Shavano Music Online

    Epiphone Valve Jr - Combo Speaker Test

    http://www.colomar.com/Shavano/AMP/ValveJrSpeakers.html - 11/2009

    What I'm trying to resolve

    I took my 5 watt Epiphone Valve Jr out to a Jam Session, It still has the stock 8 inch 8 ohm Eminence speaker in it. It was ok, but I afterwards, I could see that I wanted a bit more low end out of it, and maybe a bit more punch. It was keeping up pretty well with a 60 watt Fender Deluxe (played using a P-90 equipped Gibson Les Paul). I used a Danelectro U2 (Lipstick Pickups are more jangley, so this is why there is less bass from the guitar).

    I had tried a Valve Jr Head with a pair of external 12's at a music shop and really liked the tone, but it was too loud for what I wanted to do.

    I have read about other people doing some surgery/routing on the combo case to get a 10 into it. I figured I can get one installed too. I ordered an Eminence model 10516 - from Parts Express that has the following characteristics:

    Specifications:

    • Power handling: 75 watts RMS
    • VCdia: 1.5"
    • Impedance: 16 ohms
    • Frequency Range: 100-5,800 Hz
    • Sensitivity: 100 dB 1W/1m
    • Magnet weight: 16 oz.
    • Dimensions: Overall Diameter: 10.11",
    • Cutout Diameter: 9.13"
    • Mounting Depth: 4.1".

    With a SPL of 100 dB I thought it would be a good match with some better low end. I did a simple side by side test to see if here was a noticable difference,

    Test Process

    Radio Shack Analog Level Meter set to
    • 110
    • Weighting A
    • Slow Response
    • Distance from Front of Epiphone Valve Jr
      cabinet: 12 inches (approx 25 cm)

    Speaker impedance = 16 ohms.

    Radio Shack Analog Level Meter set to
    • 110
    • Weighting A
    • Slow Response
    • Distance from Front of Cardboard Box
      holding 10516 speaker: 12 inches (approx 25 cm)

    Speaker impedance = 16 ohms.

    NOTE: The cardboard box idea is one I saw on YouTube as a quick way to mount a speaker for general testing. Its not optimal, but at the same time, I have no plans on making a separate speaker cabinet for the 10 just for this test. The results should be close enough for this purpose. The Speaker came with hard foam packing in the box - I hollowed out some of this so that I would get a similar response as an open back cabinet.

    I used my Danelectro U2 set for both pickups (full on) and strumed a hard A barre chord multiple times to get as consistant a level as possible. I switched back and forth between speakers 3 times. This is what I found:

    The Green area shows the range of the results when I strummed for the Combo's 8 inch speaker. The Blue area shows the range when I strummed for the 10 inch speaker.

    The 10 appears to be about 2 dB louder. The tone is very similar for each speaker, but the 10 has more high end (this is likely the result of it being in a cardboard box); I expect the 10516 to have more bass response when its it the cabinet.

    Additional Information

    This sound check is not a true Speaker Sensitivity Test; it is a much simplified method of comparing speakers with very little in the way of standardized test results. It was done only for simple comparison of the 8 and 10 shown here. To learn more about professional SPL measurements, see:

    • http://en.wikipedia.org/wiki/Loudspeaker_measurement

    Other things to consider

        Woofer Diameter in Inches  
      6 1/2
        8  
        10  
        12  
        15  
        18  
       Number of Woofers 
        Total Surface Area in Square Inches  
      1
      33
      50
      79
      113
      177
      254
      2
      66
      100
      157
      226
      353
      509
      4
      133
      201
      314
      452
      707
      1017

      Part of the increase in sound level is because the larger surface area of the 10 compared to the 8 (see the above chart). The meter does show about 99 dB from the 10 (the speaker specs say 100). This tells me that the 8 is pretty high output (at around 97 dB) as well (good job Epiphone!). A drop of 3 dB is about 50% less Power. The difference between these two is around 2 dB. So going to the 10 will make it louder, without going overboard (after all, I am using a 5 watt amp because my 100 watt Twin Reverb amp is too loud for what I want to use it for).

      I prefer the analog version of the Radio Shack Sound Level Meter to the digital one - both work pretty well. There are lots of limitations in this Sound Level device as a result of its low cost, however, its an exceptional tool for checking things like cross-over networks or looking to match up speaker levels of speakers you happen to have (if you have a bunch to pick from and have no idea what thier SPL is - you can connect them up and measure them all - marking them as you go).

      Questions? Comments? Suggestions?

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