Tube amps for 5 string bass frequencies.

[loudthud]

Putting aside for a moment the idea of a 2x10 Tube combo, what happens to a speaker in a ported cabinet when it is operated below the tuning frequency? Doesn't the cone excursion get very large until Xmax cone excursions causes lots of farty distortion? If the cabinet is tuned low (30Hz), don't you get a gentle rolloff but less farty tone because the cone is still loaded by the cabinet and cone excursion is more controlled?

[bea]

The Kappalite 3015 mentioned earlier has 100.8 db.

The K3015 requires a tuning of at least 51 Hz and likes the 55 Hz of the TL606 cabs. So by no way better than, say, two Eminence Beta-12... (each of those actually requires about half of the volume of a 3015 with a very similar tuning, and both shuffle about the same amount of air as a single 3015 for 2/3 of the price but twice the weight). I run both speakers.

But anyway, since the fundamentals of a bass are musically not really important, such cabs perform pretty well with the B string, especially if You use sufficiently many of them.

A side note to the Ampeg fridge: this is a closed box with a -3 dB point at 80 Hz. Less deep bass than the playing through the 70 Hz filters of typical mixing consoles.

Anyway, who carries around a 400 watt tube amp?

Mywatt 400, 26 kg. Some people seem to like carrying that weight. BTW: the 22 kg of my Mywatt 200 and my Dynacord G-2000 are the main features of these amps i strongly dislike...

[J M Fahey]

What I read in the OP was "New TUBE?" Is this a "hybrid" with a "tube preamp?" I highly doubt it's only 40W... I'd be very surprised if it wasn't at least 200W.

To the OP, can we get a specific model?

Justin

Edit: @mhuss: if I had one, I'd carry it around. Nice amp!

SWR and 2x10" should mean 200-250W@8ohms, 300-350W@4ohms
The speakers are very good PAS woofers in cast frames, at least the "real SWR" types, I think "Fender SWR" use some kind of cheaper Eminence on stamped frames.

I have repaired SWR 10" speakers where users naively believed that a "350W" rated cabinet can actually be used with a 350W SS head (think Hartke3500 / various SSSVT Ampegs / Eden / etc.) and that 35Hz rated frequency response cabinets can actually be fed 35Hz at full power.

Damage consisting of voice coil formers turned into mini accordions after hitting the back plate or pinky finger sized holes burnt through them or cones bent backwards (think an umbrella bent backwards by the wind) .

In general I rewind them with 16 ohm coils to reduce power absorbed from amp and suggest owner to add an external 2 x 10" to share the heat *and* (the real point) double cone area and cabinet volume.

Oh well.

*Excellent* amps and cabinets but thought for Fusion Bass players, either slapper/tappers or double Bass players or their cousins: fretless guys playing with their fingers.

But for Rock? ...... go get an Ampeg. (or if in Argentina: a Fahey, he he )

[Mike Sulzer]

The K3015 requires a tuning of at least 51 Hz and likes the 55 Hz of the TL606 cabs. So by no way better than, say, two Eminence Beta-12... (each of those actually requires about half of the volume of a 3015 with a very similar tuning, and both shuffle about the same amount of air as a single 3015 for 2/3 of the price but twice the weight). I run both speakers.

But anyway, since the fundamentals of a bass are musically not really important, such cabs perform pretty well with the B string, especially if You use sufficiently many of them.

It might not matter so much in practice, but the K3015 is about 3 db more efficient and so you need about twice the power to drive the two Beta-12s, although the 12s go further up into the mid range...

Yes, forget the fundamental, just make sure that that the voice coil keeps its shape.

[Raybob]

Thanks for all the replies. The amp is 800 watts. Never got to see it, after I explained new tubes won't help and to try it through his folded horn 18 cab and see if problem exists still. Was planning to check all voltages to be sure amp functioned correctly but before I got the amp, I thought I'd ask here about amps pushing frequencies at 31hz (low B).

I remembered a time ~30 yrs ago, I played in trio, guitarist insisted I used his 18 folded horn cab w/his 5 stg bass. I forgot head used but remember feeling the air pushed on my bluejeans. I definitely remember any note lower than a D on lowest string just had no volume. E, Eb, D were fine but C# and below, I stayed away from cause they just didn't come out like the higher notes.

[Leo_Gnardo]

Thanks for all the replies. The amp is 800 watts. Never got to see it, after I explained new tubes won't help and to try it through his folded horn 18 cab and see if problem exists still. Was planning to check all voltages to be sure amp functioned correctly but before I got the amp, I thought I'd ask here about amps pushing frequencies at 31hz (low B).

I remembered a time ~30 yrs ago, I played in trio, guitarist insisted I used his 18 folded horn cab w/his 5 stg bass. I forgot head used but remember feeling the air pushed on my bluejeans. I definitely remember any note lower than a D on lowest string just had no volume. E, Eb, D were fine but C# and below, I stayed away from cause they just didn't come out like the higher notes.

Right next to the folded horn cab, that's what you might expect. Out in the crowd, say 20 to 30 feet away, another story, those low notes come thru like gangbustas. Dial the clock back 50 years, Acoustic 360 was the amp to have. Folded 18 with a built in 200W solid state amp. Sounded terrific, at a distance as I noted, for lowest notes, besides 5 string bass was rare to nonexistent back then. Along comes Ampeg with their new SVT, and they knew something about marketing: the sale is made in the music store. The SVT 8x10's, two recommended per amp, reached right down there & you could hear their massive low end without having to stand back 10 yards. Hmm.... SOLD!

I set up a 2600W rig for rehearsals at Mates in Hollywood 1994, with a couple of CerwinVega 18 "earthquake" cabs. OK standing right next to cabs, loud & low, very satisfying. But walk out toward the stage lip, OMG, lows got seriously shakin'. We identified one spot where you could stand, hit a G on the E string, and vision went fuzzy: the energy at 55 Hz was enough to shake your retinas. And that was at only 300W or so output, heh heh, there's more to go...

So, your SWR friend could use that folded 18, just trust the crowd will hear those lowest notes, they will. Beats the heck out of trying to force that out of a pair of 10's.

[Chuck H]

I went through the thread pretty fast, so please forgive if this has already been covered.

Many speaker options have been suggested. I'm going to side with Enzo, regardless of what speaker/s you choose and say that adding a more suitable cabinet for extra LF combined the combo speakers could make for a very efficient system. Something like a 1x15 sealed cabinet. However, I haven't seen a crossover mentioned. It's probable that just paralleling all the speakers wouldn't eliminate the breakup. Many bass amps and some cabinets have crossovers built in to control the frequencies assigned to individual speaker systems. If you can eliminate the lower, problematic frequencies from the combo speakers and assign them to a more suitable speaker cabinet, while also eliminating less useful higher frequencies from that added cabinet, you can create a much more efficient system. This is old school bass amp tech that I remember from as far back as the late 80's. If built in crossovers aren't present, you would need to purchase or build them. IIRC Parts Express sells speaker building parts and ready made crossovers about as reasonably as anyone.

I just want to add that considering the addition of the "rubber bumper" in the initial repair effort, there may also be a mechanical vibration. You'll need to determine that for yourself with the amp on hand.

[Leo_Gnardo]

However, I haven't seen a crossover mentioned. It's probable that just paralleling all the speakers wouldn't eliminate the breakup. Many bass amps and some cabinets have crossovers built in to control the frequencies assigned to individual speaker systems. If you can eliminate the lower, problematic frequencies from the combo speakers and assign them to a more suitable speaker cabinet, while also eliminating less useful higher frequencies from that added cabinet, you can create a much more efficient system. This is old school bass amp tech that I remember from as far back as the late 80's. If built in crossovers aren't present, you would need to purchase or build them. IIRC Parts Express sells speaker building parts and ready made crossovers about as reasonably as anyone.

Excellent advice! And don't stint on crossover components, OTOH you needn't buy the most expensive. As a crossover, even a single hi voltage film cap in series with the 10's will be an enormous help, Parts Express has them at reasonable price under their Dayton brand. 10's could be series-wired, then you minimize the value of the xo cap, and leave more power from the amp available to drive the low freq speaker where it's more needed.
I'd select a cap say 33 to 50 uF for a rolloff below 300 to 200 Hz for the 10's.

p/n 027-443 50 uF 250V $15

p/n 027-441 33 uF 250V $11

[Mike Sulzer]

I went through the thread pretty fast, so please forgive if this has already been covered.

Many speaker options have been suggested. I'm going to side with Enzo, regardless of what speaker/s you choose and say that adding a more suitable cabinet for extra LF combined the combo speakers could make for a very efficient system. Something like a 1x15 sealed cabinet. However, I haven't seen a crossover mentioned. It's probable that just paralleling all the speakers wouldn't eliminate the breakup. Many bass amps and some cabinets have crossovers built in to control the frequencies assigned to individual speaker systems. If you can eliminate the lower, problematic frequencies from the combo speakers and assign them to a more suitable speaker cabinet, while also eliminating less useful higher frequencies from that added cabinet, you can create a much more efficient system. This is old school bass amp tech that I remember from as far back as the late 80's. If built in crossovers aren't present, you would need to purchase or build them. IIRC Parts Express sells speaker building parts and ready made crossovers about as reasonably as anyone.

I just want to add that considering the addition of the "rubber bumper" in the initial repair effort, there may also be a mechanical vibration. You'll need to determine that for yourself with the amp on hand.

Adding a sub woofer and filtering the real bass out of the bass amp's speakers makes good sense. I think you need more than 1x15 to handle 800 watts, if that really is 800 watts. I wonder if that amp is already rolled off significantly at 30 Hz? 800 watts at 30 Hz into two 10s sounds crazy to me. You might have to power the subwoofer separately if you really want the fundamental.

[bea]

Speaking from memory, the K3015 is about 3 dB more sensitive as a single Beta-12. So using 2 Betas in a column will compensate for the different sensitivities quite exactly. I did a few rough estimates and it will indeed come out nearly par.

In actual applications the form factor will probably matter more: two 12"-speakers side by side will take up 60 cm or more. Despite the similar total volume it will be not that easy to build a cab where You can put a large tube amp on top if You want to maintain the better dispersion of the 12" speaker (i.e. use a vertical column).

[Mike Sulzer]

Speaking from memory, the K3015 is about 3 dB more sensitive as a single Beta-12. So using 2 Betas in a column will compensate for the different sensitivities quite exactly. I did a few rough estimates and it will indeed come out nearly par.

In actual applications the form factor will probably matter more: two 12"-speakers side by side will take up 60 cm or more. Despite the similar total volume it will be not that easy to build a cab where You can put a large tube amp on top if You want to maintain the better dispersion of the 12" speaker (i.e. use a vertical column).

I do not think you get much directivity increase at very low frequencies with two twelves. I think you just have to crank out the power, and that means efficient speakers.

[potatofarmer]

I read that comment as being about vertical vs horizontal alignments of a pair of speakers. Seems a lot of manufacturers split the difference with a diagonal pair of 12s to keep the top of the cab close to the dimension of most amps' footprints.

Speaking from memory, the K3015 is about 3 dB more sensitive as a single Beta-12. So using 2 Betas in a column will compensate for the different sensitivities quite exactly. I did a few rough estimates and it will indeed come out nearly par.

You're right about how the sensitivities line up, but the 3015 has a greater Xmax than the Beta 12. I haven't compared the two either in modeling or in real life, but according to Eminence's plans the 3015 still has the edge over a pair of Beta 12s. Someone at Talkbass came up with this:

Compare these two pdfs--

Beta 12s in cabinets:
http://www.eminence.com/pdf/cab-beta-12a-2.pdf

Look at the 1x12 bass guitar cabinet, and note it sits around 120db peak @ 150w. Two of those, with 300w @ 4 ohms, you can expect around 123-124db. Of course it falls off very fast below 100hz.

Now we look at the Kappalite 3015
http://www.eminence.com/pdf/cab-kappalite-3015.pdf

See that monster go up to 126db, and not displacement limited until you get under 40hz (where most bass amps have a pretty good rolloff).

Now, if you throw that into Winisd and you raise the tuning up to 55hz or so, you'll see a bigger low mid bump and steeper rolloff in the lows, more like you'd expect to see from a "normal" bass cab.

Those are just kind of general comparisons but bottom line, yes, a 3015 will be louder than a pair of 12a-2s

As long as you can put out 300w @ 8 ohms, anyway - over 300w @ 4 ohms and you can be damaging a pair of 12a-2s anyway.

Does anyone have a 2x12 or 4x12 cabinet with Eminence Beta-12A-2s? | TalkBass.com

Then again, Eminence's cab designs usually aren't really optimized, just a good starting point for customers who don't want to get into modeling.

[TimmyP1955]

Keep in mind that:

When someone says that the sensitivity of a woofer woofer is 99dB, they likely measured that at a peak in the response that's well above what we would call "lows".

When someone says that their box is "-3dB at xHz", if X is below 60Hz, they are likely pulling a fast one.


There's a guy who published a design for a dual Lab12 box that he says works nicely to extend the bottom end of a JBL728 dual 18. In this case, I doubt he's lying about it.

[bea]

Yes, i do indeed keep that in mind. In case of the speakers i mentioned above, i also compared the sensitivities resulting from the TSC parameters. To my understanding these model the speaker for those longer wavelengths where the directivity due to the cone geometry is still negligeable, and to me (personally) that's the "real" sensitivity.
At least for those two speakers the ratios between the TSC based sensitivity estimates and the factory specs are quite close.

To my (limited) experience this also corresponds closer to the audible experience.

BTW: the cheap Beta 12 actually belongs to those speakers performing really well for a 5-string bass (i tried). To me a clear demonstration how unimportant it is to be able to reproduce the lowest octave of a bass guitar.