Double Bass Acoustic Image Series III

[fdeck]

Hey Ric - right you are (I always wondered why guitarists can use a 50 watt amp and overpower my 650 watt bass rig.) But this Clarus/Focus difference of less than 3db is still small. I'm sure you'll hear/feel a difference by getting the bigger amp but don't be surprised if it's small. You may find it easier to get a cabinet whose efficiency betters 3db for the same money. Caution: spec rating comparisons across different manufacturers are not to be relied on. Unless you can set up a lab and do this type of testing in a controlled manner, use your ears.

I think a 3 dB difference is noticeable, even if not earth shattering. Nonetheless, I agree about sensitivity ratings. These are useless unless they are actually given as a curve. Just a single number, typically quoted at 1000 Hz, could be inflated by a resonant peak at that frequency, or anything else that emphasizes high end response such as a whizzer cone.

In tinkering with my DIY speakers, I have learned a trick for comparing sensitivity. Plug both speakers into one amp, and run them in parallel at moderate volume (i.e., considerably below clipping and at a volume where you can listen comfortably). Have a friend unplug one speaker at a time, and see how the overall volume changes. If one speaker is much less efficient than the other, you will barely notice its absence.

In the above test, if both speakers are identical, you will get exactly a 3 dB change. This will let you calibrate your ears as to what 3 dB sounds like.

Let me admit that I am presently gassing for a new amp, and the Clarus III is looking good. Leaving the details of this decision aside for a moment, here are my thoughts about speaker sensitivity.

I have a lightweight 1x12 that I am happy with. With either the GK or AI heads, I would get a fair amount of sound, ample for club gigs. If I want to be louder, I could just plug in a second identical 1x12. This would result in (approximately) twice the power due to going from 8 to 4 Ohms, and twice the sensitivity. This is a 6 dB boost. A reliable rule of thumb is that multiple drivers increase sensitivity. Cone area is also a good predictor among speakers that are designed for roughly the same response curve. Notable exceptions (Acme?) tend to be small speakers with extended low end.

 

[drurb]

In the above test, if both speakers are identical, you will get exactly a 3 dB change. This will let you calibrate your ears as to what 3 dB sounds like.

Well, not really. You have not taken phase into account. If you connect two speakers as you suggest and they were prefectly in-phase at the point at which you listened, you would have a 6 dB increase. If they were perfectly out-of-phase, you would have complete cancellation. Now, two cabinets with different crossovers and drivers are likely to be in-phase for some frequencies, out-of-phase for others, and everything in between.

 

[drurb]

In an earlier post, I wrote:

"Just a reminder that going from 300 to 600 watts buys you only 3 dB. Assuming the circuit topology is similar on the two amps you will only get 3 dB power in the peaks as well."


That is true regardless of any frequency effects. If we assume the circuits to be otherwise identical, you will achieve 3 dB more output.

The reason the lowest frequencies seem to require more amplifier power is usually because the response of the cabinet rolls off in that region. If a cabinet really did have the same sensitivity at a very low (say for the "E" string at about 44 Hz fundamental) and a mid frequency (the G string), it would take no more power to achieve the same acoustic output at the low frequency than at the higher one.

It IS true that if you are playing at a low level (and this really doesn't apply to most of us!), then the perceived loudness of the lowest frequencies will be less than those of the mid-frequencies. At higher levels the loudness "contours" flatten and this effect disappears.

The 3 dB aside, it MAY be useful to go from 300 watts to 600 watts in cases where one is just pushing the envelope on the 300 watt amp such that it distorts. Going to 600 watts might give you neede breathing room but only 3 dB of it.

Finally, by going from 300 to 600 watts, you do not achieve some magical increase in headroom. If the circuits are otherwise identical, the headroom, defined as the transient power output relative to the continuous does not change at all. For example, lets say two otherwise identical amps can deliver 1 dB of headroom. The 300 watt amp will reach 378 watts short-term, and the 600 watt version will reach 755 short-term. It's 3 dB any way you cut it.

 

[werner vw]

Hi, i wonder how a CODA Handle A low B?

Thank you

 

[Ric Vice]

Well, the rated frequency response is 30 Hz-20kHz (40 Hz-16 kHz + 3db), but in my experience that cabinet isn't well suited for a
5 string bass. It's really designed for the Double Bass. The tone quality of that cabinet, is a very aquired taste. Some like it, some don't.

Ric Vice

 

[Ric Vice]

Well, the rated frequency response is 30 Hz-20kHz (40 Hz-16 kHz + 3db), but in my experience that cabinet isn't well suited for a
5 string bass. It's really designed for the Double Bass. The tone quality of that cabinet, is a very aquired taste. Some like it, some don't.

Ric Vice

 

[Bob Gollihur]

It really comes down to purpose, tone, and volume needs. I've taken a Contra out with my five string (low B) fretless bass for acoustic style and commercial jazz gigs where that was the call, rather than URB, and it handled B string activity ok for an intimate club/bookstore environment. It ain't a rock n roll amp or for competing with a drummer who lacks a volume control.

I've recommended a Clarus/EA Wizzy rig or Wizzy combo for guys who don't need a lot of volume but do need a little more focus to cut through a mix, it's a more versatile rig for URB and eBass use.

Disclaimer: I sell 'em as well as gig 'em.

 

[Ric Vice]

It really comes down to purpose, tone, and volume needs. I've taken a Contra out with my five string (low B) fretless bass for acoustic style and commercial jazz gigs where that was the call, rather than URB, and it handled B string activity ok for an intimate club/bookstore environment. It ain't a rock n roll amp or for competing with a drummer who lacks a volume control.

I've recommended a Clarus/EA Wizzy rig or Wizzy combo for guys who don't need a lot of volume but do need a little more focus to cut through a mix, it's a more versatile rig for URB and eBass use.

Disclaimer: I sell 'em as well as gig 'em.

Good Words: I especially liked the part about the non attinuated
percussionist.

 

[Kael]

Good Words: I especially liked the part about the non attinuated
percussionist.

Funny, I've discovered that there is no part of a non-attenuated drummer that I care for......

 

[bluegreenturtle]

Could somebody please school me on something I've never been very clear on?

I am planning on buying a new head, but it seems to me like these higher wattages on the focus make it even less suitable for most cabinets.

For example, I have a bergantino ht112 which says "300 watts" on it's rating. Isn't it dangerous to run an amp that says it puts out 450 watts at 8 ohms into this cab? Or does it not work this way?? I'm really not sure? I always just tried to match the cabinets and amps pretty closely.

 

[drurb]

Could somebody please school me on something I've never been very clear on?

I am planning on buying a new head, but it seems to me like these higher wattages on the focus make it even less suitable for most cabinets.

For example, I have a bergantino ht112 which says "300 watts" on it's rating. Isn't it dangerous to run an amp that says it puts out 450 watts at 8 ohms into this cab? Or does it not work this way?? I'm really not sure? I always just tried to match the cabinets and amps pretty closely.

On a cabinet with a tweeter, you are more likely to do damage with an undperpowered head than with an overpowered head. This is because, if you overdrive the head, it will clip the waveform and splatter energy to the high frequencies. This tends to fry tweeters. The Bergie is rated at 300 watts rms. Most likely, this means the cabinet can handle 300 watts continuously. You are not likely to really push the cabient at 300, much less 450 watts continuously. If you are worried, you can always fuse the cabinets to prevent them from being overdriven.

 

[oystein]

Hi,
does anybody know if there will be a new design for the preamp in the series III. The reason I am asking about that is my experience with Contra series I, where I have gained a much better sound running my Raven Labs or Fishman Platinum preamp directly to the effect return. IMHO it shouldn't be necessary to have an additional preamp for equipment at this price level.

Oystein

btw, I am extremely lucky these days as I received my Sadowsky Metro RV4 last Saturday. Best toybass I've ever owned. I know, very off-topic.

 

[Bob Gollihur]

Hi,
does anybody know if there will be a new design for the preamp in the series III. The reason I am asking about that is my experience with Contra series I, where I have gained a much better sound running my Raven Labs or Fishman Platinum preamp directly to the effect return. IMHO it shouldn't be necessary to have an additional preamp for equipment at this price level.

Oystein

btw, I am extremely lucky these days as I received my Sadowsky Metro RV4 last Saturday. Best toybass I've ever owned. I know, very off-topic.

The preamp is essentially the same as the Series II, just a couple minor mods. You don't need an external preamp in most cases, although I prefer to keep signal cables as short as possible. If they are not, sometimes a preamp closer to the transducer, can make a difference in tone.

 

[DB66]

I'm considering purchasing a Contra Series III and an Acme Low B1 and eventually a second Acme Low B1 cab for the ultimate versatility (small, medium and large gigs). I haven't decided if I should get an 8 ohm or 4 ohm cab. So I'm wondering if I can use a Contra Series III with an Acme 4 ohm for medium gigs and a combination of 4 ohm and 8 ohm cabs together for larger gigs. What's that work out to 6 ohms or 2 ohms? Would a 4 ohm/8 ohm cab combination work? On Bob's site it says a Contra runs 450 watts at 2 ohms. Thanks.

[edit] ...or would two 4 ohm acmes work wth a Contra bringing the load to 2 ohms, thereby getting the full volume?

 

[Bob Gollihur]

I'm considering purchasing a Contra Series III and an Acme Low B1 and eventually a second Acme Low B1 cab for the ultimate versatility (small, medium and large gigs). I haven't decided if I should get an 8 ohm or 4 ohm cab. So I'm wondering if I can use a Contra Series III with an Acme 4 ohm for medium gigs and a combination of 4 ohm and 8 ohm cabs together for larger gigs. What's that work out to 6 ohms or 2 ohms? Would a 4 ohm/8 ohm cab combination work? On Bob's site it says a Contra runs 450 watts at 2 ohms. Thanks.

[edit] ...or would two 4 ohm acmes work wth a Contra bringing the load to 2 ohms, thereby getting the full volume?

You could add a 4 ohm cabinet to the Contra's (assuming it is actually 4 ohms or higher) 4 ohm cabinet, which results in a 2 ohm load. You could not add any additional cabs as it would take it below 2 ohms. OTOH, you could add two 8 ohm cabinets as they result in a 4 ohm load.

 

[Adrian Cho]

Personally, I don't think think a B1 would be all that good a match for the Contra but that's just me. What you've got there are two cabs that have very full sounds at low volume. Neither cuts through well at higher volumes. I think all you'll end up with is a huge wall of sound. Just my $0.02 as both a previous Coda and B-1 user although I've never used them together.

 

[Randy Ward]

Personally, I don't think think a B1 would be all that good a match for the Contra but that's just me. What you've got there are two cabs that have very full sounds at low volume. Neither cuts through well at higher volumes. I think all you'll end up with is huge wall of sound. Just my $0.02 as both a previous Coda and B-1 user although I've never used them together.

Adrian;
What do you think would be a good combination? Do you think the LDS design cuts better? What about having the B-1 on a stand to get rid of the acoustic coupling from the floor and possibly being able to cut through better because of the height?

 

[robgrow]

I'm considering purchasing a Contra Series III and an Acme Low B1 and eventually a second Acme Low B1 cab for the ultimate versatility (small, medium and large gigs). I haven't decided if I should get an 8 ohm or 4 ohm cab. So I'm wondering if I can use a Contra Series III with an Acme 4 ohm for medium gigs and a combination of 4 ohm and 8 ohm cabs together for larger gigs. What's that work out to 6 ohms or 2 ohms? Would a 4 ohm/8 ohm cab combination work? On Bob's site it says a Contra runs 450 watts at 2 ohms. Thanks.

[edit] ...or would two 4 ohm acmes work wth a Contra bringing the load to 2 ohms, thereby getting the full volume?

Using speaker cabinets of different types, different impedances, and different sensitivities together introduces a lot of variables. It's hard to say anything for sure without really trying it. If you want to go with Acme Low B-1's, I'd recommend getting them in the 4-ohm version and skip the AI combo altogether and get the higher-power Focus amp instead.

 

[DB66]

Using speaker cabinets of different types, different impedances, and different sensitivities together introduces a lot of variables. It's hard to say anything for sure without really trying it. If you want to go with Acme Low B-1's, I'd recommend getting them in the 4-ohm version and skip the AI combo altogether and get the higher-power Focus amp instead.

Thanks for all the suggestions. I guess I'm trying to have it all in one amp - one purchase. There's those gigs that only require a small amp and it's just easier to walk from work with a tiny amp and Eminence rather than take the subway home get all the stuff and go back out again. Since I'm getting 1099'd on all my gigs now, I might as well buy every combination and write it all off, better than paying taxes.

 

[Adrian Cho]

It all depends on what you're looking for. Erik Hansen (LowNote here) for example uses a Contra + B-1 but I couldn't imagine it myself. The LDS 3-way definitely has a very aggressive sound that will cut through anything. It's the complete opposite of the B-1 in many ways.

I agree with robgrow. If I was you I'd just skip the combo and get the Focus and a B-1 or two if you want. As for 4 or 8 ohm, it ain't gonna matter that much. The B-1 is only rated for 175 W anyway so even at the 8 ohms, the Focus has more than enough power. Then again if weight is an issue for you, Focus + B-1 is only 35 lbs but it is a good 10 lbs heavier than the AI series II combo or probably 15 lbs heavier than a series III combo.