains that are being talked about (22dB) plus will be testing with some other box speakers. Mostly will be using PS Audio DS Jr or Oppo HA-1 DAC setups, but might have to add in preamp if the gain setup is not going to give enough headroom.
« Last Edit: 20 Oct 2016, 04:00 am by zwizardofoz »

zwizardofoz

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Re: MCH-K38 - a giant killer!
« Reply #263 on: 20 Oct 2016, 03:44 am »
On the Linkwitz forum another member asked me

"Having checked out the NuPrime amp, the gain listed on the spec sheet is "x22" which I'm taking to be "voltage gain". The resulting dB gain should be a more ideal 26.85dB. Since you own the amp and I'm just reading the spec sheet, it would be interesting to know if it's voltage or dB gain."

@rustydoglim Jason would you be able to elaborate on the gain for this model, and also if there is any difference between the RCA and BAL inputs gain. And for that matter the STA-9 for which I have in a different setup with LXmini and MiniDSP 2x4

I guess I could get out a signal generator and measure it but thats a lot of messing around for what should be detailed in the specs.

zwizardofoz

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Re: MCH-K38 - a giant killer!
« Reply #264 on: 20 Oct 2016, 03:58 am »
Adding this a separate post...

The K38 is a beast...its images on the website belittle its heft and size to say the least. I was quite surprised at the size, not to say its huge, rather that it looked larger than I expected from the web site images, but the big surprise was the weight!!! And the external build quality is superb. Well done NuPrime - I am looking forward to seeing how this compares with the existing 2 x Emotiva Gen 2 XPA-5's it will potentially replace...granted its 3-4 times the price, for 8 as opposed to 10 channels.

I use it as an 8 channel amp - 4 channels for each speaker (Bass,Bass,Mid,Tweeter) in an active setup detailed here http://www.linkwitzlab.com/LX521/Description.htm and my build here http://walaneh.com/LX521/

I might just relegate the XPA-5's to HT channels duty and use the Linkwits setups exclusively for stereo use...they currently are the L/R for the HT setups.

triumph

Re: MCH-K38 - a giant killer!
« Reply #265 on: 20 Oct 2016, 08:08 am »
zwizardofoz,  what do you use for preamp/ DAC with the MCHK38?

zwizardofoz

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Re: MCH-K38 - a giant killer!
« Reply #266 on: 20 Oct 2016, 08:27 am »
Is an Active crossover front ended with a PS Audio DS Junior or via an Emotiva XMC-1


smishsmorshen

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Re: MCH-K38 - a giant killer!
« Reply #267 on: 20 Oct 2016, 08:27 pm »
Adding this a separate post...

The K38 is a beast...its images on the website belittle its heft and size to say the least. I was quite surprised at the size, not to say its huge, rather that it looked larger than I expected from the web site images, but the big surprise was the weight!!! And the external build quality is superb. Well done NuPrime - I am looking forward to seeing how this compares with the existing 2 x Emotiva Gen 2 XPA-5's it will potentially replace...granted its 3-4 times the price, for 8 as opposed to 10 channels.

I use it as an 8 channel amp - 4 channels for each speaker (Bass,Bass,Mid,Tweeter) in an active setup detailed here http://www.linkwitzlab.com/LX521/Description.htm and my build here http://walaneh.com/LX521/

I might just relegate the XPA-5's to HT channels duty and use the Linkwits setups exclusively for stereo use...they currently are the L/R for the HT setups.

Looking forward to your review/impressions. Currently on the fence with getting the K38 or the new gen3 XPA-7..

zwizardofoz

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Re: MCH-K38 - a giant killer!
« Reply #268 on: 11 Nov 2016, 11:07 am »
I cant comment on the xpa-7 G3 but it's not as flexible as the k-38 with the later having bridgable adjacent channels and of course an extra channel to boot.

My application was using 4 channels per speaker via an active crossover Pre amp inputs with speakers connected directly i.e. No internal speakers crossovers...well for the most part but there was a simple capacitor -inductor crossover as the mid range is covered by 2 drivers.

My main issue was the temperature that the k38 idles at when on or even when there is no signal. Way over what I would expect for a d class but maybe it's the class a inputs that's driving up the temp.

rustydoglim

Re: MCH-K38 - a giant killer!
« Reply #269 on: 11 Nov 2016, 08:30 pm »
MCH-K38 is a hybrid A+D design. The idling power is 40W (with all 8 channels turned on).  You save a few watts per channel by turning some of them off.

zwizardofoz

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Re: MCH-K38 - a giant killer!
« Reply #270 on: 12 Nov 2016, 02:37 am »
I'm forced to run in a non aircon room where the ambient temp when I'm not listening is up around 28 C. Thus having to get around the back to turn it off is not an option.

I think there was a trigger in so would that only put the unit in standby or would that effectively bring the unit to an almost off and not generate so much heat when not being used?

srb

Re: MCH-K38 - a giant killer!
« Reply #271 on: 12 Nov 2016, 04:00 am »
As previously stated, the idling power is 40W with the amplifier powered on and all 8 channels active, but with no input signal.

Standby normally refers to the state where the amplifier circuitry is not active except for the power required to keep the trigger relay circuitry active (and/or in the case of a remote controlled preamplifier or integrated amplifier, the IR or RF receiver circuitry active).

If the amplifier meets European Conformity CE certification, that would be limited to .5W after January 2013, but not seeing any certification logos on the available rear panel photos, it's unknown if it meets that standard.

Steve

rustydoglim

Re: MCH-K38 - a giant killer!
« Reply #272 on: 12 Nov 2016, 08:23 am »
It is CE certified. But the EU regulation about the standby power is not part of the CE cert which test for safety and EMI etc.
The standby power regulation has some leeway (I am not exactly sure what it is since I don't manage the certification). What I do know is that for some type of device, the power button is sufficient. Or there are exception for certain class of devices.

triumph

Re: MCH-K38 - a giant killer!
« Reply #273 on: 23 Dec 2016, 05:14 am »
Can the MCHK38 drive a channel at 2 Ohms? 
I'm considering wiring two 4 Ohms subwoofer drivers (that will bring me down to 2 Ohms) to help boost sensitivity, or to be used as 2 mono subs using the same signal.

I've looked online or in the documentation, and I didn't find any information regarding 2 Ohms operation.  It talks about 4 and 8 Ohms, but no mention of 2 Ohms.  Which kinda lets me believe that it won't do 2 Ohms, but figured I'd ask anyway!  :)

Thanks!

And Happy Holidays!

Evoke

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Re: MCH-K38 - a giant killer!
« Reply #274 on: 23 Dec 2016, 05:31 am »
Can the MCHK38 drive a channel at 2 Ohms? 
I'm considering wiring two 4 Ohms subwoofer drivers (that will bring me down to 2 Ohms) to help boost sensitivity, or to be used as 2 mono subs using the same signal.

I've looked online or in the documentation, and I didn't find any information regarding 2 Ohms operation.  It talks about 4 and 8 Ohms, but no mention of 2 Ohms.  Which kinda lets me believe that it won't do 2 Ohms, but figured I'd ask anyway!  :)

Thanks!

And Happy Holidays!


Happy Holidays - When you have a subwoofer that quotes 4 ohms, it may actually go lower or higher depending on the frequency. While you can run at 2 ohms (Rusty can confirm) I would never suggest going below 4. And with 8 channels, you can driver each woofer with its' own amp channel. That still leaves 6 for LCR/Surround or bi-amp.


In my case I run 4 channels at 400 watts to bi-amp my stereo speakers. The dynamics are insane. Hope my bit if input helps in some way.

srb

Re: MCH-K38 - a giant killer!
« Reply #275 on: 23 Dec 2016, 05:32 am »
2Ω paralleled load nominal, but if your drivers dip down to 2Ω or 3Ω at some frequency(s), that would be a 1Ω - 1.5Ω load, and it probably can't do that.

Since the amplifier puts out the same power at 4Ω or 8Ω, you could wire them in series for a nice safe 8Ω load.

Steve

rustydoglim

Re: MCH-K38 - a giant killer!
« Reply #276 on: 27 Dec 2016, 04:45 pm »
It can work with 2ohm, but now you wire the two subwoofer together, it could go to 1ohm which is not a good idea as it will draws a lot of current from the power supply, you are better off using two channels with two subwoofer separately.

ZAPHOD2012

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Re: MCH-K38 - a giant killer!
« Reply #277 on: 24 Mar 2017, 03:19 am »
my take ....

I have Audience 2+2 in a stereo system in the bedroom, they have been powered by Cary Audio and Parasound multi channels. Due to the weight and only stereo need i sold the Cary and Parasound for the Nuprime ST-10. I was cautious as i have hated my previous experiments with class d amps such as rotel, pioneer and wyred4sound, all cold and lifeless, boring and flat. The ST-10 was a revelation, sweet, very detailed, tight, extended and bouncy, it had life and was a joyful match with the 2+2's, i cannot remember a more enjoyable sound in 30 years, especially for the money, and the mids are incredible. In my main system i needed to replace my hernia weighted Cary 7 channel, so with my positive experience with the ST-10 I plumped for the MCH-K38 at half the weight of the Cary and hoping it would come close to the exceptional ST-10. The MCH-K38 will be used in a 5.1 system driving Audience 4+4's when they arrive from the factory. In 5.1 mode the first 4 channels will be bridged and that is how i compared it to the ST-10, not only did it equal the ST-10 but in bridged mode bettered it. Same family signature but just with a more effortless control, more open, less restrained and detailed, I am extremely surprised and very happy, what a combination made in heaven, the Audience and the Nuprime .... rock on .....

rustydoglim

Re: MCH-K38 - a giant killer!
« Reply #278 on: 24 Mar 2017, 08:25 pm »
Thank you thank you thank you. Customer's validation always bring such joy for all of us at NuPrime.