• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

tube amp

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yooy

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Joined 2005
#1
Hello,

I'm new here and want to buy a tubeamp to upgrade my hifiset.
I own a Cambridge Audio 540R surround reciever wih a preamp out and Ceratec Effeqt mkII speakers with a Efficiency: 83 dB / 1 Watt. Power-handling: 80-120 Watts and Frequency-Range: 40-22.000 Hz

Price around 1000 euro.
Models Velleman K4040
Ella EL34
WAD KaT6550
Has anyone suggestions if this is a good idea for an upgrade and can i get problems because the low efficiency of the speakers.?

Thanks.

Johan
 
#2
Those are LOW efficiency speakers. PERHAPS the WAD would work. Also, dips in the speaker's impedance curve (common in many "modern" designs) could make them poor candidates for mating to a tubed power amp.

More to the point, the preamp in a H/T receiver is of questionable quality. Why spend your money when the tube amp can't put back what the H/T preamp section has already thrown out?

If the receiver has preamp out/amp in capability, you can bypass the preamp when listening to music. Use the power amp of the receiver to power the speakers. Drive the power amp section with a tubed preamp. You'll spend less, while getting the better sound you are looking for.
 
#4
Eli Duttman said:
More to the point, the preamp in a H/T receiver is of questionable quality. Why spend your money when the tube amp can't put back what the H/T preamp section has already thrown out?
Click to expand...

This used to be true, but modern HT receivers have quite good preamp sections. People used to wax enthusiastically at the $5000 Lexicon DC-1 (a dedicated pre/pro) for music, but nowadays even a modest HT receiver will wipe the floor with it. They've gotten more careful about regulation of the analog power supplies. Moreover, with the receiver you get the advantage of being able to highpass the mains in the digital domain (assuming you have a sub). This removes the tube amp from having to handle the lowest frequencies, which is where transformers typically fall down.

Though, honestly, 83dB speakers are going to be hard for any tube amp to handle. You want to build something that can produce at least 50wpc.
 
#5
Johan,

Remember, this is a DIY site. Build it yourself. 😀 A preamp is a terrific 1st project.

Bas Horneman is Dutch. Touch base with him.
Bas' Site

Check out the sensitivity of the receiver's power amp section. That spec. will tell you if a preamp with gain is needed or a buffered level control is in order. Amps that deliver full power with less than 2 V. of drive don't need gain upstream of them.
 
#7
yooy said:

Models Velleman K4040

Thanks.

Johan
Click to expand...


Hi there......Several years ago I've serviced sim amp for a friend ....he claimed it was oscillating. True...it was unstable driving LS systems with 3rd and higher order Xover systems but not into a dummy load. I was hunting for a fault which was a design problem.........so .... I'm not a Velleman fan...I believe the manufacturer has a website of modifications that may improve performance. However some users are quite content with it.
Like cars to tinker with......there are those which like the bonnet regulary up-ended.

richj
 
#8
Johan,

PP 6550s or KT88s (essentially interchangeable) will yield 50+ W.

The O/P trafos alone will set you back a significant amount of money. Also, be prepared to work around the danger a 450-500 V. B+ rail presents. It's NOT a project for a beginner.
 
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