This amp (m-200t) is one of the "magnetic field power" type, 20 years old or so I'm guessing. Specs out at 130 watts per channel into 8 ohm, 200 watts per channel into 4 ohm, or 350 watts mono bridged into 8 ohm. I'm curious why there is no mention of bridged operation at 4 ohm. Max power output and current would go through the roof of course, but I'm wondering if I could go ahead and give it a try anyway, I will not be driving anywhere near the maximum. What's the worst that can happen? Blow a fuse?
I'm currently running them at 4 ohm with a 200 watt max, would like to see if I can get 350 watts, seems like I should be able to right, it can do this into an 8 ohm load.
I'm currently running them at 4 ohm with a 200 watt max, would like to see if I can get 350 watts, seems like I should be able to right, it can do this into an 8 ohm load.
Jan is correct here.
Manufacturers have ratings for a reason. These ratings are for your protection to keep you from blowing something sky high.
The amplifier is rated for a 8 ohm mono bridged load so this means 8 ohms and not 4 ohms. Trying to run a 4 ohm load in mono bridge mode is totally stupid and asking for some of the magic smoke to leave the amplifier.
Is it really worth it to try running a 4 ohm load in bridge mode for less than a 3 db gain in level?
What is the worst that could happen was your question.... You blow the damn thing up.
Manufacturers have ratings for a reason. These ratings are for your protection to keep you from blowing something sky high.
The amplifier is rated for a 8 ohm mono bridged load so this means 8 ohms and not 4 ohms. Trying to run a 4 ohm load in mono bridge mode is totally stupid and asking for some of the magic smoke to leave the amplifier.
Is it really worth it to try running a 4 ohm load in bridge mode for less than a 3 db gain in level?
What is the worst that could happen was your question.... You blow the damn thing up.
Hi DreadPirate,
Are you planning to bridge an amp into 4 ohms? If so, why on earth would you do that????????????????? !
The difference between 350W and 200W is less than 3 dB. The power loss due to higher voicecoil temperatures will eat some efficiency away too. Your net gain in level may therefore run 1.5 dB. Yahoo! You can barely hear that.
The Adcom doesn't like 4 ohm loads in bridge mode either. It is more powerful per channel and may give you some more headroom, but that is all you should expect if you are looking at power only.
I am just wondering what your goal is as there may be a better way to get there. Failing that you will experience diminishing returns and equipment failures.
-Chris
Are you planning to bridge an amp into 4 ohms? If so, why on earth would you do that????????????????? !
The difference between 350W and 200W is less than 3 dB. The power loss due to higher voicecoil temperatures will eat some efficiency away too. Your net gain in level may therefore run 1.5 dB. Yahoo! You can barely hear that.
The Adcom doesn't like 4 ohm loads in bridge mode either. It is more powerful per channel and may give you some more headroom, but that is all you should expect if you are looking at power only.
I am just wondering what your goal is as there may be a better way to get there. Failing that you will experience diminishing returns and equipment failures.
-Chris
Hi,
let's get back to basics.
take a dual voice coil driver that is 4+4ohm.
one can
1.) wire it up as VC in series giving an 8ohm load
or
2.) wire it up as VC in parallel giving a 2ohm load
or
3.) keep the two voice coil separate giving 4ohm & 4ohm.
Now look at the two channel amplifier capable of independant use or suitable for bridge mode BUT not into 2ohm (excluding option 2.).
The power delivered in bridge mode (from a good bridgable amp) is doubled power into double the impedance.
as an example, an amplifier that puts out 200W + 200W into 4r can do about 400W into 8r.
now attach that amp to option 1 or 3 above
option 1. gives 400W into 8r
option 3. gives 200W + 200W into each of the 4r.
Guess what, the power delivered to the speaker is just the same.
Go for the easy option dedicate a single channel of amplifier to EACH voice coil.
The same logic applies when using dual drivers in a single cabinet.
let's get back to basics.
take a dual voice coil driver that is 4+4ohm.
one can
1.) wire it up as VC in series giving an 8ohm load
or
2.) wire it up as VC in parallel giving a 2ohm load
or
3.) keep the two voice coil separate giving 4ohm & 4ohm.
Now look at the two channel amplifier capable of independant use or suitable for bridge mode BUT not into 2ohm (excluding option 2.).
The power delivered in bridge mode (from a good bridgable amp) is doubled power into double the impedance.
as an example, an amplifier that puts out 200W + 200W into 4r can do about 400W into 8r.
now attach that amp to option 1 or 3 above
option 1. gives 400W into 8r
option 3. gives 200W + 200W into each of the 4r.
Guess what, the power delivered to the speaker is just the same.
Go for the easy option dedicate a single channel of amplifier to EACH voice coil.
The same logic applies when using dual drivers in a single cabinet.
Hi Andrew,
Reality rears it's rather ugly head again. How important this is ? I don't know.
There is an efficiency penalty for having a dual voice coil woofer due to the construction of the coil. Also, the channels are now coupled together by transformer action. The same heat is dissipated as well.
My vote. A box enclosing two woofers radiating to the air. Mutual loading will also increase the efficiency a little and you've spread the heat over two voice coil assemblies.
-Chris
Reality rears it's rather ugly head again. How important this is ? I don't know.
There is an efficiency penalty for having a dual voice coil woofer due to the construction of the coil. Also, the channels are now coupled together by transformer action. The same heat is dissipated as well.
My vote. A box enclosing two woofers radiating to the air. Mutual loading will also increase the efficiency a little and you've spread the heat over two voice coil assemblies.
-Chris
Obviously, I haven't a clue about bridging amps, that's why the question seems foolish, assume a minimal level of knowledge here folks.
I have a pair of Thiel CS3.5 speakers and a single Carver amp spec'ed as described 130W into 8 ohms, 200W into 4 ohms, and 325 watts bridged at 8 ohms. There is no data bridged driving 4 ohm load. These thiels are notorious eaters of audio output, most people who own them mono bridge with Bryston 4Bs which I guess do have a rating at 4 ohms to do this.
My plan was to buy another Carver m-200t amp and dedicate one to each speaker, isn't that bridging? Each speaker is nominal 4 ohms. I was curious why no ratings were given for monobridging (which I still do not get, I'll have to read the manual it had pictures) for 4 ohm speakers, I guess the answer is that it is not advisable.
The GFA-555 seems like it has a good deal more muscle than the m-200t, which actually doesn't do too bad a job, but again, I keep hearing from owners that it just can't do these speakers justice. The GFA-555 is rated at 350 watts into 4 ohms (rather than 200 watts as the m-200t) and is touted as "high current" 80A or so, whatever that means.
I also have an older Harmon integrated, the PM665 which is a 100 watter per channel into 8 ohms, but has two enormous transformers and the manual touts its 60A high instantaneous current ability. But I haven't been able to use it because it most likely has bad caps or cold solder joints, can't get rid of this continous static.
I have a pair of Thiel CS3.5 speakers and a single Carver amp spec'ed as described 130W into 8 ohms, 200W into 4 ohms, and 325 watts bridged at 8 ohms. There is no data bridged driving 4 ohm load. These thiels are notorious eaters of audio output, most people who own them mono bridge with Bryston 4Bs which I guess do have a rating at 4 ohms to do this.
My plan was to buy another Carver m-200t amp and dedicate one to each speaker, isn't that bridging? Each speaker is nominal 4 ohms. I was curious why no ratings were given for monobridging (which I still do not get, I'll have to read the manual it had pictures) for 4 ohm speakers, I guess the answer is that it is not advisable.
The GFA-555 seems like it has a good deal more muscle than the m-200t, which actually doesn't do too bad a job, but again, I keep hearing from owners that it just can't do these speakers justice. The GFA-555 is rated at 350 watts into 4 ohms (rather than 200 watts as the m-200t) and is touted as "high current" 80A or so, whatever that means.
I also have an older Harmon integrated, the PM665 which is a 100 watter per channel into 8 ohms, but has two enormous transformers and the manual touts its 60A high instantaneous current ability. But I haven't been able to use it because it most likely has bad caps or cold solder joints, can't get rid of this continous static.
Hi DreadPirate,
Okay. Most amplifiers are not at their best in bridged mode. You are much further ahead to buy a larger, good sounding stereo amp.
The Adcom will sound better than that Carver, or a 4B (easily). There are better amplifiers out there but you must be prepared to pay for them. No cheap way out here folks!
Remember, just because you might be able to do something does not mean that you should. Bridging is really popular with car amps. Mostly due to rather low supply voltages. Sound quality is rated much lower than SPL, so don't copy them. How this became acceptable for home amplifiers I'll never know. I guess someone is trying to sell more amps.
If you really like high amounts of power, consider the ratings of the Carver Lightstar (series 1). 300W/ch into 8 ohms. 600W into 4 ohms (most woofers will fail with this amount of power). 1,200 W into 2 ohms, both channels driven at no more than the rated distortion (forgot those numbers, but who cares?). I don't know of many woofers that will put up with this amount of power over any period of time. This amp would be running off a pair of 15A 120VAC circuits.
I would respectfully suggest that if you need more SPL, get more efficient speakers (or two pairs) with a nominal impedance of 8 ohms. Given that you are being told you need in excess of 350 W per channel makes me wonder about the speakers. Not worth it in my book.
-Chris
Okay. Most amplifiers are not at their best in bridged mode. You are much further ahead to buy a larger, good sounding stereo amp.
The Adcom will sound better than that Carver, or a 4B (easily). There are better amplifiers out there but you must be prepared to pay for them. No cheap way out here folks!
Remember, just because you might be able to do something does not mean that you should. Bridging is really popular with car amps. Mostly due to rather low supply voltages. Sound quality is rated much lower than SPL, so don't copy them. How this became acceptable for home amplifiers I'll never know. I guess someone is trying to sell more amps.
If you really like high amounts of power, consider the ratings of the Carver Lightstar (series 1). 300W/ch into 8 ohms. 600W into 4 ohms (most woofers will fail with this amount of power). 1,200 W into 2 ohms, both channels driven at no more than the rated distortion (forgot those numbers, but who cares?). I don't know of many woofers that will put up with this amount of power over any period of time. This amp would be running off a pair of 15A 120VAC circuits.
I would respectfully suggest that if you need more SPL, get more efficient speakers (or two pairs) with a nominal impedance of 8 ohms. Given that you are being told you need in excess of 350 W per channel makes me wonder about the speakers. Not worth it in my book.
-Chris
Hi Anatech,
I don't follow why dual voice coil is less efficient.
Suppose we have a 4layer VC with just two ends coming to the outside.
Now lay two VC over each other each consisting of a two layer lay-up. Now we have four ends to bring to the outside.
The coil part is identical. The extra weight of bringing two extra ends is from the added copper in the tails and the glue to keep them in place.
Similarly a two layer VC could be laid up with a bifilar wound dual VC and again the only efficiency loss is the added weight of the two extra tails.
Are you saying that the weight of the two extra tails is what concerns anyone about efficiency loss or is there something else I have missed?
I used a dual voice coil simply because it made the same power comparison seem more valid and they seem to be very popular (but I don't have any). As I said earlier the equal power analogy applies to dual drivers as well.anatech said:
I don't follow why dual voice coil is less efficient.
Suppose we have a 4layer VC with just two ends coming to the outside.
Now lay two VC over each other each consisting of a two layer lay-up. Now we have four ends to bring to the outside.
The coil part is identical. The extra weight of bringing two extra ends is from the added copper in the tails and the glue to keep them in place.
Similarly a two layer VC could be laid up with a bifilar wound dual VC and again the only efficiency loss is the added weight of the two extra tails.
Are you saying that the weight of the two extra tails is what concerns anyone about efficiency loss or is there something else I have missed?
AndrewT
In the world of serious audio no one would use a dual voice coil subwoofer driver. Imagine using a stereo amplifier to drive each coil and then imagine a program material going to one channel. The other channel lets say had none but has received a pulse back on it as a result of the other channel program. This as you should know is not a good thing and can and does sometimes result in amplifier failure. In large commercial pro sound systems you don't use dual voice coil drivers for this reason.
Its best to leave the economy subwoofer drivers to the kids playing with car stereo where space is a consideration and common sense doesn't come into play.
In the world of serious audio no one would use a dual voice coil subwoofer driver. Imagine using a stereo amplifier to drive each coil and then imagine a program material going to one channel. The other channel lets say had none but has received a pulse back on it as a result of the other channel program. This as you should know is not a good thing and can and does sometimes result in amplifier failure. In large commercial pro sound systems you don't use dual voice coil drivers for this reason.
Its best to leave the economy subwoofer drivers to the kids playing with car stereo where space is a consideration and common sense doesn't come into play.
burnedfingers said:
I can think of using a dual voice coil subwoofer,
fed by both left & right channel sound.
But wouldn't be my first choice.
As below a certain frequency ??
we can not know from what direction a sound comes.
I am not sure, though, I would want use it with passive filters
at the amplifiers both outputs.
I prefer active filter + 1 subwoofer amplifier separate.
I can see two reasons to have any use of dual voice coil subwoofer
1. impedance adjustment
8 Ohm + 8 Ohm can be paralleled to 4 Ohm, or series to 16 Ohm
2. economical reason - to avoid a separate sub woofer power amplifier
lineup
Everything you are saying here jibes with what I've found so far about these speakers. They were a good purchase price-wise and fill a large room nicely, but difficult to match with an amp. There supposedly is an equalizer I do not have, perhaps it is to help with this.
When these were made and sold at $3000 15 years ago, they were expected to be matched with high end amps I'm not willing to spring for. The Adcom GFA-555 looks like it will suffice and they go for $400. I just don't have the ears to justify $1500 and it is not even my main rig.
I do not listen at particularly high levels, but this room is 500 sf and has a 13' ceiling.
The Adcom is on order and will probably do, since adding a second Carver sounds like lunacy to the experts.
I like these speakers, besides looking cool, the build quality is first rate. The front baffle is 3" thick. When something does sound good on these, it really sounds good (solo piano works are right on the money, sounds like there is a grand piano in the room), but I also find that some recordings that play fine on other systems sometimes sound flat and/or have their shortcomings emphasized. On Bill Evans Live at the Village Vanguard, the microphone picking up the bass line rattles to high heaven, the disc is barely listenable to me on these.
Thanks to all for the comments.
When these were made and sold at $3000 15 years ago, they were expected to be matched with high end amps I'm not willing to spring for. The Adcom GFA-555 looks like it will suffice and they go for $400. I just don't have the ears to justify $1500 and it is not even my main rig.
I do not listen at particularly high levels, but this room is 500 sf and has a 13' ceiling.
The Adcom is on order and will probably do, since adding a second Carver sounds like lunacy to the experts.
I like these speakers, besides looking cool, the build quality is first rate. The front baffle is 3" thick. When something does sound good on these, it really sounds good (solo piano works are right on the money, sounds like there is a grand piano in the room), but I also find that some recordings that play fine on other systems sometimes sound flat and/or have their shortcomings emphasized. On Bill Evans Live at the Village Vanguard, the microphone picking up the bass line rattles to high heaven, the disc is barely listenable to me on these.
Thanks to all for the comments.
anatech said:
Hi Andrew,
In answer to your question.
In most dual coil woofers they wind the two coils in different stacks, so there is a space in the winding. This represents the loss in efficiency as it is dead space. They used to wind them like that.
If they are wound on top of each other, I would think the bottom layer would make the top layer less efficient, requiring a few more turns. Also, a short between channels is far more likely once it overheats.
Either way, you still have transformer coupling between channels. Bad idea. I do understand why you don't have any of these.
Interestingly, they make dual winding wide range drivers for ceiling speaker use in homes. Same issues apply. Come to think of it, I've seen some dead amps under warranty and this may be the reason.
-Chris
In answer to your question.
In most dual coil woofers they wind the two coils in different stacks, so there is a space in the winding. This represents the loss in efficiency as it is dead space. They used to wind them like that.
If they are wound on top of each other, I would think the bottom layer would make the top layer less efficient, requiring a few more turns. Also, a short between channels is far more likely once it overheats.
Either way, you still have transformer coupling between channels. Bad idea. I do understand why you don't have any of these.
Interestingly, they make dual winding wide range drivers for ceiling speaker use in homes. Same issues apply. Come to think of it, I've seen some dead amps under warranty and this may be the reason.
-Chris
anatech said:
They came with an equalizer and from what I gathered prior to my purchase many owners preferred the sound without it, though I am keeping my eyes open for one. Thiel claimed these speakers as full range down to 20Hz with the equalizer.
By the way, the Oaktron drivers from my other post are 12H8 and in mint condition if you would like them, they'd be $25 the pair + shipping (they are not that heavy, stamped basket, as you probably know). This deal is just for you and is good only for today, pending approval by the manager
.
anatech said:Hi DreadPirate,
Thanks, but I use Peerless and Vifa these days. They would be great for you to build something with though.
I was thinking a 2cf cardboard box and $300/ft speaker wire, but I'm afraid they might make my Thiel purchase obsolete. It appears from eBay that some people are using these in guitar amps. More power to them. You sold these back then with a clear conscience? How do you sleep at night? (If its on a big pile of money surrounded by beautiful women, I don't want to hear it).
I did not consider that angle, that maybe they came out with the equalizer later and sold them both ways, validating their use without it. The main benefit was low extension. I'll send them an email, they are very responsive, as you would expect from a company selling $10,000 speakers (I only paid $500 for mine, by the way). I've read Some people use an alternate equalizer going by the name of Golden Flute, but I haven't been able to find much out about them. Either one seems tough to get ahold of.
Edit: Cleaned up quoted contents with DreadPirate's approval.
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