• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Pros an cons regarding bridging amplifiers

Snarfie

Active Member
Joined
Apr 30, 2018
Messages
273
Likes
123
Location
Netherlands
#1
I'm planning to buy another NAD C370 an want to bridge both of them. Now i read that bridging an amplifier means that you demping facor wil be 50% less. So 8 ohm will be 4ohm. What are the implications bridging amplifiers?. For instance could it mean that besides getting on the plus side a double amount of power but on the minus side my Low frequencies will be compromised and both amplifiers will get quite hot that is not what i aming at. Some confusion here. I was aiming at a more controlled low an more space/imaging between voices and instruments. Is it mabey better to buy an amplifier with double amount of elco capacity than the NAD C370 (which has 40.000 microfarad of capacity) but with a correct demping factor than a second NAD in bridging mode?. Will i hear between the 2 of them any difference?.
 
Last edited:

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,809
Likes
4,641
Location
The Neverlands
#2
Plus sides:
Better stereo separation (inconsequential in practice)
Double the output voltage = 4x the output power (but under conditions)

Down sides:
The Damping factor doubles but when still low it is inconsequential
When the amp is specified to 8 Ohm and not below it you may cause damage to the amp when running max power or the current limiter may kick in using 8 Ohm loads.
When the amp can drive 4 Ohm you can use it bridged with an 8 Ohm speaker.
So the impedance needs to be double that of the lowest allowed impedance.

I was aiming at a more controlled low an more space/imaging between voices and instruments.
Bridging an amplifier won't change that.
Depending on the used speaker a more powerfull amp may be a better idea.
Instead I would invest in room conditioning or roomEQ that will bring more controlled lows and batter imaging in general.
 
Last edited:

Snarfie

Active Member
Joined
Apr 30, 2018
Messages
273
Likes
123
Location
Netherlands
#3
Plus sides:
Better stereo separation (inconsequential in practice)
Double the output voltage = 4x the output power (but under conditions)

Down sides:
The Damping factor doubles but when still low it is inconsequential
When the amp is specified to 8 Ohm and not below you may cause damage to the amp when running max power or the current limiter may kick in.
When the amp can drive 4 Ohm you can use it bridged with an 8 Ohm speaker.
So the impedance needs to be double that of the lowest allowed impedance.



Bridging an amplifier won't change that.
Depending on the used speaker a more powerfull amp may be a better idea.
Instead I would invest in room conditioning or roomEQ that will bring more controlled lows and batter imaging in general.
Thanx. I already use roomcorrection software with great results (for sure better low's and imaging) was aiming to get it if possible even better with this bridging idea.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,809
Likes
4,641
Location
The Neverlands
#4
It will only bring the possibility to play louder (when the amps are capable)
Increased stereo separation is a non issue with speakers.
 

sergeauckland

Addicted to Fun and Learning
Patreon Donor
Joined
Mar 16, 2016
Messages
971
Likes
1,789
Location
Suffolk UK
#5
Completely agree with Solderdude above. The only benefit of bridging is if you're close to (or are) clipping the amplifier when playing 'enthusiastically'.

As mentioned above, the minimum permissible load impedance is doubled, so you need to know what the impedance characteristic of your loudspeakers is., and whether the impedance minima exceed that permitted, and at a frequency where it matters. For example, a minimum at 14kHz is less likely to upset an amplifier as there's not a lot of energy at that frequency, whilst a minimum at 80Hz could well upset the amp.

Depending on your attitude to DIY, a better solution might be to remove the passive crossover and use an active crossover with the extra power amp.

S.
 

Snarfie

Active Member
Joined
Apr 30, 2018
Messages
273
Likes
123
Location
Netherlands
#6
Completely agree with Solderdude above. The only benefit of bridging is if you're close to (or are) clipping the amplifier when playing 'enthusiastically'.

As mentioned above, the minimum permissible load impedance is doubled, so you need to know what the impedance characteristic of your loudspeakers is., and whether the impedance minima exceed that permitted, and at a frequency where it matters. For example, a minimum at 14kHz is less likely to upset an amplifier as there's not a lot of energy at that frequency, whilst a minimum at 80Hz could well upset the amp.

Depending on your attitude to DIY, a better solution might be to remove the passive crossover and use an active crossover with the extra power amp.

S.
These are the speaker specs.



Specificaties JK acoustics Optima 3 MKI

Frequency 37 Hz - 22 kHz, 2 dB (in normale room at 1 m distance)

System 'open' loudspeaker with woofer symetrical loaded/placed

Acoustice material Dempingsmaterial high pressurd MDF persing an bitumen, special reinforced corner construction

Loadsprekers 3, - 17 cm woofer, the woofer is build in the housing for better sublow
- 13 cm mid, Neoflexconus 8ohm
- 25 mm Dome tweeter, ferro fluid 8 ohm


filter optimised for correct fase- en amplitude behaviour, with HP 65, corssover frequency 100 Hz an 3.300 Hz

Efficiency 84 dB, SPL at 1 meter an 1 Watt in to 8 Ohm

Distorsion < 1,0 %

Amplifier power 35 Watt tot 120 Watt,

Impedance minimal 8 Ohm

Dimensions (h x b x d) 97,5 x 26 x 30 cm

Weight 25 kg


The link: http://www.jkacoustics.nl/portal/in...le&id=117:optima3-mk1&catid=55:mki&Itemid=121
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,809
Likes
4,641
Location
The Neverlands
#7
The amp is spec'd 8 Ohm so bridging an 8 Ohm nominal speaker is not the best way.
Your amp is already at the limit of the power rating of the speaker.
I reckon you could look for an amp specified to deliver 400W in 8 Ohm.

There is no guarantee it will sound any different.
Bridging the NAD is not a good idea and also won't deliver what you seek.
 
Last edited:

Snarfie

Active Member
Joined
Apr 30, 2018
Messages
273
Likes
123
Location
Netherlands
#8
The amp is spec'd 8 Ohm so bridging an 8 Ohm nominal speaker is not the best way.
Your amp is already at the limit of the power rating of the speaker.
I reckon you could look for an amp specified to deliver 400W in 8 Ohm.
Thanx for your input. Any amp you want to suggest.
 

pjug

Active Member
Patreon Donor
Joined
Feb 2, 2019
Messages
145
Likes
89
#9
The amp is spec'd 8 Ohm so bridging an 8 Ohm nominal speaker is not the best way.
Your amp is already at the limit of the power rating of the speaker.
I reckon you could look for an amp specified to deliver 400W in 8 Ohm.

There is no guarantee it will sound any different.
Bridging the NAD is not a good idea and also won't deliver what you seek.
I don't understand what you are saying regarding the 8 ohms. The C370 can drive 2 ohms, and is designed to be bridged. Now, whether it is a good idea to bridge or not I don't know. Stereophile measured the c370's damping factor at 50 so bridged it will be a little low.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,809
Likes
4,641
Location
The Neverlands
#10
You are correct...

the manual indeed states:
In Bridged Mode the NAD C370 will produce approximately 300W into an 8 ohm loudspeaker.
So 8 Ohm is the lowest you can use it bridged.
Burst power will be higher though and could possibly reach 500W or so.

It will not give the desired effect the OP is looking for.
It will just play about 4 louder and when one is of the opinion that a DF of 25-75 makes the bass sound less desirable as well.
 

DonH56

Technical Expert
Technical Expert
Patreon Donor
Joined
Mar 15, 2016
Messages
3,182
Likes
3,910
Location
Monument, CO
#11
The Damping factor doubles but when still low it is inconsequential
Output impedance doubles, damping factor halves (typo? I know you know...) Agree with the rest.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,809
Likes
4,641
Location
The Neverlands
#12
Thanx for your input. Any amp you want to suggest.
I would look into the newer class-D amps. Have no recommendations though.
I also suspect the desired changes may not be of the magnitude you are looking for.
Perhaps go to a dealer and loan a good amp (some dealers do that) and listen if it is what you are looking for.
 

solderdude

Major Contributor
Joined
Jul 21, 2018
Messages
2,809
Likes
4,641
Location
The Neverlands
#13
Output impedance doubles, damping factor halves (typo? I know you know...) Agree with the rest.
yep, I meant output resistance doubles = DF halves ... :rolleyes:
 

SIY

Technical Expert
Technical Expert
Joined
Apr 6, 2018
Messages
3,008
Likes
5,363
Location
Phoenix, AZ
#14
What an amplifier that isn't broken does: makes a small signal larger.

What speakers and rooms do: convert that electrical signal into and acoustic one and deliver it to your ears.

Work on the former will not help you achieve your goal. Work on the latter will. Oh, and better recordings, of course!
 

sergeauckland

Addicted to Fun and Learning
Patreon Donor
Joined
Mar 16, 2016
Messages
971
Likes
1,789
Location
Suffolk UK
#15
Thanx for your input. Any amp you want to suggest.
Given the loudspeaker and your existing amplifier specs, I don't see what an amplifier change or bridging will give you. Unless you play so loud already that you're clipping the amp, (Ye Gods!) then bridging won't bring you any benefits, nor really getting a more powerful amplifier.

S
 

Snarfie

Active Member
Joined
Apr 30, 2018
Messages
273
Likes
123
Location
Netherlands
#16
Given the loudspeaker and your existing amplifier specs, I don't see what an amplifier change or bridging will give you. Unless you play so loud already that you're clipping the amp, (Ye Gods!) then bridging won't bring you any benefits, nor really getting a more powerful amplifier.

S
The sound is already excelent have to learn probably to be content. Did read that 2 C370 ( not bridged) used to amplify bi-wierd speakers will generate a better image an thigter bass. But my speakers arn't bi- wierd. Also lot of people know for sure that replacing the main inn out solid metal jumpers with proper cables will creat a considerble difference did that but didn't hear any of a real noticeble difference. Biggest difference by far is using room correction.
 
Last edited:

sergeauckland

Addicted to Fun and Learning
Patreon Donor
Joined
Mar 16, 2016
Messages
971
Likes
1,789
Location
Suffolk UK
#17
The sound is already excelent have to learn probably to be content. Did read that 2 C370 ( not bridged) used to amplify bi-wierd speakers will generate a better image an thigter bass. But my speakers arn't bi- wierd. Also lot of people know for sure that replacing the main inn out solid metal jumpers with proper cables will creat a considerble difference did that but didn't hear any of a real noticeble difference. Biggest difference by far is using room correction.
Indeed. Room correction at LF, if you need it, can make a huge difference. ANYTHING to do with cables/ jumpers/ connectors will make zero difference to sound quality unless your amplifier is fundamentally unstable.

S
 

restorer-john

Major Contributor
Joined
Mar 1, 2018
Messages
2,581
Likes
4,296
Location
Gold Coast, Queensland, Australia
#18
A big consideration is residual noise when you bridge. It basically doubles. With big power amplifiers and sensitive speakers, it becomes an issue.
 

Wusbag

New Member
Joined
Jul 17, 2019
Messages
2
Likes
0
#19
If you can bi amp your speakers then use an amp running in stereo for each speaker. One channel for the highs & the other for the lows.
Increased power and you don't need to bridge.
 

Snarfie

Active Member
Joined
Apr 30, 2018
Messages
273
Likes
123
Location
Netherlands
#20
Indeed. Room correction at LF, if you need it, can make a huge difference. ANYTHING to do with cables/ jumpers/ connectors will make zero difference to sound quality unless your amplifier is fundamentally unstable.

S
Got this tip already but unfortunly i don't have bi- amping speakers. Correction i was advised to use 1 amplifier to be used only for both speaker woofers an the other only for both speakrs mids en tweeters. So not 1 amplifier for 1 speaker.
 
Last edited:
Top Bottom