Hi All, I am new to your forum and hope my laymans verbage doesn't confuse anyone...but I have a question in setting up my home stereo. I have Bose 901 Series VI speakers and a Harmon Kardon receiver and also a Hafler 500 amplifier. I would like more output in volume than the HK provides on its own and would like to add my Hafler into the system. Is it possible to set the HK and the Bose 901 system up as per Bose instructions, (using the supplied equalizer connected into the preamp system), and then send the equalized signal back into the HK receiver , to control the volume output to the Hafler...and then on to my speakers? I'm not trying to raise the roof of my house but I would like more performance than the HK is providing.
"Is it possible to set the HK and the Bose 901 system up as per Bose instructions, (using the supplied equalizer connected into the preamp system), and then send the equalized signal back into the HK receiver , to control the volume output to the Hafler...and then on to my speakers? I'm not trying to raise the roof of my house but I would like more performance than the HK is providing."
Not with that configuration. The pre amp outputs are the only outputs from the signal processing component that are tied to the volume control. The Hafler amp expects to se a signal taken from a voltage controlled output - the volume control feeding the pre amp outs.
I don't know where you were expecting to take the output to the Hafler in your proposed set up but it should be coming from the receiver's pre amp outputs.
Put the eq in the tape monitor loop of the HK and engage the tape monitor function to insert it into the signal loop. Go from HK tape out to eq in and then eq out to tape monitor in. This will feed the selected input - FM, CD, Phono, etc. - to the eq and then back the the pre amp of the HK. By engaging and disengaging the tape monitor function you'll be able to hear the eq'd vs the non-eq'd signal. From there you take the HK's pre amp out and run it to the main in of the Hafler. I'm not sure how much you'll gain from this since power, in and of itself, doesn't gain you much. You'll probably notice a change in sound character wth the Hafler but any change in actual volume levels is likely to be minimal if at all.
Thanks Jan Vigne. I'll double check my hook ups and see if there is a difference. I was just seeking more volume from my sound than I am getting. The clarity is excellent but when we have a big get together, I'd like to crank the sound up more than I am getting from the HK alone. I was in hopes the Hafler could take the already controlled sound and amplify it.
I don't know what happened to this post. There are things in here that I didn't add and that do not show up when I try to edit them out. I'm hoping you can make sense of what the forum has done to this post. If you have any questions, ask them and I'll hope for the best when answering.
In purely "on paper" terms doubling the wattage will result in a not quite +3dB increase in volume potential. Another doubling - or a move to four times the amount of the original amp - will add another +3dB potential. When someone would come into the shop where I worked, if they said they were looking at getting more volume, we generally assumed what they really wanted was twice as loud as what they already had. To arrive at that point you would have to increase the original output rating by approximately 10 times.
Two things to consider here are what "potential" means and what "on paper" means. "Potential" volume increases will occur at the very top of the dynamic scale, not at average volume levels. At average volume levels two amps working into the same speaker load will be producing pretty much the same wattage - "watts" being a combination of voltage and current with some amplifiers unable to produce sustained current capacity. But you can assume the two amps would be playing at essentially the same average wattage as long as neither amp was running into clipping distortion on peaks where the amp mometarily is required to produce higher output levels. If the lower powered amp is clipping peaks with a slightly to obviously harsh distortion, then adding another three dB of potential volume might minimize the distortion. But the increase would only occur at the very top of the peak dynamic range, not at average volume levels. The amp would play cleaner but probably not really any noticeable amount louder. Experience tells me and lots of other folks that three dB of potential on peaks normally isn't going to satisfy most people who'd "like to crank the sound up more than I am getting from the HK alone." In all probability, you're going to have to head towards that ten times the amount of watts available from the HK.
"On paper" means not all amps are created equally. The Bose eq asks a lot of any amplifier by goosing up the frequency range at both ends to accomodate those 4 1/2" drivers. The accumulated load of nine drivers becomes a difficult task for most amplifiers. How well an amp responds to the load along with the required eq makes the 901's a not very favorite amp for someone seeking to "goose it up" every now and then. Some amps have more current capacity than others and they will sound more powerful than another amp of equal or at times even higher rated wattage. My recollection of the Hafler is it isn't truly one of those amps. Along with that, as a general opinion, the HK amps are known for being able to drive difficult loads with good "high current" delivery into most speakers. I do suspect the Hafler will have a somewhat bigger power supply and might sound a bit more powerful than the HK but, once again, most peole looking for the ability to "crank it up" just aren't going to be satisfied with the difference between the two amps. YMMV.
If cranking it up is your goal, you would do better to buy a speaker that is meant for that purpose. Look for a speaker system rated at, say, 94dB or higher "sensitivity" with 1 watt (or 2.83 volts) of power into the speaker. Kep the lowest impedance point of the speaker at 6 Ohms or higher, low impedance speakers will require higher current from an amplifier and may negate any sensitivity increases. Adding another 3dB of "sensitivity" to the speaker spec while maintaining a relatively high and stable impedance will be the same as adding twice as many watts to your amplifier and will allow any amp to run more within its comfort zone without clipping peak passages. In most average domestic rooms a speaker rated at 100dB should be more than satisfactory when run from a good 25 watt amplifier. Another route would be to buy some powered speakers meant for DJ work. You can find these at any shop that sells to musicians. Most of these speakers will have horn loaded drivers which will push the "efficiency" of the drivers up and make the most of whatever number of available watts are in the included "self powered" amplifiers.
On paper numbers can be manipulated in any way the manufacturer cares to. What you see as a spec on an amplifier or a speaker system can oftentimes only be true under certain conditions which would normally not be found in everyday useage. Audition whatever you buy before a purchase whenever possible and always make certain a product does what you expect before you take it home.
I got it now. Thanks for breaking it down for me. I'll get a different set up for entertaining. As for in my house I do like the clarity of sound in particular with symphonies with the HK set up as you laid out in your first post. Thank You again