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Dahlquist DQ-1LP crossover owners

Hello,

I am interested in a Dahlquist crossover that is for sale. The owner is not very familiar with it. Does anyone know if if it gives the 6dB/octave bass response boost that dipole subs need.

Bass from dipoles naturally rolls off. So a dipole bass driver has to be EQed up (6 dB/ octave) as frequency goes down.

Please advise.

Best regards,
f456gt
f456gt OP
38 posts
 
Thanks chaps for the info about the Dahlquist.

I was planning to buy one to use with a pair of Gradient W-63 OB clones using two 12" Peerless 830500 drivers per side, it is very similar to the prototype built by Sigfried Linkwitz.

The problem with the crossover is that the sub needs a 6dB/octave boost because it is a dipole and I would guess most off-the-shelf solutions don't offer this.

The subs will be connected to my pair of QUAD ESL-63. I would also like to use my spare QUAD 405-2 for the subs.

I considered the Rythmik OB kit using two GR SW12-8FR and one A370PEQ Servo amplifier) but the dual driver configuration costs $1,200.
I am retired, with a fixed income and the price is a little bit stiff.

The price of the Gradient project would cost $252 for the drivers, plus the price for a crossover. I will build the enclosure myself, I have plenty of baltic plywood left from other projects.

Best regards,

Horacio
bdp24's avatar
bdp24
9,788 posts
 

Yeah Horacio, the GR Research/Rythmik OB/Dipole Sub isn't exactly cheap, though it is worth what it costs. And the First Watt B4 x/o for dipole subs is about the same price as a pair of those subs, $1500 list, discounted to about $1200.

Rodman, the Dahlquist is actually perfect for use with Tympani IV and IVa bass panels, as they require exactly what the DQ-LP1 provides---a 250Hz, 18dB/octave electronic filter. But that is in addition to the acoustic roll-off of the speaker, which is not textbook dipole (for some reason).

f456gt OP
38 posts
 
bdp24, one more question, I know about Nelson Pass but I know nothing about the First Watt B4. Can it be used with the pair of dual drivers dipoles that I want to build?

Best regards,

Horacio
bdp24's avatar
bdp24
9,788 posts
 

Horacio, I just looked it up on the First Watt website, to refresh my memory. The B4 is a regular x/o, but there is a special version of it---the B5, made especially and specifically for full-range drivers with woofers in open baffles. Go to the First Watt site for all the details.

Regarding the Dahlquist DQ-LP1 and the Magneplanar Tympani-IV and IVa loudspeakers, I remember why the Tympani requires the 3rd order (18dB/octave) low-pass filter that the DQ-LP1 provides rather than the 1st order required to compensate for the 6dB/octave roll-off caused by the dipole cancellation found in all open baffle woofers: It is to create the correct relationship between the Tympani’s woofer panels and it’s midrange/tweeter drivers, in terms of phasing.

By the way, the T-IV requires a 1st order-6dB/octave high-pass filter at 500Hz, but the T-IVa a 2nd order-12dB/octave h-p filter at 400Hz. The Dahlquist provides the former, but not the latter. That’s one reason I got the First Watt B4---it provides 1st-2nd-3rd-4th order filters, both high-pass and low-pass, from 25Hz to 3200Hz, in 25Hz increments. Incredible!

f456gt OP
38 posts
 
Hi bdp24,

I have just received an email from a First Watt dealer.

He said that the B-4 is a two-way crossover. If you want to have three-way active crossover system, you will need two B-4’s and connect them in a cascading fashion. A “6 dB boost” of sorts can be achieved by attenuating the top-end(s) and having a linestage preamp with more gain (if needed) or power amps with more sensitive inputs (if needed).

The B-4 and set up is complex. I agree with Nelson Pass who has said that with active crossover a person “needs to know where they are, where they are going, and when they’ve arrived.” Crossovers with millions of combinations are not for everyone. I agree with him after reading the owners manual.

I will go with the Rythmik OB.

Happy Memorial weekend.

Cheers.


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