Start of quest under anthonys drake makes noise (4)

[BP28]

http://cgi.ebay.com.au/BBC-Rogers-LS3-7-Speakers-Quad-303A2-amplifiers-/220676545750?pt=UK_AudioVideoElectronics_HomeAudioHiFi_HiFiSpeakers&hash=item336158dcd6

 

just looking at this on ebay and wondering if I could do something similar by purchasing a second 303. Anyone gone down this path before?

 

BP.

[Owen Y]

Those are mono amps. I understand that it's not easy to convert a stereo amp to mono. (Anyone care to enlighten?)

 

Theoretically not a lot to be gained in using a pr of stereo amps, (with only one ch per amp connected to a spkr each), but having tried this many yrs ago, some benefits can accrue as the PSU in ea stereo amp is only having to deal with the demands of one ch.... ie. stronger bass.

 

Cool 303s those, with carry handles & Cannon connectors,

[BP28]

Are you sure they are mono? I did a quick search on 303A2 earlier and they material I was reading discussed an electronic crossover on the input, with one side of each amp driving bass, and the other the tops. Thats why I was thinking what about two 303s with a crossover. I was interested in your idea of just using side of each 303, allbeit an innefficient use of resources with one side unused. This is possibly a dumb question, but could you use both sides and sum the outputs, or does that do somehting strange with phasing, or ohmage or someting...? (So left signal into both sids of a 303, then combined, right signal into the other 303).

 

I liked the look of them too, thought the whole rig would be a good home recording/computer monitoring setup.

[Jon1553552729]

I have a pair of Quad 405 II vertical biamped on my KLS3 loudspeakers. They are also bi-wired so one channel feeds mid/top and the other channel feeds bass.

 

Provided you make up the cable correctly (from your pre-amp) you should be able to have all channels working properly on each amp. In effect it is a cheap method of creating a mono-block.

[BP28]

That sounds cool Jon - but I'm a little confused if you mean bi wired or bi amp. Is the left side input feeding one 405 and the right the other, with all four channels getting a full range signal. And, one half of a 405 sending to the bass input of one speaker and the other half to the treble (and similalry for the other 405 and other speaker)?

 

If so I can't do the same thing as my speakers are not bi wireable (smgas; B&W DM4). I suppose I could look for alternate speakers (I'm not keen on modifying vintage gear).

[Ross F]

The 303 is definitely stereo. I think its predecessor, the 202 was only mono - these were the pre-stereo days after all. Interesting application of a vintage power amp. Are there any impedance issues? Is there a crossover just before the power amps. Pardon my ignorance

[Jon1553552729]

I am vertically amped (so 1 loudspeaker, 1 amplifier) and bi-wired so I have 4 inputs on the KLS3 loudspeaker - one pair for mid/top and the other pair for bass and 4 outputs on the amps (essentially both channels) .

 

So I have the left channel from my pre-amp feeding both channels on the left-hand 405 (I have not converted from the original din plug so the wiring is easy). The same for the right hand side.

 

Hope that makes sense!

[Owen Y]

 

BP28;134546 wrote:

Are you sure they are mono?

Not sure, but it appears that some of those BBC configured 303s were mono, with (filters also).

 

Your scheme sounds good, if you plan line level xover filter/s in front.

 

I believe that it is def not recommended to drive both ch's of a stereo amp from one preamp ch (without a xover/filter).

[BP28]

thanks all for the comments, I think I might try to get another 303, and then take from there, even if it takes a while to figure out the final arrangement. The worst thing that will happen is I'll own another grat peice of classic gear.

 

Cheers,

 

BP