How do I know whether my speakers are IEC compliant?
What is the advantage of bridging two amp vs one big amp?
- Thread starter Alan0354
- Start date
Superampman
AK Member
Here is the original brochure:
I can play them according to my spl meter at my listening position 13ft. away to 107db. The amps get quite warm but not hot. This is with the extended bass switch engaged. The switch was added subsequent to the first models sold because of the impedance dip at 30hz. Flip it down and no more amp killer.Attachments
Superampman
AK Member
The Citation 16s sound great bridged. I tried them with my Kappa 9s. But you may have to replace the RCAs with better/tighter ones. Otherwise they might be a bit noisy.
Superampman
AK Member
It's not a lie since the extended bass switch allows you to make your own decision how hard you're going to drive your amp. The description in the brochure makes it clear under what circumstances it should be in the 'down' position.
FOH Engineer
Lunatic Member
Wo
Like manuals often says specs can be changed without notice..wonder if the 30 hz rolloff or if you will non extended bass originally was a non switchable 30 hz filter...changed to a switchable set frequency HPF or a roll off filter...pretty nicely engineered speaker if the future mods are already allowed for in the first run..
Wow a spec sheet change...not that it really matters, but I wonder how many versions/mods have been factory re-engineered over the retail shelf life.
Like manuals often says specs can be changed without notice..wonder if the 30 hz rolloff or if you will non extended bass originally was a non switchable 30 hz filter...changed to a switchable set frequency HPF or a roll off filter...pretty nicely engineered speaker if the future mods are already allowed for in the first run..
Superampman
AK Member
What the switch does is bypass the 15mh inductor for the woofers. So the first gen ran full tilt. Hence the amp killer designation.
savatage1973
Addicted Member
The "extended range" switch does nothing more than add a 1 ohm resistor to the woofer circuit to "protect" lesser amps--and utilizing that feature kills the bass response. It is a strange crossover in that there are two 4 ohm woofers wired in-phase and in-series, which would lead you to believe an 8 ohm load, but there is a choke wired across that virtually "shorts" them.
Superampman
AK Member
Right, it puts that resistor in the path of that huge inductor causing all the havoc.
whoaru99
Epic Member
You'd have to ask the mfg, if nothing is published in the documentation.
savatage1973
Addicted Member
But we digress--the OP was regarding bridging vs a single monster amp--in general (and this is a HUGE generalization) is that bridging the "average" amp reduces its ability to handle low impedance loads (although providing a higher output at 8 ohms), and there are issues with distortion and other "artifacts" if both sides (channels) of the amp are not calibrated identically when bridging to mono. I'd much rather use monoblocks or stereo amps vertically bi-amping, rather than bridging.
whoaru99
Epic Member
Except that doesn't really work if the point needs to be more power.
And, some "monoblocks" are just already bridged amps.
Ha ha, I think I was kicked out of the thread already!!! I really want to talk about technical advantage and disadvantage, not intend to ask who has what. I tried to steering the discussion back by talking about current injection into the ground but got totally ignored.
I my opinion, you only do bridging with high end amplifiers to push it one step higher. You really don't worry about whether they can drive 2ohm load as they can in most cases. If you have an average amp and you want to get better sound, trade up to a better amp and forget bridging. Why pay double the price to buy two average amps to do bridge if you can spend the money to get a better amp?
Most of the better amp has big heatsink, at least 4 pairs of output transistors ( even my Nakamichi PA-7 has 7 pairs and huge heatsink that can support at least 100W of heat). You don't question whether it can drive 2ohm load!!! If the amp has problem driving 4ohm, forget bridging, get a better amp. If you amp has excess distortion, no bridging is going to help that.
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Lesterbest
Super Member
What is the advantage of bridging two amp vs one big amp?
There is none IMO. Pwr is relatively cheap today.
There is none IMO. Pwr is relatively cheap today.
I tend to agree, I brought up the advantage about bridging avoid injecting current to the ground return. But I keep thinking about it, you can do that with normal amp by careful grounding. If it has never been a problem, why fix it?!!!
Particularly what I said in my last post, can you really make two $750 amp compare to a $1500 amp after bridging. I seriously doubt that. If the "average" amp has high distortion, bridging is not going to make it better. If the amp cannot even drive an 8 ohm load after bridging, what good does that do?
If you amp is already 150W, why make it 600W? You are listening at home!!! You know how loud is 10W signal?
whoaru99
Epic Member
I think some of your points are becoming a bit red herring-ish, in regard to "average" amp vs "good" amp. Does anyone really think they're turning a Kenwood into a Krell by bridging it? I don't think so.
But, they may be saying they're turning their Kenwood amp into a more powerful amp that keeps them out of clipping. So, better sound may in fact result from bridging a couple average amps than one unbridged average amp simply because the bridged amps are not running into clipping. And, two Kenwoods are almost certainly less cost than one big Krell.
The point is, as often the case, each situation has to be looked at. There is seldom one blanket statement to be made and apples to be compared to apples.
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Any Krell is going to cost a lot more than two Kenwood.
I don't know the names of the better quality new amps, I can only talk about the older ones. I don't think the better amps has improve much if any in the last 30 years since the higher voltage ( 200V+) and higher fT( fT of 30MHz or over) became available in the 80s. I am more thinking about whether two new Kenwood can touch...say....the old Threshold S300 to name one. You can fill in Bryston, Aragon, Conrad Johnson etal, all are step or two higher than average, but not get into Krell type.
As I said, I started this thread to talk about the advantage and disadvantage in theory between the two. I want to talk about how the THD, ground current, and other technical comparison.
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whoaru99
Epic Member
Another point to consider is that people who go to bridged amps often own one of the amps already, and probably have for some time. So the cost for the second amp is more incremental than a decision to outright buy two amps or one bigger.
As far as advantage, again, power. If bridging provides headroom to avoid clipping then it's likely to sound better than the same amp not bridged. Yes, as mentioned, some negative characteristics may be additive in bridging, but the scope of those things is still small in the big picture; i.e. 1 penny to 2 pennies is a 100% increase...but it's still just two pennies.
As far as advantage, again, power. If bridging provides headroom to avoid clipping then it's likely to sound better than the same amp not bridged. Yes, as mentioned, some negative characteristics may be additive in bridging, but the scope of those things is still small in the big picture; i.e. 1 penny to 2 pennies is a 100% increase...but it's still just two pennies.
I am going to try to steer the discussion back to more theoretical comparison between the two. I gave it a lot of thought since, this is what I come up so far:
1) I don't see bridging help in THD department at all. Since the signal of two sides are exactly opposite ( inverted, opposite phase or whatever you call). The signal "add" to each other. So any distortion harmonics "add". So bridging does not improve THD at all.
2) I first thought and posted in post #7 that return current does not go to the ground in the bridge amp and therefore the ground is quieter. BUT after much thoughts, this is only good in theory where the power is completely detached from the ground. BUT in real circuit, we have the main reservoir capacitor goes to the ground from both rails, it's not going to be any better than a normal amp with careful star ground.
3) Bridge monoblock enable to put the power amp much closer to the speaker on each side to shorten the speaker cable. I have done FFT to show speaker cable cause increase of 3rd harmonic( don't ask me why, I just observed and posted here recently with pictures). BUT, I also experiment to proof doubling the cable reduced the 3rd harmonic. So you can always counteract long speaker wires by doubling up the cables. Sure a lot simpler than doing bridging. So this is not an advantage.
4) Bridging enable you to use lower rail voltage to get the same output power. This will be a good reason 30 years ago when transistors cannot handle the voltage in order to get higher power output. Back in the days, unless you do a stacked emitter follower like the old Threshold by Nelson Pass, you are limited to about +/-40V rail and that limit the output power to about 80W into 8ohm or 160W into 4ohm. With bridging, you can get 4 times the power to 320W with 8ohm speaker without using the stack emitter follower technique. BUT this advantage is gone since the introduction of higher voltage transistors in the late 80s. You can get transistor that can withstand 250V. People don't have to think twice to use +/-100V rail to get about 560W into 8ohm speaker. So this reason of bridging is gone.
Tell me what else did I miss.
Alan
1) I don't see bridging help in THD department at all. Since the signal of two sides are exactly opposite ( inverted, opposite phase or whatever you call). The signal "add" to each other. So any distortion harmonics "add". So bridging does not improve THD at all.
2) I first thought and posted in post #7 that return current does not go to the ground in the bridge amp and therefore the ground is quieter. BUT after much thoughts, this is only good in theory where the power is completely detached from the ground. BUT in real circuit, we have the main reservoir capacitor goes to the ground from both rails, it's not going to be any better than a normal amp with careful star ground.
3) Bridge monoblock enable to put the power amp much closer to the speaker on each side to shorten the speaker cable. I have done FFT to show speaker cable cause increase of 3rd harmonic( don't ask me why, I just observed and posted here recently with pictures). BUT, I also experiment to proof doubling the cable reduced the 3rd harmonic. So you can always counteract long speaker wires by doubling up the cables. Sure a lot simpler than doing bridging. So this is not an advantage.
4) Bridging enable you to use lower rail voltage to get the same output power. This will be a good reason 30 years ago when transistors cannot handle the voltage in order to get higher power output. Back in the days, unless you do a stacked emitter follower like the old Threshold by Nelson Pass, you are limited to about +/-40V rail and that limit the output power to about 80W into 8ohm or 160W into 4ohm. With bridging, you can get 4 times the power to 320W with 8ohm speaker without using the stack emitter follower technique. BUT this advantage is gone since the introduction of higher voltage transistors in the late 80s. You can get transistor that can withstand 250V. People don't have to think twice to use +/-100V rail to get about 560W into 8ohm speaker. So this reason of bridging is gone.
Tell me what else did I miss.
Alan
Lesterbest
Super Member
"i.e. 1 penny to 2 pennies is a 100% increase...but it's still just two pennies."
Spoken like a scholar who graduated summa cum laude from the London School of Economics.
Spoken like a scholar who graduated summa cum laude from the London School of Economics.
Binkman
Lunatic Member
From my reading the most common amps are emitter follower in 'stages' for more refined circuits. In preamp THD can be as finite as requiring to measure same. Regardless the output in power is always 'iffy' MHO.. it's pretty finite to the ear. I have some nice grado headphones that are equally pleasant in that venue of a good pre for same. the better pre's are like 0.0002 or a tad off a good instrument that can actually measure THD to that percent. Lab environment.
