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Radford STA15 epiphany - now what about Tannoys?

Marchbanks

Marchbanks

Hat and Beard member
I recently had my STA15/SC22 serviced after two decades of non-use. Yesterday, having had it back home for a few weeks, I thought I really should try it out. A pair of BC1s given to me by an ex-BBC colleague a few years ago and virtually unused since seemed the ideal partners so I plugged a Raspberry Pi into the back of the SC22, put a wooden chair at the opposite end of the junk room and sat down with iPeng open on my lap.

Three hours later I was still there, having now decided I wanted the Radford to be my main amplifier. I really hadn’t imagined it, or the BC1s, would sound so good. But I was sitting in a sparsely furnished 5m x 3m room, whereas my living room is twice that size and full of absorbent chairs, curtains and carpets. Will the Radford run out of puff? I’ll try to find out later in the week, but (trying to fix problems even before they arise!) if the answer is yes would the Radford go well with Monitor Gold era Tannoys? I read that they are even more sensitive than the BC1s if I need to squeeze out every available dB. I remember a friend having Tannoy corner speakers with Monitor Reds and Quad IIs, and they never seemed short of volume. I can’t remember how big they were though - are the larger ones less, more or as sensitive as the smaller ones?

At least if I do go down the Tannoy route I’ll have a stack of kit to sell in order to finance it!
 
What a nice surprise/experience :). The Radford should work supremely well with your proposed Tannoys.
 
A good ten Watt tube amp like my Leak Stereo 20 will go louder than anyone sane could ever want into Monitor Golds and it sounds so, so right. The Radford will be superb into Tannoys. The perfect tool for the job.
 
YNWOAN said:
The Radford should work supremely well with your proposed Tannoys.
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Tony L said:
A good ten Watt tube amp like my Leak Stereo 20 will go louder than anyone sane could ever want into Monitor Golds and it sounds so, so right. The Radford will be superb into Tannoys. The perfect tool for the job.
Click to expand...

Are the larger diameter drivers pretty much as sensitive as the smaller ones? That would leave size of wallet and size of cabinet as the main considerations!
 
Their free-air sensitivities actually go up from 91.5dB for 10", through 93.5dB for 12", to 95dB for 15" (all wrt 2.83V @ 1m)
 
If i still had my Radford 15 i wouldnt be using the sc22 Im sure it held it back.

I ran mine into Els57 and Nightingales NM1

fabulous
 
All things being equal a bigger driver will always be more sensitive than a smaller one - however, it’s all relative.
 
Marchbanks said:
Are the larger diameter drivers pretty much as sensitive as the smaller ones? That would leave size of wallet and size of cabinet as the main considerations!
Click to expand...

Not much in it, but the larger ones are a bit more efficient. Cabinet size is very significant too, Tannoy drivers like very roomy accommodation. All are easy to drive, the bigger ones have bass.

Over the years I have owned 15” Monitor Golds I’ve tried quite a few amps (my own and those belonging to others), both valve and solid state, and my preference would be for a really nice push-pull tube amp. I rate my very carefully restored (not tweaked/botched) Stereo 20 as the best I’ve heard through them, even though it actually lives upstairs driving the JR149s. I haven’t personally liked SETs into Golds, but the largest I tried were 300Bs. On paper not much difference to the litle 10 Watt Leak, but in practice the Stereo 20 had way more grip and not a hint of compression. The EL34 Radford will be superb. I used a Prima Luna Prologue 2 for a good while running EL34s and it was seriously good, though ultimately I prefer the Stereo 20, I suspect despite less power it has better output transformers.

The one thing I’ve never tried is a real solid state powerhouse, I’d love to hear the Tannoys (and the 149s) on the end of an old-school Krell or similar monster class A job just to see what it did, but to my ears 10-30 really good valve Watts is all you’ll need unless you are a heavy metal fan with about 1/3rd hearing left.
 
Thanks for the information and advice. I might try running the STA15 with my B4 pre - but I have to say the SC22 has impressed me well enough so far. And it was good to be able to turn the treble control down half a notch on overly bright recordings.
 
I moved the Radford and BC1s into the living room for some serious listening today. I noticed a few intriguing things:

A little bit of the ‘immediacy’ had disappeared - presumably, as I mentioned before, the effect of a more acoustically dead room.

A tiny bit of buzz was coming through the speakers, caused by the SC22. I’m sure I didn’t hear this upstairs, which was odd.

Disposing with the pre altogether and plugging the DAC straight into the STA15 gave a substantially lower level. The Squeezebox was at around 85% level to give a comparable volume to 50% with the SC22 set at mid-volume. Again there seemed to be a little less excitement - maybe that’s another way of saying ‘distortion’?

So at the moment I’m not sure a passive pre is going to be sufficient, which is a shame. On the other hand (buzz apart) I still have no real problems with the SC22.
 
The only problem is with my ears! With no preamp at all the source was on occasions flat out to give me the sort of volume I sometimes like. But maybe you were in a smaller room, or one not so full of sound-absorbing furniture, or with more sensitive speakers. And I’m almost certainly older and therefore deafer than you!

(Blimey, these BC1s are something else as well. Retro rules!)
 
To answer your first post - I have a Radford STA15 and Tannoy GRF Rectangular 15" (early HPDs not Golds) - I also replaced the SC22 as I felt it muffled the sound with a Music First Passive Pre and although my room is not as big as yours I am sure the Radford will not run out of 'puff'.
 
Thanks Jon, that fits in with my observations so far. I’m currently using a Bottlehead valve pre in pretty much zero gain mode and the BC1s are certainly loud enough. I imagine HPDs would be a couple of notches lower on the volume control and MGs possibly one more.
 
I think it’s about time I tried to listen to a 15” Tannoy/STA15 system to settle any doubts in my mind as to whether it will work for me or not. Is there anyone within a 90 minute or so drive of Birmingham with the Tannoys who would be prepared to let me bring my Radford over?
 
In very near future I'll have some very good condition 15" hpd Tannoy Amesburys for sale once I've finished the restoration...
 
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