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Advice on Amp for KEF 104ab Speakers

 
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skyhawk
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Joined: 21 May 2013
Posts: 5

PostPosted: Tue May 21, 2013 4:33 pm    Post subject: Advice on Amp for KEF 104ab Speakers Reply with quote

Hi, new to this forum, this is my first post. I own a pair of KEF 104ab Speakers. Bought them in the late 70s and have loved them ever since. Sound great. They still work and are in great condition.
Would like some advice on what would be a great integrated amp for them. I just bought a Cambridge Audio Azur 752BD Blu Ray Player which is suppose to have a great sounding CD section. That will be my main source. I have been looking at the Jolida 302CRC tube amp which is 50 watts per channel. Was wondering if that would be a good match for the KEFs. Their price is within my budget of around 1200 to 1600 dollars. Would like a tube amp or hybrid if possible.
Would also like to know what the db efficiency of the speakers are? Any suggestions on other amps, preferably tube, would be a good match at this price level.
Thanks for the help.
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iso
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Joined: 29 Aug 2011
Posts: 215
Location: Finland

PostPosted: Wed May 22, 2013 12:31 am    Post subject: amp suggestion Reply with quote

If integrated amp is not 100% must... I would say something like Audio Research Classic 30 or 60 or later V35 or 70 with balanced inputs would be good all around, neutral and dynamic hybrid amp. If more romantic tube sound is preferred, Conrad Jonson Premier 11a or maybe MV60 would be fine. I suppose decent examples would go between 1000-1600USD. But you must have decent preamp, passive preamps are not for these.

Best Regards

Kimmo
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skyhawk
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PostPosted: Wed May 22, 2013 1:46 am    Post subject: Reply with quote

Thanks for the info. What do you mean by passive preamp? Actually I would love to have audio research. I've seen the new VSI60 but it is out of my price range. I assume if I could afford it, it would be a good amp for these speakers.
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proffski
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Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Wed May 22, 2013 9:32 am    Post subject: Reply with quote

A term invented by the market. You cannot amplify passively unless you use a transformer to increase voltage.
What these “Passive Pre-Amps” are in fact variable attenuators.

Link:
http://goo.gl/p4X3i
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audiolabtower
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PostPosted: Wed May 22, 2013 10:22 am    Post subject: Reply with quote

The 104aB was pretty inefficient so I would get the max watts you can, although a tube amp may suit better than solid state in overload.
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proffski
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PostPosted: Wed May 22, 2013 11:15 am    Post subject: Reply with quote

I can personally vouch for their inefficiency!
They came into their own when I used them with a Crown Amcron DC300 amplifier, plenty of headroom and no amplifier clipping which must have destroyed many a T27 tweeter.

Again I can assure members of achieving this more than once with underpowered amplifiers.
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iso
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Joined: 29 Aug 2011
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Location: Finland

PostPosted: Wed May 22, 2013 1:32 pm    Post subject: passive preamp Reply with quote

Yes there is actually no such thing as passive preamap... but term is quite widely used for box with pot and inputselector... or such like One Thing audio trafo style attenuator. But anyway these amps were quite lifeless, when I used to drive them directly from CD players level pot. It does not make any sense, as impedance match should have been OK, but Premier 7 preamp made Premier 11a and CL60 to work quite much better.

I have not used VS and VT series amps so I can not say too much about them... VT100 seems to have reliability issues... final cathode follower before otput tubes is overloaded, etc... Classics do have some shortcomings like bias servo which does not work exactly as specified... but there has been no reliability issues even due this servo.

I have used CL60 for 3 years and 60wpc has been more than enough for me. CL30 is 30wpc item, and I think that it is most likely better amp than CL60 if there is no need for higher power. Both amps use triode connected 6550´s and will drive loads quite well.. they, like revemped V35/70 series amps are the last to use Bill Johnsons croscoupling tecniques in standad series ARC poweramps... I think some VT Reference series mono amps did use croscoupling slightly later.

I have tried to sort one issue in CL60, slight 1-2mV hum in the output. It can be heard when efficient spekers are used. It is originatiing from bias suply. Higher capacity C- cap made 9 dB improvment to hum level. When the amp is on the kitchen table next time, I will rechek if I can make bias suply crounding perform better. CL30 is slightly quieter in this repect due different layout. I must point out that this is no major issue. I made remark about hum to one CL60 owner and he said that his CL60 is the quietest amp he has ever used. But, it is in the design as my mesurements were very close to original factory specs.

I hope you will find this heplfull.

Best Regards

Kimmo
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proffski
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Joined: 22 Aug 2003
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Location: Tewkesbury UK

PostPosted: Wed May 22, 2013 5:15 pm    Post subject: Re: passive preamp Reply with quote

Passive Pre-Amp.

Did that not once mean Pre-Amplifier, or is there something I have missed?


Noun:

1. An electronic device for increasing the amplitude of electrical signals, used chiefly in sound reproduction.

2. A device of this kind combined with a loudspeaker, used to amplify musical instruments.

3. One that amplifies, enlarges, or extends.

4. Electronics A device, especially one using transistors or electron tubes,
that produces amplification of an electrical signal.
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