[jonbee]

No, I've not.

[gregfisk]

Jonbee, for reference have you tried a Crown XLS 1500 in your system? I have and found the top end and upper midrange harsh but was hoping for a comparison to get a better feel for the upper frequencies of the ST-10.

[srb]

It may be possible that "some" of that quality you like is due to a higher carrier frequency (around 550khz-600khz) of the NuPRIME.  I looked around, but didn't see the stat for the N-core.  Have you read anywhere what it is?

From the Hypex datasheets, the switching frequencies are:

 Module        Min            Typ          Max   
----------------------------------------------
NC400      470kHz      480kHz     530kHz

NC500           -           450kHz         -

NC1200     440kHz      480kHz     520kHz


Steve

[MttBsh]

Just an update- I've listened to the ST-10/10H for a few days, an I do like it better than the NAD M51/modded N-core Nc-400 I'd been happily using for the last 3 years. The tonality of the ST-10 is equally detailed but more laid back on top than the N-Core, which necessitated I turn up the ambience tweeters on my Von Schweikerts a bit, but the upper mids are more relaxed and natural on the ST-10. I should note that the VSs are a little laid back on their own, so this observation wouldn't necessarily apply to other speakers. Bass range is a bit better defined, too. No downside I've heard.
I still like the N-Core a lot, and moved it to my office, where it sounds great.
The N-Core cost about $2200 in parts, plus my labor. At $1600 the ST-10 equals or betters it and is the biggest amp bargain I've heard, and with the 10H it offers really fine performance that may well be impossible to beat for the $.
It's hard to imagine it being that much better modded, but I'm thinking about the TDSS upgrades. More later if I do that.

Thanks jonbee for the update. After reading your impressions of the ST-10 I've decided I need the amp too. Thanks for taking the time to share your findings!

[John Casler]

From the Hypex datasheets, the switching frequencies are:

 Module        Min            Typ          Max   
----------------------------------------------
NC400      470kHz      480kHz     530kHz

NC500           -           450kHz         -

NC1200     440kHz      480kHz     520kHz


Steve

Thanks Steve, I had heard around 450kHz, but never had seen the spec

[gammajo]

I have been enjoying my Nuforce (now Nuprime) Reference 20 monos for over a year. I think my equipment is good enough to hear differences. Speakers Von Schweikert VR 55 acktive ($60,000 and multiple Best In Show, Golden ear and Editors choice awards), Cables all Delphi Ultra ($40,000) Front end is Ayon CD 5s with NOS tubes). The Ref 20 beat all amps tried in my system which were many and to my ears all other I have heard in other systems including big name and reputation class A. It also beat my modded Ref 9V3se and from feedback beats the Ref18 by a small but significant degree in finesse, liquidity, detail, and dynamics.
I would love to hear my 20's against the current amp in discussion. My 20's I think are helped by my tubed preamp. I would guess that this new design adds a touch warmth and perhaps bloom that I get from my tubed pre to the neutral (not cold) Ref 20.
Indeed Nuprime is great bang for the buck, but beyond that creates provides a total cure for upgraditis if the rest of the system is up to the same standard.

[MttBsh]

I would love to hear my 20's against the current amp in discussion.

According to Nuprime, the ST-10 (current amp in discussion) is virtually identical in sound to the reference 20, it just has considerably less power. The question is, given a low wattage system and high efficiency speakers, would there be any sonic benefit in selecting the ref 20 over the ST-10?

[rustydoglim]

As the power exceeded a certain level, the design has to change. Cost goes up exponentially instead of linearly as power goes up.

[gregfisk]

As the power exceeded a certain level, the design has to change. Cost goes up exponentially instead of linearly as power goes up.

If you were answering MttBsh's question, which I was hoping you would, I personally didn't get the answer. So, the design had to change, did it change the sound? A lot of us don't need all of the power but still want the quality of sound. I'm personally sold once I get a handle on the differences between going with (2) ST-9s or the ST-10. I too run a really good tube preamp which adds a quality to the music I have never had with SS preamps or any other tube pre for that matter. I've tried several SS amps in my system, class ab, b, bd and d and have been most happy with the Butler 2250 which is a hybrid amp with one tube per channel on the output stage. I still feel like the upper freq. are a bit hard but the midrange is very nice. If I could find an amp that could smooth out the upper mids and highs I would stop looking for amps and start spending money on other parts of my system like a new dac or roon with HQplayer running on my mac mini.

[maty]

"I still feel like the upper freq. are a bit hard but the midrange is very nice..."

You need a good soft equalizer.

[rustydoglim]

If you were answering MttBsh's question, which I was hoping you would, I personally didn't get the answer. So, the design had to change, did it change the sound? A lot of us don't need all of the power but still want the quality of sound. I'm personally sold once I get a handle on the differences between going with (2) ST-9s or the ST-10. I too run a really good tube preamp which adds a quality to the music I have never had with SS preamps or any other tube pre for that matter. I've tried several SS amps in my system, class ab, b, bd and d and have been most happy with the Butler 2250 which is a hybrid amp with one tube per channel on the output stage. I still feel like the upper freq. are a bit hard but the midrange is very nice. If I could find an amp that could smooth out the upper mids and highs I would stop looking for amps and start spending money on other parts of my system like a new dac or roon with HQplayer running on my mac mini.

Since ST-10 and Ref 20 amps have different designs (they do come from the same topology), they will sound different (but close). How close?
See the Amp Comparison chart.  I said that many times in all the topics. The Amp Comparison chart is the gold standard and you should treat it like a spec.  This chart was debated and discussed with engineering and also based on listening test. So it is the best we can offer.

But keep in mind that the differences between these amps are quite small.

[Eugene]

Hi Rustydoglim, thanks for your reaction on my question. I have another question. For driving my speakers the lf and mf/hf needs separate amp's. If I use 2 K38's with bridged channels for full power, two bridged channels of each K38's will not be used. Is this a bad thing for this amp? Thanks, Eugene

[gammajo]

GregFisk The  later Nuforce/Nuprime amps are very revealing so all things that can make the treble hot or harsh need to be addressed such as tweeter design, room reflections, cables, source and vibration control. With these correct, then the Nuforce/Nuprime designs to me are beautiful in the highs - detailed, liquid, fast, and natural and I am very sensitive to any glare, tizziness or imbalance in the highs, for example cymbels and bells sound correct in attach, body and decay and upper violins are natural with correct bite but not grating. Hope this helps

[S Clark]

. If I could find an amp that could smooth out the upper mids and highs I would stop looking for amps and start spending money on other parts of my system like a new dac or roon with HQplayer running on my mac mini.

Since you are already familiar with and like what hybrids offer, you might look at Moscode.  When they come available used, they are usually reasonably priced, and are quite musical in their mids and highs. 

[jonbee]

Jonbee, for reference have you tried a Crown XLS 1500 in your system? I have and found the top end and upper midrange harsh but was hoping for a comparison to get a better feel for the upper frequencies of the ST-10.

No, haven't heard it. The open, smooth, natural mids and highs as well as the very powerful, clean bass are the elements of the ST-10 that stand apart. Refinement and slam.
Last night I watched the James Taylor at Beacon Theater dvd, which has been a standard of mine for sound quality which I often come back to. Sony made it a showcase for their recording technology at the time, pulling out the stops. I've never heard it sound so good, from top to bottom, front to back. Just wonderful.

[rustydoglim]

Hi Rustydoglim, thanks for your reaction on my question. I have another question. For driving my speakers the lf and mf/hf needs separate amp's. If I use 2 K38's with bridged channels for full power, two bridged channels of each K38's will not be used. Is this a bad thing for this amp? Thanks, Eugene

Not at all, the front panel has the on/off buttons for each channel. You just turn off the unused channels.

[Eugene]

That's great to hear. Now I will look for a home demo arrangement to find out the remarkable qualities of this amp.

[gregfisk]

I want to thank all of you who answered my questions and gave me sound advice. It is very much appreciated, now I just need to make a decision on what amp(s) I will buy.

If anyone has any other input of their personal comparisons between the ST-9 or ST-10 regarding the upper frequencies I would love to here them. Otherwise I will probably just take a leap of faith and pick one.

Thanks again for all the input.

Greg

[Tubegem]

Not at all, the front panel has the on/off buttons for each channel. You just turn off the unused channels.

Going on the opposite direction, any chance we will see a 3 channel version of this amp (K-33) with both balanced and un-balanced inputs. 
 

[rustydoglim]

I will think about making something more flexible.