Double Bass Question about doubling with my AI Coda

[lowEndRick]

I have been obsessing over a solution for my doubling rig. I use a 2-channel Acoustic Image Coda and several different cabs depending on the gig (Schroeder 12" 4ohm for most gigs, the Coda 10/5 combo cab for small venues, and a 15"Celestion speaker in an Armadillo ported cab for bigger no-PA support gigs). I am very satisfied with my upright sound and tone with my 40' Kay and 2014 Cleveland both with Lifeline pickups. I also play a Fender roadworn pbass that I have been running straight to the Coda. I dial the tone way back on the pbass and I get a very nice warm, vintage sound but not much bite. I also think sometimes that it could use a little compression.
I was thinking of maybe adding an Aguilar Preamp for the pbass. Anyone know how effective it would be adding this preamp to the Coda?
I also question my cab situation. My Schroeder 12" does a good job, but after playing some Aguilar cabs I was thinking that my Schroeder is not as lush in the lows as the Aguilars. I could pair my Schroeder 12" 4ohm with my 15" 8ohm for more low end, and I think the ohm calculation would be ok with the Coda. Anyone know for sure if this would be ok? I also considered just buying a Aguilar SL112 8ohm and selling the Schroeder. Any advice or thoughts on a cab purchase for my rig?

 

[yodedude2]

... I could pair my Schroeder 12" 4ohm with my 15" 8ohm for more low end, and I think the ohm calculation would be ok with the Coda. Anyone know for sure if this would be ok? ...

if you have an a.i. amp that says "2 ohms" on the back side, it would be okay to run one 4 ohm cab and one 8 ohm cab in parallel. my a.i. gear really hits its sweet spot at 2.67 ohms ~

 

[lowEndRick]

if you have an a.i. amp that says "2 ohms" on the back side, it would be okay to run one 4 ohm cab and one 8 ohm cab in parallel. my a.i. gear really hits its sweet spot at 2.67 ohms ~

Thanks! I had spoken to Rick Jones a lot in the last 15-20 years and I vaguely remember that he once said that I could easily go down to 2.67ohms. Sadly, as most of you probably know, Rick passed in April. Such a kind and generous guy, and a total genius.

 

[yodedude2]

^^ indeed. there are only a few of rick's amps (series 3, maybe?) that are not designed for 2 ohm loads. most of his amps are. there should be a sticker on the back that states the minimum ohms rating.

if you do run a 4 ohm and 8 ohm cab in parallel, be aware that the 4 ohm cab will receive twice the power of the 8 ohm cab.

obtw i used to run an a.i. focus series 3 with a 15" schroeder pl at 4 ohms & a fearful 12sub at 8 ohms. that rig was awesome ~

 

[lowEndRick]

if you do run a 4 ohm and 8 ohm cab in parallel, be aware that the 4 ohm cab will receive twice the power of the 8 ohm cab.

Hmm, so the Coda provides 650w at 4ohms. Does that mean the Schroeder 12" 4ohm gets 650w and the 15" 8ohm gets 325w? The 15" is rated at 400w. I worry more about underpowering the 15". Any thoughts?

 

[shwashwa]

i would try a preamp in front of the amp for electric bass before you do anything. there are so many to choose from

 

[Francois Blais]

Hmm, so the Coda provides 650w at 4ohms. Does that mean the Schroeder 12" 4ohm gets 650w and the 15" 8ohm gets 325w? The 15" is rated at 400w. I worry more about underpowering the 15". Any thoughts?

No.
That means the 4 ohms speaker will get 2/3 of the total power provided by the amp, and the 8 ohms speaker with get the third. (half the power gotten by the 4 ohms)
Assuming the amp will produce 750 watts at 2.67 ohms, the 4 ohms will get 500W and the 8 ohms 250W.
I don't know what power the Coda will deliver at 2.67 ohms.
But you get the picture.

 

[lowEndRick]

No.
That means the 4 ohms speaker will get 2/3 of the total power provided by the amp, and the 8 ohms speaker with get the third. (half the power gotten by the 4 ohms)
Assuming the amp will produce 750 watts at 2.67 ohms, the 4 ohms will get 500W and the 8 ohms 250W.
I don't know what power the Coda will deliver at 2.67 ohms.
But you get the picture.

Yeah, I get it. Thanks. I believe it is less than 750 at 2ohms. That really under-powers the 8ohm 15".

 

[yodedude2]

... I worry more about underpowering the 15". Any thoughts?

why is that a worry? i suggest you try that setup out first before worrying ~

[post 7 explains the matter perfectly, thanks mr. b!]

 

[brianrost]

lowendRick, which Coda version do you have…series 2, 3, 4?

I’ve used my Coda s3 with a Bergantino HT112 cabinet and the HT112 totally swamps the internal speakers volume…huge difference in sensitivity. I did the math once and the HT112 was 12 dB louder than the internal speakers with the same wattage.

My amp has a switch to disable the internal speakers, so I just disable the internal speakers. Not all s3 amps have that switch, my Contra s3 for example does not. It’s also not shown in the manual, so I don’t know how common it is. With the internal speakers disabled I can either run at 8 ohms with a single HT112 or 4 ohms adding my second HT112, it gets crazy loud either way. Seems silly to lug a combo amp around to use as a head, though

Just to complicate calculations: The s3 manual specs the internal speakers as 4 ohms, power is 400W RMS with the internal speakers but only increases to 500W RMS with a 4 ohm extension (2 ohm load). The internal speakers for s4 are 8 ohm for Coda and 4 ohms for Ten2 plus the wattage is a bit different, 300W RMS into 8 ohms, 500 W RMS into 4 ohms. The back panel still says 2 ohm minimum but there’s no spec for the wattage.

 

[lowEndRick]

lowendRick, which Coda version do you have…series 2, 3, 4?

I’ve used my Coda s3 with a Bergantino HT112 cabinet and the HT112 totally swamps the internal speakers volume…huge difference in sensitivity. I did the math once and the HT112 was 12 dB louder than the internal speakers with the same wattage.

My amp has a switch to disable the internal speakers, so I just disable the internal speakers. Not all s3 amps have that switch, my Contra s3 for example does not. It’s also not shown in the manual, so I don’t know how common it is. With the internal speakers disabled I can either run at 8 ohms with a single HT112 or 4 ohms adding my second HT112, it gets crazy loud either way. Seems silly to lug a combo amp around to use as a head, though

Just to complicate calculations: The s3 manual specs the internal speakers as 4 ohms, power is 400W RMS with the internal speakers but only increases to 500W RMS with a 4 ohm extension (2 ohm load). The internal speakers for s4 are 8 ohm for Coda and 4 ohms for Ten2 plus the wattage is a bit different, 300W RMS into 8 ohms, 500 W RMS into 4 ohms. The back panel still says 2 ohm minimum but there’s no spec for the wattage.

Thanks for your reply. I think I have a series 4, but I am out of town so I can't confirm. I have owned and extensively used this amp for nearly 13 years. I should have been more clear about how I use the Coda. When paired with any of my cabinets, I just pull the Coda head out of the combo speakers, so it is head straight to the cab(s). My Coda says 600w at 4ohms and 300 at 8ohms. I believe Rick said it is more like 650. The back panel also says 2 ohm minumum.

 

[Michael Eisenman]

^^ indeed. there are only a few of rick's amps (series 3, maybe?) that are not designed for 2 ohm loads. most of his amps are. there should be a sticker on the back that states the minimum ohms rating.

My Series III Focus is designed for 2 ohms.

 

[Michael Eisenman]

I was thinking of maybe adding an Aguilar Preamp for the pbass. Anyone know how effective it would be adding this preamp to the Coda?

I suspect that you have the Coda+ with the Docking System, since you said that you can pull out the head from the cab.

Regarding using the Aguilar preamp with the amp, you can run it into the effects return for the P-Bass channel, bypassing the internal preamp. The only disadvantage that I can think of is that you will lose the HPF function, since the effects loop comes after the internal preamp.

 

[lowEndRick]

why is that a worry? i suggest you try that setup out first before worrying ~

I worry because of information I have received from companies like Acoustic Image, Epifani and Gollihur.
Check out this example: Choosing Speakers and Amps to Work Well Together

 

[brianrost]

Thanks for your reply. I think I have a series 4, but I am out of town so I can't confirm. I just pull the Coda head out of the combo speakers, so it is head straight to the cab(s). My Coda says 600w at 4ohms and 300 at 8ohms. I believe Rick said it is more like 650. The back panel also says 2 ohm minumum.

Series 4 has four EQ bands (bass, low mid, hi mid, treble) and only a high pass filter (no notch).

If the head is removable, that’s the “Cabrio system” which was available as retrofit for series 3, standard in the series 3+ and series 4. Sounds from the wattage numbers that you have s4. My Coda and Contra are s3 and were never converted to the Cabrio system. If you are using the head alone, then you're free to use whatever cabs you like.

AI wattage is spec'ed in most manuals with “>” which is "greater than” suggesting it’s conservatively rated. The difference between 600 and 650W is negligible. The power stage was redesigned in each iteration.

Series 3

3+

Series 4

 

[yodedude2]

I worry because of information I have received from companies like Acoustic Image, Epifani and Gollihur.
Check out this example: Choosing Speakers and Amps to Work Well Together

ah yes, one must listen to be sure they are not pushing an amp too hard when powering their speakers. sage advice. such distortion can quickly fry a tweeter.

in your particular instance, i don't think that 200 watts on tap is underpowering a single 15", even moreso in that the 12" will receive ~ 400 watts of power near full volume in this scenario. i reckon you'd be more likely to toast the 12".

 

[lowEndRick]

ah yes, one must listen to be sure they are not pushing an amp too hard when powering their speakers. sage advice. such distortion can quickly fry a tweeter.

in your particular instance, i don't think that 200 watts on tap is underpowering a single 15", even moreso in that the 12" will receive ~ 400 watts of power near full volume in this scenario. i reckon you'd be more likely to toast the 12".

The 15" is 8ohm and rated at 400w. The 12" is 4ohm and rated at 400w. I play with the 12" alone most of the time with Master at 12 o'clock and the Level between 7-10 o'clock. I never have a problem. Based on the Gollihur article I believe I would be best off with an amp that provides at least 400w to each cab. Am I wrong?

 

[yodedude2]

i.m.o., it depends on how you interpret gollihur's advice. it seems the suggestion in that article centers about the idea of pushing a smaller amp too hard, causing the amp to distort, which can damage a speaker. it's easy to agree with this premise. but, it's not a matter of underpowering the speaker causing speaker damage per se, but rather a matter of driving an amp beyond its design limits that leads to speaker damage. gollihur explains this clearly in paragraph 7. to expand on his example, even if one did use a 150 watt amp with a 1,000 watt rated speaker, the speaker would not be in trouble as long as one kept the amp within its design limits and not 'clipping' it (i.e., not using the Hartke amp "with all the knobs dimed"). it's not the 'mismatched' wattage ratings that are the problem here; it's the probability that one does not understand how to use their amp properly. the hartke amp in the example was likely fine powering the swr cab until the user pushed the amp beyond its limits.

it's not a case of being right or wrong in your particular scenario; it's a matter of context in the way the speakers and amp are being used together. if you are using a 4-ohm 12" and an 8-ohm 15" in the manner you describe, the analogy gollihur provides, i.e., a civic motor in an escalade being floored on a freeway entrance ramp, doesn't fit at all. ultimately, gollihur's premise stands as good advice--if one is 'diming' their amp, they risk speaker damage and should use an amp with more headroom instead.

obtw, with a difference in ohmage ratings such as you describe, you are not going to get equal wattage output to both cabinets. if you are that concerned about matching the amp to the cabinets, then you need to get an 8 ohm 12" or a 4 ohm 15", not a different amp.

edit: as an aside, i'm an ebg player, and i used to run a 4-ohm 15" schroeder paired with an 8-ohm 12" fearful 12sub on gigs for years, using an a.i. series 4 head (the model name escapes me at the moment).

 

[lowEndRick]

edit: as an aside, i'm an ebg player, and i used to run a 4-ohm 15" schroeder paired with an 8-ohm 12" fearful 12sub on gigs for years, using an a.i. series 4 head (the model name escapes me at the moment).

Oooh, that's really helpful to know. Thanks! Do you remember the wattages those cabs were rated at?
At the moment I am thinking of maybe buying an Aguilar SL112 8ohm 250w and the Aguilar preamp. I think I would be more comfortable pairing that with my Coda and my 15" 8ohm 400w. I imagine that will give me the sound I want for bass guitar and maintaining what I currently have with my upright (nearly full time bluegrass player).

 

[yodedude2]

Oooh, that's really helpful to know. Thanks! Do you remember the wattages those cabs were rated at?

not exactly, but they were both nominally rated in the 400 - 500 watt range.