General passive-line level filtering issues. (BD-Design)

by Tom Russell , Monday, February 18, 2008, 12:53 (5911 days ago) @ Bert

Bert

I'm not using the exact set-up you mention with the horn amp driving the bass amp but I do use the passive filter values you gave to me with 150s and compact bass cabs. As you know, I use an amp that is specially designed to drive the 150s directly, without a filter. It has the output chokes and transformers wound to roll off at 150hz. I use a line level Y with one leg going from the source directly to the 150 amp and the other leg going to your passive filter, which is built onto an RCA plug that fits into the bass amp. An autoformer does the volume control for the CD player and the phono stage. This works pretty close to perfect. I realize that it has been said in this thread that this connection method will not work well but all I can say is my usual response,"Just listen to the system". We all know how critical(read negative) hifi guys can be. I've had many guys sit in the listening chair and, although it is easy to see that they are trying their best to come up with something to say, not one of them has been able to come up with a single negative critique of the sound of this system. That pretty much says it all. The system has it's own sound, of course, but I agree it is hard to find anything negative to say about the sound of this system. This set-up seems to simply work. I have an active crossover that I initially used. Aside from the passive filter being quieter, I couldn't tell any real difference so I went with the simpler and quieter solution. Overall, the system is essentially silent.

The sound of your bass cab, and it's ability to integrate with the horn, is surprisingly good. I always knew the horn would be fine but I had concerns about using a reflex bass. It sounds a lot better than I imagined. I also listen to a full range electrostatic/ direct drive system so I know what integration sounds like. Even with the electrostats in the same room as the horns, I have no problems with the bass from your horn system.

I have also bought some Orpheans, just had to try them, but - and a BIG but it is - they have been lost in transit for a long time now. Honestly, I don't think I'll ever see them. If the Orpheans do show up, I have always planned on hooking them up in essentially the same manner as the 150s, with the addition of a filter on the Orphean and different bass filter values, obtained from you, of course. The last paragraph in your post seems to say you will not support someone using your horn and your bass cab in the same configuration. You certainly helped me in the past when you gave me the filter values that I am currently using. This is of particular importance to me as I still hold out some hope that the Orpheans might arrive. If they ever do show up, I'd want to use your filter values for the Orphean/Compact system and for the Orphean high pass filter. I bought the Orpheans thinking that I'd get the filter values from you, just as I did for my Oris horns.

While on the filter subject, how much, if any, does the distance from the horn to the listener, and the distance from the bass cab to the listener, figure into the filter design? I have been thinking of ways to further fine tune the system. Moving the bass cabs away from the horn, closer to the listener, is something that I have been thinking about. Is there a formula for determining the best relationship between the horn, the bass cab, and the listener? Also, when the horn is atop the bass cab, what the best horn driver to bass driver center to center distance? If the bass cab was moved closer to the listener, or if the horn center to bass driver center distance is changed, would the same filter values be correct? I'm just looking to do things as well as I can. I know that I could try moving things around and hear what happens but I don't want to be trying to reinvent the wheel when you have already figured all of this out.

Thanks

Tom

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