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Replacement speaker for Dr.Bass cab

twinfallsbass

twinfallsbass

Jan 24, 2005
1,561
2,253
#1
Hi. I just bought a Dr.Bass RX115's off of TalkBass, it's a 8ohm cab, I also have a Dr.Bass BL212 and it's 4ohms. For a SHORT time I stacked them together with my Traynor YBA 200, whoa, did that sound Gooooood! I did some searching on T.B. and found that combining 4ohm and 8ohm ( 2.67 ohms ) cabinets is a BAD thing for tube amps ( I guess that's a hot debate in itself ). Is there any updated info on this mismatching cab impedances debate, is it alright/not alright. To make these cabs match I would need a 4ohm speaker so I would get a combined 2ohm load when stacking them and in turn satisfy my Traynor YBA's needs. Is there anyone out there who was in the same boat as me and changed out their speaker so the cab impedance's match? What speaker did you use? I have and email out to Marc at Dr.Bass, waiting for a replay.
 
#3
Blues Cat said:
If the YBA200 is rated @ 2 ohms minimum then 2.67 should be fine.
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That's what I thought until I started looking through the threads on that very subject. There are people that say it's ok and people who say it's not. I guess it has something to do with what the output transformer and tubes want to see, they want to see either 2, 4, or 8ohm loads, not some bastard load like 2.67ohms LOL. Like I stated earlier, I played through the combination of those two cabs with my Traynor and it sounded sweeeeet, no smoke, no fireball.
 
#4
Blues Cat said:
If the YBA200 is rated @ 2 ohms minimum then 2.67 should be fine.
Click to expand...

That would definitely be true for a solid state output section on an amp. They have super low output impedence, its current issues, sagging power supply voltages that cause trouble at low ohm ratings. Anything above the rated ohms is generally fine, within reason.

I've heard tube amps need to be more precise. Heard they have taps on the output transformer for various ohm ratings. Putting a 4 ohm speaker on the 8 ohm outputs, or vice versa, or 2.67 on the 2 ohm taps can be problematic. I'm not a tube expert, more familiar with solid state, so I could be wrong.

But I believe tube amps are a completely different animal from solid state as far as driving different ohm loads.

Randy
 
#5
TFB I would call Traynor Mon morning and see what they say. I've read that they're very cool and accessible.

If they say it's cool then you don't run the risk of voiding the warranty.;)

twinfallsbass said:
That's what I thought until I started looking through the threads on that very subject. There are people that say it's ok and people who say it's not. I guess it has something to do with what the output transformer and tubes want to see, they want to see either 2, 4, or 8ohm loads, not some bastard load like 2.67ohms LOL. Like I stated earlier, I played through the combination of those two cabs with my Traynor and it sounded sweeeeet, no smoke, no fireball.
Click to expand...
 
#8
Has anyone tried these:
Eminence Basslite C2515 Neo 15"Recommended for bass guitar. Excellent in either sealed or vented enclosures.

Specifications: *Power handling: 300 watts RMS *VCdia: 2.5" *Le: 0.39 mH *Impedance: 4 ohms *Re: 3.72 ohms *Frequency range: 52-2,500 Hz *Magnet weight: 7 oz. *Fs: 38 Hz *Sensitivity: 98 dB 1W/1m *Vas: 9.2 cu. ft. *Qms: 4.7 *Qes: 0.50 *Qts: 0.45 *Xmax: 4.5 mm *Dimensions: Overall Diameter: 15.32", Cutout Diameter: 14", Mounting Depth: 6.9".
 
#9
If it was true that a tube amp's impedance had to be so precisely matched, then you'd never find a speaker to match. No speaker is at its exact rated impedance but it depends on what frequency it's trying to reproduce. At least, that's what I've heard. I haven't measured the impedance of any speakers while they are actually reproducing music, but I have heard it varies depending on frequency.
 
#10
Excellent point 62

62bass said:
If it was true that a tube amp's impedance had to be so precisely matched, then you'd never find a speaker to match. No speaker is at its exact rated impedance but it depends on what frequency it's trying to reproduce. At least, that's what I've heard. I haven't measured the impedance of any speakers while they are actually reproducing music, but I have heard it varies depending on frequency.
Click to expand...
 
#12
I've designed speakers specifically for tube amps, and to make a long story short I'd say that if a given tube amp is happy with a "2 ohm" load then it will be happy - and probably even happier - with a 2.67 ohm load.

Also, as 62bass noted, the real-world impedance of a loudspeaker usually varies considerably with frequency. Tube amps and solid state amps interact differently with the speaker's impedance curve, which can present both challenges and opportunities to the speaker designer.

twinfallsbass, if you really like the combination described in your initial post, note that changing the 15" to a 4 ohm driver will change the sound. For one thing, that 4 ohm driver will draw twice the wattage as the 8 ohm one, so it will play about 3 dB louder (all else being equal), and that will change the tonal balance. I suggest you not change anything.
 
#16
Another thing you could do is put two 16 ohm 3012HOs (or deltalite 2512 IIs) in the 212, and run them both at 8 ohms. :)

Since you're usin tubes, you get the full 200ish watts whatever you run it at ohm-wise, sot hat might be a better option.

Especially since those RX cabs are made of MDF and might not be braced for the beefcake of a bigger speaker. I have heard of people rattling MDF cabs really badly with 3015LFs.
 
#17
Thanks rpsands. I actually just got off the phone with Traynor about the whole " mismatching cab impedances " thing. They said, although it is not optimum as far as power distribution goes, it was fine to run this head with a 2.67ohm load and it will not hurt the amp or shorten the life of the tubes. They also told me that the whole " 2.67ohms is bad for tube amps " pertained to older style tube amps. So there you go, people who have Traynor YBA 200's can mismatch their cabs without hurting their tube amps:hyper:. Glad that's over with;)
 
#20
greenboy said:
Probably could have been over sooner if had read various threads about the Traynor head ; }
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Actually I did do a search, this is not my first time around the block ( no offense ), all I found were topics on the manual biasing issues and people trying to install KT88's. I read for hours on the subject of the " 2.67ohm " issue and did not see one thread containing the Traynor YBA 200. Thanks for your input.
 

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