Line 6 Spider IV 15- ok to use 8 ohm spkr instead of 4 ohm?

[Steve A.]

I'm on a never-ending quest for the best ss practice amp under $100 that has enough power for gigs at small bars. I think that the Trademark 10 is perfect but there is not a lot for a clean setting (the clean mode gets dirty really fast- you need to keep the gain control no more than 1 or maybe 2 or you will get a very ugly un-Fenderish break-up. I've put a clean boost pedal in the FX loop when I need a little more oomph!

Back to the Line 6 Spider IV 15 (the most popular 15 watt in America?) I got a good deal on a used one and I figured I could dial in better tones than I was getting on the GC sales floor. I did get some tones that would work for me except for a hollowness that I attribute to the 8" 4 ohm speaker. I have several 8 ohm 8" speakers around but none that are 4 ohm. While I would feel comfortable putting an 8 ohm speaker into a tube amp looking for a 4 ohm load I have avoided doing that with ss amps. [The article cited below says that ohms MUST match in a tube amp. I don't think that matters as much if you are not cranking your amp up to 11- or even 6 or 7.

I have seen wattage ratings for some PA and bass amps that will say something like 100 watts in a 2 ohm load and a lower number (50W?) for a 4 ohm load.

So does anyone have an idea of what might happen if I connect an 8 ohm speaker to the Line 6?

Thanks!

Steve

P.S. My guess is that it would work but that it would have less power (perhaps 8 or 10 watts instead of 15?)

P.P.S. This link was on the top of a google search for "power amp speaker output ohms"

OHMS & IMPEDANCE from the OUTPUT (speaker) perspective - FAQ courtesy of GollihurMusic.com

[Enzo]

If the speakers are otherwise identical, if you pull out a 4 ohm one and replace if with an 8 ohm one, it will simply draw half as much power from the amp. It is a solid state amp, so it doesn;t care all all what impedance you use as long as you don't go below whatever minimum it is rated for.

[Steve A.]

Thanks for your quick reply- I will try swapping out the speaker tonight. Using 8 ohms the output device (whatever it might be) should run cooler and probably last longer. Do you remember changing out a lot of Phase Linear output transistors in the 70's? I used to send transistors out to 65 service depts at Pacific Stereo in the 70's...

So if the speaker output was shorted out would that fry the transistors? Would it be a good idea to add a fuse to the output?

Steve

[Enzo]

Does that actually have transistors? I always assume Line 6 stuff uses power ICs.

Fusing the output won;t protect the amp, semiconductors can blow FAR faster than any fuse can blow.

[Steve A.]

Does that actually have transistors? I always assume Line 6 stuff uses power ICs.

I always thought that the power IC's had transistors inside of them cranking out the watts. Not discrete transistors but still some sort of semiconductor junctions. So I figured that calling them transistors would cover all bases. I learned electronics out of the 1976 Radio Amateurs Handbook that my boss handed me so I'm not familiar with all of these new fangled devices.

"Semiconductor Steve" was what the service techs called me when they'd phone in at Pacific Stereo in the 70's. It had been "Transistor Steve" before that but when I took over the stock of diodes and IC's I moved up in the world. What led to my downfall was the transistor cross-reference book I put together listing specs for all of the transistors and distributed to all 65 service departments. When the new manager came in he "unapproved" my cross-reference book because I had the transistors sorted by the specs and not by the transistor number to make it easier for the service techs out in the field to find substitutes for transistors they didn't have in stock. So he told me that he would not approve of using company resources to print and distribute my book. I said "Okay- I'll print them up at Kinko's and mail them out myself." He considered that to be gross insubordination- he had learned electronics in the Navy- and within a few weeks I was fired from my job as Parts Dept Supervisor.

[Enzo]

Well, yes, inside the IC would be transistors. Transistors, diodes, and resistors mainly. Since they are all blended together, it is hard to say whether an actual transistor junction burns out or if some bit of silicon linking two different transistor junctions burns out instead in there.

[pdf64]

I think many of the better modern silicon based amps have some current feedback in the power amp topology, to mimick the output impedance of a tube power amp.
A different value load may affect the operation of this.
I recall a thread in which someone reported problems when they used a 16 ohm speaker on a Marshall silicon based amp intended for 8 ohm load.

[Steve A.]

I think many of the better modern silicon based amps have some current feedback in the power amp topology, to mimick the output impedance of a tube power amp.
A different value load may affect the operation of this.
I recall a thread in which someone reported problems when they used a 16 ohm speaker on a Marshall silicon based amp intended for 8 ohm load.

To keep the load at 4 ohms can I put a high wattage 8 or 10 ohm resistor in parallel with the 8 ohm speaker? That would cut the power in half which would not be a problem for me and I could see if I can eliminate that hollowness I mentioned with a different speaker.

Thanks!

Steve

[Steve A.]

Well, yes, inside the IC would be transistors. Transistors, diodes, and resistors mainly. Since they are all blended together, it is hard to say whether an actual transistor junction burns out or if some bit of silicon linking two different transistor junctions burns out instead in there.

You're right. We'd get special orders for the power and driver(?) transistors but they would normally have the diodes, resistors and capacitors in stock so we would not get a special order for them.

[J M Fahey]

Short answer: if the original speaker works, use it.
If you want to try an 8 ohms one, swap it and let your ears be the judge.
You will break nothing at all, although I suspect sound will not change that much either.
Line 6 are no fools by a long way; they will save money like anybody else but will not fit cr*p speakers there.
Don't think that swapping a cheap 8" speaker for a different but still cheap equivalent one in the same little cabinet will work wonders.
To get a *real* improvement I would plug your amp "head" into a, say, 4 ohm 2 x Vintage 30 speaker cabinet or something equivalent, but I guess it's beyond acceptable budget.

[Steve A.]

Short answer: if the original speaker works, use it.
If you want to try an 8 ohms one, swap it and let your ears be the judge.
You will break nothing at all, although I suspect sound will not change that much either.
Line 6 are no fools by a long way; they will save money like anybody else but will not fit cr*p speakers there.
Don't think that swapping a cheap 8" speaker for a different but still cheap equivalent one in the same little cabinet will work wonders.
To get a *real* improvement I would plug your amp "head" into a, say, 4 ohm 2 x Vintage 30 speaker cabinet or something equivalent, but I guess it's beyond acceptable budget.

The Line 6 speaker is designed for typical settings for rock, with a lot of overdrive (to give you some idea the 4 presets are Clean, Crunch, Metal and Insane.) I'm not looking for that sound- I'm looking for a nice clean sound that works for steel guitar. So I will try swapping a few speakers to see if it helps. For starters I will try my favorite 8" speaker- the Eminence Beta 8A which is intended for large PA cabs and is rated for 225 watts. I move it from amp to amp- for awhile I had it in my Kustom Tube 12 which gave that amp a nice bass response. Before that it was in Valve Junior Combo.

Steve

[J M Fahey]

Well, that Eminence Beta is a very good speaker and absolutely not what I was thinking about
when you said "I have a couple spare 8" speakers"
That said, it is much smoother (flatter) than any regular guitar speaker, but not very loud, unless driven by insane power.
I fear those 15W (reduced to 10W by impedance mismatching) will not allow much headroom.
Fine to play at home, probably not so at any live gig.
*I* would build a fire breathing little amp with that speaker driven by, say, a couple bridged LM3886 or something similar, around 100W into 8 ohms.

[Steve A.]

Any suggestions for removing the back panel on the Line 6? I've seen quite a few Chinese amps in which they didn't allow the glue to dry before putting on the rear panel. I just tried drizzling some 91% rubbing alcohol in the tiny gap between the back and the cabinet but that didn't help. I might try hot water next.
I guess I may need to call out the big guns- get my crowbar to put some force into it. (I would put a piece of very solid pine shelving between the crowbar and the top of the cabinet to protect it since I may return it to GC.)

The Beta 8A is only one of many 8" speakers I have around to test it with. BTW I was thinking of building a small cabinet for the Beta 8A which I would plug into my 200W ZT Lunchbox amp:



The 200W figure is only to get peoples's attention. Technically it does put out 200 watts but the designer said it is really like an honest 65 watts.

Steve Ahola

[Steve A.]

The tolex on the cab and back panel had gotten glued together at the top on the left side and it took a little persuading to remove it. (I used a board to keep from bruising the cabinet.)

Damn, it sure sounds nice with the Beta 8A! I think that it might be the lower mids that was weak on the stock speaker which gave it that hollowness I couldn't live with. The bad news is that I am going to have to buy another Beta 8A because this one will be staying in the Line 6 which is as loud as I'd want it to be.

When I say "clean" it is not like I am Andrés Segovia looking for pristine crystal clarity- what I mean by "clean" is like how amps used to be before they started to push the envelope on distortion. The Line 6 breaks up nicely- unlike the Tech 21 Trademark 10 which "cracks apart" rather than "break up" if you set the clean channel gain higher than 2.

The Beta 8A also tames the other channels a bit.

Thanks for all of the advice!

Steve Ahola

[Enzo]

When I think steel guitar, my thoughts turn to a nice big smooth 15 and a solid state amp.