bass crossover help

[foldedhorn]

I will try not to confuse you or me even more.

I have a pair of Decware 9 watt tube amps (monoblocks)

A pair of La Scalas

And a Dynaco tube cd player that has an adjustable output that I use as my volume control. I do not use a pre amp. I believe in the purist path possible.

My problem is I feel the bass is weak and also not "full" I think this is due to 9 watts. There is not enough power to push the driver to allow it to become full the driver makes noise, loud noise, but it seems to be lacking something. I know La Scalas start at like 35hz so the bass will be missing anyway but I don't feel that is all of it.

My Idea is this, to get a more powerful transistor power amp to drive only the drivers. Keeping the tubes to drive the mids and highs. for I feel the tubes sound beautiful at doing this.

So my problem can the klipsch crossovers handle two different power sources coming in and regulate the power so they are equal coming out. With nine watts tubes driving only the mids and highs and lets say 200 watt transistor pushing the drivers wont the drivers be super loud and the mids and highs substantially lower.

or is there a magic box somewhere that can do this

Thank you for your help

[leok]

The fundamental problem probably isn't power. With less sensitive speakers than your LaScala (RF-7 at 101dB at a Watt and Forte-II at 99dB at a Watt) I get plenty of bass. There are those who may use a bit more power than the 8 Watts I have as max power in either the pp or Tripath-based amp, but the problem manifests itself more as overall lack of clarity at what I consider ridiculous amplitudes, not as reduced bass.

The LaScala doesn't go as low as either the RF-7 or Forte-II, but where it does go I would expect it to be very solid and accurate. Maybe a LaScala owner can help out here.

leok

[Erik Mandaville]

Hi, Folded horn:

I can maybe add just a little bit. I agree that using a CD player straight into the amps can be a good solution -- with a few provisions. First, how far away from your amps is your CD player? The reason I ask this has to do with the length of interconnect and related capacitance of long cable lengths. This can really rob a system of good performance due to the subsequent roll off of (especially) high frequencies. What complicates the issue more, is that you are using the variable output of your CD player -- understandably, since you need some way to attenuate the signal. I don't know what the value (in ohms) of the variable output is (basically on on-board volume control), but it's generally not the best option to have a potentiometer on the output of a circuit -- this can once again pad down the frequency extremes; and if you're using longish cable runs (anything over a few feet)the higher output impedance associated with the variable output on the CD player may have trouble 'driving' the extra capacitance of either 1)long cable runs, or 2) interconnect with intrisically high capacitance/foot. Some cables are more than 35pf/foot, which is quite high, and an example where the interconnect should be kept as short as possible. If you have your CD player right above or below the amps, than it shouldn't be too much of a problem.

Also, the potentiometers installed on many variable output CD players are not very high quality. It could be a better solution to use (if available) the 'fixed' (full output) outputs on the CD player, and go from those into a so-called 'passive preamp.' Ideally, a transformer-based (I'm working on a design for one right now...)input section with fairly high impedance for good sensitivity, but with low output impedance for better 'drive'capability for a variety of amplifiers.

As far as bi-amping your system, I think your idea is excellent! You will need to make some changes on the crossover in order to do this -- in effect, separating the mid and high pass filters from the coil on the woofer. But this gets more complex: I haven't checked on this, but I believe the La Scala woofer is a 16 ohm driver. This means that the network is a sort of series/parallel design: Two 8ohm drivers (tweet and mid)are wired in series with each other (for 16 ohms)and then wired in parallel with the 16 ohm woofer. This brings the average impedance of the La Scalas back down to 8 ohms. Thus, if you separate the essentially two branches of the crossovers (there are really 3), then you will end up needing to drive a 16 ohm woofer and the resulting 16 ohms (tweeter + mid) derived from separating the woofer from the other two drivers.

But! I'm not really too familiar with the actual parts on the Decware amps, but it may be possible (check with the company)to re-wire the output transformer for a 16 ohm load. This way, you could use the Decwares for the midrange and tweeter, but are still left with needing to match the impedance of the woofer to whatever amp you use with that.

This just gets complex,huh!?

Before going into all of that, try to see if you your CD player has fixed outputs. Don't the Decware amps have a volume control already on them??? If so, this may be another reason your not yet happy with the sound. If they do have volume controls, just go straight from the fixed outputs on the CD player into the amplifiers, and use the on-board volume pots (on the amplifiers) to adjust the volume.

Hope this helps at least a little bit....

Erik

[Erik Mandaville]

Or!

Reconnect the midrange and tweeter horns in parallel instead of series. This will give you an 4 ohm load -- most amps have 4 and 8 ohm taps on output transformers. 16 ohm availability is less common.

I need to find the schematic of the network -- I haven't seen it in awhile, and this was done off the top of my head!

Erik

[Stephen328]

OR

You could buy a subwoofer.