What class is my amp?

[realysm42]

Its a Roksan Caspian M2 integrated.

I've had a look and can't find anything to tell me what realm it operates in, can anyone help please?

[istari_knight]

Roksan's site states "Audio class A analogue integrated amplifier."

Thats bull, its quoted power output is 85w/8Ω, 125w/4Ω... Almost certainly class AB. I shouldn't worry about it IME its makes very little difference to anything other than your leccy bill ;)

[Ali Tait]

First watt or two will be class A, rest class AB.

[realysm42]

Roksan's site states "Audio class A analogue integrated amplifier."

Thats bull, its quoted power output is 85w/8Ω, 125w/4Ω... Almost certainly class AB. I shouldn't worry about it IME its makes very little difference to anything other than your leccy bill ;)

Yeah, I thought the claim of class A was just a phrase, it never gets that hot!

Cheers for looking.

[twickers]

Kind of upper middle class then.

[istari_knight]

For what its worth you can generally tell true class A amplifiers from their appearance:


Massive heatsinks
Weigh a ton
Run too hot to touch
Waste energy & destroy the planet :D

[realysm42]

For what its worth you can generally tell true class A amplifiers from their appearance:


Massive heatsinks
Weigh a ton
Run too hot to touch
Waste energy & destroy the planet :D


Sound good?!

[istari_knight]

Sound good?!

I haven't tried enough of them to give a meaningful answer to be honest but will say that you cant judge an amplifiers quality by what class it operates in.

[realysm42]

True say. I don't think in could stomach the bill tbh.

[Clive]

Relative to the halogen lights many folks seem to have blazing away, the juice used by a class A isn't that much, unless you run them 24/7.

[walpurgis]

I haven't tried enough of them to give a meaningful answer to be honest but will say that you cant judge an amplifiers quality by what class it operates in.

But you're in with a decent chance of something nice sounding with Class A, from my experience. I own four fine sounding examples. I've yet to find an A/B or
D or T model that quite gives what I like.

[Ali Tait]

Aye, no switching distortion with class A. The best amps I've heard have all been class A.

[istari_knight]

Heres an interesting page from Rod Elliot that gives an objective viewpoint: http://sound.westhost.com/class-a.htm

[Mr. C]

Interesting pints of view regarding amplifiers.

The two most important issues regarding how amplifiers sound.

1. Correct implementation of the desired 'class' which ever one it is.
2. Correct Amplifier / speaker impedance

Class 'A' is generally favored by those listeners who had had bad experiences with with poorly designed class a/b solid state amplifiers.

A big lush sound, lots of texture, no harshness or grain great timbre and lots of depth.

Again they are good and bad examples of class 'a' in both solid state and valve designs.

[apollo]

Relative to the halogen lights many folks seem to have blazing away, the juice used by a class A isn't that much, unless you run them 24/7.

Unless the amp happens to be a Symphonic Line Kraft 300/400 :eek:

I know someone who owned a Kraft. He said it used to make a great room heater in the coldest winters.. besides making great music.

[Reffc]

Unless the amp happens to be a Symphonic Line Kraft 300/400 :eek:

I know someone who owned a Kraft. He said it used to make a great room heater in the coldest winters.. besides making great music.

...or some 845 Monoblocks which at idle dissipate almost half a kilowatt!:stalks:

[Clive]

...or some 845 Monoblocks which at idle dissipate almost half a kilowatt!:stalks:
Which is 10 halogen lights....how many kitchens have these blazing away? LEDs are one way but they don't work too well in place of valves! :lol:

[walpurgis]

Yes, I've noticed my room gets noticeably warmer when the H-Fi's been on a while. My wall thermometer can be seen steadily climbing, whether I use valves or solid state (all Class A).

[realysm42]

Is class a utopia, apart from the heat it creates, or are there strengths of other classes?

What happened to class c?

[Yomanze]

Looking at the rest of your system the Caspian is outclassed! Nice enough amps but huge improvements to be had for similar money.

[Yomanze]

Is class a utopia, apart from the heat it creates, or are there strengths of other classes?

What happened to class c?


Class A has no crossover distortion as the amps are 'always on' rather than 'pushing and pulling' alternately as with class B and class AB amps. The more crossover distortion the more grain and artificial sound. Of course there are class B amps that sound very natural and grain free.

[realysm42]

Looking at the rest of your system the Caspian is outclassed! Nice enough amps but huge improvements to be had for similar money.

Yeah, I'm starting to think that. Wait until you see the DAC I'm about to demo :eyebrows:

Tbh, the next step for me will be a pretty and power combo (probably) but tell me what you'd recommend for similar money?

[YNWaN]

Aye, no switching distortion with class A. The best amps I've heard have all been class A.

I have to say, I've heard what I thought were some very average Class A amps and a couple that I would consider as outright bad - so adherence to a particular topology does not guarantee success.

[walpurgis]

Actually, I'm beginning to think class is just a Bourgois concept aimed at the Proletariat.



Seriously though, the operating principle used by Devaliet in the D-Premier amplifier is interesting. Apparently a combination of Class A driving Class D. It has been described by some reviewers as possibly the best amplifier they have ever heard. I'd love to try one, but it's out of my price range (at the moment).

[Ali Tait]

I have to say, I've heard what I thought were some very average Class A amps and a couple that I would consider as outright bad - so adherence to a particular topology does not guarantee success.

Never said it did. Just said the best I have heard were class A.

[RobbieGong]

So generally speaking of course :eyebrows:, is AA class any good ?

[istari_knight]

So generally speaking of course :eyebrows:, is AA class any good ?

Its just another marketing term for a circuit design that reduces switching distortion....

JVC "Sliding Bias"
Technics "Class AA"
Denon "Optical Class A"
Pioneer "Non-Switching Amplfier"
Quad "Current Dumping"

IIRC the Technics system had an awful lot in common with Quads "current dumping" I have lots of details on my external drive... Give me a 10 mins I'll look for them...

[Clive]

Its just another marketing term for a circuit design that reduces switching distortion....

JVC "Sliding Bias"
Technics "Class AA"
Denon "Optical Class A"
Pioneer "Non-Switching Amplfier"
Quad "Current Dumping"

IIRC the Technics system had an awful lot in common with Quads "current dumping" I have lots of details on my external drive... Give me a 10 mins I'll look for them...
Ohh, I thought an AA class was something entirely different.:cool:

[istari_knight]

"Since developing it in 1985 , Technics has used the Class AA circuit in many amplifiers. Conventional Amplifiers had one amplifier to carry out two functions; Voltage amplification & driving the current to the speakers. The Class AA Amplifier combines two separate amplifiers that perform these functions separately. The two amplifiers are the Class A voltage Control amplifier, which Controls the entire amplifier, and the class B current drive amplifier, which makes the drive current to the speakers. This combination means you get the great sound of Class A and the driving power of Class B.

The MOS Class AA uses a MOS-FET, which has outstanding input & output linearity in the voltage Control amp and a bipolar transistor in the current drive amplifier for its High current drive ability. The result is that no unwanted sound is added, separation & positioning are good, and that the sound source is expressed with a high degree of precision."

:eyebrows:

[RobbieGong]

I can vouch for my AA Class Technics SU VX800 http://www.radiomuseum.org/r/technics_stereo_integrated_amplif_46.html being an absolute stonker, clean clean sound, power, detail and very very musical :D

[walpurgis]

I've owned Technics 'AA' amplifiers. My daughter is using one I gave her. They do tend to sound decent.

I believe 'AA' is basically 'AB' with heavier biasing towards DC and works in Class A at lower levels, until the signal amplitude crosses the 0db median and switching/crossover into Class AB takes place. This would be regardless of whether mosfets or discrete transistors were used.

[istari_knight]

I've owned Technics 'AA' amplifiers. My daughter is using one I gave her. They do tend to sound decent.

I believe 'AA' is basically 'AB' with heavier biasing towards DC and works in Class A at lower levels, until the signal amplitude crosses the 0db median and switching/crossover into Class AB takes place. This would be regardless of whether mosfets or discrete transistors were used.

Thats what they called "new class A" as can [hopefully] be seen here:

http://i26.photobucket.com/albums/c129/istari_knight9/new-class-a-page-0_zps79aa4e70.jpg
http://i26.photobucket.com/albums/c129/istari_knight9/new-class-a-p2-page-0_zps396bbdf7.jpg

"Class AA" & "Class A+" were very similar to Quads "current dumping" as can [hopefully] be seen here:

http://i26.photobucket.com/albums/c129/istari_knight9/class-a-page-0_zps28fd9900.jpg

It took me ages to locate those on my HDD! ...Really need to get more organized :doh:

[walpurgis]

The key point is "both transistors" (1st para).

Quite how this is applied I don't know, Sounds like overlapping AB. Presumably during the overlap the signal divides and is shared and I'm assuming with reduced output on each transistor to avoid a jump in amplitude.

[Yomanze]

Yeah, I'm starting to think that. Wait until you see the DAC I'm about to demo :eyebrows:

Tbh, the next step for me will be a pretty and power combo (probably) but tell me what you'd recommend for similar money?

What DAC? Regarding amps I'd look out for an LFD Mistral or Silver Signature integrated or if you are looking for power amps a PA0 SE, PA2 or PA2M. I do have a spare PA0 SE power amp that you could borrow when you get down to auditioning...

Sent from my Nexus 4 using Tapatalk 2

[UV101]

if you want a stupidly under priced and under rated Class a amp, look at this!!!

I've posted these on the forum previously and I've seen a couple change hands on here too.

45Kg's 160,000uF of reservoir caps. Not many 100w Class A amps for around the £500 mark :eyebrows:

mgVF-dL-s1w

l_qQc9iV5ng

EDIT........and the volume goes all the way up to 99 YAY!!!

[hal55]

Nice amp, I use the JA99C, basically the power amp section of yours and also Class A, with a Shengya preamp (same as Germany's Vincent). Truly lovely combination.

Hal55

[Yomanze]

That amp won't be class A for all 100 watts as it doesn't have the necessary heatsinks. It will be a high bias class A/B design with maybe 6 watts or so in class A.

[UV101]

.

[UV101]

That amp won't be class A for all 100 watts as it doesn't have the necessary heatsinks. It will be a high bias class A/B design with maybe 6 watts or so in class A.

What amp?

[istari_knight]

The Jungson's rated for 80wpc@Class A apparently: http://www.troelsgravesen.dk/JungSon.htm

As was said the other day though, just 'cos its class a doesnt mean its any good... As you can see on troels site its full of opamp stages & electrolytics in the signal path :spew:

Nothing a bit of DIY cant sort out though ;):D

[UV101]

What opamps?????

There is 1 Opamp and its on the input stage for converting single ended to balanced......that's it!!! The pre and power are fully discrete operating in class A.

The 2nd Opamp you can see on that report is for the phono stage that's only present on the later models (mine has no phono stage built in)

If you are confusing all those black boxes for opamps, then those are actually relays for switching in the attenuation resistors for the volume control which is a only normally see on some very very high end stuff.

There are indeed elco's in the signal path on the input and between pre and power (which I dislike). Mine have all been changed to mundoft supreme bypassed with silver/gold oil supreme's. however, don't think that this was rubbish before the changes because its not. Pretty much every principle I apply to all my work is employed here by design. Something you will not see on a commercial amp until you start spending new car money :D

[istari_knight]

My mistake, the line stages are discrete I was looking at the phono stage.

I'm sure its fine if you like that sort of thing.

[Yomanze]

What amp?

The Jungson amps. May well be a lot more than 6W class A, but this is what 80W of pure class A looks like:

http://cdn.head-fi.org/c/c2/c2916b53_49547_big.jpeg

[anthonyTD]

What opamps?????

There is 1 Opamp and its on the input stage for converting single ended to balanced......that's it!!! The pre and power are fully discrete operating in class A.

The 2nd Opamp you can see on that report is for the phono stage that's only present on the later models (mine has no phono stage built in)

If you are confusing all those black boxes for opamps, then those are actually relays for switching in the attenuation resistors for the volume control which is a only normally see on some very very high end stuff.
Looks well laid out and put together, which makes things a lot easier to work on...:)
A...

[Ali Tait]

Looks like 10w class A from the article.

[UV101]

It's not too bad.....

Mk1input boards. Left board is std with the Elna starget cap in the signal path (only for single ended) and the right with the 1st mods I did which was to swap the Elna for a wima film and the the Opamp for a HA version of the LME49720.

http://i497.photobucket.com/albums/rr332/Trunky1812/jungson/20120923_204029_zps160b0a18.jpg

Here's the rest as work was ongoing.....

http://i497.photobucket.com/albums/rr332/Trunky1812/jungson/20120924_075032_zpsbe1a7223.jpg

All I can say is this is a very powerful class A amp which is very well designed both from an electronic point of view and also engineering. It's sounds exceptional..... The only downside is the size, weight and heat it produces which are probably enough to make it not everyone's cup of tea.

[UV101]

Looks like 10w class A from the article.

Nope.......
http://www.jungson.com/files/reviews/ja88d_aus_aug06.pdf

You need to be careful, there are several versions on the JA88D. There is a class A version and a class AB version ;)

http://www.china-highend-hifi.com/prod0112313112.htm

[Ali Tait]

Nope.......
http://www.jungson.com/files/reviews/ja88d_aus_aug06.pdf

You need to be careful, there are several versions on the JA88D. There is a class A version and a class AB version ;)

http://www.china-highend-hifi.com/prod0112313112.htm

From the article linked to above, there is reference to the Duro power amp, which it says is basically the power amp section of the JA88D. If you read further down, a tech has measured how much class A output is available-

http://www.troelsgravesen.dk/Duro.htm

[Ali Tait]

Basically 10.2W into an 8 ohm load.

[istari_knight]

:doh: Should have read your sig! It wasn't my intention to put down your choice of amplifier. Although I would never entertain one they do look nicely put together :peace:

[Mr Kipling]

Unless the amp happens to be a Symphonic Line Kraft 300/400 :eek:

I know someone who owned a Kraft. He said it used to make a great room heater in the coldest winters.. besides making great music.

Their cheese slices aren't so hot though. . .

[UV101]

Basically 10.2W into an 8 ohm load.

My mistake...... They are shit, don't buy one ever....

[UV101]

:doh: Should have read your sig! It wasn't my intention to put down your choice of amplifier. Although I would never entertain one they do look nicely put together :peace:

:D

Like I said, not everyone's cup of tea, but I've been through a few amps and this one is not too shabby. I purchased without listening based on what I could see in the circuit diagram. Turned out to be a fairly well educated decision ;)

[Ali Tait]

When did I say that? In fact, I'm considering getting a pair of Duro to drive my OB's.

I'm just interested in the facts, and letting others know them. The fact is, this amp does not produce what the makers claim it does. That does not take away the obvious sound quality available, reading the many positive reviews of the amp. 10w class A is a useful amount, and with reasonably sensitive speakers will remain in class A operation for over 90% of the time at a guess, probably more.

[YNWaN]

Never said it did. Just said the best I have heard were class A.

No, I appreciate that - I suppose what I meant was that some of the best I have heard have been Class A, but mostly, they have not been.

[Ali Tait]

Don't have that much experience with SS stuff in general. What would you say was good?