Most people where? Not here I don't think. Anyway, how does this set up work? It seems to me it's about balancing the sound pressure into each half of the room from each speaker?
The only explanation I can think is some kind of (work?) hardening of either surround or spider, but could impregnated cloth or rubber be subjected to that? Perhaps the rubber surround was actually made from santoprene, which can have excellent long term stability, but also may contain plasticisers. Which do not always have a lot of staying power. Dunno, remains interesting find.
In the end, it does not seem to matter much for loudspeaker alignment. Vas and Fs are on a seesaw. Take for example Keele's formula for an optimum BR enclosure: Vb=15(Q^2.87)Vas. When Fs goes down, Q also goes down, compensating at least to some extent for the increase in Vas.
I did the North West Audio Show (Cranage Hall, Cheshire) in 2017 and we had a very small room - 3m x 3.5 or 4m IIRC. The 703’s did not work in the room (to be expected) but the LS50’s were fantastic. I used the bungs with the middle section removed and placed them about 1/2 a meter from the rear wall for some reinforcement and used a 100 watt amp. Quite a few people came back for a second listen and were very positive about the sound. Keep in mind the show had speakers ranging from half the price of the LS50’s all the way up to 20 grand horns, 22 grand B&W’s, big KEF Blades etc.
I played Bill Frisell (always fantastically recorded), George Benson, Manhattan Transfer (on vinyl) and some classical stuff.
I played Bill Frisell (always fantastically recorded), George Benson, Manhattan Transfer (on vinyl) and some classical stuff.
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Best way to test an RIAA IMV is with an inverse filter fed from a square wave. I got the idea after reading a Baxandall article on it. He just mentioned how it worked and I tried it. Turns out it’s amazingly sensitive to response anomalies.
An Accurate Inverse RIAA Network
Of course now you can do it with a sound card, but where’s the fun in that?
Haven’t seen that - very nice write up as always from Rod Elliot.
(How’s the Bernstein/Gershwin CD BTW?)
I don't know what to say
Be Joyful. It may not be exactly the speakers he wanted, but when someone is happy with their purchase and the purchase is affordable fidelity (for given value of affordable) all is good with the world.
I don't think, Bonsai, because I've not listened a lot during the first two days: may-be 3 tunes ? Too disagreeable.
I have the habit to change speakers from studio to studios, and never changed my mind with "habit": too dangerous ;-)
I thought they were "broken-in", because I bought them used. So I had email the seller and his answer was it has not used-them more than few hours because he had a better system in //.
No, very little, my triangle is 2m50. ;-(
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I agree Vacu.
Burn-in time does not seem to matter much for loudspeaker alignment.
But as T-S parameters vary with test signal level a lot, one has to be careful as to the level of test signal.
It should be at the “small signal” range but not too weak (IMO close to the level that produces 1/4 Xmax cone excursion)
George
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Mark,
This is not a competition! I am I think way cheaper than you.
First is what I used from a 15 volt supply to a 12-14 volt fan. As I knew all the parameters a very simple design.
Second is the same idea modified to run on 24 volts and minimize the voltage drop as you did.
Third adds a regulator to limit the fan to 24 volts.
I think the secret is the LM34 temperature sensor. It produces .01V per degree F. It has a maximum input voltage of 35 volts and draws 90 uA. (It also seems to have gone way up in price since I laid in my supply of them! I paid under a $1.)
ES
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In a related subject, I was contracted to provide a thermal stabilizing circuit with interesting constraints: it had to hold the temperature of a heatsink within +/- 1°F, had to be non-contact and had to drive a fan. Since the temperature of the air leaving a heatsink is time-delayed from the temperature of the device mounted to it, using the air temperature as the sensing element can result in a sawtooth thermal variation or very slow response to ambient changes. I ended up using a ZTP-135 optical IR thermopile as a sensing element looking at the device on the heatsink driving a PWM fan controller chip from Microchip. Once the tracking was tweaked the circuit worked well, but is too elaborate and expensive for consumer devices, as I found out trying to adapt it for ham radio use.
Howie
The nontrivial bits:
LM34/35 temp sensor IC costs $2.05 qty=1 for the cheapest model link 1
Vishay thermistor costs $0.61 qty=1 link 2
Cheapest medium power transistor (fan driver) in stock costs $0.41 qty=1 link 3
My chosen PMOS (fan driver) costs $1.12 qty=1 link 4
ES $2.05 + $0.41 = $2.46
MJ $0.61 + $1.12 = $1.73
Mark,
I guess when I run out of LM34s I will have to use the LM334 and two resistors. The LM334 LM334Z/NOPB Texas Instruments | Mouser is $.87
Has anyone come across a replacement for the now defunct TI TMP006 thermopile chip? I have a project where ZTP-135 is just too big.
I hide this unsightly material in one of the castle's jails, to prevent the Castafiore from asking me to play her his recordings.
And if she finds out and asks me one day, I can lock her up.
Nb: Did I have to buy an aerosol of red paint?
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