Krell Imports

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dmurfet

Guest
I am scoping around for a Krell power amp - perhaps a TAS or similar - and I notice the prices in the US are massively cheaper than in the UK (unless I am mistaken). I appreciate that in order ot make them work, I would have to get an expert to step up the voltage to the power supply, or replace the power supply - but does this really justify the price differential?

Thanks for any advice

David
 
C

CogPaul

Guest
Recent krell equipment has a voltage detection chip - this needs to be changed by the importer ( Absolute Sounds in the UK) - they charge between £450-650 to change a unit to UK voltage depending on the item - I am certain that the TAS will have this chip (as the HTS2 and Showcase do). Consequently it is not as simple or inexpensive as just altering transformer windings!

Only way around is this to buy a PS Audio P300 or similar that takes UK voltage and outputs US voltage AND frequency - these sell for around $650 on Audiogon - you must get a US version!They can be switched inside to accept UK voltage

Paul
 
D

dmurfet

Guest
So this is a yet unexplored territory for competition...as I suspected....so either I cough up the eight grand they want for a tas or, and is more likely I look for a KAV500 for a quarter of the money....

No problem - just lets me know the lie of the land!
 

lovegroova

Well-known Member
I have a 250a3 and it's a fab amp, even more so at those prices.
 

GaryG

Active Member
I bought the home cinema package off the classified's specifically for these amps and was somewhat miffed to say the least when I got them home to find that they were fractionally too big to fit in my racks :mad: (they fit on top, but I already have Krell monoblocs on top).

I was feeling pretty pleased with myself when I collected them as they look like they've just come from the dealer, absoluteley mint condition. Answering some email queries on them last night motivated me to unpack the 2 channel version and give it a whirl perched on the top of a spare stand in front of all the other equipment. Have to say, I was a bit disappointed, not quite the Krell sound I'm used to. Sitting thinking about it, it occured to me - given that the projector I bought in the package had less than 300 hours use on it - that the amp may not be fully run-in, especially if it had been used for the rear channels, rather than the front L/R (with the 3 channel amp providing the center and rears). So, I left it playing a CD for 24 hours and listened to it again tonight. Ahh haa, what a difference, that's more like it! :clap: In fact it's pretty damn close to my Krell monoblocs, without the heat (MDA 300's, which are essentially KSA150's converted for mono operation). I'm going to do some serious A/B comparisons to see just how close they are, I may do a u-turn and keep the KAV 250's to replace the monoblocs and cut down on the amount of heat generated.
 
A

adol

Guest
GaryG said:
In fact it's pretty damn close to my Krell monoblocs, without the heat (MDA 300's, which are essentially KSA150's converted for mono operation). I'm going to do some serious A/B comparisons to see just how close they are, I may do a u-turn and keep the KAV 250's to replace the monoblocs and cut down on the amount of heat generated.


Gary, the ksa150 have nothing in common with the mda300 neither in technology nor design

The mono version of the ksa150 is the KMA160 (the M is for mono, and the s for stereo).

In fact the mda300 you own, is a very special and unique serie from krell. MDA is for Monaural Differential Amplifier. Basically each monoblock is made of 2 monoblocks who upgrade the signal in mirror configuration, in the output section a device makes a comparison between the two amplified signals and takes the most coherent with the input non-amplified signal.

The main benefit is in the accuracy between the input and output, the hard thing is that it requires twice the amount of electronic components, which needs to be perfectly paired. That is why the mda series consumes a lot of power and due to its class A design produce a lot of heat

This technology abandoned by krell after the mda series is currently used by theta technology with its citadel and enterprise flaghship monoblock
 

GaryG

Active Member
Adol

I was told the MDA 300 was essentially a KSA 150 in bridged mode.

"MDA: Monaural Differential Amplifier. Krell announced the MDA-500 and MDA-300 in 1991. They feautured fully differantial from input to output, this will take almost the doubble of components for each channel. The KSA-250 and KSA-150, was the to amplifiers the MDA amplifiers were based on. Also you could convert your KSA-250 and KSA-150 to one MDA amplifier"

from the following link:

http://hem.passagen.se/xayide/krell/KrellAmplifiers.html


Do have a link with further information on what the MDA 300 is based on?
 
A

adol

Guest
There is an important difference between bridge mode and differential mode, basically the bridge mode "adds" the power of two channels in one, while the differential mode duplicates the signal in order to increase accuracy.

Let's say your mono signal is labelled 1 on its upper signal wave and 2 on the lower,

the mono mode makes a 1+2=3, 3 being the output power, the differential mode makes 2-1=1

therefore if you include the distortion and other lack of accuracy factor the result of the 2-1 operation is strictly the distortion and other factors, so the output signal of a differential amplifier is exactly the amplified input.

On the contrary a bridge mode which performs the 1+2 operation adds both distortion of the 1 and the 2, so the output signal has few in common with the input.


Of course the 2-1 operation only works if both duplicates signal are amplified exactly the same way, this is why a differential amplifier is very hard to make and this is why krell abandonned this technology. Actually they didn't exactly abandonned the technology, they created the sustained plateau bias, which includes some kind of analog control between the input and output that can be called in some ways a simplified differential technology

As you probably guessed, i am a complete krell fan, i particularly like the mda series, their outstanding performance in the bass section is almost unmatched, among the deepest and precise i've ever heard
 

GaryG

Active Member
Adol

Thanks for the clarification, out of curiosity, which Krell amp do you consider to offer the best sound quality (excluding the Master Reference stuff).
 

alexs2

Distinguished Member
GaryG said:
Adol

Thanks for the clarification, out of curiosity, which Krell amp do you consider to offer the best sound quality (excluding the Master Reference stuff).

gary...like adol,I'm also a long term Krell fan,and have owned a few of the older models....originally a KSA 100,which has the traditional Krell qualities of bass control and power,but,in comparison to both other models,and especially newer models,a veiled midrange...still good,and way better than most £1500 power amps today,but just something to bear in mind.

The KMA models were a substantial step forwards in terms of sound quality,with a far more detailed and clearer midrange,but also much better bass delivery,without emphasizing that part of the frequency spectrum.

These models,incl the KSA250,were beautifully made,and virtually unbreakable(driving 1 ohm loads with no problems,and doubling the power output with each halving of load down to 1ohm).

The KSA-S series were Krell's next,and whilst much more efficient,in using a sliding bias scheme to reduce power dissipation,they were also a step back in terms of sound quality.....all of that was remedied in the FPB amps...powerful,relatively efficient,and superb sound.

If you have the money,the newer FPB amps are superb,and again there,the newer the better if you can,but failing that,avoid the KSA-S series,...I have set of KMA 100s which I would only part with for a set of Levinson 20.5s(assuming cash and electricity bills would permit!).

In overall terms,your MDAs are still excellent,and almost the equal of the Levinsons for bass power and control,and would need you to go to a new(ish) FPB to find something better.
 
A

adol

Guest
i completely disagree with alexs, i think the fpb are an insult to the legend of krell, they do perform well but completely lack the magic of older models.

i wouldn't recommend to buy a fpb, it is better to try to source an older pair of kas or kma for almost the same price.

the best model from krell was without any doubt the krs, krell reference standard, a massive behemoth absolutely fabulous in every ways. Of course he is huge, acts like a real heater and consumes a lot of energy, so he is very hard to put inside a normal apartment, but except these few troubles it is pure and absolut magic

second to the krs comes the kas-1, a 2 chassis design with separate power supply, much more domestic than the krs

finally the ksa xxx S is excellent, but only on easy load, its special design in sliding a class doesn't match well with current demanding speakers
 

GaryG

Active Member
Interesting comments, diametrically opposed!

Alexs2, I remember your Krells from this thread:

http://www.avforums.com/forums/showthread.php?t=65287&page=3&pp=15&highlight=krell

Adol, I've had my MDA 300 for about 7 years and having listened to the FPB stereo amps over the years and flirting with a Bel Canto eVo-4 was debating going for the latest MCX monoblocs, but would be buying 'blind' as I wouldn't get a chance to demo them against the MDA 300's. I changed my DAC back in June of last year and have been in turmoil since trying to get my system back in balance. The MDA 300's are good but the treble seems harsh and grainy when used with DACs such as the Wadia 27ix and Audio Synthesis Discrete. In fact, I had a rush of blood to the head today and bought back the version of the DAC I sold back in June to compare with what I have now just to make sure I have actually moved forward.
 
D

dmurfet

Guest
Hi Gary

Have sent you an email. I'm having a rush of blood if you can push me over the edge!

:eek: :eek: :eek:

David
 
D

dmurfet

Guest
CogPaul said:
Recent krell equipment has a voltage detection chip - this needs to be changed by the importer ( Absolute Sounds in the UK) - they charge between £450-650 to change a unit to UK voltage depending on the item - I am certain that the TAS will have this chip (as the HTS2 and Showcase do). Consequently it is not as simple or inexpensive as just altering transformer windings!

Only way around is this to buy a PS Audio P300 or similar that takes UK voltage and outputs US voltage AND frequency - these sell for around $650 on Audiogon - you must get a US version!They can be switched inside to accept UK voltage

Paul

A quick google did not shed much light on the PS Audio P300 - could you advise - it looked like it was working as a UPS not a step up / frequency changer. [email protected], that US stuff looks cheap.
 

alexs2

Distinguished Member
dmurfet said:
A quick google did not shed much light on the PS Audio P300 - could you advise - it looked like it was working as a UPS not a step up / frequency changer. [email protected], that US stuff looks cheap.

See www.psaudio.com for a full description.

It's not in any way a UPS,but could be likened to a power amplifier,outputting a waveform at 50 to 120Hz and with the capacity to vary the waveform also.

Basically,as their website says,a regenerative power supply,and by all counts very well received.
As for buying US used gear via Audiogon,just remember the warranty angle if anything goes wrong.

Also bear in mind that for a Krell,even one of the little ones,a 300W supply would be totally inadequate.....you would need one of the bigger ones,which are expensive......in fact,having checked that,there is nothing in their range that would supply a TAS.
 
D

dmurfet

Guest
I'm still looking to see what I would need, but expensive is not so expensive in US dollar terms especially if you consider buying DVD, Processor, and multiple power amps. (not all at once sadly!)
 

GaryG

Active Member
According to the manual, the KAV250a consumes 210w at idle up to a maximum of 1850w. The KAV250a/3 consumes 235w at idle up to a maximum of 1930w.
 

alexs2

Distinguished Member
dmurfet said:
I'm still looking to see what I would need, but expensive is not so expensive in US dollar terms especially if you consider buying DVD, Processor, and multiple power amps. (not all at once sadly!)


If you see GaryG's post,you'll see that whilst the PS Audio 1000 would be ok for some of the time,it would be likely to run into problems both at start up,when the amps will draw maximum power as the caps charge,and also at high power,when it's 1000W rating will easily be exceeded.

The PSAudio Powerplants are very good for low power or signal processors,but not as much use on very high power amps where you may find their power loadings being exceeded.
 
D

dmurfet

Guest
Yes - I started doing my sums for a 250 watt amplifier and the numebr went up way too fast as I added more channels..........

I'm still not beat - now to buy a 3000 mile cooker cable to run under the sea..........with a US plug on it..... :D :D :D
 

alexs2

Distinguished Member
If I were you,I'd be happy with a decent run of very good quality,heavy cable for powering Krells....I've tried a variety of stuff with mine,Incl Kimber etc and found the best is still the 30A+ screened cables they came with(Transparent or Spectral i cant remember at this time),but they do sound a LOT better with these than most other cables incl ordinary mains cables I've tried.

The connectors at both ends are silver soldered internally which also makes a big difference.
 

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