Mono Bridging Carver Amp Into 4 ohm Load - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th January 2007, 12:25 PM   #1
Plundering the Planet From the Comfort of Home
diyAudio Member
 
DreadPirate's Avatar
 
Join Date: Jan 2006
Location: Northern Virginia, USA
Default Mono Bridging Carver Amp Into 4 ohm Load

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.
  Reply With Quote
Old 20th January 2007, 12:58 PM   #2
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
Your amp is not capable of running bridged in 4 Ohms, as each output only see half the load = 2 Ohms
Worst case; All output devices get fried
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 20th January 2007, 01:08 PM   #3
diyAudio Member
 
Join Date: Nov 2002
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.
  Reply With Quote
Old 20th January 2007, 01:25 PM   #4
infinia is offline infinia  United States
diyAudio Member
 
infinia's Avatar
 
Join Date: May 2005
Location: Californication
Default Re: Mono Bridging Carver Amp Into 4 ohm Load

Quote:
Originally posted by DreadPirate
What's the worst that can happen? Blow a fuse?
All your outputs could short and depending on how good/fast the amp protection is, a real good possibility to smoke your speaker as well.
__________________
like four million tons of hydrogen exploding on the sun
like the whisper of the termites building castles in the dust
  Reply With Quote
Old 20th January 2007, 11:02 PM   #5
Plundering the Planet From the Comfort of Home
diyAudio Member
 
DreadPirate's Avatar
 
Join Date: Jan 2006
Location: Northern Virginia, USA
Boy, you solid state guys like to beat around the bush! How about just coming out and saying I might have problems?

This cunning plan to use the Carver's at 4 ohms has been abandoned, an ADCOM GFA-555 is on order to fulfill the requirements in its stead.
  Reply With Quote
Old 21st January 2007, 02:19 AM   #6
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
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
  Reply With Quote
Old 21st January 2007, 09:05 AM   #7
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
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.
__________________
regards Andrew T.
  Reply With Quote
Old 21st January 2007, 11:12 PM   #8
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
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
  Reply With Quote
Old 22nd January 2007, 12:48 AM   #9
Plundering the Planet From the Comfort of Home
diyAudio Member
 
DreadPirate's Avatar
 
Join Date: Jan 2006
Location: Northern Virginia, USA
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.
  Reply With Quote
Old 22nd January 2007, 01:44 AM   #10
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
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
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SI T-amp - Bridging for mono block use? midside Chip Amps 3 5th October 2006 02:53 AM
Bridging Charlize amp to mono? bbaker6212 Class D 2 17th March 2006 12:02 AM
Bridging Mono Blocks jwatts Tubes / Valves 8 12th February 2005 07:23 PM
Bridging 2 mono blocks of lm3886 rs1026 Chip Amps 7 3rd November 2004 12:23 PM
amp bridging eating fuses, but load seems ok da_madaxeman Chip Amps 3 28th April 2004 11:03 AM


New To Site? Need Help?

All times are GMT. The time now is 06:34 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2