Yes George, and we all owe Ralph Karsten a debt of gratitude for bringing to our attention (mine anyway) the matter of the AES standard for balanced connections---which wires get soldered to which XLR pins. Of course, if your "balanced" output is called that only because it is on XLR jacks (the output being in no way truly balanced), the balanced cable won’t get you any benefits anyway. And learning that some gear is made with its’ pseudo-balanced and single-ended outputs wired together shocked me. How lame! I’m sure Ralph will have a counter-argument to that of Martin Colloms in the Stereophile article! |
Right you are George, but some power amps (for instance my Music Reference RM-200 Mk.2) have (true) balanced inputs (created by Modjeski with discrete components, no opamps or transformers. He's a very clever designer) only, and some pre-amps have (true) balanced outputs only (Atma-Sphere's, for example). I'm sure the Pass x/o provides benefits over the First Watt B4 other than balanced outputs, but that to me is academic. I don't have the $ for the Pass! |
I just (in the past week) sold my DQ-LP1. I at one time used it as rodman suggests, for just the 3rd-order low-pass filter, installing a capacitor on the input jacks of my power amp for high-pass filtering, THE way to do it if a 1st-order filter (6dB/octave) is steep enough for your needs. You CAN use the DQ-LP1 to do the same, but you need to match the replaceable-cap value to the input impedance of the power amp anyway, so you may as well do it inside the amp, and save yourself the cost (and potential sonic penalty) of an extra pair of interconnects. The B4 is MUCH more versatile than the DQ-LP1, providing 1st/2nd/3rd/4th-order filters---both high-pass and low-pass, in 25Hz increments from 25Hz to 3200Hz., and level controls for either (but not both) filter, for bi-amp balancing. As George said, fully discrete, no opamps or ic’s. Cute little bugger, but single-ended only. If you need balanced, you must go up to the Pass x/o, which is a lot more dough. |
I got my B4 used for $750, I think it was, and that was the last one I've seen come up for sale. I read Nelson discontinued it as a finished product, offering it only as a kit, but Steve (hifidream) may know better. |
@hifidream, the pre- .7 series Maggies are just about the easiest to bi-amp speakers available. The .7 have series crossovers, so it takes internal surgery to bi-amp them. The earlier models have parallel crossovers, and as you know a line-level x/o can be easily substituted for the stock speaker-level one. In the owners manual for my Tympani T-IVa, bi-amping is encouraged. I have a First Watt B4 x/o for just that purpose. |
Ah, NOW I get it George. As usual I was thinking in perfectionist terms; gotta keep the op more in mind. |
The thing is, to bi-amp using the internal speaker-level x/o is to not reap some of the major benefits of bi-amping: keeping the woofer frequencies out of the m/t amp, eliminating the effect of the woofer's emf on the m/t drivers (they remain electrically connected through the x/o), etc. May as well just bi-wire, in the opinion of some. |
@sleepwalker65, I’m all for bi-amping, but haywood310 needed to be alerted to the fact that to do it correctly is much more involved than merely putting an external x/o and a second amp onto a pair of loudspeakers. The internal speaker-level x/o must be discarded, the outboard line-level x/o doing all the filtering. And that will NOT work if any of the drivers used in the speaker required any compensation network filtering to sound as the designer intended them to. As I said above, Magnepan used to make their speakers so as to be easily bi-amped, and endorsed doing so. The .6 and earlier Maggies had parallel cross-overs and two pair of speaker cable connectors (which made bi-amping simple), but switched to series x/o’s for the .7 models (bi-amping them requires cutting into the x/o, installing another set of binding posts, etc.). Some of the monitoring loudspeakers used in recording studios come with filtering and a separate power amp for each driver, but they sound very different from audiophile speakers. On the other hand, adding a sub or four to just about all loudspeakers provides many of the benefits of bi-amping, plus more. They present their own challenges to optimize in a room and system, of course. |
Adding powered subs is a form of bi-amping, providing many real benefits with no penalties. |
Even the good active x/o's (Bryston, Pass, First Watt, Marchand) provide only "textbook" filtering: 1st/2nd/3rd/4th-order (6/12/18/24dB per octave). None of them provide compensation networks, which lots of loudspeaker x/o's include, even some employing 1st-order filters (such as Thiel). Look at the x/o schematic for your speaker to see how complex it is. |
A line-level cross-over can not necessarily be used in place the speaker-level one installed inside that speakers' enclosure. The speakers' cross-over often contains electronic parts that are used in "compensation networks" needed to optimize the behavior of the speakers' drivers. You need to get a schematic of the cross-over, to see what you are dealing with. Some loudspeakers come from the factory set up to allow bi-amping---for instance the older .6 series Magnepans, but most speakers aren't. Are your Dunlavy's? |
