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Second guessing myself, Can I get some guidence?
by myers570 on 2011-09-09 14:08:58

Hello all!

I've been second guessing myself ever since I bought my Spider Valve HD100 and it's connection to my 4x12 Line 16 cab.

On the back of the cab there's 2 ports. Both ports say 8 ohms above them and one says 4ohms mono below it (see attached picture)

On the back of my head there's mutliple 1/4 inch jacks. I currently have it placed in the further most left jack that says 8 ohms pair.

What should my signal flow be here? I appreciate any help that I get and thank you in advance!!!

photo(1).JPG

-Shawn Myers-photo.JPG



Re: Second guessing myself, Can I get some guidence?
by spaceatl on 2011-09-09 14:23:45

That looks right....4 ohm tap on the amp to a 4 ohm cab....I assume all 4 speaker are working...

If you want to be more sure of what the impedance is, turn off the amp, pull the plug out of the amp and leave it attached to the cabinet...Get a multimeter and set it to Resistance...red test lead on the tip of the plug and black test lead on the sleeve...You should read something within a tenth or 2 of 4 ohms (3.8-4.2)....This isn't the real impedance average...rather the DC resistance...but it is always pretty close...

Another tip...You can bounce a 9V battery on the cable putting the + on the tip and - on the sleeve of the plug and make sure your speakers are in phase...they should all push outward...This can also show you if you have a blown speaker...



Re: Second guessing myself, Can I get some guidence?
by myers570 on 2011-09-09 15:30:00

Thank you for your reply. The thing that confuzes me is that it says 8 ohms on 2 jacks and says Left and right above their respective jacks. On the head what jack would I use to go to what input on my cab? Yes all 4 speakers are there and do work. Thanks again!



Re: Second guessing myself, Can I get some guidence?
by spaceatl on 2011-09-09 15:46:13

You have a stereo cab...If it were on a stereo power amp (two power amps) you would have and 8 ohm load on each amp...2 speakers on each amp...When you combine two 8 ohm loads, the load becomes 4 ohms...Your cab has a switch on in it...when you use only the right hand jack, it combines the 8 ohms loads and makes it 4 ohms...It is also mono because it is powered by a single amplifier (You Spider Valve is a monoblock amplifier)...The SV has two jacks on the 4 ohms output so that you could optionally run two 8 ohm cabinets...It combines the load...that is why is says 4 ohms: 8 ohms pair...

You could optionally use two cables to the 4 ohm...8 ohm pair jacks on the amp...it would be exactly the same thing.



Re: Second guessing myself, Can I get some guidence?
by myers570 on 2011-09-15 11:38:53

Sorry for being so troublesome here. So I shouldn't run 2 jacks from my head from lets say section C? Or should I run one cable from section B under the 16ohm pair considering it says 8ohm right and 8 ohm left? Once again I apologize, I overthink so much with this stuff and like to be sure I am getting it right. Thank you!



Re: Second guessing myself, Can I get some guidence?
by Nick_Mattocks on 2011-09-15 12:08:25

8 Ohms per side on your cab into the two sockets in the 4 Ohm section means the two halves of your cab are running in parallel so the load the amp sees is 4 ohms.  

If you just run one cable into the 4 ohm socket on your cab into the 4 ohm output on your amp, the jack socket in the cab is switching the speakers to parallel so you still get a 4 ohm load.

The result as far as the amp is concerned is the same i.e a 4 ohm load will be seen whether you use one or two cables.

Nick



Re: Second guessing myself, Can I get some guidence?
by spaceatl on 2011-09-15 12:31:28

+1

Technically, it is better to use two speaker cables in this case...Likely it won't make an audible difference, but the resistance and capacitance would cut in half...That's always a good thing in terms of cable response...each pair gets a home run...That is actually safer for a tube amp also...



Re: Second guessing myself, Can I get some guidence?
by Nick_Mattocks on 2011-09-15 14:03:29

Agreed - and there can be a benefit too if for some reason the mono (switching) jack (Left/mono) gets worn or dirty over time and doesn't properly engage both sets of speakers - I have a Marshall 1922 mono/stereo cab that was exhibiting dropout on one of the two speakers a couple of weeks ago because of this - I've had the cab about seventeen years (scary - I was thinking it was nearer eight ) and this would obvilously affect the speaker load impedance (with that particular speaker cab it's 16 ohms per side or 8 ohms mono).  A short time later after a bit of a service all was well again, but dual speaker cables would have prevented the issue, so yep dual cables provides an added element of safety.



Re: Second guessing myself, Can I get some guidence?
by spaceatl on 2011-09-15 14:44:00

I have modifed most of my amps (two more to go) to use Neutrik NL4 speakons...All my cabs are speakon...1/4 jacks and plugs were designed for telephone operators, not speaker line voltage...okay, I will get off my soapbox now...



Re: Second guessing myself, Can I get some guidence?
by Nick_Mattocks on 2011-09-15 14:46:26

Good move



Re: Second guessing myself, Can I get some guidence?
by cgtrox on 2011-09-21 11:42:03

No wonder my old cab sounded "tinny".

cgtrox



Re: Second guessing myself, Can I get some guidence?
by Samzee on 2011-09-21 15:21:43

All my cabs are speakon...1/4 jacks and plugs were designed for telephone operators, not speaker line voltage

This interests me.

After a little reading, I've seen some people saying that speakon cables are "basically pointless" for use of under 300 watts or so, besides offering a better connection and contact. They're speaking in terms of sound quality. Can you confirm or deny this? You say that standard 1/4 inch cables weren't designed for speaker line voltage, so that would make one think that a much higher current capacity would be conducive to a better signal.

Could you enlighten me on the subject?



Re: Second guessing myself, Can I get some guidence?
by SSstormtrooper on 2011-09-28 21:11:57

1/4" instrument cable should never be used to hook up an amplifier head to a speaker cabinet.TRS cable should always be used.TRS stands for tip,ring and sleeve(meaning it has two conductors and a grounding shield).TRS is speaker wire that can handle the current and is grounded properly and is the ONLY connection used to hook an amp to a cabinet besides XLR.

My expensive 100 watt Mesa combo even came with a 10 foot chunk of 1/4" TRS cable in bubble rap to join to ancillary equipment I suppose.

1/4" TS(Tip and Sleeve) Guitar/Instrument cable is a very fine wire/conductor meant to carry very small voltages and is only used for such.Extreme damage to your equipment can occur when using this type of cable as amp to speaker connectors.

Easy way to check as stated above: Guitar cable(TS) has two rings on the plug,whereas Amplifier to Speaker cabinet cable(TRS) has three rings on it.

This isn't the same as a debate about a friend recommending expensive speaker-wire for his home entertainment system it is a totally different ball of wax.

Just google 1/4" TRS and some good info pops up,I would have posted some links but I'm not sure about the rules of external links.Hope this helped some,Cheers!



Re: Second guessing myself, Can I get some guidence?
by spaceatl on 2011-09-28 22:02:42

Basically, by using 11AWG I will never have to worry about the strands breaking in my cables...If you use a cable and connector that is within specification, it won't be after a year of gigging...strands break...resistance increases...If you are just within spec, you will be below spec after a year...that can be quite audible...but you might not notice since it happens slowly...

The approach I take is effectively like connecting the speakers directly to the output transformer...The NL4 allows me to home run each speaker from the tap...This is done for safety...So in order to use large cable, I have to use a connector that supports 11 AWG and has the same or less resistance inductance as the cable I am using...1000 watt NL4...Basically, I don't ever have to worry about my speaker cable...or should I say garden hose...

I made my living for a long time as a pro audio engineer...So that might explain some of my madness in this regard...I use speaker jacks and plugs for speakers....I use signal jacks and plugs for signal...keep it simple...There is also less chance of ever plugging in anything incorrectly since the connectors are keyed for the purpose...

In terms of the connector, there is no chance that it can ever be pulled out by accident...They are designed for pretty extreme abuse and last for years where 1/4 connectors do not...The contacts are also arcless (like the approach of using TRS with the ring bypassed)...It means if you happened to remove the conector while the amp was hot, the connector will not short the amp or arc on the contacts...

I do think the amp sounds better after doing this...maybe its just happier...I can't say I gained any real headroom or anything like that...Maybe it's just an audio placebo...you might think I am freak and that's ok...We guitar plyers do wierd ass shit to get our tone right...this is just one of those things I do so I don't ever have to worry about it...



Re: Second guessing myself, Can I get some guidence?
by Samzee on 2011-09-28 22:52:29

Stormtrooper (excellent username btw) -- I was actually talking about standard speaker cable vs. high-gauge speaker cable with NL4 connectors, not speaker cable vs. instrument cable. But thanks for the response.

Space -- Hah, no I don't think that's freakish. I actually really like the "garden hose" idea. Seems more durable, safe, and just all-around better. I find myself sort of OCD in that way as well. Even if it didn't improve the sound to anyone's ability to hear, I'd feel better that my amp is electrically happier. Thanks for the reply.




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