Using WinISD for Traynor TS-215 mod

[shrugs]

OK to get robustness and go down to 27.5 Hz I think you will find that the limiting factor will be not cubic feet but cubic dollars.
FOZ should be along shortly to point you at his answer to that.

As bgavin already pointed out "Whether or not you NEED A0 is subjective, especially in a live mix."
27.5Hz is the fundamental of the lowest note that will go through this cab, yes. It's one whole step down from your average 5 string bass.

300W doesn't seem all that much to ask from a modern cab design either.

When I mix music like this, I certainly don't need to have the bass rumbling at 27.5Hz for it to be audible and clear, I'm not sure why that would be different in a jam space. With my current rig, in the full mix setting, the lowest notes get a bit lost. You can still hear that there is bass, but which note is being played can be a bit unclear. I'm aware this may be due to room modes as well. Yes the room is treated but you know, it's no professional studio. I think that a low tuning is my second priority behind being a robust backline cab, and not nearly as important.

 

[shrugs]

OP don't get carried away with the A0 or whatever. The CB158 is a great sounding bass guitar driver and you've made a good choice. Look at the medium vented cabinet design for it at Eminence's website. It's about half the size of your cab, and you have two drivers. (Convenient...) Tune it to 50Hz as per the design and you will be very happy.

Remember, the king of bass cabs, the 810, rolls off at 70 Hz but nobody complains there's no bass.

You're good.

I'm taking a look now at the [Invalid or Expired Link Removed] for medium vented cab. As people have suggested I'll certainly need a HPF at 40 Hz. Do most of y'all deal with HPFs by building a passive HPFs and putting it inside the cab? Is there a place I can buy one? I can't seem to find one on the Eminence site. I wouldn't mind building one if I had the component values / schematic.

 

[agedhorse]

No, passive HPF's are not effective and I think you will find to be extremely large and expensive too.

You already have essentially a medium sized vented cabinet. The problem is that your expectations and your DIY desires with this cabinet appear to have a wide space between them... I do not think the gap can be closed as easily as you think. You just haven't realized it yet.

 

[shrugs]

No, passive HPF's are not effective and I think you will find to be extremely large and expensive too.

You already have essentially a medium sized vented cabinet. The problem is that your expectations and your DIY desires with this cabinet appear to have a wide space between them... I do not think the gap can be closed as easily as you think. You just haven't realized it yet.

Are passive HPFs not effective in general or just not in this scenario for some reason?

So my expectations are 300W or greater power handling, and solid for a 5 string bass with a low A0. If that is definitely too much to ask for this 6 ft^3 cabinet, so be it! That's why I'm here, I want to learn why that is the case and move on.

 

[Doufuss]

Are passive HPFs not effective in general or just not in this scenario for some reason?

So my expectations are 300W or greater power handling, and solid for a 5 string bass with a low A0. If that is definitely too much to ask for this 6 ft^3 cabinet, so be it! That's why I'm here, I want to learn why that is the case and move on.

A passive HPF is a bad idea especially at those frequencies. Like Aged Horse says, expensive and massive. Broughton Audio among others make them in pedal form, and a really cool semi parametric eq PLUS HPF and LPF filters is made by Tech21. (Qstrip)

Note - You will probably want to increase the diameter of the ports in your cab to reduce chuffing at higher power. Or add a couple more. Play with WINISD and look at port velocity.

With 2 drivers in that cab you'll comfortably be able to drive it to volume levels that will cause permanent hearing damage in a few minutes with just a couple hundred watts. So, my opinion only, don't get too hung up on an HPF.

Finish the cab and play the hell out of it.

 

[micguy]

There are a lot of recommendations on here about other aspects, but one thing I'll throw in is:

You want people to be able to put a higher powered head on your cab, and not blow it up. An 8 ohm (not 4) set of drivers would be a better choice given that objective - with many heads, you'll still be able to get as much out of it as it'll give (excursion limits), no solid state head will ever balk at operating at 8 ohms, and you will be less likely to have the thing go South on you.

 

[shrugs]

Note - You will probably want to increase the diameter of the ports in your cab to reduce chuffing at higher power. Or add a couple more. Play with WINISD and look at port velocity.

With 2 drivers in that cab you'll comfortably be able to drive it to volume levels that will cause permanent hearing damage in a few minutes with just a couple hundred watts. So, my opinion only, don't get too hung up on an HPF.

Finish the cab and play the hell out of it.

Oh, I was under the impression that given my current WinISD setup (as seen in the first post and the graphs in reply to agedhorse), that I 100% needed a HPF or I was gonna blow up my drivers at a typical "punk in a small room" scenario. If that's not the case... is your only recommendation to increase the port holes from 3.5"? According to WinISD, my current setup keeps port air velocity below 17m/s, should that be okay?

 

[Doufuss]

Shrugs you are indeed better off with an HPF. But you can get by without it, like people did for decades by using their ears and not abusing their gear. I'm not modelling the speaker, so I can't say but I would think if the eminence design uses two 4" ports, then you would need more port area with the second driver and the big cab. But, if you say it's good, it should be good. Try it with the 3.5" ports and see.

 

[shrugs]

You want people to be able to put a higher powered head on your cab, and not blow it up. An 8 ohm (not 4) set of drivers would be a better choice given that objective - with many heads, you'll still be able to get as much out of it as it'll give (excursion limits), no solid state head will ever balk at operating at 8 ohms, and you will be less likely to have the thing go South on you.

I was under the impression that the most common load for a bass amp was 4 ohms, so I was headed that route. I have a Traynor Monoblock B (solid state) that is rated at 4 or 2 ohms, just like the Ampeg SVT (tube), which is a standard. Could you explain why I'd be less likely to have the thing go South on me at 8?

 

[agedhorse]

I believe that for typical punk applications, a HPF will be essential to survival. Especially feeding them the signal that you described.

Port chuffing isn’t necessarily a bad thing as the drivers are at the end of their limits, it may help you hear that you are close to damaging your speakers.

 

[shrugs]

Shrugs you are indeed better off with an HPF. But you can get by without it, like people did for decades by using their ears and not abusing their gear. I'm not modelling the speaker, so I can't say but I would think if the eminence design uses two 4" ports, then you would need more port area with the second driver and the big cab. But, if you say it's good, it should be good. Try it with the 3.5" ports and see.

Oh in my original post I have 6 ports! All 3.5" x 6" which got me to a safe port air velocity

 

[agedhorse]

I was under the impression that the most common load for a bass amp was 4 ohms, so I was headed that route. I have a Traynor Monoblock B (solid state) that is rated at 4 or 2 ohms, just like the Ampeg SVT (tube), which is a standard. Could you explain why I'd be less likely to have the thing go South on me at 8?

Because the amp will deliver less power into an 8 ohm load.

 

[micguy]

I was under the impression that the most common load for a bass amp was 4 ohms, so I was headed that route. I have a Traynor Monoblock B (solid state) that is rated at 4 or 2 ohms, just like the Ampeg SVT (tube), which is a standard. Could you explain why I'd be less likely to have the thing go South on me at 8?

The speaker will draw half the power if it’s 8 ohms.

 

[shrugs]

Because the amp will deliver less power into an 8 ohm load.

Is that only true of solid state amps due to the lack of output transformer?

 

[pie_man_25]

I've got an older sealed YS15 with a legend B158. Different cab, different volume, no ports, no HPF, I use a 5 String sometimes tuned a half step down. It works, two guitars and a drummer.

 

[Foz]

You can do what you propose [maintain equal loudness of your rig all the way down to the 20 to 30 Hz band] but understand it is a dark territory versus simply building a musical instrument speaker system. For most folks this is home theater territory because your quoted 27 Hz center frequency is on the cusp of infrasound [below the audible], and thus starting to transition into physical effects versus tones = the realm of Low Frequency Effects [LFE] is used to make your guts shake from pod racer engine vibrations and dinosaur stomps... it is non-trivial to use such musically.

If you want to chase that rabbit I would suggest a stand alone sub-sub box be used to augment your rig in the below typical musical instrument cab low frequency limit [40/50 Hz].

Be aware that in a modest sized room, making signal this low in the audible band, you are not just using the speaker box - the boundaries of the chamber become an integral part of signal propagation and thus these dimensions are of much greater import than applies to higher frequencies. The room dimensions and structural materials as well as the placement of this box in the room will become more critical than you are familiar with when using a typical MI cab.

Good Luck!

===

Are you really sure you need 27 Hz? I suspect your current rig's amp/cab are weak below 50 Hz - and this is where your perception of lack of heft arises- you might want to check that out before you go nuts.

A 1515/66 fearful will do a lot below 50... just saying.

So build one, I dare you.

 

[agedhorse]

Is that only true of solid state amps due to the lack of output transformer?

Yes. You stated that you were using a solid state amp.

 

[bgavin]

OP,
Passive crossovers and HPF at low frequencies require VERY large inductors and capacitors.
Look up the components of a Linkwitz-Riley 24db/octave HPF.
They are huge and pricey. And complicated.

An active HPF that works at the signal level is FAR more practical than a passive one at speaker levels.

Also, get over the wattage thing.
Your concern is SPL, not wattage.
Figure out how much SPL you need, then go from there.

 

[agedhorse]

Passive HPFs are also lossy.

 

[shrugs]

Are you really sure you need 27 Hz?

No, I'm not sure at all lol, that's why I'm here. I started with 55Hz and got the idea of 27Hz from a few words bgavin suggested, but I may have misinterpreted.

Yes. You stated that you were using a solid state amp.

I stated that this cab will be used as a backline cab where the head is a variable. Yes, I do personally own two solid state heads but they will not be the only heads used with the cab, and that's really why I was after the idea of "robustness", but as bgavin pointed out I think SPL is probably more what I'm after.

Also, get over the wattage thing.
Your concern is SPL, not wattage.
Figure out how much SPL you need, then go from there.

Thanks for the input, this seems to make sense to me. The higher the SPL of the cab, the less I have to turn the amp up, meaning I'm putting less power into the thing, meaning the cab wont have handle as much power. Did I get that right? Also, how would I go about figuring out what SPL I need? Simply by putting an SPL meter in front of the bass cab while jamming at full volume?

I'm also still curious about how one would fasten a 4" diameter PVC to the back of the speaker baffle. Any tips there?