Classe amplification

[Neuphonix]

Hi all,

I have an opportunity to do a home demo of a Classe CA401 power amplifier.

Was wondering if anyone had any experiences with this model or Classe amplifiers in general that they could share.

Can't find a whole lot about this particular model, what there is seems to be generally positive.

It is A-B but seems to be strongly bias toward A (read somewhere that it uses some sort of sliding bias(?) which allows it to provide around 85w of class A before switching)

I'm just interested in hearing how a more powerful amplifier compares to the AMP35P with my new Kefs.

Anyone have anything to share? Dave? Cno?

 

[CnoEvil]

Nothing to share but a guess, I'm afraid.

I would expect the Classe to exert more control over the speakers, but while smooth, it might not quite have that addictive quality that only comes from true Class A. I also suspect that the bass would be a little tighter but wouldn't sound as deep.

I have generally found that high bias amps never sound quite as good as the real thing. Remember that 85W of Class A would get to 85 Deg C, and have a weight heading towards 85 kg.

Classe is certainly one of the brands that I think would work very well with the 205/2s.....along with Electrcompaniet (AW250), Plinius (SA 103), McIntosh (MC275), Audio Analogue (Class SE / Duescento) and VTL (ST-150). David and Frogfish like Bryston.

IMO and for my taste, Refs like a high current (and high power if poss) amp with a hint of sweetness or they can sound a little analytical

I have heard a lot of amplification, and there is very little I would swop the 35i for. If you are tempted, make sure you have a very long listen before making a decision...probably a week at home.

I suspect this might be a difficult, but intriguing decision...... :?

 

[Macspur]

Hi there,

Must say I'm a bit surprised you're even considering changing the beloved MF!

I understand Classe is supposed to be a top brand and particularly well matched with B&W, but whether it's better than the MF power amp, I'm not sure... like Cno says all you can do is have a good home demo and hear for yourself.

Good luck... looking forward to another interesting experience of yours.

Mac

www.macsmusic.blogbubble.net

 

[Neuphonix]

HI mate,

intriguing indeed.

http://www.classeaudio.com/discontinued/specs/ca401.htm

It is quite a big amp at 60kg & draws much the same in standby as the 35i @ 350w
Not expecting a night and day shift, just interested to hear if a more powerful amp does have any noticeable effect. I guess at 90dB the 205/2 are not the most demanding load & at my normal listening volumes I'm not sure I need the extra power.So more an experiment for the sake of experiementation, I think they'll let me have it at home for a week, I am going to push for two.There are a few other questions about change over cost / age & condition of the unit (haven't seen it yet) / reason for sale to be nutted out.They also sell Pass Lab which I always seem to read about very favourably. No trade in deals there though so probably a bit beyond my budget at the moment. Have you heard any Pass gear?Do you have any thoughts about the mixing of brands ie MF pre-amp with another power?Why do you mention that you think there will be less bass? Just a strength of the 35i, or another technical reason?
I found this discussion which was interesting, few mentions of use with Kefs:

http://www.audiokarma.org/forums/archive/index.php/t-243860.html

With this one particular quote about the adaptive biasing:
This amp runs considerably into class A to a point and then runs A/B to be more efficient into higher demands. I think I remember that it is class A to 100 watts then class A/B above that.

I decided to go straight to the grapevine to put an end to the speculation, so I contacted Classe technical support. According to Robert Adam, the CA-300 and CA-400 have adaptive biasing. This probably explains their convoluted 24 hour bias adjustment procedure. Bias is kept low at idle to reduce heat, and increases under the load as output increases. Both models run class A up to 20% of rated power before running in class B. That means 60W and 80W respectively

 

[CnoEvil]

You don't need the extra power, but it will be very interesting to see what effect it has, as the Refs thrive on it.

I have never heard a Pass Labs amp, but they have a great reputation.

It's only a hunch, but the MF AMS power amps do fantastic bass, and I think I read somewhere (but could easily be wrong) that Classe, while having very good bass, don't have the best bass out there.

I remain sceptical about 80W Pure Class A.....The AMS50 weighs 60kg, gives 50 Watts into 8 Ohms, and has a power consumption of 600W (and the 35i was measured drawing over 400W).

 

[Neuphonix]

@ Mac

thanks Mac, I'm not REALLY considering all that seriously, just this dealer is a very bad man!!! He keeps calling me to chat about new things that have been dropped off to the store :doh: Can't see it being a night and day difference such as I experienced with the speaker change over.

@ Cno

You're right I have read in a few thread that bass isn't one of the Classe strengths, but then this seems to be mostly when being compared to some pretty high end amps. I really can't see it being a weakness relatively speaking.

I share your skepticism about the pure class A definition. Also the age of the amp makes me pause, any repairs could be costly.

Any reservations about mixing different brands of pre / power?

 

[CnoEvil]

Any reservations about mixing different brands of pre / power?

It's not an area I'm strong on, but I think you need to check if output / input impedances would be compatible.....the dealer or manufacturers should be able to confirm.

Sound-wise, I don't see a problem.....but it's a case of suck it and see.

 

[matt49]

I have never heard a Pass Labs amp, but they have a great reputation.

I heard the Pass Labs INT-30A. A really fine amplifier, very similar in sound to the MF AMS35i, I think. I auditioned it against the Luxman L-550 AII and preferred the Pass Labs by a considerable margin.

:cheers:

Matt

 

[CnoEvil]

I have never heard a Pass Labs amp, but they have a great reputation.

I heard the Pass Labs INT-30A. A really fine amplifier, very similar in sound to the MF AMS35i, I think. I auditioned it against the Luxman L-550 AII and preferred the Pass Labs by a considerable margin.

:cheers:

Matt

I remember, now you mention it.

A Devialet might also be a good match with Refs. :shifty:

 

[Neuphonix]

[/quote]

I remember, now you mention it.

A Devialet might also be a good match with Refs. :shifty:

[/quote]

Don't go there :shame:

Thanks for the input Matt, much appreciated.

 

[WishTree]

I had Classe CA-2100 driving KEF Reference 201/2 at home for a short period. The Classe was with me for long time, so I was familiar how it sounds. Where as KEF was with me for less than week (used product - so all run in etc).

IMO, the combination was one of the best that I owned and there is a great amount of lightness to the sound. I will not go in detail about what I remembered but all in all it's a good combination.

Coming back to what I think, I would go with what Cno says. I used have Pathos Inpol2 and that was the best amp ever for me (though I did not hear AMS 35i). Pure Class A amps have some kind of sweetness and in Pathos it becomes slightly more evident but some how it is never overly done. And, KEF reference, really need that.

If I have to put a combo blindly based on what I heard, I would put Pathos and KEF Reference together. When it comes to Classe amplification, they are almost neutral but again IMO, they go better with 800 series of B&W. For lack of any other better way of putting it, the slight warmth of 800 series goes well with the superb control and 'leanness' of Classe. I am saying all this based on CA 2100 and not the bigger counterparts from Classe but this gives an idea.

I am reading a bit on the amp offered to you, and it looks like it is completely in a different league. If the price is something that you can live with and there is enough support for Classe from your dealer (given that this is an old'ish model), then I think it is worth a home demo. But given your 35p, I have a feeling it might be purely academic activity !

 

[MUSICRAFT]

Hi Neuphonix

I owned a CA-401 and used the CA-401 with many speakers including KEF Reference. I now use a Krell FPB600 which is an amp around five years older then the CA-401.

I'll recommend that you should carry on using the AMS-35P. If you want to try a different power amplifier then Krell FPB200 or a FPB300 are also worth bearing in mind.

All the best

Rick @ Musicraft

 

[Frank Harvey]

As well as the Bryston 4Bsst2" I'd also recommend trying the Chord SPM1050, or even the SPM1200 (if within reach). They seem to match the 205/2's just as well as the Bryston, but do have a bit of a different sound - they certainly seem to reach a little deeper than the Bryston

 

[MUSICRAFT]

Hi Neuphonix

I see that you also use JL Audio's Fathom f112 and f110 subwoofers. Very nice 8) Out of interest what configuration do you use the Fathom f112 and f110 subwoofers in please?

All the best

Rick @ Musicraft

 

[Neuphonix]

Thanks everyone for the replies, really appreciate the input.

Seems the general consensus is to stay with the 35P.

I'm only really considering the Classe because it is a trade in unit with a dealer who will let me trade for it, the change over cost would be fairly reasonable. But TBH it would have to be pretty special for me to part ways with the 35P.

Few too many factors going against it, age of the unit & spending more money not the least of them. But they will let me demo so what the heck, got nothing to lose.

I'll let you all know how things progress.

David & Rick do you have any reservations in regards to mixing brands of pre-amp / power amp?

Do you think that the extra power offered by the Classe will have any benefit for the 205/2?

@ Rick regarding the Fathoms. I was using them in my hifi set-up through a Bryston 10B sub active cross-over with my previous speakers, Focal Diablos. Since making the swap over to the 205/2 I haven't felt the need. Did try running them via the RCA outs on the pre-amp but I wasn't happy with the way they worked. Might try fiddling again, but feel at the moment the Kefs give me plenty of bottom end.

I'm definitely no expert & my room probably has a few issues, but I tended to find that using subs was a bit hit & miss. Sounded fantastic on some tracks & not so great on others. I also think that trying to have them set-up for Hifi & HT complicated the matter further.

So at the moment they are just being used for HT, for which they perform admirably, two subs is a bit ridiculous, but hey!

I originally wanted to buy the velodyne DD+ subs, but found the JL Audios to be much better VFM. The ability to have been able to set the DD+ up on different pre-sets (hifi or HT) which I could swap between via remote would have been very useful.

Do you use a sub? If so what sort?

 

[CnoEvil]

- I think experimentation is never wasted, as the only real way to get more knowledge, is to try stuff. Other people's descriptions can be helpful, but are no substitute.

- Remember, any amp that gets very hot is likely to take a greater toll on its electrical components, so age could be an issue.

- Refs love power/current, but you have to like how it makes them sound. I didn't like them on the end of Linn Klimax gear, nor surprisingly with the Rega Osiris. The 35P is very capable, and considerably more potent than the 35i.

- Mixing brands is quite normal eg. A Tube Pre of one brand (like Croft) with a SS Power.

- I have always preferred the seamless presentation of a well designed speaker, that has enough scale for my needs, than trying to integrate a sub.

 

[Neuphonix]

- I think experimentation is never wasted, as the only real way to get more knowledge, is to try stuff. Other people's descriptions can be helpful, but are no substitute.

- Remember, any amp that gets very hot is likely to take a greater toll on its electrical components, so age could be an issue.

- Refs love power/current, but you have to like how it makes them sound. I didn't like them on the end of Linn Klimax gear, nor surprisingly with the Rega Osiris. The 35P is very capable, and considerably more potent than the 35i.

- Mixing brands is quite normal eg. A Tube Pre of one brand (like Croft) with a SS Power.

- I have always preferred the seamless presentation of a well designed speaker, that has enough scale for my needs, than trying to integrate a sub.

Yes this is a concern for me. Imagine having to replace the transformer in that thing, it's massive!

Interesting you say the 35P is more potent than the 35i. I thought that it was basically the same amp? Do you mean the gain on the pre-amp?

After an expensive little period of sub experimentation I have to agree with you. Have moved the crossover on now & am think of selling the smaller sub to a friend. Whilst I do love the thought of having 2 subs, it is overkill for my room, particularly if only used for HT, the 12" has more than enough ooompf.

 

[CnoEvil]

Yes this is a concern for me. Imagine having to replace the transformer in that thing, it's massive!

Interesting you say the 35P is more potent than the 35i. I thought that it was basically the same amp? Do you mean the gain on the pre-amp?

After an expensive little period of sub experimentation I have to agree with you. Have moved the crossover on now & am think of selling the smaller sub to a friend. Whilst I do love the thought of having 2 subs, it is overkill for my room, particularly if only used for HT, the 12" has more than enough ooompf.

It's not just the gain on the Pre. If memory serves, it also has around 4 times the current (80 Amps vs 20 Amps) of the 35i, is heavier, and draws even more current from the grid. It's not for nothing that it cost the same as the integrated.

I think you will have difficulty making worthwhile improvements to your system, without spending a fortune. Room treatment is probably the only area where this might happen (and cables, including Mains Cables :shifty: )

 

[MUSICRAFT]

Thanks everyone for the replies, really appreciate the input.

Seems the general consensus is to stay with the 35P.

I'm only really considering the Classe because it is a trade in unit with a dealer who will let me trade for it, the change over cost would be fairly reasonable. But TBH it would have to be pretty special for me to part ways with the 35P.

Few too many factors going against it, age of the unit & spending more money not the least of them. But they will let me demo so what the heck, got nothing to lose.

I'll let you all know how things progress.

Rick do you have any reservations in regards to mixing brands of pre-amp / power amp?

Do you think that the extra power offered by the Classe will have any benefit for the 205/2?

@ Rick regarding the Fathoms. I was using them in my hifi set-up through a Bryston 10B sub active cross-over with my previous speakers, Focal Diablos. Since making the swap over to the 205/2 I haven't felt the need. Did try running them via the RCA outs on the pre-amp but I wasn't happy with the way they worked. Might try fiddling again, but feel at the moment the Kefs give me plenty of bottom end.

I'm definitely no expert & my room probably has a few issues, but I tended to find that using subs was a bit hit & miss. Sounded fantastic on some tracks & not so great on others. I also think that trying to have them set-up for Hifi & HT complicated the matter further.

So at the moment they are just being used for HT, for which they perform admirably, two subs is a bit ridiculous, but hey!

I originally wanted to buy the velodyne DD+ subs, but found the JL Audios to be much better VFM. The ability to have been able to set the DD+ up on different pre-sets (hifi or HT) which I could swap between via remote would have been very useful.

Do you use a sub? If so what sort?

Hi Neuphonix

Thanks for your reply and your welcome.

No, as long as the performance of both ultimately contributes to the system as a whole then I feel it is also perfectly ok to use pre and power amplification from different manufacturers.

The extra quantity of power will be benefit to you if you feel that the AMS-35P hasn't got enough power left to enable you to listen to your system at the levels that you would like to. Even if this is the case and all things equal and despite its extra resevoir of power however whether the CA-401 tonally gels well with your speakers and electronics is another matter.

If you're after more power then here in the first instance try and keep it 'in house' by looking at power amps from MF as (without wishing to state the obvious) technically and sonically at least another MF power amp should be closer to the AMS-35P.

As for alternative makes of power amplifier of over ten years ago I'll still recommend that you should also look out for a Krell FPB200 or a FPB300. I feel Krell's weightier, smoother, gutsy and dynamic balance not to mention their rip roaring power delivery should enable them to be a good match for your speakers and electronics. I stand to be corrected however I heard that KEF also used or use Krell amplification to partly develop their speakers.

Anyway, sorry to hear that you found the subs a hit and miss for your hi-fi. JL Audio have recently released their new CR-1 active crossover. Worth a try as being from the same manufacturer as your sub woofers might help with integrating the subs seamlessly with your speakers.

I wouldn't say using two Fathom f112's is ridiculous. The more the merrier. At the moment we are using a Fathom f212 and Fathom f113. JL Audio's new E110 and E112 subwoofers are on their way and for our AV system we hope to be using a configuration consisting of an f212, f113, two (stacked) E112's and two (stacked) E110's.

All the best

Rick @ Musicraft

 

[MUSICRAFT]

It's not just the gain on the Pre. If memory serves, it also has around 4 times the current (80 Amps vs 20 Amps) of the 35i

Hi CnE

The AMS-35P has four times more current then the AMS35i however just to clarify the the AMS-35P has a peak current of 40 Amps and the AMS35i has a peak current of 10 Amps.

All the best

Rick @ Musicraft

 

[CnoEvil]

It's not just the gain on the Pre. If memory serves, it also has around 4 times the current (80 Amps vs 20 Amps) of the 35i

Hi CnE

The AMS-35P has four times more current then the AMS35i however just to clarify the the AMS-35P has a peak current of 40 Amps and the AMS35i has a peak current of 10 Amps.

All the best

Rick @ Musicraft

Rick, is "peak to peak" current different (ie. double)?.......as that was what I was quoting.

Edit. A bit of googlage says (I think) that it's the difference between the two peaks of the sine wave.......you learn something every day, so thanks for the heads up.

:cheers:

 

[Neuphonix]

It's not just the gain on the Pre. If memory serves, it also has around 4 times the current (80 Amps vs 20 Amps) of the 35i

Hi CnE

The AMS-35P has four times more current then the AMS35i however just to clarify the the AMS-35P has a peak current of 40 Amps and the AMS35i has a peak current of 10 Amps.

All the best

Rick @ Musicraft

Hi Rick & Cno

thanks for the replies, apologies for not coming back sooner.

I just had a quick look in my 35P manual and it says that "Current peak-to-peak = 80amps" not 40? Am I missing something obvious?

So progress report on the Classe adventure, finally heard back from the dealer & unfotunately another customer had taken the ca-401 home for a demo & he didn't think it was coming back. Told me he'd let me know if the guy changed his mind, but it sounds like I may have missed the boat on that one. Oh well, not to be, TBH after the responses on the thread so far I think that it's probably for the best.

However.........

I have stumble across a potential opportunity to pick up an ex-demo AMS-50 for a very attractive price!!! OMG when will it end

So, what do you think? It all gets a bit convoluted but I may or may not be able to home demo. Have heard this amp at a friends house with the Diablos, & obviously am familiar with the AMS sound. Will it give me more or will I only hear the benefits a high volume?

@ Rick: had to laugh a myself, after saying that two subs is OTT in my room I may now be moving the F110 & F112 on to move onto 2 x F113!!!! >)

(Why can I never get the red devil icon to work , am I not evil enough?)

 

[CnoEvil]

Here is my take: If you imagine AC current as a sine wave, then a "peak to peak" of 80A, is 40A above the centre line, alternating to 40A below.....so you have to halve the 80A to get the actual current.

The AMS50 should give more of everything and drive the Refs even better (especially the bass)......as I've said before, they do like power. Whether it's worth the cost in terms of buying it and then running it (power consumption)....only you can decide. I will be very (very) intrigued with what you think.

 

[Neuphonix]

Here is my take: If you imagine AC current as a sine wave, then a "peak to peak" of 80A, is 40A above the centre line, alternating to 40A below.....so you have to halve the 80A to get the actual current.

The AMS50 should give more of everything and drive the Refs even better (especially the bass)......as I've said before, they do like power. Whether it's worth the cost in terms of buying it and then running it (power consumption)....only you can decide. I will be very (very) intrigued with what you think.

If I can move the 35P on for a reasonable sum the changeover should be quite reasonable.

Not too worried about the power consumption side of things.

Just trying to work out a way to do a home demo first.

The only real drawback is the size of the thing. It won't fit in my rack like the 35P & will require significant shift of kit.

U wanna buy a 35P?

 

[CnoEvil]

I won't be buying anything unless my finances take a U-turn!

You have to find a way of doing a home demo......if only for the good of the forum.