Need to confirm mismatch alright

lovekeiiy

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I'm considering getting a new amp head and cabinet. Right now, I just have some practice combo amps. Thus, I haven't had to concern with ohmz mismatching or wattage issues.

I'm thinking about getting a Joyo Dualklonz head; depending on the tubes uses, puts out 15-25W with 8/16ohmz or 4/8ohmz respectively. Joyo has a nice 2x12 cab to go with it, but their cabs tend to be sparse, especially the white one that goes well with the head

I was thinking of getting a Panama tonewood 2x12 cab. Most reviews I've been able to find--read and watched--speak well of the cabs. There are some negatives I've read about quality control towards bad speakers, but the customer service experiences I've read Panama try their best to correct the situation.

The Panama cabs are 16ohmz. From what I read, I should be ok to run the cab with an amp running 8omhz; just does not run the speaker as well.

From what I can tell, the cab looks to be 100W; could be more depending on the drive configuration. The Dualklonz puts out 15 to 25W depending on the tubes used.

I'm not just not sure in my research but seems to be solid. Just looking to confirm or feedback.

Dualklonz


Panama Tonewood cabinet


Thank you for help in advance.
 

Bobby Mahogany

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Probably the speakers in the cab are wired in series,
so they "add". Two 8 ohms in series = 16 ohms.

If you wire them in parallel they "split",
so two 8 ohms in parallel = 4 ohms.

That could be the solution to your problem.
Unless they are 32 ohms in series.

I would tend to get the right cab to match the amp.
The manufacturer has already solved the problems for you.
 

dc007

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You could get by running from the 8ohm tap on the amp to a 16ohm cabinet but you will experience a lot less volume and loss of dynamics. Best to match them.
 

ErictheRed

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Just rewire the cabinet to be 4 ohms, it's not rocket science. Or ask the manufacturer to wire it that way when you order it, it's not any easier or harder than wiring it for 16.
 

Matt_Krush

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A single step impedance mis-match is fine (with most robustly built heads)*.
You just won't deliver full power to the cab.

*Now..a Joyo...while I am sure it probably does sound fine, there isn't any real world history or data on how durable these are.
However, it appears to use a massive toroidal output transformer and those are quite capable of a single step impedance mismatches.
 

lovekeiiy

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That's for the input thus far. I get the independence should match. The issue is that the head can change ohms and wattage depending on what tubes are inserted. The amp is kind of like modeling amp, but it does not really model. It changes to the circuitry via switches, which allows it to get a similar sound to various amps or create now tones.

From what I can tell, and I'm not fully certain, it appears the speakers in the cab are 8omhz since the 1x12 cab uses the same speaker. Thus, I'm making the assumption the wiring for the speakers is in series, which would give the 16ohmz.

My concern is mainly if I run one of the tubes, such as the EL34 that are 8omhz or 4omhz, will I damage anything if the cab is 16ohmz (series wiring). The tubes selected can affect the tone. Below is a screenshot of the manual page showing this. I haven't read the manual detail, so I don't know what it says about possible mismatching. Given how the amp works, rewiring to 4 ohms may be the best path for use with this amp.

I suppose it could be possible to add a toggle to switch between parallel and series wiring, which I believe would give 4ohmz and 16ohmz respectively assuming the speakers are 8omhz. It's been along time since I've done that wiring and my sodering skills are lacking; I've done it but only done it a few times. I'm not sure possible to do a three-way switch to get the 16omhz, 8omhz, and 4omhz. I don't think it would be necessary.

From I've read, it appears the wattage output of 15-25W should not be an issue with cab since it appears it will have a rate of at least 100W; it could be higher depending on the speakers chosen.

Unfortunately, most of the videos I can find on the head, where they are demoed are with the Joyo cabinet. I found one with Phil X using a Mesa Boogie, but no idea which one. Below is a picture of the back plate, but I suspect it'll be minimal use.

 

ErictheRed

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Tubes have absolutely nothing to do with output impedance. You should match the output impedance of your amp to your cab for many reasons, mostly because if you don't you could damage your amp. It's also extremely easy to do in 99.9% of cases, just swap the speaker wiring from series to parallel (or vise versa), and choose the appropriate output setting on your amp. It's not rocket science and you're way over thinking this.

Swapping tubes might affect the output power of your amp, but all you need to do is make sure that the total power rating of all of your speakers summed together is equal to or greater the max power output of your amp.
 

northernguitarguy

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Tubes have absolutely nothing to do with output impedance. You should match the output impedance of your amp to your cab for many reasons, mostly because if you don't you could damage your amp. It's also extremely easy to do in 99.9% of cases, just swap the speaker wiring from series to parallel (or vise versa), and choose the appropriate output setting on your amp. It's not rocket science and you're way over thinking this.

Swapping tubes might affect the output power of your amp, but all you need to do is make sure that the total power rating of all of your speakers summed together is equal to or greater the max power output of your amp.
But do you see the table in the manual above? It does indicate different cab impedance requirement based on the power tubes used. :dunno:
 

ErictheRed

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But do you see the table in the manual above? It does indicate different cab impedance requirement based on the power tubes used. :dunno:
I see; it looks like EL84s and 6V6s will be using different circuitry in the power section. It's hard to know exactly what's going on without seeing a schematic. I assumed different power tubes of the same "familly," so to speak.

Anyway it's still not rocket science, just get an 8 Ohm cab because that will work with any setting on that amp. Or get a cab with two 8 Ohm speakers and wire it in series or parallel, depending.
 

northernguitarguy

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rabidhamster

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So the amp is designed to pair w a specific ohm cab the company sells.
But it's also designed to swap tubes which may change the impedance marginally.

Was the amp designed to have to swap speakers when you swap power tubes?
If no, and it does seem to be no, one would assume it's ok to use the amp at its stated impedance with any choice of acceptable power tubes.

A single step ohm mismatch should be fine even with all of that, if not ideal. Some folks mismatch ohms on purpose for a certain tone. But if you don't have the cab yet just buy one in the right ohm rating.
 

The Ballzz

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Interesting video and amp! My biggest question surrounds the power tube usage. All of the listed power tubes are 8-pin/octal, except for the EL84, which is a 9-pin/noval? I'm wondering if they have two different pairs of power tube sockets, or if they use/provide some sort of adapter for the EL84?
I'm Confused?
Gene
 

The Ballzz

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Hmmm.....
I went to the JOYO website and the amp does appear to have two pairs of power tube sockets. It seems that the amp is no longer available, new and I have a couple/few guesses as to why? One) The amp is fairly high priced for an amp without any proven track record! Two) It appears possible for some to inadvertently (or maybe even intentionally) try to have the EL84 tubes in at the same time that other tubes are in the "octal" sockets. This would likely cause some serious issues! Three) With all the relay switching options, I'm going to bet that even one relay acting up could render the amp useless.

Nice ideas, but I suspect the amp would not be very reliable. It would be nice to be proven wrong!

Just Sayin'
Gene
 




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