Roksan Kandy K2 BT Initial Impressions Review

[drummerman]

Also, if I do get it, I will have to position it next to one of my speakers. Now,I would be worried about the magnets in the speaker effecting the sound or even worse shortening the lifespan of some of the internals! Is there anything to worry about? And would it be best to have the transformer nearest the speaker, or the other side of the chassis,and the circuit boards etc?

Cheers!

No, otherwise active speakers wouldn't exist.

Having said that, microphony with solid state components are another often debated subject. Undisputible with valves but more controversial otherwise.

My take; Don't get to hung up about equipment support other than TT's but avoid any places subject to vibration anyhow.

 

[radiorog]

Also, if I do get it, I will have to position it next to one of my speakers. Now,I would be worried about the magnets in the speaker effecting the sound or even worse shortening the lifespan of some of the internals! Is there anything to worry about? And would it be best to have the transformer nearest the speaker, or the other side of the chassis,and the circuit boards etc?

Cheers!

No, otherwise active speakers wouldn't exist.

Having said that, microphony with solid state components are another often debated subject. Undisputible with valves but more controversial otherwise.

My take; Don't get to hung up about equipment support other than TT's but avoid any places subject to vibration anyhow.

Cheers DM.

 

[J.Curry]

In addition, it might be helpful to refer to Herb Reichert's Stereophile review of the K2 BT in regard to conveying piano. Very positive indeed!

 

[radiorog]

Hi vlad, this might interest you...I have made some enquiries as I am looking into buying a k2bt. I have questioned a shop and then roksan themselves about the power rating of the bt. Roksan told me.today that the k2bt is powered at 145w into 8ohm. The statements online and in some brouchures,and also the printing on the back of some of the chassis stating 175w into 8 ohm is incorrect. Apparently the error was made my someone and the wrong specs were printed,even on the back of the amp itself. I found this very surprising as I am sure you will too. The k2bt is a huge amp compared to my brio r....over double the size, maybe 3 times the size....I am really excited to seeing how it sounds.

 

[dim_span]

Wait.....!!

Vlad, did the sound of your amp change over a period?

Did I read right?

Did it 'open up' and those kinds of things over time?

I made a drastic switch from the loud and harsh Pioneer A400 + AR11B, to B&W CM1 + Roksan K2 BT all within 2 months. The bigest change came from the speakers, but also the smooth powerfull unclipped sound from the Roksan contributed. At first everything sounded too dull and warm. Took me 3 months to really 'burn in.'

Yikes .... The old Pioneer A400 is one of my favourite old (cheap)amps ... they are 'not cheap' anymore, and some guys still get over £160 for these one ebay

Needs to be partnered proper though ... connect a Marantz CD63 MKII K1 Signature CD player and a pair of Mission 753 speakers , some decent copper cables/interconnects (Yes, they do make a difference)... and you have a system that costs approx £500 and that sounds better than some new systems of £4k .... (if set up properly)...

and I have compared

I have set this sytem for many of my clients who were keen to get a cheaper decent system (I don't sell hifi for a living)

If the room is small, the above Pioneer A400 amp, with the Marantz Signature CD player connected to Mission 751 (non Freedom) speakers is good aswell

If you like stronger Bass, the Pioneer A400 amp, with the Marantz Sig CDP connected to an old pair of B&W DM2 transmission speakers (the 1st version), sounds very good

So don't knock the A400 .... it's very good when partnered properly .... not good with a deck/vinyl though

I may get one for my desktop system for spotify

 

[Vladimir]

So don't knock the A400 .... it's very good when partnered properly .... not good with a deck/vinyl though.

My A400 lead a very speaker promiscuous life, I assure you. I also modded it according to Tom Evans mods and the results were even more impressive.

However, as soon as I got the big Harman HK6900 through the door, the A400 had to retire. I ended up gifting it away to a friend. To him it rocks like no amp he has ever seen.

Its major flaw is the high input sensitivity. It already enters clipping at 10 o'clock. If partnered with efficent speakers above 90dB with no less than 5ohms of impedance, that amp can sure put on a show.

 

[radiorog]

You could be right regarding the iec regulations. But I was asking roksan today which amp is the latest and therefore which one should I be looking at buying, and they told me about the mistake and that the correct printing on the back of the amp should be 140w into 8 ohm. The shop i was talking to said roksan were very interested i seeing the pictues quoting 175w into 8 ohm and i directed them to this thread...I hope you dont mind. I might give them a call in a few days to see if they have discovered any more information. d

 

[dim_span]

So don't knock the A400 .... it's very good when partnered properly .... not good with a deck/vinyl though.

My A400 lead a very speaker promiscuous life, I assure you. I also modded it according to Tom Evans mods and the results were even more impressive.

However, as soon as I got the big Harman HK6900 through the door, the A400 had to retire. I ended up gifting it away to a friend. To him it rocks like no amp he has ever seen.

Its major flaw is the high input sensitivity. It already enters clipping at 10 o'clock. If partnered with efficent speakers above 90dB with no less than 5ohms of impedance, that amp can sure put on a show.

compare apples with apples .... I've never heard one, but the Harman HK6900 delivers 170 Watts per channel into 8 Ohms ...,. the Pioneer A400 delivers 65 Watts into 8 Ohms ... The Harman HK6900 costs a lot more than the Pioneer ...

but I'm still confident that the Pioneer A400 connected to the Marantz signature CDP and Mission 753 speakers are hard to beat when comparing to some new systems costing £4K ... I've compared at Richer sounds

i

 

[Vladimir]

compare apples with apples .... I've never heard one, but the Harman HK6900 delivers 170 Watts per channel into 8 Ohms ...,. the Pioneer A400 delivers 65 Watts into 8 Ohms ... The Harman HK6900 costs a lot more than the Pioneer ...

but I'm still confident that the Pioneer A400 connected to the Marantz signature CDP and Mission 753 speakers are hard to beat when comparing to some new systems costing £4K ... I've compared at Richer sounds

The Roksan mopped the floor with the upgraded A400. *unknw*

 

[dim_span]

compare apples with apples .... I've never heard one, but the Harman HK6900 delivers 170 Watts per channel into 8 Ohms ...,. the Pioneer A400 delivers 65 Watts into 8 Ohms ... The Harman HK6900 costs a lot more than the Pioneer ...

but I'm still confident that the Pioneer A400 connected to the Marantz signature CDP and Mission 753 speakers are hard to beat when comparing to some new systems costing £4K ... I've compared at Richer sounds

The Roksan mopped the floor with the upgraded A400. *unknw*

we are way off topic and got sidetracked ... but just for info ...

the A400 GTE (Toms Evans version), was not as good as the A300 Precision ... (Tom's own words)

I have the A300 Precision.... amazing amp, (I also have the Tom Evans Pioneer CDP and his tweaked Pioneer tuner)

it has amazing soundstage when the speakers are set up proper , but it needs to be partnered with the correct speakers

BTW, Tom no longer servises the A400GTE

but he still services the A300 Precision (and can offer the 'full monty' upgrade if you have a stage 1 or stage 2 tweaked amp )

if you can find one, buy it .... they are good value and prices have increased considerably over the past 2 years

 

[Vladimir]

As a graphic designer I work with print all the time. IMO it is not a likely mistake to make, especially with the legal consequences for exporting and selling goods with incorrect specified power data. They have the silk screen template since the begining of the K series and they changed from 125W to 140W when the K2BT came out.

If they made a mistake and wrote 175W the first time and then corrected the issue by writing 140W in the following batch, why did they kept printing 175W on the new K3 which uses a significantly changed silk screen template?

Also why did they change back from the upgraded 8x680uF United Chemicon caps and Noratel transformer to 8x100uF general purpose Samwha and generic chinese transformer? 800uF and 5440uF certanly makes a difference in the power specs.

And why did they go from 125W > 140W > 150W > 140W in the brochures and online specs?

I think they had issues with suppliers or the better parts were simply not feasable for the price, considering Roksan is a small scale manufacturing operation. I asked Roksan about certain parts before I bought the amp and they never replied. So I asked Henley about the change in the transformer and through Henley Roksan repplied that they use different suppliers for their parts. Nothing more in details.

Obviosly they have some issues and due to those the K2BT was not consistent. I hope the K3 will have a better career.

 

[Vladimir]

I have the A300 Precision....

Even less power... You must move on to fleawatt valve amps. *biggrin*

 

[Vladimir]

Hi vlad, this might interest you...I have made some enquiries as I am looking into buying a k2bt. I have questioned a shop and then roksan themselves about the power rating of the bt. Roksan told me.today that the k2bt is powered at 145w into 8ohm. The statements online and in some brouchures,and also the printing on the back of some of the chassis stating 175w into 8 ohm is incorrect. Apparently the error was made my someone and the wrong specs were printed,even on the back of the amp itself. I found this very surprising as I am sure you will too. The k2bt is a huge amp compared to my brio r....over double the size, maybe 3 times the size....I am really excited to seeing how it sounds.

I made calculations myself based on what the power supply can deliver and it is a healthy 100W RMS per channel continuous, including losses and not considering large caps. Plus it has regulated rails, so it works very well within its design limitations. That is a very good result in my book for an integrated. All the K2 competitors are half that power considering their power supplies and mostly relly on large filter caps to prevent clipping. The extra 50W or 75W per channel are only for short bursts in transient peaks to prevent clipping.

The 175W per channel in 8 ohms is printed again for the K3 series, therefore I doubt it is a mistake. If it is a mistake they have to pull out all the amps from the market. It is most likely power consumption at high THD, relevant to print on the back (under 1200W power consumption) for regulatory agencies such as the IEC.

 

[radiorog]

As a graphic designer I work with print all the time. IMO it is not a likely mistake to make, especially with the legal consequences for exporting and selling goods with incorrect specified power data. They have the silk screen template since the begining of the K series and they changed from 125W to 140W when the K2BT came out.

If they made a mistake and wrote 175W the first time and then corrected the issue by writing 140W in the following batch, why did they kept printing 175W on the new K3 which uses a significantly changed silk screen template?

Also why did they change back from the upgraded 8x680uF United Chemicon caps and Noratel transformer to 8x100uF general purpose Samwha and generic chinese transformer? 800uF and 5440uF certanly makes a difference in the power specs.

And why did they go from 125W > 140W > 150W > 140W in the brochures and online specs?

I think they had issues with suppliers or the better parts were simply not feasable for the price, considering Roksan is a small scale manufacturing operation. I asked Roksan about certain parts before I bought the amp and they never replied. So I asked Henley about the change in the transformer and through Henley Roksan repplied that they use different suppliers for their parts. Nothing more in details.

Obviosly they have some issues and due to those the K2BT was not consistent. I hope the K3 will have a better career.

mm, you raise some good points. Especially regarding the caps. The amp they have given me, which is still in box and going back due to another reason, does have samwha caps. So you say they should be upgraded united chemicon ones ideally. Well, I think I have some more questions for Roksan tomorrow.!

 

[radiorog]

..... would you know the serial number on your amp vlad?

 

[Vladimir]

BTW Samwha are in no way bad caps. Meridian, Rega, Naim and Roksan all use them and they have proven to be reliable for filtering in audio use sice they are good general purpose caps. They still work in the by now antique active Meridian speakers.

The main filtering caps are 8200uf each. That is somewhat low for such a large integrated. 10,000uf per channel is considered minimum and 40,000uF ideal. Now if you add the 680uf x 8, you get in total 13,640uf per channel, which is nice, especially because there are many caps to reduce output impedance, not just two big ones. Ask any DIYer about this and he will confirm that the 680uf united chemicon caps were a good decision.

Yes, I see the serial on the back. Not sure if it's smart to post it online.

 

[radiorog]

BTW Samwha are in no way bad caps. Meridian, Rega, Naim and Roksan all use them and they have proven to be reliable for filtering in audio use sice they are good general purpose caps. They still work in the by now antique active Meridian speakers.

The main filtering caps are 8200uf each. That is somewhat low for such a large integrated. 10,000uf per channel is considered minimum and 40,000uF ideal. Now if you add the 680uf x 8, you get in total 13,640uf per channel, which is nice, especially because there are many caps to reduce output impedance, not just two big ones. Ask any DIYer about this and he will confirm that the 680uf united chemicon caps were a good decision.

Yes, I see the serial on the back. Not sure if it's smart to post it online.

[/quote

Well, I know nothing of electronics really, so I will take your word ;-)

Doesn't 2 x 8200 = more than 680 x 8??

I find it really strange that roksan denied by this to me today about the upgraded versions. Surely being found out not to be telling the truth to customers is worse than the reality of why they no longer produce the upgraded model? Anyway, I shall make more enquiries.

Just wondering how you could get the serial number to me....Facebook? But then I'd have to give my details open to the world! =-O

Any ideas what you think I should do, in that I'm thinking of cancelling my order and looking around to try and fins one of these illusive upgraded versions!

 

[radiorog]

.....had a quick look, and the transformer in the amp I have is a noratel one. But I can't see a power rating. And the samwha caps I can see are the two big one furthest from the transformer. Are these the ones you referred to being replaced, as I don't know where you mean when you mention the power amp circuitry. So at least it looks like the transformer is still upgraded right?

 

[Vladimir]

.....had a quick look, and the transformer in the amp I have is a noratel one. But I can't see a power rating. And the samwha caps I can see are the two big one furthest from the transformer. Are these the ones you referred to being replaced, as I don't know where you mean when you mention the power amp circuitry. So at least it looks like the transformer is still upgraded right?

Kandy always had that nice Noratel untill now when they started using ocassionally a generic replacements. Might be just as good, I dont know, but I like my Noratel. Apparently you have the exact same one.

Here is what is writen on the sticker on mine.

S1/S2 = 2 * 39V , 5A

S3/S4 = 2 * 13V

S5 = 14V , 1.1A

Those are 5 secondary supply rails. 2x39V for the power amp, 2x13V for the pre and 14V for the standby and front plate circuitry.

The maximum the power supply can give to the power amp is 2x39x5 = 390VAc or 195VAc per channel. Divided by 1.41 to get RMS, we have 138VAc RMS in AC, when it passes rectification it increases a bit but lets be conservative and just stay with 138W RMS per channel. Since the amp is class AB, power is lost in heat by at least 25%. That leaves us 103W RMS per channel pure continuous power, no caps to provide bursts of energy in transients.

Caps have dual role of filtering ripple, noise, stabilizing the supply and working as reservoirs of current when impedance drops. Transformer takes 230VA AC from the mains and splits in smaller rails, in this case 2 x 39VAc. Then AC power goes to the rectifier bridge and it gets converted in DC but the signal is nasty, rippled, noisy, with remains of AC. Next come the filtering caps to smooth out the signal and send it next to the power amp.

Considering the heatsinks are small for this large integrated, it really doesnt need any much energy accumulated in the filtering caps and would not be very smart to add more power. The caps are not big so are quickly discharged in transient peaks, but are equally fast in recharge from the rectifier bridge and the Noratel. In the K2 circuitry the caps work mostly for filtering, unlike in other amps with smaller transformers who relly on more capacitance from the filtering caps to help the voltage rails from sagging in transient peaks. The Roksan has regulated supply rails and has very large transformer that charges small capacitance banks very very fast with those nice rectifier diodes.

The power section has its own rectification, so we are talking pure continuous 100W RMS per channel. That is good enough for me. Next stop Electrocompaniet, Krell, Accuphase.

So, why did they add bigger caps, change ratings etc. Who knows, maybe they were chasing specs.

 

[radiorog]

Vlad, thank you very much for the very I formative and interesting breakdown of the transformer and resistors. Today I have learned something so it is a good day! I will check the label on ghe transformer when I get home later. And I think I have those two large samwha caps then. This is all good news. As for the 8 small caps...im am not sure where these are.is there any chance you could send a pic like the one before with rings around the 8? All in rhe purpose of curiosity and learning of course. Thanks again. l

 

[drummerman]

As a graphic designer I work with print all the time. IMO it is not a likely mistake to make, especially with the legal consequences for exporting and selling goods with incorrect specified power data. They have the silk screen template since the begining of the K series and they changed from 125W to 140W when the K2BT came out.

If they made a mistake and wrote 175W the first time and then corrected the issue by writing 140W in the following batch, why did they kept printing 175W on the new K3 which uses a significantly changed silk screen template?

Also why did they change back from the upgraded 8x680uF United Chemicon caps and Noratel transformer to 8x100uF general purpose Samwha and generic chinese transformer? 800uF and 5440uF certanly makes a difference in the power specs.

And why did they go from 125W > 140W > 150W > 140W in the brochures and online specs?

I think they had issues with suppliers or the better parts were simply not feasable for the price, considering Roksan is a small scale manufacturing operation. I asked Roksan about certain parts before I bought the amp and they never replied. So I asked Henley about the change in the transformer and through Henley Roksan repplied that they use different suppliers for their parts. Nothing more in details.

Obviosly they have some issues and due to those the K2BT was not consistent. I hope the K3 will have a better career.

mm, you raise some good points. Especially regarding the caps. The amp they have given me, which is still in box and going back due to another reason, does have samwha caps. So you say they should be upgraded united chemicon ones ideally. Well, I think I have some more questions for Roksan tomorrow.!

Get yourself a Sony STR-DB930 in good condition and marvel at Nichicon Fine Gold ... everywhere!

 

[Vladimir]

As for the 8 small caps...im am not sure where these are.is there any chance you could send a pic like the one before with rings around the 8? All in rhe purpose of curiosity and learning of course. Thanks again.

Those are the 8 caps, indicated in red circles on the picture I linked.

 

[Vladimir]

Get yourself a Sony STR-DB930 in good condition and marvel at Nichicon Fine Gold ... everywhere!

You can imagine for how cheap Sony gets these nice Nichicon caps from a company in Japan and with Sony's economy of scale. British companies do away with general purpose caps to scrape every cent they can to survive on the market.

Also I'm thinking of the Marantz PM-8005 and its shielded 600VA transformer for 85W per channel rating. It has just two smallish caps 10,000uF each but that massive tranny will never let those cans run out of juice.

How about that Noratel donut inside the Cyrus 8vs.

Similar solution like the Roksan. One big Noratel and few Samwha caps and it blasts away. Elna Silmic II used only where it counts, in the signal paths most likely.

 

[radiorog]

Hi Vlad, I've just checked the transformer and caps. The transformer is the noratel with the same measurements as on your label...happy days!

The 8 caps are also as yours, 680uF, with the two big ones being the 8200 samwha. Super happy days!

Well, I'm totally happy with the component specs now, if they pass your critical eye, that's good enough for me! ;-)

It looks like the backplate is the only difference.

Thanks for all your help so far Vlad, its been really useful in selecting a new amp.

Now just can't wait for the replacement to arrive (a small scratch on the one I initially received).

Rog.

 

[Vladimir]

Wohoo! *drinks*