how to bridge an amplifier?

[Corky]

I have an old whiteley pageman amplifier which i need to bridge to get the 100w output but i cant find the manual to do it only a single page which i have attached i think this is probably an easy thing to do but im unsure, ive spoke to the manufacturers and they dont have have the manual or the now how. any help would be much appreciated, regards

 

[Nigel Goodwin]

It says the instructions are in section 6.6 - do you have that?.

It also says bridging it 100/50V line ONLY - not low impedance.

What EXACTLY are you trying to do?.

 

[Corky]

no i dont have that, i have a chain of speakers which require 100w feed, it needs to be this amplifier as i already have it, it says i can bridge it to get this btu im unsure how

 

[Corky]

under tech specs it says i can

 

[KeepItSimpleStupid]

I get what's required for output bridging. That's the easy part because you have 4 independent transformers and series connections pose no problems, but parallel connections require the voltages to be the same.

So, something has to be done on the input side, so you have a single level control and a single input I would think.

Typical bridging for solid state amps requires one to invert one input and connect the speaker to both positives. Not with this amp.

It's 100V line to voice coil bridging.

This tube amp has a bridge switch: https://www.google.com/url?sa=t&rct...TsIZpLGhzRT9y3Q&bvm=bv.74115972,d.eXY&cad=rja

So, the real key is for parallel operation, the output voltages have to be nearly identical.

Tube amps like to be loaded a bit or they do nasty things.

The transformer connections are easy. The input connections bother me. You can see the advantage of a single level control and a single input.

A lot of the stuff I found by searching yields some not so good information.

benb here, **broken link removed** has the right idea, but the discussion is tube vs solid state. benb says the amp would be less bothered, "i.e. lower current, and he's probably right. The real question is bridging transformer coupled amps.

If you can endure the outputs levels are close, then bridging is easy. It;s just paralleling the outputs paying attention to phase. Fuses in each (2) of the 100 V outputs would offer some protection.

Using an AC voltmeter and a signal generator and connecting the outputs in series, you could adjust the input for the least output and then reconnect properly.

 

[Nigel Goodwin]

no i dont have that, i have a chain of speakers which require 100w feed, it needs to be this amplifier as i already have it, it says i can bridge it to get this btu im unsure how

Again, you're been rather vague - what kind of speakers? - in particular are they 100V line?, if so presumably they are simply wired in parallel.

 

[audioguru]

A "chain of speakers" connected to a paging amplifier that has output transformers also has a transformer on each speaker so it can produce maybe 1W at 100V, using cheap thin wire.
The dual amplifiers are spec'd at 50W each into 8 ohms or can be bridged to produce one 100W output into 8 ohms.
The 100V transformer outputs cannot be bridged, but can have two separate 100V outputs at 50W each.

Cut the 100W chain of 100V speakers in half and power each half with one of the 100V/50W outputs.

 

[KeepItSimpleStupid]

The 100V transformer outputs cannot be bridged, but can have two separate 100V outputs at 50W each.

AG: You didn't read the excerpt of his manual

100V or 50V line at 100W
using Zone 1 and Zone 2

The independent power amplifiers of Zone 1 and Zone 2 may be coupled together via their output transformers, to create a single 100 Watt output circuit. N.B.. 100V / 50V line only. Please refer to section 6.6. for further details

Care to try again?

 

[KeepItSimpleStupid]

Paralleling the 100 V channels of both amps is easy. What has to be done to ensure the inputs are the same, I dunno.

It could be done the hard way, but one would have to keep everybody's fingers away from the gain controls. The gains could be set equal easy enough with an AC voltmeter and signal source by looking at the subtracted output with a load.

 

[Nigel Goodwin]

There are a large number of header connections, labelled 'HD' - presumably one or more will require configuring for bridging the amps - so I suspect you need either:

1) Section 6.6 as already mentioned.

2) A shematic diagram.

3) Someone who has done it on the identical amp.

However, why not contact technical support?, via LiveChat if you like:

https://www.canford.co.uk/Products/...PLIFIER-2x-50W-8-100v-70W-4-2-zone-wall-mount