Tannoy 10" Monitor Gold + Quad 303 - Overpowered?

[willbart]

Fit of recklessness - I just spent more than I can really afford on a pair of the Tannoy LSU/HF/III.LS/8's - 10" Monitor Gold.
These are pretty sensitive (around 90.5dB I think, depending on xover setting) & my Quad 303 runs fairly hot into my old KEF's which are 87dB; should I do something about the output? 
I know the Quad is supposed to enjoy a high-z; is there a way to make it "see" around 15 Ohms?

The amp runs well and has been serviced & recapped but the power supply has been upgraded:
Huge reservoir caps and it takes a long time to shut down; it's connected to studio kit potential for pops/feedback loops - I'm normally v careful with it but accidents can happen!

Should the speakers be protected?  Or would a new amp be sensible?

Thanks

 

[ruffrecords]

I used to have a pair of those. They are 8 ohm impedance and work fine from a low source impedance power amp, including the 303. Just turn down the volume a bit.

Cheers

Ian

 

[willbart]

Thanks Ian
I'm thinking about a passive pad on the amp - maybe a switched potential divider, just a few resistors in series between the + & ground on the input, with maybe a DP 6-pos switch.  Do you know what a good overall resistance would be, without affecting the amp's input impedance much?

I sometimes do multi-channel work & run through RME AD/DA's - that kit has high headroom & not subtle when losing sync or with power loss; what was at a nice low level instantly goes to about +13dB through all channels!  A permanent passive safety net before the power amp would be nice.

Thanks

 

[radardoug]

One thing with the Quad amps is there is no speaker protection against a d.c. fault. On Ebay you can buy a kit with speaker protect relays, cheap as chips. Uses a specific i.c. made for speaker protection. It will also trip on big transients. Good insurance against having to do an expensive recone.
See here
https://www.ebay.com/itm/UPC1237-Speaker-Protection-Board-AC12V-24V-OMRON-Relay-Stereo-2-channels-for-AMP/322719012657?hash=item4b238d5731:g:5xkAAOSwdg5a1Hox

 

[gridcurrent]

Quad 303 outputs are AC coupled.

 

[radardoug]

Ah, maybe I'm thinking of the 405.

 

[ruffrecords]

Thanks Ian
I'm thinking about a passive pad on the amp - maybe a switched potential divider, just a few resistors in series between the + & ground on the input, with maybe a DP 6-pos switch.  Do you know what a good overall resistance would be, without affecting the amp's input impedance much?
Thanks

A regular 10K should be OK I think.

Cheers

Ian

 

[willbart]

Ah, maybe I'm thinking of the 405.

Thanks Radardoug, Gridcurrent, Ian

I'm not sure about terminology; is the coupling the output capacitor? C1? I think they were replaced with 11000uF's along with the reservoir caps, would they make the relay unnecessary?
Or can you set a threshold at which it kicks in?

I'm still worried about basic high volume - the speakers are only 20W (I think) & with the amp at about 45 a pad on the input will still be a good idea: there's still  potential for accidental line level.  I wanna be v careful with these things

And if I just use -24dB all the time, the pops will never make a dent