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elgee 10th November 2011 07:48 PM

Best type of pre-amp for valve/tube power amp
 
Hi everybody. Please excuse me if I get some of the terminology and assumptions wrong. I am very new to all of this and have already made one faux pas on another thread (I don't think I made a very good impression at all because everything went very quiet).

I've just bought a Velleman K4040 power amp which I am awaiting delivery. I was hoping to run it direct from my Marantz CD6000OSE cd player but have been told that it might not deliver as much power as it would through a pre-amp.

I don't need enormous amounts of power anyway but am more concerned with getting the best quality reproduction that I can. The speakers are Kef UniQ 80 floorstanders - a 2 way design from the mid 80's which lacks a bit of bass if anything.

My questions are:
  • What type of pre-amp would you recommend solid state or tube?
  • If I went for ss would it compromise the valve amp characteristics?
  • Would it be possible/ desireable to use a sub woofer to beef up the bass slightly? Or, should I be looking a buying 3 way speakers instead?
I listen to quite a range of stuff - modern, pop, lots of classical etc. As an example, double basses in orchestral works tend to be quite 'blurry/washed out and indistinct' if that makes sense. The higher register instruments are distinquishable from the others when say,the emphasis is on the woodwinds, or on the horns etc.

Any ideas gratefully received.

Thanks,
Les G

sreten 10th November 2011 07:54 PM

Hi, You can run it direct from a variable output CD player, rgds, sreten.

You could add line level passive EQ between the two to boost bass a little.

elgee 10th November 2011 07:57 PM

Thanks sreten. I'll try it that way when it arrives. Thanks again.

ChrisA 11th November 2011 05:54 AM

The best sounding and lowest distortion preamp is a length of wire. It has a gain of 1.0 and zero THD. Hard to beat those specs.

But you have to try it. If after using just a direct cable you find you need to run the volume controls up to "9" and the amp is still not producing full power then you need the preamp.

If you have money to spend and want better sound the best return on the investment will be to address whatever is the "bottleneck" or weak link. That would not a a preamp. Look first at the room itself and placement of the speakers. Some of the smearing could be reflections from room boundaries (walls, floor, ceiling)

Fix the part of the system that is closest to your ears (the room) and work backwards. So nest are the speakers then the power amp, pre and the source. The stuff close to the eras has the most effect

GloBug 11th November 2011 06:02 AM

"The best sounding and lowest distortion preamp is a length of wire. It has a gain of 1.0 and zero THD. Hard to beat those specs.

But you have to try it. If after using just a direct cable you find you need to run the volume controls up to "9" and the amp is still not producing full power then you need the preamp."

What he said. Your amp should run all "line level" devices fine.

Preamp would be needed with a record player, microphone, electric guitar etc. (not that your going to do that)

richwalters 11th November 2011 06:33 AM

The 1980's KEF range has a low efficiency: I had a couple of cabinets with B300B's units which had a low 85dB/w sens and the closed box cabinets a low Q below 1; i.e thin bass that has to be pushed by a fairly powerful amp and the nomex voice coils come to the rescue. Generally I'm disappointed by their range and time has moved on....people like a fuller more 2nd harmonic bass pronouncement and box Q of 1.2-1.4 ;....and above this is a boom box.
My subsequent approach is now a controlled reflex; doubling up driver units using 2 bass and midrange drivers per enclosure, space permitting.

richy

richy

M Gregg 11th November 2011 07:02 AM

Quote:

Originally Posted by elgee (Post 2776924)
Hi everybody. Please excuse me if I get some of the terminology and assumptions wrong. I am very new to all of this and have already made one faux pas on another thread (I don't think I made a very good impression at all because everything went very quiet).

I've just bought a Velleman K4040 power amp which I am awaiting delivery. I was hoping to run it direct from my Marantz CD6000OSE cd player but have been told that it might not deliver as much power as it would through a pre-amp.

I don't need enormous amounts of power anyway but am more concerned with getting the best quality reproduction that I can. The speakers are Kef UniQ 80 floorstanders - a 2 way design from the mid 80's which lacks a bit of bass if anything.







My questions are:
  • What type of pre-amp would you recommend solid state or tube?
  • If I went for ss would it compromise the valve amp characteristics?
  • Would it be possible/ desireable to use a sub woofer to beef up the bass slightly? Or, should I be looking a buying 3 way speakers instead?
I listen to quite a range of stuff - modern, pop, lots of classical etc. As an example, double basses in orchestral works tend to be quite 'blurry/washed out and indistinct' if that makes sense. The higher register instruments are distinquishable from the others when say,the emphasis is on the woodwinds, or on the horns etc.

Any ideas gratefully received.

Thanks,
Les G

If the Velleman is at the same gain as the original the output from the CD player will take it up to disco levels.....

You do not need solid state or tube in the pre-amp just a selector for the source and a variable resistor---volume control. Nothing else--this is the piece of wire theory!

Anything put in the signal path is going to add some distortion or gain..If you have got to use some powerd pre use a unity gain device...valve like the Aikido....I have listened to the Vellman and with 1.5-2V in ie CD level output it was very loud... :) Trust me you won't need any powerd preamp. Just a way of adjusting the volume. You could just put an I pod in with the volume set very low to start with and with a slight increase it will be very loud.

However if you are using a record player ..Then you will need a gain stage designed for RIAA. Make sure you match the impedance of the speaker to the closest tap...IT has not got to be spot on just close...ie single speaker with a 6 ohm you can try the 8 or 4 tap and see what sounds the best....

Regards
M, Gregg

elgee 11th November 2011 07:34 AM

Quote:

Originally Posted by richwalters (Post 2777444)
The 1980's KEF range has a low efficiency: I had a couple of cabinets with B300B's units which had a low 85dB/w sens and the closed box cabinets a low Q below 1; i.e thin bass that has to be pushed by a fairly powerful amp and the nomex voice coils come to the rescue. Generally I'm disappointed by their range and time has moved on....people like a fuller more 2nd harmonic bass pronouncement and box Q of 1.2-1.4 ;....and above this is a boom box.
My subsequent approach is now a controlled reflex; doubling up driver units using 2 bass and midrange drivers per enclosure, space permitting.

richy

richy

I would like to try adding extra drivers to improve the sound but I'm not sure how to do this. I'm a novice in these sorts of thingss, although I am quite a prctical sort of person and would like to take on a few audio projects to improve my set up. Does anyone know of any websites that would give help me with this upgrade and give me ideas generally.

Regards,

Les

elgee 11th November 2011 08:20 AM

The Kef Q80 specs. are:

Frequency response: 57Hz to 20kHz +/-3.0dB (-6dB at 40Hz)
Sensitivity: 89dB at 1m for 2.83V (corrected for wall mounting)
Maximum output: 110dB
System: SP3137
Drive units: B200 bass/midrange unit (SP1280), BD200 passive radiator (SP1288), NT25 tweeter (SP1353)
Crossover network: SP2189


I was thinking that making these 3 way might be a solution. Is it possible to use the existing crossovers and also add a bass driver? Is this feasible do you think?

Les

DF96 11th November 2011 09:53 AM

I'm no expert on speakers, but I do understand that they have to be designed as a system. You can't just add on something to an existing design, except possibly a separate subwoofer fed via a carefully designed set of filters.


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