Help me - need new speaker(s) and possibly cab mods - porting/tuning/etc gurus wanted

[bolt_thrower]

Hello my fellow TBers, here's the deal. I bought a late 60's Traynor YT-15 2x15" cab a couple of days ago on the cheap because the speakers were/are busted AFAIK. Here are two pics:




The cab is sealed (no ports) and measures approximately 40.5"x19.5"x13.5". There is also a "divider" which separates the cab in the middle which essentially isolates the two speakers.

I now need to decide what to do with it. My two ideas are:

1) Keep the cab as is (sealed, non-ported 2x15" with the "divider") and just get two new speakers. With this option, I have no idea what speakers would work and how it would sound. A sealed cab will not be able to push the super lows as much as a ported cab, right?

2) Convert the cab into a large, 1x15" cab with a port, something like this project by another TBer:
Cab project is completed, and sounds great!
Again, I'm not sure what my speaker choices would be, but I've been reading the Eminence datasheets and it looks like they provide some sample cab ideas that fit my cab's dimensions. With this choice, I have no idea what to do with the divider since the air needs to be shared inside the cab. If I cut a hole in the divider (still keeping the divider there though), would that provide enough air flow inside the cab?

My main questions are the following:
- Which of the two choices would be better?
- What would the two sound like (would either choice be louder than the other)?
- Which of the two options would handle the power better (i.e. no farting out and ability to handle the low B)
- What speakers should I be looking at?
- What should I do with the divider if I want to follow the second option (or even the first option)?

Thanks!

[billfitzmaurice]

Your amp determines how much sensitivity you need. An UberDriver is no good if you don't have the power to push it.

[BassmanPaul]

For a start you'll need to keep the shelf. It's part of the bracing for the cabinet and I think you'll find the back screws into it. I'd keep the cabinet as a twin 15.

Download WinISD and put your cabinets dimensions into that program and see if you can get a driver match. Seem to me, but only what I've read, that the 3015 appears very tolerant of a range of cabinet volumes. If I'm wrong here I'm sure I'll soon be "educated"!

Paul

[bolt_thrower]

Originally Posted by billfitzmaurice

Your amp determines how much sensitivity you need. An UberDriver is no good if you don't have the power to push it.

Hmm, I guess that I'd like to get some efficient speakers. I plan on running this cab with my Acoustic 140 which puts out 125W @ 4 ohms.

Originally Posted by BassmanPaul

For a start you'll need to keep the shelf. It's part of the bracing for the cabinet and I think you'll find the back screws into it. I'd keep the cabinet as a twin 15.

Download WinISD and put your cabinets dimensions into that program and see if you can get a driver match. Seem to me, but only what I've read, that the 3015 appears very tolerant of a range of cabinet volumes. If I'm wrong here I'm sure I'll soon be "educated"!

Paul

I'll definitely try the software out. As for the shelf, I was thinking of just cutting a hole in the middle of it if needed and keeping the brace part intact so that I could still attach the back to it. Yes, the back does screw onto it, but I'm damn sure that it's not necessary since the second generation of the YT-15 didn't have the middle shelf.
Would an unported dual 15" cab be a good choice though if I don't want it to fart out on the low B?

[billfitzmaurice]

Originally Posted by bolt_thrower

Hmm, I guess that I'd like to get some efficient speakers. I plan on running this cab with my Acoustic 140 which puts out 125W @ 4 ohms.

All instrument drivers have similar efficiency. With that small amount of power the concern is the response curve, to make the best use of the power you have. You simply don't have the power to make use of a high excursion driver capable of deep lows. Load it with a pair of Beta 15s and leave it sealed. Be sure to line the box with foam or polyfill batting; hard to believe cabs were ever sold unlined.

[bolt_thrower]

Yeah, old Traynor cabs weren't exactly the best designed.
How do you think would the Beta 15s handle the lower bass notes (down to the low B) in the sealed cab? Thanks for the rec!

EDIT: I have no problem with keeping it sealed since I think I would like the tone of a sealed cab (from what I've read, sealed cabs tend to be more compressed and middy which I love), my only concern is the farting out which I would love to avoid.

[billfitzmaurice]

Originally Posted by bolt_thrower

How do you think would the Beta 15s handle the lower bass notes (down to the low B) in the sealed cab?

As well as anything will with that amp. You don't have enough power to outrun them.

[Mr. Foxen]

Is that going to be your sole amp/cab? Guessing from the name it might not be, if you have another cab for actual lows, maybe consider speakers intended for guitar, some come in 15", that will give some more driveyness.

[bolt_thrower]

^ For the time being, it will be my only cab.

Originally Posted by billfitzmaurice

As well as anything will with that amp. You don't have enough power to outrun them.

Allrighty then. I'm not worried about getting the lows since I've played my Acoustic through a bunch of cabs including a couple of 8x10 fridges. It was just as loud as the SVT-3 Pro that I put it up against and I liked the tone better, so I'm not really too worried about a lack of low end. I think that I will most likely go with the Beta-15s, especially with the following (quick reply!) advice from Traynor. I also emailed Eminence and I'll just wait and see what they can tell me.

I got this email from Traynor today.
"Hi there. Your YT-15 was probably made very early in 1967 or late in
'66. That I can say with confidence. The rest is probably up to you.
The cabinet is unvented so resonant frequency is a speaker spec you
do not need to worry about as much as you would if it were vented.
There are lots of fifteens out there you could use, it mostly depends
on what you want to hear. In basic terms they need to be 8 or 16 Ohms
wired in parallel for 4 or 8 Ohms overall, depending on what your amp
wants to see. Speaking of which, the pgm power rating should be at
least equal to and preferably better than your amp's output rating.
Going down to 30Hz for low B on a 5-string isn't a huge challenge for
most 15s either so again, most speakers will work (remember, a lot of
what you hear out of a bass amp is 2nd harmonics down around E or
lower). Efficiency can be important. Look for not less than 98dB
@1W@1m. I could maybe suggest our #7475. It's the one we use in the
TC115, our only current bass cab with no tweeter. It's 8 Ohms,
400Wpgm. Ask your dealer for pricing.
Good luck with your project. .
Mike Holman

[bolt_thrower]

Originally Posted by billfitzmaurice

Load it with a pair of Beta 15s and leave it sealed. Be sure to line the box with foam or polyfill batting; hard to believe cabs were ever sold unlined.

From doing some research, I think that I will go with this option, the bonus appeal being that the Beta-15s are pretty cheap! How should I go about lining it, all sides and back? I have some ~1" thick foam, would that work or is that too thick?

[billfitzmaurice]

Originally Posted by bolt_thrower

How should I go about lining it, all sides and back? I have some ~1" thick foam, would that work or is that too thick?

That should be fine.

[bolt_thrower]

Calling Bill F!! I think that I will be getting new speakers for the Traynor soon and I was wondering what you would say about putting Delta-15LF's in there over the Beta-15's. I contacted Eminence's customer support a while ago and they told me that the Delta-15LF's will work too and they'll have more power handling. How well do you think they would work compared to the Beta-15's? I did a WinISD simulation and they look pretty similar, I want to see what you have to say. Here are the gain and SPL screencaps of the simulation (Beta=yellow and Delta=green):

[WingKL]

Looks like you'd be giving up some sensitivity and gaining some weight if you went with the Delta 15, to trade for higher power handling. I wouldn't do it if I were you.

[bolt_thrower]

Yeah, that's all I got out of the simulation too, but I was thinking that maybe there was something else. I'm hoping that Bill can chime in on this.

[dhomer]

By the looks of those charts, the Delta LF should provide a little "cleaner" low end than the Beta. If you prefer a little more "boom" in the bottom, the Betas would be the choice.

[gregoire1]

Originally Posted by bolt_thrower

^ For the time being, it will be my only cab.

Allrighty then. I'm not worried about getting the lows since I've played my Acoustic through a bunch of cabs including a couple of 8x10 fridges. It was just as loud as the SVT-3 Pro that I put it up against and I liked the tone better, so I'm not really too worried about a lack of low end. I think that I will most likely go with the Beta-15s, especially with the following (quick reply!) advice from Traynor. I also emailed Eminence and I'll just wait and see what they can tell me.

I got this email from Traynor today.
"Hi there. Your YT-15 was probably made very early in 1967 or late in
'66. That I can say with confidence. The rest is probably up to you.
The cabinet is unvented so resonant frequency is a speaker spec you
do not need to worry about as much as you would if it were vented.
There are lots of fifteens out there you could use, it mostly depends
on what you want to hear. In basic terms they need to be 8 or 16 Ohms
wired in parallel for 4 or 8 Ohms overall, depending on what your amp
wants to see. Speaking of which, the pgm power rating should be at
least equal to and preferably better than your amp's output rating.
Going down to 30Hz for low B on a 5-string isn't a huge challenge for
most 15s either so again, most speakers will work (remember, a lot of
what you hear out of a bass amp is 2nd harmonics down around E or
lower). Efficiency can be important. Look for not less than 98dB
@1W@1m. I could maybe suggest our #7475. It's the one we use in the
TC115, our only current bass cab with no tweeter. It's 8 Ohms,
400Wpgm. Ask your dealer for pricing.
Good luck with your project. .
Mike Holman

I'm just impressed with your response from Traynor. Most companies wouldn't respond at all. They were very helpful.

[bolt_thrower]

Yeah, Traynor's customer support was great, but it didn't seem very technical. Eminence's customer support was great too, even more so than Traynor. I'm still not 100% sure of which speakers to go with, so please chime in if you'd like.