[orientalexpress]

Is there a 30 days try period?it's all about synergy with speakers.i hate to spend $3k and find out it's doesn't good or better then what i have.

lap

[rustydoglim]

P20 is not applicable in this discussion about power amp. Don't confuse the Preamp Stage of a power amp with a Preamp that does input selection and volume control.

Ref 20 is A+F+S
For a long time we have been using OpAmp just like everybody else. A high quality OpAmp circuit can be very good, as used also by many reference amps. But you can't tune the sound. So if you want to sound like tube, then you have to use transistors with tube characteristic. But unlike a tube what is one big transistor with all its good and flaws, we can do a lot with class D and transistors.
Ref 20 wasn't meant to sound like tube.
A Full Bridge class D power stage is more expensive but has an edge over Half Bridge design. So ST-10 and Ref 20 use Full Bridge design.
Switching Power Supply has to be used for so much power density.

I think what we are doing is really a revolutionary steps in Class D, not that the technique was not known by some of the most knowledgeable analog engineers. But it is the extensive mix of analog design techniques and class D designs that is ground breaking. You won't hear about magazines talking about this because nobody wants to promote budget amps with super high end designs.

With regards to a two channel K38, I stated that we have no plan, simply because K38 was designed to be the best amp for movies and music. Further more, the sound characteristic of K38 is quite "American". We have equally important customers in France (who have similar taste as the Chinese) that prefer STA-9, or Japanese and Germans who preferred neutral sound. So here lies the difficult of coming out with a STA-10. How do we strike the balance? So for the mean time, go buy K38

[bh46118]

Jason, I'm going to put you on the spot, for your personal listening which sound profile do you prefer ?

[rustydoglim]

Jason, I'm going to put you on the spot, for your personal listening which sound profile do you prefer ?

You will all be disappointed that I have very little time for music listening (well, I really need Omnia). When I am not traveling 50% of the time, at home I work long hours (I enjoy what I do, taking products to market and creating brands so it is not work to me). I am confined to my home office after 9pm and not allow to play music loud that disturb my family (heavy school work etc).

So, what I have at home is constrained by family and personal need, not necessary my dream system.  I am not into classical music or have room and time for large system. So I have the HD-AVA with the old NuForce S-9 speakers which is perfect for me. 
The HD-AVA amp is in between STA-9 and K38, sort of leaning slightly more toward music listening than movies.
I watch downloaded movies and TV programs so HD-AVA is perfect for me.  It is also connected to my home network by ethernet cable to access my Synology NAS where I kept everything there. So, one device that does everything for me.
I have WR-100 connected to HD-AVA for online streaming via Spotify.  HD-AVA already has AirPlay built-in for streaming.

On my desk, where I literally live 1/4 of my life, this is the setup 
Facebook on iPad Pro, social media on iPhone 6+, computer in the middle, hidden behind the computer are NuPrime uDSD (for MacBook Pro) and Encore mDSD (for iPad Pro).  The Celsus Sound SP One speakers are great as monitor speakers but can also rock the room.

[Rocket_Ronny]

Nice setup. I found at one time I did most of my listening in front of the computer as well. Now it seems it's in the truck. Did not stop me from adding a pair Rythmik FM8s to the main system. Have not hear them yet, but soon. 

Gave the speakers to my son and his professional video company, but you get the idea. He and his friends love the speakers and is their introduction to high end audio.


In the end, it still is all about the music.


Rocket Ronny

P.S. How did you get your computer keys colored like that.

[rustydoglim]

P.S. How did you get your computer keys coloured like that.

You can buy it at < $2 with free shipping from http://www.aliexpress.com  (search for keyboard skin)

[MttBsh]

Jason,
Thanks for the listing of sound characteristics of Nuprime's different amps, I really appreciate it. I like the sound you describe for the K38, but I currently have SET amps and high efficiency speakers so the K38 is probably too much power, so I am leaning towards the ST-10, which, from what I've read, strikes me as the K38 sound with the lower power I need.
My question: my preamp is a Tortuga LDR, which produces an extremely fast, clean, and refined sound - and then warmth is added in my mono tube amps. I prefer clean and fast over warmth, but do you think replacing my tube amps with the ST-10 would render the sound too lean in my set up? I know it's all a matter of personal preference but I am interested in your thoughts. Thank so much!

[Eisener Bart]

P20 is not applicable in this discussion about power amp. Don't confuse the Preamp Stage of a power amp with a Preamp that does input selection and volume control.

Ref 20 is A+F+S
For a long time we have been using OpAmp just like everybody else. A high quality OpAmp circuit can be very good, as used also by many reference amps. But you can't tune the sound. So if you want to sound like tube, then you have to use transistors with tube characteristic. But unlike a tube what is one big transistor with all its good and flaws, we can do a lot with class D and transistors.
Ref 20 wasn't meant to sound like tube.
A Full Bridge class D power stage is more expensive but has an edge over Half Bridge design. So ST-10 and Ref 20 use Full Bridge design.
Switching Power Supply has to be used for so much power density.

I think what we are doing is really a revolutionary steps in Class D, not that the technique was not known by some of the most knowledgeable analog engineers. But it is the extensive mix of analog design techniques and class D designs that is ground breaking. You won't hear about magazines talking about this because nobody wants to promote budget amps with super high end designs.

With regards to a two channel K38, I stated that we have no plan, simply because K38 was designed to be the best amp for movies and music. Further more, the sound characteristic of K38 is quite "American". We have equally important customers in France (who have similar taste as the Chinese) that prefer STA-9, or Japanese and Germans who preferred neutral sound. So here lies the difficult of coming out with a STA-10. How do we strike the balance? So for the mean time, go buy K38

Thank you very much for detailed answer!
I plan to buy Ref-20 in the end of this year, even I contacted already with dealer and discussed regarding terms.

[Eugene]

I'm reading with much interest this thread. My speakers are the Apogee Full Range and the low frequencies and mid/high frequencies must be driven separately which is done by a crossover. Is there a possibility to build a crossover in this mighty amp? Thanks for the reaction(s).

Eugene
 

[mresseguie]

With regards to a two channel K38, I stated that we have no plan, simply because K38 was designed to be the best amp for movies and music. Further more, the sound characteristic of K38 is quite "American". We have equally important customers in France (who have similar taste as the Chinese) that prefer STA-9, or Japanese and Germans who preferred neutral sound. So here lies the difficult of coming out with a STA-10. How do we strike the balance? So for the mean time, go buy K38

Jason,

I can appreciate that you must weigh choices and consumers' preferences when you decide which variation to put into production. Nonetheless, I'm telling you now that I would jump at the chance to buy a two-channel version of the K38 (assuming I don't cave in and purchase an ST-10 or dual STA-9 beforehand). I have until September/October to decide. Hint hint.

Regards,

Michael

[mresseguie]

Oops! Double post. 

[rustydoglim]

My speakers are the Apogee Full Range and the low frequencies and mid/high frequencies must be driven separately which is done by a crossover. Is there a possibility to build a crossover in this mighty amp? Thanks for the reaction(s).

It can be done but doesn't make sense from a commercial point of view. We have to design products that are appealing to most people. In any case, you normally have crossover(s) as input to the amp for active speaker configuration.

Nonetheless, I'm telling you now that I would jump at the chance to buy a two-channel version of the K38 (assuming I don't cave in and purchase an ST-10 or dual STA-9 beforehand). I have until September/October to decide. Hint hint.

The sound of K38 comes from the preamp stage which has 8 channels combined, even though the amp module is 2 channels. So it is not that straight forward to make a stereo amp and we have to redesign the preamp stage. And then put into production bla bla bla, and four months would be gone. So, it would be better off if we just design a new preamp stage (probably between K38 and ST-10 sound) and pick the class-D stage from one of the amps.

[rustydoglim]

My question: my preamp is a Tortuga LDR, which produces an extremely fast, clean, and refined sound - and then warmth is added in my mono tube amps. I prefer clean and fast over warmth, but do you think replacing my tube amps with the ST-10 would render the sound too lean in my set up? I know it's all a matter of personal preference but I am interested in your thoughts. Thank so much!

I think ST-10 will be just the right balance for you. STA-9 will sound too warmth for your liking.
I can't emphaisze enough that everyone should refer to the amp comparison guide. It was created with the input of the chief engineer who designed all these amps.

[mresseguie]

The sound of K38 comes from the preamp stage which has 8 channels combined, even though the amp module is 2 channels. So it is not that straight forward to make a stereo amp and we have to redesign the preamp stage. And then put into production bla bla bla, and four months would be gone. So, it would be better off if we just design a new preamp stage (probably between K38 and ST-10 sound) and pick the class-D stage from one of the amps.

I think ST-10 will be just the right balance for you. STA-9 will sound too warmth for your liking.
I can't emphaisze enough that everyone should refer to the amp comparison guide. It was created with the input of the chief engineer who designed all these amps.

I do understand. I just wanted to let you know others are interested. In all likelihood I will purchase an ST-10 because I'll pair it to a tube preamp and separate DAC. The power of the dual STA-9 is seductive, but it may be too warm sounding.

[gregfisk]

The sound of K38 comes from the preamp stage which has 8 channels combined, even though the amp module is 2 channels. So it is not that straight forward to make a stereo amp and we have to redesign the preamp stage. And then put into production bla bla bla, and four months would be gone. So, it would be better off if we just design a new preamp stage (probably between K38 and ST-10 sound) and pick the class-D stage from one of the amps.

I do understand. I just wanted to let you know others are interested. In all likelihood I will purchase an ST-10 because I'll pair it to a tube preamp and separate DAC. The power of the dual STA-9 is seductive, but it may be too warm sounding.

Michael,

So the STA-9 is supposed to be warmer than the IDA-8? You own the  IDA-8 correct? How warm do you think that amp sounds?

I'm also running a tubed preamp and have tried a few solid state amps, with a couple of them being class D. The issue I'm having is the upper midrange on up. It's always a bit harsh with some music. Some of the amps I've tried warm up the mids but they don't do anything for upper mids and highs. Hard to make a decision from looking at a warmth chart so was hoping for some input from you or others that own these amps.

[JeffB]

I read this whole thread with great interest because somehow I misread the initial price of the K38 as $300.
Darn it.

[JackD]

Greg and Michael

I have run the ST-10 with both the W4S STP-SE  and now the Modwright LS-100.  In both cases the DAC in the chain was the Aqua La Voce S2.  Both of these are very good combinations with the Nola KO's and their combined 8 tweeters. The edge would go to the combo of the ST-10 and the Modwright.  Just for fun I temporarily tried the IDA-8 in this system replacing the Modwright and the ST-10. I still used the Aqua DAC. This combo was far to warm for me.  The IDA-8 in my case has worked the best with the Golden Ear Triton 5 which can be slightly forward if paired with the wrong amp/preamp combo.  If the STA-9 is in that direction I don't think it would be to my liking.  I find the ST-10 to be pretty much neutral and don't find it lean in any way. 

Jack

[James Romeyn]

My friend is at the show.  I shall request he visit.  He has the $10k Bricasti M1 SE DAC, and like many of us, is not often impressed.   

This really makes me want to hear the STA-9. My objection to SMPS is based on reliability more than on sonics.

I saw two Hypex Ncore NC400 BTL mono (400/800/1200W @ 8/4/2 Ohm, 1 Ohm minimum), each amp powered by one Hypex SMPS1200A400 (1200W).  Someone shorted both speaker outputs of the two above amps for about thirty seconds.  Absolutely no damage resulted, not even a blown PS fuse.

I can't imagine anything more bullet proof.  Certainly SMPS are not inherently unreliable.   

[mresseguie]

Gregfisk and JackD,

How are you guys doing?

Let's see if I can say all the things I want to, answer questions, and not get chastised for hijacking John's original post. [Brace yourselves. This is going to be long.]

First about the IDA-8:

I've had it now for almost nine months. I've powered Fritz LS/5-R (83.5dB) two-ways in Taiwan and GR Research LGKs while we are traveling the States this year. Oh, yeah. It briefly powered my Jeff Bagby designed Adelphos speakers (87dB) very nicely. I must admit that I really like this amp. It is easy to use; it's got super connectivity options; its size makes it very easy to bring along, and it's got enough power to drive most speakers loudly enough for my needs. This is Nuprime's entry-level amp for crying out loud. My only complaint about it is that it is underpowered for my LS/5-R speakers - and we all know that is not a 'problem'. It simply means I paired the wrong speakers to this amp (or visa-versa). The IDA-8 can produce decent volume with the LS/5-R speakers, but there's not enough oomph to make them sound 'right'. The LGK speakers sound terrific powered by the IDA-8. They are well matched. The same holds true for my Adelphos speakers - well matched.

Just how warm is the IDA-8?

Well, I have a difficult time answering this. It is warmish sounding, but I got to audition a good quality Taiwanese made integrated EL34 tube amp while I was in Taiwan. The two amps sounded completely different. The tube amp sounded amazing. Guitar, piano, vocals, snare drums(!!) ....I finally got why folks go gah gah over tube amps. My AVA 400R doesn't do that and the IDA-8 doesn't do that like the EL34 did either. Aren't EL34 amps 'warm'? Anyway, I must admit I spend a lot of time listening to female vocalists, guitar, cello, Jazz and other music that sounds especially good on warm sounding amps. Is this because this music sounds especially good on my IDA-8, or is it that I simply prefer this music?

Soon after my wife and I returned to Oregon, I spent a wonderful evening at Aldcoll's (Alan) house. He hosted a small G2G. In preparation for this G2G, I requested an ST-10 and a DAC-10H from John; two DACs from Tommy of Digital Amplifier Company; and a passive preamp from Tortuga Audio (never did get the preamp/don't know why). One of the participants brought over his South Korean made Waversa DAC plus a couple other components to pair with it. I brought my IDA-8, my 400R, my AVA T8 tube preamp,  my Rythmik F12G sub, and a bottle of Kavalan Single Malt Solist Sherry Cask Whiskey - 59% alc. Alan presented a Modwright amp (150w/ch??), an Iliana(sp?) preamp, Daedalus Audio Pan speakers (awesome!) and my Gustard X20u DAC that he had kindly taken delivery of while I was still in Taiwan. [Poor guy had to break it in for me for nearly two months. I'm sure it was a terrible burden. ]

We had a small mountain of equipment. I got to hear the ST-10 paired to the DAC-10H, to my X20u, and to the DAC DACs. The DAC-10H/ST-10 sounded great, clear, non-fatiguing. The ST-10/X20u sounded a tad bright, but the sound stage was huge. [Turns out the X20u had been set to a 'forward/aggressive' setting, but we didn't try it with the more laid back setting. ] The DAC DACs lost to all the other DACs - small sound stage/SQ not up to the other DACs IMHO. The DAC-10H/ST-10/AVA T8 combination and the X20u/ST-10/AVA T8 combination sounded 'right' to my ears. I loved all the music that was played. It was warm, beautiful midrange, solid bass, and clear highs.

I had to return the DAC-10H and the ST-10 to John, so I decided to hand deliver them since my wife and I were going to be in LA for a couple days anyway. Once at John's man cave, we spent a few hours listening to the K38 powering the new Evoke Eddie speakers. A DAC-10H was used in this setup. The combination sounded amazingly good. Unfortunately, everything was new to me. The room, the speakers, the amp were all strange to me, so I cannot sit here and tell you which part influenced my experience. I just know it all sounded fantastic.

JackD,

I think I got to hear much of what you hear with your amp/preamp/DAC combination. I know different manufacturers/different sounds, but essentially the same. Based on my above experiences, I want the ST-10. The only thing holding me back is the worry that even the ST-10's 150watts won't be enough to make the LS/5-R speakers sing the way they want to sing. This is why I asked Jason about making a two-channel K38 (more power). It's also why I wonder about the dual STA-9 amps (massive power). I suspect that the dual STA-9 amps will just be too warm for me if paired to the X20u and a tube preamp (probably going to buy a new tube preamp soon).

I brought my IDA-8 to the States with the intention of selling it in September after my wife and I return to Oregon. That may not happen now. The more I use it while we travel, the more I appreciate its potential, its convenience, and all-round high quality. If I don't sell it, I'll give it to my 24-year-old son to 'care for it'.

Gregfisk,

If you're still reading this....I see you live in the great PNW. I expect to drive through your area in the first few days of September. I will still have my IDA-8 as long as it isn't stolen during our travels. Do let me know if you want a short listen....

Have I answered all the questions, babbled enough, and not irritated the lords of this circle?

Quick thought: I think I answered my own question about which amp I want. I'll get the ST-10 unless <by some miracle> I can con Jason into manufacturing an new two-channel K38. Oh, Jason...

Regards,

Michael
Currently in Albuquerque, NM.

[JackD]

Michael

I think the ST-10, which was actually tested at 195 wpc by a German magazine, will be more than enough for your Fritz speakers.  The combination of it, the X20U and a good tube preamp will be a really good set-up.  Which tube preamp is another question and will be determined by how much you want to spend and if you want new or used.  I have owned Odyssey amps since 1999, but never an Odyssey preamp.  I think the Candela, new or used, would be a good option. There is one that has been for sale for a couple of months on another site that I have resisted as I have too many as is.  I am also intrigued by the Backert Labs Rhumba though twice as much.  There is a member here and on another site that is using the X20U with the ARC REF-5 and the Nord amps and really likes the combo with VSA speakers.  Again SS DAC, tube preamp to Class D amp.  Another option unless smitten by the Fritz speakers is to try the 60 day demo from Spatial on their open baffle speakers.  I really like mine and the number of owners on this site grows on an almost daily basis.  With them you can run almost any amp you like.  I ran mine for a while in the main room with an EL-34 amp. Once you find the spot you want to settle in and have a budget in mind the possibilities are endless.

Jack