| Impedance-series wiring????? [message #1242] |
Sun, 20 January 2002 01:35  |
Country_Gene
Messages: 42
Registered: December 2001
Location: Northwestern New Jersey
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I think this has been posted before, but I can't find it.
I've seen a lot about how to calculate a cabinet's total impedance when speakers are wired in parallel (which most seem to be). But how do you figure the total impedance if the speakers are wired in series? Are there any problems with doing this?
I have three 12" 8ohm speakers lying around and I was thinking about building a cabinet for two of them. I figured this would be a good winter-time project. Can anybody help me out on this?
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| Re: Impedance-series wiring????? [message #1243 is a reply to message #1242] |
Sun, 20 January 2002 09:37  |
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Two speakers in series: add the two together, so you get 16 ohms. (If you used all 3 speakers, add them together, for 24 ohms). That's why most cabs are wired in parallel (Two 8 ohm speakers wired parallel equals 4 ohms), because the amp puts out more power into 4 ohms than into 16 ohms.
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| Re: Impedance-series wiring????? [message #1244 is a reply to message #1242] |
Sun, 20 January 2002 12:41 |
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Gene's statement about having three 12" speakers prompts me to inquire of those who own Kustom 3x12 cabinets. I know Fox and Don are 3x12 owners as well as myself. What are your impressions about these somewhat rare cabinets. Mine is a bass cabinet....I use it in conjunction with a 2x15 on a 200 head when I want to add some punch to the sound. I have also heard guitar through it and it sounds nice for that too. Gene may want to build one of these! BC!
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| Re: Impedance-series wiring????? [message #1246 is a reply to message #1244] |
Sun, 20 January 2002 16:45 |
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An easy way to remember is parallel divides the impedance and you add impedance in series. This is when you are using like ohm speakers. A formula to use with multiple speakers would be 1 over R1 + 1 over R2 + 1 over R3 etc. = 1 over T. R1,R2, and R3 are the impedance of each speaker and T is the total. It's hard to describe in the post, but for example if you had a 8 and a 16 ohm speaker wired in parallel you divide 1 into 8 and you will get .125, then divide 1 into 16 and you get .0625, add the two together and you get .1875. Now divide 1 by .1875 and you have 5.33 ohms total for load for both speakers. Keep in mind that the 8 ohm will be louder than the 16 ohm. Another thing is that the 8 ohm will be handling 75% of the power and the 16 will be handling 25% of the power. This formula works well for multiple speakers in a cabinet. Kustom used 16 ohm speakers in the 3x15 and 3x12 cabinets all wired in parallel, which figures to about 5.6 ohms. The k200 heads will deliver max output at the 4 ohm. Don
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| Re: Impedance-series wiring????? [message #1250 is a reply to message #1249] |
Mon, 21 January 2002 22:25 |
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You could rewire the 2x15 cabinet to a series and it would give you a 16 ohm load. Wire the 2x12 cabinet in series and you have another 16 ohm load cabinet. Both cabinets wired to the K200 head will get you to a 8 ohm load and you can safely run both cabinets from the same head. The downfall with that is if you run one cabinet the amp will not be matched. The K200 series are designed to run between 4 and 8 ohms, 4 ohms producing 100 watts rms and the 8 ohm load will yeild about 65 watts. I would suggest keeping the cabinets wired to a 4 ohm box and picking up a 100 watt slave amp to drive the 2nd cabinet. With that arrangement you can use the K200 head on either cabinet and when using both cabinets just add the second amp. The K200 should have the RCA jack on the back to feed the second slave amp. There are a lot of ways to wire the heads, just not enough space here to give all the combinations. Don
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| Re: Impedance-series wiring????? [message #1329 is a reply to message #1250] |
Fri, 08 March 2002 18:48 |
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I replaced the 3 speakers in my 3X12 with 8ohm Jensen C12N's, i wired 2 in series and connected the third to them in parallel (just a guess). Puts the cab @ 5.33ohms.
does this sound like a good idea? any thoughts from the xprts?
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| Re: Impedance-series wiring????? [message #1330 is a reply to message #1329] |
Sat, 09 March 2002 01:41 |
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You have a correct impedance at 5.33ohms. The problem I see with that wiring arrangement is the pair that are wired in series is taking 50% of the load or 25% for each speaker in the series combination and the 8 ohm that is wired it paralled with the other two will be taking other 50% of the power. The speaker that is in parallel will be louder than the pair wired in series. If you were to wire the three speakers in parallel you would have 2.66 ohms. A little to low for the kustoms, but a lot of peavey amps will run a 2 ohm load. If you were to wire three 16 ohms speakers in parallel you would still get the 5.33 ohm load. each of the three speakers would be taking 33% of the power. Three speakers are hard to match using 8 ohm speakers. Kustom used 16 ohm speakers in all the 2x12, 3x12, 3x15, 2x15, 4x12 and cabinets. Don
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| Re: Impedance-series wiring????? [message #1332 is a reply to message #1331] |
Sun, 10 March 2002 02:35 |
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Ah, very good question. There has been reports that the amps were supplied with 8 ohm speakers according to the date codes on the speakers and pot dates, and some have reported having 16 ohm being originals. I really don't know for sure. I have had originals in both 8 and 16 ohms. I would guess the 8 ohm would be a standard as kustom amps always ran with a 4 to 8 ohm load in those years. Maybe the 16 ohms were used when the 8 ohm speakers weren't ava. You can always run more ohms to a ampaand not do damage. Running less than recomended can fry a amp rather quickly. The schematics I have for the K25 and K50's don't really show the recommended impedance of the speaker. Any one else have some thoughts. DOn
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| Re: Impedance-series wiring????? [message #1334 is a reply to message #1332] |
Sun, 10 March 2002 15:07 |
KustomBlues
Messages: 490
Registered: June 2001
Location: Michigan
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Sure do! According to some Kustom manuals that Kustom Dan has, the originals in the K25 and K50 models were brown and gold back, 16 ohm Jensens, exclusively. Originals will have the white painted Kustom logo stamped on the frame. If it's not there, the speaker has been replaced. I know that my K50 (bought from Don) and my K25, both have the original jensen speakers in them. They are both 16 ohm jensens, originals. They have a yellow dot near the positive speaker terminal, and meter appropriately. Kustom manuals do not lie! Ask Kustom Dan about it, I have. Deb
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