I have a valve amp and I am clueless
 

On 2008-09-29 23:35:18 +0100, Andy Evans said:

The Avantic is a superb toy - a lovely retro machine.

For all that, if I wanted the best sound possible I'd buy some big
full range ribbon speakers - the bigger the better. I happen to know
of a pair of Apogee Caliper Sigs coming up for sale on ebay and you
might just get them before they're listed by phoning Rupert on
07920054344 in the next couple of days.

You'd need at least 15 watts to drive them properly - push pull 300b
should do it.

You could use the Avantics for the treble and bi-amp, but I'd be
tempted to sell them for a good price and get a push pull 300b amp
instead. All that assumes a preference for good sound over tasty retro
amps - a big gimme.

Andy

Andy
Thanks for the tip on the speakers. I know that if I want the best
sound possible I'll need to spend a lot more money than I currently
want to. Also sadly those speakers just wouldn't fit well into my
little pad and I'd rarely get the chance to play them at a suitable
volume anyway. So...I'm very happy for now with the lovely Avantic
(dunno if it's retro, it's younger than me) and would hate to see it up
on ebay just yet. Thanks anyway...

Dave

I have a valve amp and I am clueless
 

In that case, if there is a tap on the OPT to give a load match to 3
ohms, the Rout without NFB will be 1 ohm, and loads below 4ohms nominal
will be tolerated OK.

The impedence of the speakers is around 3 ohms. So as you say you
figure for a low ohm tap on the secondary. I'm getting good sound with
a PPP 6S4A amp with a nominal 8k a-a into 4 ohms, which works out just
about OK. Sounds fine. My brother uses a Nagra VPA 845 PP valve amp,
which sounds great. A friend uses a KT88 amp with feedback. That works
too. All of us have Caliper Sigs, though my friend just upgraded to
Duettas. Drool.


25Watts class AB1 is easy from 300B and if speaker sensitivity is above
88dB/W/M, sound is OK but the higher the sensitivity the better.

Apogees are what, about 85db - something like that.

What's so great about ribbons though?

Have you heard the big Apogees? They're now built down under.
http://www.apogeeacoustics.com/index.html

Are you anywhere near Queensland's "sunshine coast"?

Andy

I have a valve amp and I am clueless
 

In article
,
Andy
Evans wrote:

In that case, if there is a tap on the OPT to give a load match to 3
ohms, the Rout without NFB will be 1 ohm, and loads below 4ohms
nominal will be tolerated OK.

The impedence of the speakers is around 3 ohms. So as you say you figure
for a low ohm tap on the secondary. I'm getting good sound with a PPP
6S4A amp with a nominal 8k a-a into 4 ohms, which works out just about
OK. Sounds fine. My brother uses a Nagra VPA 845 PP valve amp, which
sounds great. A friend uses a KT88 amp with feedback. That works too.
All of us have Caliper Sigs, though my friend just upgraded to Duettas.
Drool.


25Watts class AB1 is easy from 300B and if speaker sensitivity is
above 88dB/W/M, sound is OK but the higher the sensitivity the better.

Apogees are what, about 85db - something like that.

I suspect that may be rather 'optimistic'. :-) If you look at something
like MCs review of the Apogee Caliper in HFN (1986) he reported a 2.86V
sensitivity of just 80dB. Very different to needing 88dB or more! If my
memory isn't playing me false, some other Apogees had even lower
efficiencies and/or impedances.

If you then factor in what Patrick went over (although that wasn't the
actual point of my previous comment which actually took what he
described for granted) you may find an even lower effective sensitivity
for reasons I assume are now obvious! :-)

Slainte,

Jim

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I have a valve amp and I am clueless
 

Andy Evans wrote:

In that case, if there is a tap on the OPT to give a load match to 3
ohms, the Rout without NFB will be 1 ohm, and loads below 4ohms nominal
will be tolerated OK.

The impedence of the speakers is around 3 ohms. So as you say you
figure for a low ohm tap on the secondary. I'm getting good sound with
a PPP 6S4A amp with a nominal 8k a-a into 4 ohms, which works out just
about OK. Sounds fine. My brother uses a Nagra VPA 845 PP valve amp,
which sounds great. A friend uses a KT88 amp with feedback. That works
too. All of us have Caliper Sigs, though my friend just upgraded to
Duettas. Drool.


25Watts class AB1 is easy from 300B and if speaker sensitivity is above
88dB/W/M, sound is OK but the higher the sensitivity the better.

Apogees are what, about 85db - something like that.


With 85dB its getting a bit hard to drive and I'd like to have 50W
available....

What's so great about ribbons though?

Have you heard the big Apogees? They're now built down under.
http://www.apogeeacoustics.com/index.html

I wasn't aware of that.

There is another ribbon company, Ambience on the sth coast NSW.

Are you anywhere near Queensland's "sunshine coast"?

No, I'm in Canberra, 300km sthwest of Sydney.

I prefer really well done dynamic cones and domes.

Patrick Turner.

Andy