| jwcullison |
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Reply with quote | #1 |
I was waiting to hear if there was going to be an active XO by Bruce but there doesn't seem to be anymore chatter with this.
I have some power hungry McIntosh speakers in which I have a big solid state amp pushing them. However, I would like to have the Beasts pushing the HF....which for this speaker is 250Hz and up. I can use the SS amp to push 250Hz and down.
The manufacturer states biamping using the internal passive XO is fine....but afraid to do this with a tube amp w/o an active XO in front of the Beast. They recommend with a tube amp, to put an active high pass in front of the tube amp set to one octave lower than the XO point. Then connect to the HF speaker terminals using the internal XO.
Now I use an active Ashly XO with my custom horn system and using a T16 to run the HF section with good success. But really wasn't wanting to use standard "pro equipment" to use with my McIntosh Speakers (XRT1K's).
If there is any possibility to use the Beast for the HF of my Mcintosh speakers w/o an active.......please someone tell me how to do this safely.
jc
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| Phil |
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Reply with quote | #2 |
Since nobody more knowledgeable has answered this question, I will weigh in with what I have learned.
If your speaker has one or more capacitors in series with the HF driver, you can't use the Beast for the top end in a biamp configuration. The Beast needs to pass DC to the speaker. There are lots of suggestions in here if you search the site on how you can get around this (e.g. put a resistor in parallel with the driver and filter) but I would suggest that unless your room is huge or you wish to cause hearing damage, the Beasts would probably be able to drive your speakers to a healthy volume.
I was thinking about using mine in a similar configuration, driving my Martin Logan SL3 panels with the Beasts and using a SS amp for the woofers, but really I have more than enough power in my space without biamping. And I would have to disable the manufacturer's filter (which also equalizes the panels somewhat) so there's no real benefit.
Anyway, should you choose the Beasts, you will be very pleased with them. I would be willing to bet that if you tried them, you would forget about the imagined benefits of biamping and just enjoy the music.
Best,
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| jwcullison |
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Reply with quote | #3 |
I appreciate the input.
The delay of response on here pretty much steared me into a different set of amps. I got no answer to some other inquiries of mine on this forum.
I know the Beasts will power just about anything but that wasn't my goal. I wanted to biamp.
I know the Beasts are great and will possibly look into them again. It will probably be awhile.
Thanks again.
jc
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| david lucio |
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Reply with quote | #4 |
I am currently actively bi-amping the beasts on my line array loud speakers where they are driving the 12 - 5-1/2" Eton mid bass drivers. I am using solid state for the 12 Fountek 5" ribbons. I originally thought of using the Beasts for the high frequencies as the crossover is set at 2500hz@60db using the DEQX Speaker/room correction and digital crossover in front of the amps.
I am driving the beasts with balanced outputs and I have the line transformer option in the amps. I did it this way because with my amps and JJ tubes I can never get the dc offset to sit at zero. It comes on at about -.700mv and as the tubes warm this gets down to +/-<100mv. It never stays the same and after using it for several hours the DC bias may drift a little more positive. I do not want excessive DC offset on my expensive tweeters during start up but I can easily overcome this with a speaker delay relay. I don't know if all other builders have expereienced this issue but I blame it on the tubes. dave
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| Bruce Rozenblit |
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Reply with quote | #5 |
100 mV is pretty good for a monster 160 watt OTL amp using high power pentodes. That's why I designed it with a DC offset meter that only gives a reading when the test button is pushed and I tell people to only take measurements with the same amount of warm up time so the amp will be close to the same temperature and give consistent readings. The DC will move around but is negligible and has no effect on anything. With 100 mV of offset. the speakers are dissipating less than 0.08 watt of heat. I've had customers with very expensive speakers use malfunctioning T8 amps (shorted output tube) and pump 8 volts DC into their speakers for months and never had any idea there was a problem. I don't want people to see these small fluctuations because they don't understand them and consequently will needlessly worry about them. The 6C19pi by the way, has much better DC stability because it is a low power triode but is not suitable for such high power applications. The T16 will usually hold within 5 mV which is much better than most solid state amps. The JJ EL509 has the best DC characteristics of any big power tube I have ever come across. I can't give you perfection. There are always compromises. The amp is safe and stable and sounds better than just about anything out there, but it isn't perfect. I would also like to add that your amps are scratch built and that could also contribute to some minor fluctuations.
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| C.B. |
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Reply with quote | #6 |
Quote: Originally Posted by david lucio
...I do not want excessive DC offset on my expensive tweeters during start up but I can easily overcome this with a speaker delay relay... The topic of a speaker delay relay has been discussed before on this forum. All of BR's amps need to see a small DC resistance at start-up to reach a stable operating condition. Unless you jumper the relay with a small resistor, a delay-on relay is a bad idea. Well, unnecessary, at any rate.
I agree with BR that the small amount of DC offset is not a problem with the big output tubes and most speakers. I have Newform Research ribbons, and have never had a problem, even when I was running the failure-prone Ei EL519s. On my scratch-built T8s, I even replaced the original digital panel meters (resolution down to .001 mV) with analog types (same ones as used on the old SC150). Result--no more obsessing about miniscule DC offset at the output, especially after padding the input to the meter with a 5k resistor.
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| david lucio |
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Reply with quote | #7 |
thanks for the feedback, my beasts are running very well and sound perfect. I myself am not worried about the dc drift and it seems logical as the tube heaters have to warm up the tube for a few minutes. I am very happy with the amps. The amps are totally dead quiet even with my ear on the driver with no tube hiss or hum of any kind. I have no plans to add a speaker protection circuit. After I retire I may build a second pair-now that would be a system!!!
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