Question regarding Carvin power amp in bridge mode.

R

RGx

Member
My set up is an Ultra through a Carvin DCM200L. I hook up from the Axe Left Out --> Left Input Carvin. Then the 8 ohm from mesa to the 1st speaker in Carvin. The dilemma I'm having is that I hit the bridge button the other day and my rig sounded twice as loud and this was awesome. But when I turned the rig on today with the bridge button on, the sound went back to low and the bridge button seems to now have no effect. The speakers aren't blown. Anyone have any advice on what I'm maybe doing wrong? I really need a little more volume from the poweramp like I had that day when it was bridged. I appreciate it.
 
Did you remember to push both the impedance select switch AND the bridge switch and also use the two inner (red) speaker connectors?
 
t0aj15 said:
Did you remember to push both the impedance select switch AND the bridge switch and also use the two inner (red) speaker connectors?
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Yes, make sure you are using the right speaker posts.

I believe the carvin has 1/4" output connectors as well, so if you are using those, I think the output 1 channel is what you need to use.
 
I'm pretty sure bridging only works with the middle banana plug posts and channel 1 is the only control, channel 2 has no effect
 
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The bridge function effectively doubles the power by using both sides of a stereo amplifier (or two mono amps, which is a little more involved) to drive a single speaker load. That's why it would get louder. You do need to consider speaker load as the ohm floor (lowest load you can safely drive) goes up when you bridge power. You can toast a bridged amp with too low a load the same as an unbridged amp.

Really, if the connector was left in the channel one connection only when you hit the bridge switch I am not sure why it would get louder but I can say it isn't supposed to be connected like that. I don't know if this could cause the bridge function to go out. When bridged, you should only connect to one specific output... the center one, as noted in the above replies, and no other connections used. Power is dependent on impedance of speaker load and setting of the rear impedance switch. When bridged, I run the Carvins I have in my PA (2000s) exactly as they instruct: load matched, connected to the specified banana clip connection although I don't think mine has an impedance switch.

Lot of info, but no real answer there... maybe you can use the answers provided to troubleshoot. All Carvin power amp manuals are available at Carvin.com - Guitars, Amplifiers & Pro Audio
 
Thank you all for the quick reply's. I took a picture at practice last night of the set up. Does this model have the impedance select switch? If it's the "Min. Load Select", then I have tried that as well. In the picture I'm using all left connections, but I have also tried the right. What do I do with those inner red speaker connections? A normal instrument cable doesn't fit through there. I'm running through channel 1 as well.
HE9aF.jpg
 
Ouch, you should read the manual.
I havent a clue on why it was louder one day to next, but thats not a correct setup for bridged.
First never make connections or or change any switch settings with the power on.
I would unbridge that switch until you get the correct banana connection for the center posts.
when you do, the left red post is the positive terminal and the right red is the neg.
Really, read that manual and google poweramp banana plugs
 
I now realize how noob this looks with the bridge button pushed in. I wonder why it was louder for me initially though. The manual does say to use RED left as input 1 (first channel) positive. However I know nothing of banana plugs. What is necessary for me to use in order to bridge? Maybe a link to a cable I need to buy or how I achieve this? I appreciate the responds and sorry once again for my noobish questions.
 
Monster Cable Performer 500 Speaker Cable 1/4" with Banana Connectors 10 Foot | Musician's Friend is a version with individual post connectors (each half of the wire on it's own pin). Sometimes bridging connectors are spaced slightly different from regular connections.

If it is spaced like a standard banana connector (so called because it is shaped kind of like a banana) then this is a cheaper item: Musician's Gear Banana-1/4" Speaker Cable 14 Gauge 10' 2-Pack | Musician's Friend

And yes, the minimum load switch is the impedance switch. It determines what minimum you can use.
 
What you need is a simple banana to 1/4" speaker cable such as this;

Planet Waves 1/4" Male to Banana Plug Male Speaker Cable 10 FT | Musician's Friend

One end is a pair of banana plugs +/- (usually red/black) the other end is a standard 1/4" plug.

The red banana (hot) lead goes to the left red out on the amp and the black banana (ground) lead goes to the right red out on the amp, the 1/4" plug goes to the speaker cab. I realize this may be somewhat confusing, but believe me it's correct.

Also remember to depress both the BRIDGE and the MIN. LOAD SELECT buttons and also make all connections with the amp turned OFF.
 
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Keep in mind that with the cables you bought they don't appear to be marked +/- so you should test for polarity and mark the cable accordingly.
 
t0aj15 said:
Keep in mind that with the cables you bought they don't appear to be marked +/- so you should test for polarity and mark the cable accordingly.
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If you look at the second picture, one is marked red and one is blue, i'm assuming that means positive/negative? Also how do I test polarity?
 
RGx said:
If you look at the second picture, one is marked red and one is blue, i'm assuming that means positive/negative? Also how do I test polarity?
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I saw that, but looks like orange/blue to me. Either way it would be a mistake to assume anything. Easiest way to check polarity is with a multi-meter.

If you don't have one of those then a 9 volt battery will work, but you have to be able to see the speaker cone for this to work. Simply plug the 1/4" end of the cable into the speaker cab then while looking at the speaker cone touch the two terminals on the battery to the two banana plugs on the other end of the cable. If the polarity is correct the speaker cone will move forward when the battery is applied, if the cone moves backward instead reverse the battery and do it again. When you have the cone moving forward the banana plug attached to the hot or + terminal on the battery is the hot lead and should be plugged into the left(ch 1)red output on the amp with the other going into the right(ch 2) red output.
 
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On dual banana plugs there is a tab On one side. It says COM, for ground. The MF one has it.

You don't need a multimeter to check polarity either. Just unscrew the collar on the 1/4" side and look where the orange and blue wires are attached. Tip is positive, big lug is ground.
 
t0aj15 said:
I saw that, but looks like orange/blue to me. Either way it would be a mistake to assume anything. Easiest way to check polarity is with a multi-meter.

If you don't have one of those then a 9 volt battery will work, but you have to be able to see the speaker cone for this to work. Simply plug the 1/4" end of the cable into the speaker cab then while looking at the speaker cone touch the two terminals on the battery to the two banana plugs on the other end of the cable. If the polarity is correct the speaker cone will move forward when the battery is applied, if the cone moves backward instead reverse the battery and do it again. When you have the cone moving forward the banana plug attached to the hot or + terminal on the battery is the hot lead and should be plugged into the left(ch 1)red output on the amp with the other going into the right(ch 2) red output.
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This is correct, but in the OP's case.. seems there's a little more education required.
No-one in this thread has talked impedance matching and ratings matching.. Given what I have read here, there's a good chance the OP could take the provided feedback, run some BIG amp in bridged mode and blow his cab speakers right away. The DCM200L is not a large amp, but the same rules apply.
SO.. some basics..... (trying to keep it simple and non-technical).

Rule of thumb: An amp (to cater to transient signals and peaks in audio content) should produce 1.5 to 2.25 TIMES the rated (Program, continuous, RMS) power of the speaker cab at the specified load rating (Ohms) of the cab you plan to power.

NOTE: Program, Continuous and RMS ratings are "generally" the same value, but not always. A good way to check is that normal operating wattage is about 50% of PEAK power handling. If PEAK is 500w, then normal operating wattage is probably around 250w.

Example: If you have a 300 watt 8-ohm cab, you should use an amp that produces between (300*1.5) 450w and (300*2.25) 675w at 8-ohms. If you have a 300w 4-ohm cab, your amp needs to produce between (300*1.5) 450w and (300*2.25) 675w at 4-ohms.

Note that most amps are rated at 8 and 4-ohm loads (higher end [$$$] are rated for a 2-ohm load), and the 4-ohm output levels (in watts) is usually around TWICE that of the 8-ohm rating. When you bridge an amp - you are doubling it's output levels and also cutting the load rating in HALF.

Bridging Example: Suppose you have an amp (eg: QSC PLX3102) rated for 550w at 8-ohms per channel, 900w at 4-ohms per channel, and 1550w at 2-ohm per channel loads. Bridged, it can produce 1900w into 8-Ohms or 3100w into 4-Ohms. Again, note that most amps cannot run with a 2-ohm load in BRIDGED MODE !!!.

Say you have two 8-ohm cabs rated 1000w Program EACH. Connecting each amp channel to a speaker is not enough power - 550w into a 1000w speaker. IF you bridge the amp and daisy-chain (parallel connections) the speakers - have a single cable from back of amp to 1st speaker, then cable from 1st speaker out to 2nd speaker in - you will have a 4-ohm load (approx 8-ohm+8-ohm/4) and the amp will produce 3100w. Each speaker will see 1550w, which is within the rule of thumb margin for a 1000 speaker. The above example can be applied to any size speaker wattage and amp.

The problem occurs when you produce 3100w bridged into a 4-ohm speaker rated for 300w !! You will probably blow iton the first chord. MAKE SURE YOUR power and IMPEDANCE ratings match up !!

Things get sticky when talking measurements/ratings... different vendors measure output in different ways for both amps and speakers. In Carvin's case, they rate their amps output power (watts) as RMS values - approx. 55% of total output the amp can produce. For the DCM200L, it produces 100w RMS per channel at 8-ohms.. a PEAK of about 180w.
It's rated at 200w RMS bridged at 8-ohms. IT is NOT RATED for a 4-ohm bridged load, so I assume it does not support that.

In other words - in bridged mode, the DCM200L requires an 8-ohm load to produce about 360w PEAK (200w RMS). Connecting a 4-ohm cab will damage/blow the amp. Make sure you ONLY connect an 8-ohm cab.

PS: NEVER USE GUITAR CABLES BETWEEN an AMP and SPEAKER !!!
Their impedance is WRONG!.. Buy SPEAKER cables...
 
Reincaster & s0c9,

While both of your post's are correct my attempt to explain the solution to the OP's question was to get an obvious beginner to a successful solution to his problem rather than educating him in electronics, accept it as such and nothing more.

Also Reincaster many cables such as the ones I use (Planet Waves)have sealed ends so unscrewing them is not possible, so there is no way of knowing unless you know how to 'test' them. Thus my attempt at explaining a short concise method that will work in 'ALL' cases.
 
t0aj15 said:
Also Reincaster many cables such as the ones I use (Planet Waves)have sealed ends so unscrewing them is not possible, so there is no way of knowing unless you know how to 'test' them. Thus my attempt at explaining a short concise method that will work in 'ALL' cases.
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Cables like that have clearly marked which is hot and ground. Just like any other set of banana plugs. If you look at ANY dual banana connector there is a tab that designates the ground, if not, they are color coded like your planet waves cable. Any respectable cable manufacturer designates the ground wire in a banana connector. I have never seen a banana cable that didn't designate the ground wire, for that matter. Only needed to check if one was wired by someone other than the manufacturer, or non retail

Many cable are in fact, sealed cables, BUT not speaker cables. The PW is the first speaker cable I have seen that is sealed.

You're method is not wrong, but it's just easier to look at the banana connector and it tells you which is the ground.
 
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