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4R5

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Everything posted by 4R5

  1. That's a '20s or 30's speaker for a radio. Your best bet is to join Antique Radio Forums and post the pictures there. That group is knowledgeable in speakers of that vintage.
  2. Thanks for the full specs, have been looking for them for a while.
  3. Good points, thanks. My original quest was to try to replicate Pete B's values. Granted his tests were 16 years ago, but the drivers were then already 30+ years old. I did find that one of my Seas woofers, a 25TV-EW but with a round rim, not the more typically seen rim with the mounting "bump outs" had a different set of TS parameters than the other one with the "bump outs". Like wise the 15 ohm version TS parameters more closely matched the round rim 8 ohm driver. The 8 ohm one with the "bump outs" had TS parameters close to Pete B's data.
  4. Stromberg Carlson RW-486 12" woofers. 8 ohm. Fs 45Hz Good condition, no voice coil rub. Chrome in good condition, no rust. The banding around one magnet has stains. I ran TS parameters on one, contact me for more info. Suffice it to say that they are best suited for a large enclosure or possibly open back. $30 for the pair plus shipping Ship to lower 48 US only.
  5. Looking for a single 3016Aa 12" woofer, found in Realistic / Radio Shack Optimus 5B or Nova 8B speaker systems. I'll consider a pair of them.
  6. Correction: what value of series resistor. Thanks!
  7. Pete, one more question, when you mention 2 to 3 volts for mids & woofers, is thatat the driver or at the source? What series resistor do you typically use?
  8. Hi Pete, thanks for the reply. First off I mentioned Win ISD which was a mistake, I'm using REW for analysis. I did measure Fs with a stand alone generator and frequency counter, ironically I found Fs to to go down with drive voltage. This is one of the 15 ohm Seas drivers: Drive Voltage Fs 100mV 37Hz 200mV 37Hz 300mV 36Hz 400mV 36Hz 500mV 35Hz 600mV 35Hz 700mV 34Hz 800mV 34Hz 900mV 33Hz 1V 33Hz 1.5V 31Hz 2V 30Hz 2.5V 29Hz REW runs their Z at 100mV. Yet their value is what I measured at 1V. I did verify accuracy, I used a measured 21.1 ohm resistor and REW reports back 21.1 across the frequency spectrum. I do have a scope, will take a look at the waveform. How did you measure your driver - manually or with another program? Thanks!
  9. I should add as you can see in the table, Fs for the 15 ohm is much higher than the Seas spec for the 8 ohm, and even my 8 ohm Fs is higher. Also the Qe & Qm values are almost 2X what PeteB measured, which contributes to the higher Qts values.
  10. I was reading PeteB's posting about the Dynaco A25 Speakers Specifically his measured T/S parameters of a Seas 25TV EW woofer that he had. I recently picked up 4 of the 15 ohm version of the 25TV EW that was used in the Dynaco A-50, assuming the T/S parameters would be close to the 8 ohm version. What I found is the Qts and VAS values are way off from what PeteB posted. I then pulled a 25TV EW woofer from one of my A25s and found those measurements are off as well. I'm using WinISD with a sound card (no external power amp) with a 121 ohm series resistor. Here's a table of my results along with PeteB's results. 25 TV-EW Seas Spec 25 TV-EW Pete B data 25 TV EW 2674 date 8 ohm measured 25 TV EW 15 ohm measured Sd 285 350 350 350 Fs 20 - 25 23.6 31.3 33.9 VAS 205 109.69 103.54 Re 5.7 6.96 12.19 Qe 0.48 0.973 0.928 Qm 4.2 7.321 7.552 Mms 30 37.5 41.06 36.99 no 0.36 SPL ref 88 87.6 BL 8?.8 6.6 7.597 10.175 Qts 0.35 0.43 0.859 0.827 Cms 0.631 0.596 Rms Dd 211 211 Le 4.603 5.967 added mass 32.78 32.678 Am looking for suggestions as to why my values are so far off. Thanks
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