Amplifier Opinion Needed

zingo

I've been considering changing from my integrated 300B amp to an integrated class A SS amp for my Klipsch Fortes. Obviously it will be a different sound, but I've enjoyed the class A SS amp that I had previously; plus the grass is always greener on the other side. With the Pass Labs integrated out of the question at $7K, I've been search for other options, and found have found the Audio-gd C-400.

The website states that the amp is class A, and already owning an Audio-gd product, I know that Kingwa is a smart dude and other than some interesting Chinese to English translations, their technical info is correct. This amp would be pair with my Klipsch speakers, so I'm not looking for a class A/B design.

The other reason I'm interested in one of their amps is because of the ACSS connections similar to Krell's CAST system: ACSS (Audio-gd Current Signal System) is Audio-gd's system for transmitting audio signals in the current domain.

Any input you can give would be great!

lanchile

What about Bryston B100 ? it is a very well build integrated amp and the sound is awesome and a 20 years warranty a big plus!. I do not like class A amps... too much "energy" waisted.

zingo

That's good looking amp, but I do not need an integrated DAC as I love the one I have now from Audio-gd.

Has anyone used the Krell CAST system? It seems like a good technology transmitting in the current domain.

zingo

After doing some research lanchile, I don't think I gave the B100 enough credit as I can't find a bad review on it! Do you know what class amplification it is?

Outfitter03

Audiogon Bluebook says 100W, Class AB. And it looks like they hold their value almost 100% on the used market.

PolkClyde

lanchile wrote: »

What about Bryston B100 ? it is a very well build integrated amp and the sound is awesome and a 20 years warranty a big plus!. I do not like class A amps... too much "energy" waisted.

I thought class A amps were the "APEX" of all amps.Didn't they say that in StereoPhile magazine? I would love to have that baby in the picture...Do I need to take out a loan for that?...let me go back and read it again.

PolkClyde

I need to ask my dad for $7K. I can hear my dad now,saying, "can you drive it to work" or "can you wear it to church" When I was living at home,he and I use to get in to it,about me buying all this Audio gear.A funny story guys.one year for Christmas, he bought me one speaker.Hey fellows, you need two for stereo,right? true story.He said,nope,"you are not going to get two,one is all you need.Listen in mono,HAHAHA. I have since, made up for that one speaker, he bought me years ago. All of my audio gear today,is worth a lot.probably,not even close to what you guys have.Don't tell my dad,I just bought a new Blu-ray player. The Oppo 95 Universal Player,a waste of money?,maybe. my dad would think so.

heiney9

There is no way that is a pure class A design as in "single ended" like the Pass. The chassis and heatsinks aren't large enough for it to be a 100wpc in class A. It's funny this subject just came up because there was some discussion about a well known company (I won't name them because that's not the point) that advertised their mono blocks as pure single ended class A amps capable of 100wpc @8 and 200wpc @4. The chassis and heat sink are small. When the potential buyer inquired he was told this.

"The amps will operate in full class A mode up to about 50 watts. But the class distinction is no longer a technical concern since we use output MOFSETS that operate into the giga-hertz region.
In other words, they are so fast the crossover distortion becomes a moot point"

Ok, if that's over your head you may not understand it, but that explanation is the exact opposite of the marketing hype that the amps are Single Ended class A. In fact the above quote is stating they are high bias A/B amps. Said amps most likely don't operate in class A for 50wpc because the chassis and heasinks and output devices aren't nearly enough for that claim either.

I am not saying your amp in question is poor or won't sound good. What I am saying is the term "Class A", gets used A LOT and it can have a lot of different meanings and in the end how the maufacturer interprets that phrase can have a huge impact on how something sounds.

Class A is a huge buzz word that everyone wants to use.................but there is a HUGE variation between designs where manufacturer's use that phrase.

I would guarantee this amp is an A/B amp not full class A. If you look at other manufacturer's of "true" class A amps in that wattage range they're chassis are huge, the heatsinks are huge, the tranny's are huge and the price is huge (ala Pass Labs). There is no getting around it if you are looking for that kind of wattage in pure Class A amplification.

Now that all being said there are some really nice sounding class A/B amps available but you won't mistake them for pure single ended Class A and if you are looking for 300B type sound cue's...............Single ended Class A is where you are likely to find it. But it ain't cheap.

YMMV

H9

zingo

I floated the class A question to Kingwa, about the above amp (which retails for $1000), and here was his response: The C400 is a class A design which can avoid swtich distortion but it had no the large static current and heat. In our products, only the ST1 is the large current class A amp. The ST1 he is referring to is their 45w, single ended class A monoblocks pictured below. I'm not sure what low current verse high current class A means...

fishbones

Whew, those look like pure Class A alright! Looks like they would heat up a 3 story house in the winter time (true class A style). I like how they isolate the transformers from the rest of the circuit. Brock, your shedding some light on what is actually true Class A, keep it coming! I have wondered how some of these "Class A" designs some of the manufacturer's are touting can be as thin as a pancake and barely have any heatsinks?

bikerboy

Hi Jake,
I count 8 output devices per channel I believe. That will be the big difference compared to your 300b amp. It would use one output device per channel. Am I on the right track with my thinking? I think there will be a purity of sound with fewer devices that cant be had with many devices reproducing the same signal.

heiney9

fishbones wrote: »

Whew, those look like pure Class A alright! Looks like they would heat up a 3 story house in the winter time (true class A style). I like how they isolate the transformers from the rest of the circuit. Brock, your shedding some light on what is actually true Class A, keep it coming! I have wondered how some of these "Class A" designs some of the manufacturer's are touting can be as thin as a pancake and barely have any heatsinks?

Actually the mono's "look" closer to 45wpc pure class A, but the heat sinking is smallish. I doubt those get that hot, there isn't enough surface area (based on the photo) to dissipate all that much heat. I would still bet on a high bias A/B scheme.

Bottom line is there are very few pure class A amps on the market and those touting 100wpc.....yada, yada, yada,.......are taking liberties using the term "pure Class A or Single Ended class A". I still think pure class A is the better sounding amp, but then I haven't heard every single amp made.

Again before anyone gets their panties in a bunch.........I'm just dialoging here not passing judgment on quality, etc, etc. There are some fine A/B amps out there. I just take exception to a manufacturer(s) who bends the definition of a term like pure Class A and actually misrepresents his product in a way that a buyer believes one thing when in fact it's another.

I was floored at the response I posted from the other manufacturer about their marketing vs. reality. This response came from the designer and head of the company, and no it wasn't Nelson.........

H9

zingo

Lanchile, where do you live as I'd love the opportunity to demo a B60.

I was just chatting with James over at Bryston, and he actually recommend the B60 to me over the B100 for my horn system. Apparently, the B60 has a simply circuit path and output stage than the B100, which may lend itself well to the horns. Plus, even though the B60/100 are class A/B, they supposedly have a "first to last watt" philosophy similar to Pass.

megasat16

heiney9 wrote: »

Again before anyone gets their panties in a bunch.........

H9

Hey hey...what do you mean now and who you are calling out?

megasat16

Even for pure Class A SE amps

1. You don't need a gigantic heatsink if it's only designed to run around 8 ohms only.

Or / And

2. If you have some kind of forced air (gas) cooling the heatsink or water cooling for that matter.

FTGV

heiney9 wrote: »

... since we use output MOFSETS that operate into the giga-hertz region.

That would be applicable if he were using them in a switching output stage of a Class D amp where the fast switching speed of FET's are advantagous,for Class A not so much.:rolleyes:

heiney9 wrote: »

Actually the mono's "look" closer to 45wpc pure class A, but the heat sinking is smallish.

It's hard to tell what the actual dimensions are but it appears to me that there might be enough heatsink TO support 45 w of Class eh .

zingo wrote: »

I'm not sure what low current verse high current class A means...

He would be refering to the Class A/B unit as low standing current and the Class A unit as high standing bias current.

FTGV

megasat16 wrote: »

Even for pure Class A SE amps

1. You don't need a gigantic heatsink if it's only designed to run around 8 ohms only.

The fin design and resulting temp coefficient are key.

megasat16

FTGV wrote: »

The fin design and resulting temp coefficient are key.

Yes, absolutely! The thickness of fins, design, orientation, materials, backing block and temp coefficient are very important for heatsink sizing.

I also think the 45W monobloc in the picture above is using the whole aluminum chassis for additional passive cooling so the heatsink can and may seem a little be less massive to H9. :biggrin:

heiney9

You guys love picking my words apart..........don't you? :biggrin:

Just dialoging and I did state (based on the photo) but somehow that didn't get quoted.

I was very disappointed when I heard about the company that was touting it's amps as Single Ended class A @ 100wpc to find out the comment about the gigahertz Mosfets. I had been saying that for years that the size of the chassis and heat sinks it was physically impossible, not to mention the smallish tranny and low number of output devices, but no one really believed me.

H9

FTGV

heiney9 wrote: »

You guys love picking my words apart..........don't you? :biggrin:

Absolutely

I was very disappointed when I heard about the company that was touting it's amps as Single Ended class A @ 100wpc to find out the comment about the gigahertz Mosfets. I had been saying that for years that the size of the chassis and heat sinks it was physically impossible, not to mention the smallish tranny and low number of output devices,

Then I assume this is a well known product that has been around for a time with the designer making Charlie Sheen like claims for it?

but no one really believed me

I'm sure I would have.