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New member Username: ChhipliPost Number: 1 Registered: Dec-06 | I am planning to biamp my PSB Stratus Silveri with two NAD C370s (I couldn't get a C270). I have them connected now without an active crossover. As Rod Elliot recommended, I am planning on putting an active crossover between the preamp and the two amps. I am using the preamp part of one of the C370s. I need some help/recommendation in the following: - How can I get/buy a good active crossover for this? - What should be the cutoff frequency for the PSB Silveri? |
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Gold Member Username: NuckPost Number: 5104 Registered: Dec-04 | Hello C. I have the Silvers(older), but the Silver I's have not changed the XO. I have changed the XO's a bit, as well as added a changeout set of silk dome tweets from the old 800 series. You realy might like to look into the factory XO's, Ist and 4th order, and not really so bad at all. I still have mine. If you do pull them out to look, replace the 10w ceramic resistor on the high XO with a 25 watt unit. Then let 'er rip! |
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New member Username: ChhipliPost Number: 2 Registered: Dec-06 | Thanks Nuck for your response! Are you recommending to take out the crossover circuit from the speakers and use them to breakout the frequencies (LF and HF) before feeding the amps. What I was trying to do is to crossover the frequencies before the amps and feed only LF into one and HF into the other. I understand I need an active crossover (instead of the passive one in the speaker). From your note I getting ideas about improving the speakers also. But that was my next project. I have not ventured inside the speaker yet. ;-) |
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Gold Member Username: NuckPost Number: 5106 Registered: Dec-04 | C, if I understand correctly, you want to go from the pre-outs to another set of circuitry and bypass the speakers XO's altogether. I cannot imagine me doing better than the speaker's designer. Maybe you are, but keep 2 rules in mind. 1; Don't make it worse. 2; Don't mess up a good working system. Why do you seek an active XO, when the passives in the Silvers are quite good? Have you pulled them to have a look at the XO's? Have a look, pal, tell me what you need. I have run hundreds and hundreds of watts through these speakers. And hundreds. |
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New member Username: ChhipliPost Number: 3 Registered: Dec-06 | Hi Nuck, I am not really an expert in this. However, let me explain what I am trying. I had the NAD C370 and the PSB speakers for a while. They are great. I got here after using multiple systems - Yamaha-Bose, Kenwood-Infinity etc. I thought of biamping the speakers. I don't agree with Biwiring. So I got another NAD C370. I couldn't get a C270 which was my preference. Now my objective is to separate out the LF and HF from the Preamp out and use one amp for the HF and the other for the LF. In order to do that I will need an active crossover. The PSB Passive crossover is in the speaker. I want to seperate out the LF and HF before the amp. Please refer to the following site for further details: http://sound.westhost.com/bi-amp.htm I totally agree with the site from a physics point of view. But I have not seen anyone do it. Please let me know if this is clear. Thanks for your help! |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 9558 Registered: May-04 | . It is not quite as easy as Mr. Elliot makes it look. He speaks in theory and not always in application in his articles. You will need to know a few things before you begin; where the original designer placed the crossover frequency, what order and type the filters for LP and HP are, and whether there are any correction filters such as baffle step or notch filters included in the original crossover. There is no point in trying to change the mechanics of the drivers by altering their crossover point or the amount of rolloff each drivers sees from the original design. Changing from a L-R filter in the passive design to a Butterworth in the active unit will make a difference in the final product. If you don't allow for correction filters, which most active crossovers don't attempt, you will more than likely make the situation worse rather than better. The parts the original designer put in the crossover are there for a reason, to achieve the best sound possible from the drivers employed. Unless you think you can do better than the original design by manipulating an active crossover, I would stick with the same values you are starting with in the passive Xo. Keep in mind that many of the active crossovers you'll find available for a reasonable price might not be as transparent to the signal as the original passive crossover in the speaker. Most of the active Xo's are meant for pro audio applications and not consumer audio. You can place "active crossover" in a search engine and find numerous units for sale. Ignore the car stereo junk and find equipment meant for pro audio use. If what Nuck says is correct, you'll have a difficult time finding an active crossover with the ability to apply a first and fourth order filter. Most active crossovers are second order and a few can be set to fourth order. I would strongly suggest you work under the "do no harm" banner. You might try strapping the two amplifiers in mono and using separate amplifiers for each channel rather than active crossovers if you can't find the filter set you require. I've read Elliot's article several times. Just what do you expect to gain from this experiment? . |
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Gold Member Username: NuckPost Number: 5113 Registered: Dec-04 | Choice #2, if you really want to tinker...pull the XO's offa the binding board and offer them outside air. Easier to tinker with. Try lowering the resistance of the ceramic tweeter power resistor, .2 ohms at a time. |
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Gold Member Username: NuckPost Number: 5114 Registered: Dec-04 | BTW, Ch, have you pulled this XO assembly? Please describe what you see. (it's heavy). |
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New member Username: ChhipliPost Number: 4 Registered: Dec-06 | I understand the practical difficulty of my proposed solution. As suggested I will bridge my amps use them as monoblocs. In the NAD C370 manual, they suggested that we don't bridge the amps for any speakers less than 8 ohm. The PSBs are 4 ohms. Do you foresee problems in overdriving? Any precautions I need to take? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 9567 Registered: May-04 | . Any precautions? Yep, don't do it. When a manufacturer receommends not lowering the impedance of the load, you should take them at their word. Apparently the NAD is bridged in parallel which halves the impedance load the outputs see. This makes a nominal eight Ohm speaker appear to be a four Ohm speaker and a four Ohm becomes a nominal two Ohm load. Not many consumer amplifiers are stable at two Ohms and a bridged amplifier is even less so. You can call PSB and ask about the actual impedance swing of the speaker, but it probably drops blow four Ohms at some point which would give the amplifier less than two Ohms to work into. This is not a recipe for success unless you grade the final effort on what amplifier you buy next. . |
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New member Username: ChhipliPost Number: 5 Registered: Dec-06 | Thanks Jan for your opinion! Can I expect any gain in biamping speakers without using external active crossover? I definitely felt the power but not much quality improvement. However, I am yet to set up my full system up in the new house (we moved in couple of weeks earlier) with the proper CD player. I was playing from an ipod. Otherwise, I guess, I have an excellent NAD C370 for sale! :-) Would you recommend a tube amp for the HF? I feel using two disimilar amps may get me into trouble. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 9573 Registered: May-04 | . You still haven't told me what you expect to gain or what you hope to gain from all this. As I said, Mr. Elliot sometimes speaks in theoretical possibilites vs. the realities of the world. Bi-amping is not going to magically transform your system. If you cannot find the crossovers to accomplish a well set up actively bi-amped speaker system, you are out of luck there. If you can't strap your amps into mono and run them on your speakers, you are out of luck there. I can't tell you what you might accomplish using the crossovers in your speakers. Some speakers respond quite well to this method of bi-amping and others do not. In all honsesty your question regarding a tube amp suggests you are fishing around for something and I don't know what it is. No, I would not suggest a tube amp for the HF unless you can give me a good reason why a tube amp might be better than what you presently own. My opinion is you will run into trouble mixing most tube amps with most solid state amps. . |
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New member Username: ChhipliPost Number: 6 Registered: Dec-06 | Jan, like many others I was experimenting to get "better" sound from my system. I don't want to buy very expensive system. With the amps and the speakers I have I am trying to figure out the best combination. I have heard better music systems than mine. I am not setting up a Home THeatre. My primary concern is pure stereo music. In my trials so far biampimg improved the system but marginally. Then I came across Mr Elliot's site. A short answer to your question (what do you want) is to get a better sounding music system with the amps and the speaker I have. Of course I do my aution and trials. I am not simply going to follow whatever I read in forums. I do have ears and I follow them. But it is always good to know what others are trying. Thanks for your insights. |
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Gold Member Username: NuckPost Number: 5134 Registered: Dec-04 | C The silver drops to 3.1 ohms and goes up to like 30 or so.No tubes for you! |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 9576 Registered: May-04 | . If the rising impedance is in the high frequencies, then a tube amplifier would still be appropriate for bi-amping the upper frequncies. The tube amplifier would never see the extreme impedance dip that is more than likely located in the deep bass region. But that isn't the reason for my hestitance at combining tubes and solid state. . |
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New member Username: ChhipliPost Number: 7 Registered: Dec-06 | Do you recommend bi-amping? If so for what reasons and what should be the optimum configuration? Most good speaker manufacturers provide HF and LF connectors. Why? Bi-wiring doesn't make sense from any point of view. It is same as using a low gage cable. I tested this with high-end systems to validate only what my physics taught me. Jan and Nuck - I am really thankful for your advice so far. The Tube Amp discussion was really helpful. I asked many earlier but this was more informative. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 9582 Registered: May-04 | . Bi-amping a speaker normally makes a noticeable improvement in the sound quality. Whether it makes enough improvement to justify the cost of the system is another matter. There are no "optimum" set ups for all systems. Bi-wiring, when done properly, can also make a noticeable difference in quality and easily can be seen to give benefits beyond simply larger guage cable. Cruise the archives of the forum for more imformation on bi-wiring as this topic has been discussed many times. . |
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New member Username: ChhipliPost Number: 9 Registered: Dec-06 | I agree on the Bi-amping. I am sorry, bi-wiring can't work by any concepts in Physics. However, I will read through the other postings. |
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Gold Member Username: NuckPost Number: 5160 Registered: Dec-04 | I have bi-amped the Psb in a few ways. Classe ca200 amp for the low, Rotel 100wpc for the highs worked ok, but the input impedence of the rotel is lower than the Classe, and the highs were too much(I have no tonal controls). Bi amp with 4 channels @100wpc Rotel. Again a better sound, lower power and the Rotel sound that I like. A few options can be found here http://www.audionote.co.uk/resources/spkr_an-e-d.pdf Pages 5&6. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 9585 Registered: May-04 | . OK, like I've always said, I'm not an engineer; but why apply only the laws of Physics when you are dealing with electronics? Mr. Elliot describes the benefits of bi-wiring in this article; http://sound.westhost.com/bi-amp.htm#bi_wiring Think about how electrons want to flow and you should see the answer to why bi-wiring can make a difference. If that doesn't work for you, read the threads. . |
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Silver Member Username: Arande2400dB could probably d..., 4000 isnt ev... 100,000dB FU... Post Number: 578 Registered: Dec-06 | "This ain't a city, it's an arm's race!" That quote might make sense to you if you think about electrons and bi-wiring. |