How best to drive RS 2.5's
- Thread starter Ricm
- Start date
Kencat
Super Member
Whitehall said:
Check out this treatise on bi-amping:
http://sound.westhost.com/bi-amp.htm
Section 1.3 discusses power distribution. The whole article is quite interesting.
Hope it helps some.
nailzgun
Infinity - Threshold nut
I recently did the bi-amp experiment with my Ren 90's. Much to my surprise I hav returned to a single amp. I do now bi-wire and nave noticed a big improvement.
The experiment was running a Class a Threshold 100 w/ch for th highs and a 150 w/ch Threshold Stasis A/AB for the bass. This provided a ton of current capability and sounded great.
Part B was to then use my Threshold Stasis 250 w/ch to run the whole thing. Maybe it is just me but the coherance of the sound improved. And this is a big amp. 50 amps peak current per channel. The other 2 combined were only about 35 amps peak per channel.
The bi-wire opened up the sound stage tremendously, and improved bass response.
In conclusion the great Infinity speakers of ours like amperage. I think anyone will be best served finding gear that supply this as opposed to getting bogged down in wattage. Granted an amplifier that can put up serious amperage numbers costs more, but well worth the investment.
The experiment was running a Class a Threshold 100 w/ch for th highs and a 150 w/ch Threshold Stasis A/AB for the bass. This provided a ton of current capability and sounded great.
Part B was to then use my Threshold Stasis 250 w/ch to run the whole thing. Maybe it is just me but the coherance of the sound improved. And this is a big amp. 50 amps peak current per channel. The other 2 combined were only about 35 amps peak per channel.
The bi-wire opened up the sound stage tremendously, and improved bass response.
In conclusion the great Infinity speakers of ours like amperage. I think anyone will be best served finding gear that supply this as opposed to getting bogged down in wattage. Granted an amplifier that can put up serious amperage numbers costs more, but well worth the investment.
Whitehall
Super Member
Got a passive bi-amp setup as of last night fo the RS 2.5s.
The bass is driven by a 270 wpc Sony TA-N80ES (at 4 ohm) with the top end driven by a 105 wpc McIntosh MC2105. The latter has autoformers so has some "tubey" sound characteristics according to many.
The bass is very clear but the top still sounds harsh.
I also realized that there is another level of complexity with bi-amping - phasing. The bottoms are pretty easy to tell but top end needs to be tested. Now, all four connections must match phase.
I also think I should play with room acoustics too.
The bass is driven by a 270 wpc Sony TA-N80ES (at 4 ohm) with the top end driven by a 105 wpc McIntosh MC2105. The latter has autoformers so has some "tubey" sound characteristics according to many.
The bass is very clear but the top still sounds harsh.
I also realized that there is another level of complexity with bi-amping - phasing. The bottoms are pretty easy to tell but top end needs to be tested. Now, all four connections must match phase.
I also think I should play with room acoustics too.
totem
Addicted Member
Whitehall re your comment about the upper end harshness, I am running a mosfet pwr amp that has a reputation for a smooth sound and also found some
recordings edgy. I had a piece of acoustical material which I cut in half and placed behind the upper sections about 2 feet or so away on the wall. This has
helped in the over all balance of the high end. I will post a pic. of my crossovers
which were redone prior to me getting them, to take a look at. I am not able to really comment as to whether they are done right but I am sure that some work is required on speakers this age to sound as they were originally meant.
recordings edgy. I had a piece of acoustical material which I cut in half and placed behind the upper sections about 2 feet or so away on the wall. This has
helped in the over all balance of the high end. I will post a pic. of my crossovers
which were redone prior to me getting them, to take a look at. I am not able to really comment as to whether they are done right but I am sure that some work is required on speakers this age to sound as they were originally meant.
Army
Addicted Member
I hastily hooked up the 2.5's to the behringer Xover today and whoa major roll off on the high end...
Bass improved drastically, a much fuller richer sound!
But the roll off on the highs and mids was not welcomed, it was way to much.
I invited AKer DaveElton over to have a listen and we played around (carefully because the instruction manual sucks) with the Behringer and inverted the high and mids and increased the gain by 12db and :thmbsp: :thmbsp:
With the Behringer Xover you can adjust it to get about any sound you want by using the invert and gain, but it does take some careful adjustment.
If I was to do it over again (which I might) I'd spring for the next level up or the digital Behringer.
At some point I'm going to buy a test CD and a SPL meter to see how close this is set.
Anyway this my first attempt at using an external crossover, take it for what its worth
Bass improved drastically, a much fuller richer sound!
But the roll off on the highs and mids was not welcomed, it was way to much.
I invited AKer DaveElton over to have a listen and we played around (carefully because the instruction manual sucks) with the Behringer and inverted the high and mids and increased the gain by 12db and :thmbsp: :thmbsp:
With the Behringer Xover you can adjust it to get about any sound you want by using the invert and gain, but it does take some careful adjustment.
If I was to do it over again (which I might) I'd spring for the next level up or the digital Behringer.
At some point I'm going to buy a test CD and a SPL meter to see how close this is set.
Anyway this my first attempt at using an external crossover, take it for what its worth
totem
Addicted Member
RS 2.5 crossovers
When I bought these 2.5s I was told that the crossovers had been worked on.
Since there were some comments regarding this being a "problem" ie availability
of suitable components, I have some pic,s of what has been done. I am curious to here any comments (if the values can be seen) whether the job was done properly, since I did not see an original setup I can only assume.
When I bought these 2.5s I was told that the crossovers had been worked on.
Since there were some comments regarding this being a "problem" ie availability
of suitable components, I have some pic,s of what has been done. I am curious to here any comments (if the values can be seen) whether the job was done properly, since I did not see an original setup I can only assume.
Attachments
Whitehall
Super Member
I switched the taps off the MC2105 to 4 ohm and that helped witht he harshness. But what REALLY helped was turning them out a bit so my ears were no longer directly on-axis for the tweeters.
That's much better. It also seems that the rig needs maybe 30 minutes of warmup time to settle into the good sounding groove. In an unheated garage can't help with that either.
I'll see if I can get some photos of my crossovers too - they seem more complex than Army's - at least from memory.
That's much better. It also seems that the rig needs maybe 30 minutes of warmup time to settle into the good sounding groove. In an unheated garage can't help with that either.
I'll see if I can get some photos of my crossovers too - they seem more complex than Army's - at least from memory.
Well, here's my contribution to the RS 2.5 crossover lineup. AFAIK, these have not been modified. The caps are, from top to bottom:
Top blue: 700 mf, 100 VNP
Second blue: 125 mf, 100 VNP
Big silver: 1,100 mf, 100 VNP
Tall blue: 700 mf, 100 VNP
Vertical surface mount silver: 50 mf, 100 VNP
Bottom blue: 125 mf, 100 VNP
If anyone knows where to find non-polarized electrolytics of that size, I'd love to find a supplier.
David
Top blue: 700 mf, 100 VNP
Second blue: 125 mf, 100 VNP
Big silver: 1,100 mf, 100 VNP
Tall blue: 700 mf, 100 VNP
Vertical surface mount silver: 50 mf, 100 VNP
Bottom blue: 125 mf, 100 VNP
If anyone knows where to find non-polarized electrolytics of that size, I'd love to find a supplier.
David
Attachments
totem
Addicted Member
Perhaps I spoke to soon re Army,s crossovers not being original since David,s
show a cap glued in place also. Since there seem to be a group of us running these, it
makes sense that the first place to start would be with the crossovers, unless the drivers need work. If we can have perhaps EW take a look at an original schematic we then can confirm if any past work is acceptable, or what can be
done to upgrade an original.
show a cap glued in place also. Since there seem to be a group of us running these, it
makes sense that the first place to start would be with the crossovers, unless the drivers need work. If we can have perhaps EW take a look at an original schematic we then can confirm if any past work is acceptable, or what can be
done to upgrade an original.
Army
Addicted Member
Whitehall said:
Here's some good help with bi-amping and the difference between passive and active bi-amping. http://sound.westhost.com/bi-amp.htm
It makes a lot of sense to me after hearing the difference between passive and active bi-amping and why going active sounds much better on the low end.
After playing the 2.5's and watching the meters on my Spec 2's it looks to be about a 1 to 10 ratio. When the woofers are peaking at 1 watt the tweeters and mids are hitting .01 with the active crossover. I would go with a 1 to 9 ratio to be on the safe side.
So using your Sony (270wpc) on the bottom end and your 50 wpc Mac on the mid/high end there would be very little risk and should work and sound great!
Kencat
Super Member
Army,
What you propose may need to be reconsidered, if I understand what is written in the article you have referenced ( I have been rereading that one over and over for quite a while now, trying to grasp all those concepts). Please refer to section 1.3 on power distribution. The equal power point is shown (50%/50%) at a crossover of 350 Hz. This to me is saying that if the bass needs 200 WPC to avoid clipping, then the mid and tweeter circuit still also needs 200 WPC. Those mids are still getting some low frequencies even though they may look tiny compared to the big woofs.
So, it depends on that woofer xover point. I'm just throwing this out for discussion, as it could lead to some damage with a small powered amp being used on the mid/tweeter section if not fully understood. The 9:1 ratio per the chart occurs at a xover of 5,000 Hz.
If I'm not gettin it, anyone please chime in. Army, those amp meters may not be showing the whole picture. This quote from the above article; "but it is only when an oscilloscope is used that the true picture emerges." is important I think :yes:
Anyway, It is very interesting to see how the interest in active/passive bi-amping is rapidly gaining steam on AK, as it seems to be a heavy topic on the Speaker forum as well. As members general knowledge increases, the level of sophistication of technological use and interest also keeps increasing.
Wonder what next years technological forays will bring (after everyone has conquered bi-amping and it is common place) :scratch2:
What you propose may need to be reconsidered, if I understand what is written in the article you have referenced ( I have been rereading that one over and over for quite a while now, trying to grasp all those concepts). Please refer to section 1.3 on power distribution. The equal power point is shown (50%/50%) at a crossover of 350 Hz. This to me is saying that if the bass needs 200 WPC to avoid clipping, then the mid and tweeter circuit still also needs 200 WPC. Those mids are still getting some low frequencies even though they may look tiny compared to the big woofs.
So, it depends on that woofer xover point. I'm just throwing this out for discussion, as it could lead to some damage with a small powered amp being used on the mid/tweeter section if not fully understood. The 9:1 ratio per the chart occurs at a xover of 5,000 Hz.
If I'm not gettin it, anyone please chime in. Army, those amp meters may not be showing the whole picture. This quote from the above article; "but it is only when an oscilloscope is used that the true picture emerges." is important I think :yes:
Anyway, It is very interesting to see how the interest in active/passive bi-amping is rapidly gaining steam on AK, as it seems to be a heavy topic on the Speaker forum as well. As members general knowledge increases, the level of sophistication of technological use and interest also keeps increasing.
Wonder what next years technological forays will bring (after everyone has conquered bi-amping and it is common place) :scratch2:
Whitehall
Super Member
I would think that the low frequency response cutoff for the woofers would matter too re the powr approportionment. A woofer that can pump out 20 Hz to 350 Hz will require lots more juice than one that goes silent at 80 Hz on the low side.
Per Echowar's point about the big capacitors protecting the amp from woofer resonances, checking the crossover schematic shows that the 2 ohm coil is protected with a 700 mF low pass capacitor, the 4 ohm coil has either 1100 or 1800 mF depending on the position of the "single/bi-amp" switch (can't tell from the schematic.)
The Sony has 1 ohm ratings for dynamic power so maybe it is tough enough. However, I'll have to think about this one some more.
Per Echowar's point about the big capacitors protecting the amp from woofer resonances, checking the crossover schematic shows that the 2 ohm coil is protected with a 700 mF low pass capacitor, the 4 ohm coil has either 1100 or 1800 mF depending on the position of the "single/bi-amp" switch (can't tell from the schematic.)
The Sony has 1 ohm ratings for dynamic power so maybe it is tough enough. However, I'll have to think about this one some more.
