The Dahlquist DQ-LP1 is an active crossover device that provides high and low outputs for bi-amping your system. The preamp output goes to the DQ-LP1 and its high output goes to one amp/speaker combo and the low output to another amp and speaker combo. You can set the crossover frequency from the front. In case you have different amps for both, you can set the level for the bass. I have a SE tube amp for the top and a Hafler DH-200 driving a set of Monitor 7Bs for the bass (yes, I know its full range but it works for me).
The theory is that instead of having one speaker go full-range, both high and low, you assign two speakers to cover the two frequencies often allowing each to work better. The other side of things is interesting. Most bi-amping comes from home theatres where sub-woofers are used to play the opening scenes from Top Gun where you can rattle your neighbor’s eyeballs from a mile away. For you bass-heads, there’s left, right, and dual center-summed outputs for rattling teeth in your area code. Just imagine 4 1000w sub-woofers...
But the original intention was to add warmth and extend the bottom. The reality is that at low volumes the bass still comes through. Almost the equivalent of using a loudness control at low volume to boost the missing bass. Nowadays, that loudness switch is a hit or miss.
So for me bi-amping is more than the sum of the two. I get better highs and extended bass. The mini-monitors by themselves sound great but is missing bass umph, the 7Bs are Ok full range but without the mid-range magic. I get both with bi-amping.
I’ve had this for decades and a while back the left low output went AWOL. Simply missing. I seem to have left channel problems. First my master DH-101 had noise in the left channel phono. The other Hafler DH-101 I have had an intermittent left output. The DH110 had a normal left channel but low volume in the right.
I suspected a bad IC but the effort to fix this was high enough for me to postpone tackling it until late last year.
I needed a schematic and the ones on the web needed better resolution to see the parts values accurately. Lucky I had had a subscription to Van Alstine’s Audio Basics and the schematic there was readable. The next problem was the parts layout – there wasn’t one. So I was down to replacing parts til it worked (yes, I know I should have signal traced the circuit and did this and did that and I did do some of them).
The parts in the unit were circa 1975 or so. The caps - polyester like the suits BUT HP of the Absolute Sound used this unit (with Van Alstine mods – which I’ll get to later) to create his Frankenstein – the QRS/1D. It was an Infinity and a Magneplanar hybrid (no batteries though).
The next set of issues was that the ICs (4558s) were soldered directly onto the board so I needed to remove all the ICs, add sockets, buy some 4558s in case one of the ICs were bad (and one of them turned out to be bad).
Then I thought there might be an RCA connector problem.
So, between all these issues I decided to do a ground-up restore like the car guys do.
The theory is that instead of having one speaker go full-range, both high and low, you assign two speakers to cover the two frequencies often allowing each to work better. The other side of things is interesting. Most bi-amping comes from home theatres where sub-woofers are used to play the opening scenes from Top Gun where you can rattle your neighbor’s eyeballs from a mile away. For you bass-heads, there’s left, right, and dual center-summed outputs for rattling teeth in your area code. Just imagine 4 1000w sub-woofers...
But the original intention was to add warmth and extend the bottom. The reality is that at low volumes the bass still comes through. Almost the equivalent of using a loudness control at low volume to boost the missing bass. Nowadays, that loudness switch is a hit or miss.
So for me bi-amping is more than the sum of the two. I get better highs and extended bass. The mini-monitors by themselves sound great but is missing bass umph, the 7Bs are Ok full range but without the mid-range magic. I get both with bi-amping.
I’ve had this for decades and a while back the left low output went AWOL. Simply missing. I seem to have left channel problems. First my master DH-101 had noise in the left channel phono. The other Hafler DH-101 I have had an intermittent left output. The DH110 had a normal left channel but low volume in the right.
I suspected a bad IC but the effort to fix this was high enough for me to postpone tackling it until late last year.
I needed a schematic and the ones on the web needed better resolution to see the parts values accurately. Lucky I had had a subscription to Van Alstine’s Audio Basics and the schematic there was readable. The next problem was the parts layout – there wasn’t one. So I was down to replacing parts til it worked (yes, I know I should have signal traced the circuit and did this and did that and I did do some of them).
The parts in the unit were circa 1975 or so. The caps - polyester like the suits BUT HP of the Absolute Sound used this unit (with Van Alstine mods – which I’ll get to later) to create his Frankenstein – the QRS/1D. It was an Infinity and a Magneplanar hybrid (no batteries though).
The next set of issues was that the ICs (4558s) were soldered directly onto the board so I needed to remove all the ICs, add sockets, buy some 4558s in case one of the ICs were bad (and one of them turned out to be bad).
Then I thought there might be an RCA connector problem.
So, between all these issues I decided to do a ground-up restore like the car guys do.