Fane 12-250TC Retro Speaker.

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Scottmoose
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Re: Fane 12-250TC Retro Speaker.

Post by Scottmoose » Thu May 17, 2018 10:17 am

Speaking purely in the abstract, Fane state Qts = 0.64 on the data sheet assuming a voltage source amplifier & no series R in the circuit. Using the Qe & Qm values it looks like it comes out a touch higher, around 0.658

80 litres undamped = system Q (Qtc) of roughly 0.91 (with light damping that drops to the high 0.8 regions, but inapplicable here).

Since the output Z of the amplifier artificially raises driver Q, in 80 litres you'd get the following:

1ohm, Qtc = 1.0
2ohm, Qtc = 1.13
2.5ohm, Qtc = 1.2
3ohm, Qtc = 1.235
4ohm, Qtc = 1.34

I'm not up on valve amps, but as far as I'm aware most of the classic US SET amps had output impedances in the rough 2.5ohm - 4ohm region & which for the sake of interest the engineers at Fostex assumed would be the case for their FExx6E, FExx6En, FExx8ESigma & FFxx5K series drivers.

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Re: Fane 12-250TC Retro Speaker.

Post by IslandPink » Thu May 17, 2018 10:26 am

Good info - 2.5R is most typical, eg. something like a 300B into a 3k>8R transformer. The anode resistance would be 750R which becomes 2R on the output, + add a bit for DCR of the secondary.
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Re: Fane 12-250TC Retro Speaker.

Post by Cressy Snr » Thu May 17, 2018 10:35 am

Scottmoose wrote:
Thu May 17, 2018 10:17 am
Speaking purely in the abstract, Fane state Qts = 0.64 on the data sheet assuming a voltage source amplifier & no series R in the circuit. Using the Qe & Qm values it looks like it comes out a touch higher, around 0.658

80 litres undamped = system Q (Qtc) of roughly 0.91 (with light damping that drops to the high 0.8 regions, but inapplicable here).

Since the output Z of the amplifier artificially raises driver Q, in 80 litres you'd get the following:

1ohm, Qtc = 1.0
2ohm, Qtc = 1.13
2.5ohm, Qtc = 1.2
3ohm, Qtc = 1.235
4ohm, Qtc = 1.34

I'm not up on valve amps, but as far as I'm aware most of the classic US SET amps had output impedances in the rough 2.5ohm - 4ohm region & which for the sake of interest the engineers at Fostex assumed would be the case for their FExx6E, FExx6En, FExx8ESigma & FFxx5K series drivers.
Actually the cab is damped, sort of. The inner walls all have 2" of rockwool insulation on all surfaces. There is no wadding in the cab airspace though. However, those figures are interesting in themselves, for the simple fact that by looking at them, you can easily corellate the numbers with the effect on the music they have, as your output impedance goes up.

Explains also why not bypassing the cathodes of the output valves in a single-ended amp, is generally a bad move, unless of course, you actually like crap bass. :wink:

All good clean fun :) .
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Re: Fane 12-250TC Retro Speaker.

Post by Scottmoose » Thu May 17, 2018 12:08 pm

Lagging a sealed box is quite normal. I'd expect 2in rockwool to drop system Q by about 5% depending on specific type & density. Possibly a bit conservative there.

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Re: Fane 12-250TC Retro Speaker.

Post by chris661 » Thu May 17, 2018 4:27 pm

Scott's put it better than me, but the above Q-factors vs output impedance were what I was alluding to.

Higher-than-textbook Q is fine, up to a point. It looks like you've found that point.

Chris

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Re: Fane 12-250TC Retro Speaker.

Post by Cressy Snr » Thu May 17, 2018 4:37 pm

chris661 wrote:
Thu May 17, 2018 4:27 pm
Scott's put it better than me, but the above Q-factors vs output impedance were what I was alluding to.

Higher-than-textbook Q is fine, up to a point. It looks like you've found that point.

Chris
I like living on the edge. :wink:
It does go to prove what I said earlier though re the designs I was doing in the 70s. Providing you don''t go much over 1 with the system Q, there is little to worry about.

With the Q raised above that, by the high output impedance of the SET with unbypassed output cathodes, I got a sound just like all the bought speakers I used before I resumed DIY. And they all had transistor amps driving them. :lol:

I love it when the numbers back up my blithering about. :mrgreen:
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Re: Fane 12-250TC Retro Speaker.

Post by ed » Fri May 18, 2018 6:38 am

an interesting thread just started on diyaudio, about triple cones. Interestingly there's a chap with some W bins, which I made back in the 1980s and were the inspiration for the pipi that I made..

http://www.diyaudio.com/forums/full-ran ... 250tc.html
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Re: Fane 12-250TC Retro Speaker.

Post by chris661 » Fri May 18, 2018 8:41 am

ed wrote:
Fri May 18, 2018 6:38 am
an interesting thread just started on diyaudio, about triple cones. Interestingly there's a chap with some W bins, which I made back in the 1980s and were the inspiration for the pipi that I made..

http://www.diyaudio.com/forums/full-ran ... 250tc.html
Ah yes, he does like his W-bins. Claims they're good for midrange duty, too, even with all the hard 90-degree turns.
He also says that 2x 2x12" cabs (sealed) with vintage 50w Fane units do very well for "disco" in medium-sized venues. YMMV...

There's been another thread on diyAudio that's been running for ages about the 12"s, and the 15" one started up as soon as the drivers were announced.

Chris

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Re: Fane 12-250TC Retro Speaker.

Post by Scottmoose » Fri May 18, 2018 10:22 am

Aye, except you did it properly, Ed. I don't quite know what Nigel is using his for, but presumably it isn't going to be home audio in the sense that any of us would, since his are regular W bins with the driver mounted internally, so the HF & a good portion of the upper mids are going to be AWOL. OK, the Fane does have a peaking on-axis HF response which will compensate a bit (Lowthers were originally designed to be used as indirect radiators, which is one reason most have that giant peak ~7KHz - 12KHz) but not that much.

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Re: Fane 12-250TC Retro Speaker.

Post by ed » Fri May 18, 2018 10:28 am

yeasssiir

I was immediately intrigued by that because the W bins are front loaded and I had a sneaky feeling this might upset the hf response.. Mine were strictly for back line bass duties though so I'm only guessing how they might perform with an HF unit.

The concept was awesome in back loaded mode though
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Fane-Tastic Musical Soireé

Post by Cressy Snr » Sat May 19, 2018 7:22 pm

So Chris and Dave (Thermionic Idler) turned up at my place earlier today with an array of amps, mixers and preamps, to have a go with them through my 12" full-range, Fane sealed box speakers. A splendid time was had.

I had decided on an amp bake-off with the Fane's as the reference speaker, so bacon butties consumed, courtesy of Mrs Cressy Snr, we set out on the journey, speakers warmed up and flooding music into the room through the NVA mutant amp.

First up was a ruddy great Crown pro amp from Chris:
Reggae from Razoof and my passive control unit.
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Ass kicking bass and dynamics with grin-factor in spades.
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Re: Fane 12-250TC Retro Speaker.

Post by Cressy Snr » Sat May 19, 2018 7:31 pm

The Crown PA amp was used with a specialist mains cable with quantum beeswax filled fuses in all the important electrical pinch points. I mean unless you are using these incredible devices, you are not getting the most hi from your fi.
Note the green label on the plug, denoting that the lead has been subjected to a proprietary cable burn in process that exactly aligns the magnetic flux with the ley line that passes through the nearby village of Denaby Main.
Image

Note also the expensive interconnects designed to give each amp the maximum chance of giving its best.
Image

No bake off can be regarded as valid unless the cables are the best you can afford.
Happiness is not good for the economy Matt Haig.

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Re: Fane 12-250TC Retro Speaker.

Post by Cressy Snr » Sat May 19, 2018 7:41 pm

Next, we added the Dieselpunk preamp of doom that Dave had built and documented on this very forum:
Image
I must say that this was one of the best active preamps I've ever heard. Remote control, automatic level setting and all mod cons and it was simply transparent to the source; a great piece of design.

Robert Cray and a powerful amplifier; who could ask for more?
Happiness is not good for the economy Matt Haig.

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Re: Fane 12-250TC Retro Speaker.

Post by Cressy Snr » Sat May 19, 2018 7:46 pm

As an interlude, and after some Monkey Business from Chuck Berry, we had a mess about with Chris's mixer and some multitrack studio recordings. These were fed through to Chris's own mini monitors.
Image
These sounded excellent and it was easy to mix with them. They were unfailingly musical at all times
Happiness is not good for the economy Matt Haig.

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Re: Fane 12-250TC Retro Speaker.

Post by Cressy Snr » Sat May 19, 2018 7:54 pm

This 5KW dual mono bastard, kicked some serious butt on Maria Callas "Carmen" on vinyl, through the Fanes.
Effortless is the word I'm looking for. The feeling of singer in room and whipcrack dynamics was fooking awsome, even though we were constrained from letting rip, by consideration for the neighbours and the rest of the surrounding area :lol:
Image
Was It musical? yes it was. Barring a slight thinness to the strings in places, which never turned hard or harsh, it turned in a great performance. Sledgehammers and walnuts do come to mind, but it was great fun.
Happiness is not good for the economy Matt Haig.

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