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Teej's DIY Combo

teej

teej

Aug 19, 2004
2,952
919
40
Sheffield, AL 35660
www.facebook.com
#1
It all started back in May. My band really got going, and we started practicing more and more at eachother's houses, but frankly, my GK and Omni 10 (or even my Omni 10.5) aren't portable enough for practice and whatnot.

That's when I started playing through my friends Peavey Rage 158. Laugh all you want. It works wonderfully in a pinch as a bass amp. The problem with the Peavey, though, is that A) it's a guitar amp and B) driving all that bass for extended periods will cause it to self-destruct. It's also, C) not loud enough.

Financial troubles, however, delayed the project, and it was eventually abandoned. Then a couple weeks ago, my cherished GK 1001RB-II blew a pair rectifiers, rendering it useless, and that was a wake-up call to stop using my main amp for practices. I decided that I needed an amp solely for coffee shops and rehearsal.

THE AMP:
The powerplant for this combo is a Hartke 1400. I've never used Hartke anything before, but I'm told they're hit and miss. I know some of you TB'ers swear by your Hartke stuff and rave about the sound. For this combo, however, I'm not concerned about the sound so much as I am the reliability. That's why I like Peavey gear so much -- all of their amps are built like tanks. In fact, I was going to buy a Peavey TKO with a bad speaker and transplant the amp section, but as everyone knows, Peavey's durability comes at the cost of weight. I've got weak bones, so the amp must be lightweight. And what do you know, the Hartke is lightweight!

Let me throw some 1400 specs at you:
- 140w @ 4 ohms (80 @ 8)
- Contour Preset 4-Band Eq
- Switchable Compression
- Total Harmonic Distortion: Less Than 1% At Rated Power
- Signal-To-Noise: 68.6 dBm
- Bipolar Design
- Passive/Active Input Jack
- Headphone Out
- Effects Send & Return
- 2 3/4"H x 17 9/16"W x 10 3/4"D

I don't know what a lot of the technical bits mean, but I do know it's got 140 watts, which (I think) should be enough to be heard along with two guitarists and a drummer.

THE DRIVERS:
I can't decide. My goal is to have a small but loud combo.
- A 15 takes care of the loud, but would require a large cab.
- I like the punch and clarity of a 10, but I'm afraid it won't have enough volume, and a 2x10 setup would make the cab bigger than I'd like.
- I'd go with a single 12, but no one makes a 4-ohm 12" driver, except Carvin (see PS-12), but it's got less-than-stellar tech specs.
- As of the posting of this thread, I'm REALLY leaning toward a 2x8 setup. I can fit two drivers within the 20" cab width I've established, but will they be loud and be able to produce good bass?

(NOTE: The GK was fixed, and my existing cabs are light enough, but I'd still like to single box that I can grab in a hurry.)
 
#2
why not fix the rectifiers and keep using the GK. by using it regularly you should be more confident that it will work at a gig or similar, unless there is a repeat problem with it. using the amp within its capabilities shouldnt degrade anything. its not like you have a tube amp with nos tubes your trying to save for when it is really needed.

im sure most people happily use the same amp for gig and practice, and if they dont its so they dont have to carry the thing around all the time.
 
#3
black_labb said:
why not fix the rectifiers and keep using the GK. by using it regularly you should be more confident that it will work at a gig or similar, unless there is a repeat problem with it. using the amp within its capabilities shouldnt degrade anything. its not like you have a tube amp with nos tubes your trying to save for when it is really needed.

im sure most people happily use the same amp for gig and practice, and if they dont its so they dont have to carry the thing around all the time.
Click to expand...

Agreed. An amp should not wear out with use. Fix the GK and then couple it with a lightweight 8-Ohm cab. Pushing 8 Ohms, the GK will always run cool, yet it will still be more powerful than the Hartke.
 
#4
Well I did fix the amp (it's still going to GK for a check-up and upgrades), but I've already got the Hartke and necessary building materials. And both of my existing cabs -- an Omni 10 and a 10.5 -- are light enough. I'd just rather have a single box that I can snatch and toss (not literally) in the passenger seat for those unscheduled practices, or something that I can leave over at a bandmate's house. I still use my GK for at-home practice. And this way, I don't have to make two trips -- one for the bass, and another for the amp and cab.

Then again, I could make another 10.5, but modify it so that it has a built-in two-space rack for my GK, but I'll save that as another project.
 
#5
I don't know about good 8 inch drivers that would work, but another option is an Eminence BP102 10-inch which is available in 4 ohms. It's a pretty hefty driver and would probably be more potent than many lesser 12-inch drivers. You would probably have room to add a horn or upper-midrange driver as well. Just a thought.
 
#7
teej said:
Yeah, the BP102 was my first choice. I'd really prefer a neo. driver to keep the weight down, but it seems no one makes them in 10 or 12" 4-ohm flavors. You think the 102 is enough, though?
Click to expand...

Well, I don't have first hand experience with that Eminence driver ( just the 2510. I also built a pair of O10.5s) but from it's specs it looks like it would work pretty well. It does have a 6.2mm xmax which is quite good for a 10-inch driver and more than many other similar drivers. I'm sure you know that it's used in some of Bill's Tuba and Titan subs.

Maybe you can try an experiment to get an idea of how a 1x10 would hold up. Have you tried your O10.5 with your GK head, or even the Hartke (yeah I know you'll get less power at only 8 ohms, and maybe this is somewhat of an apples to oranges comparison), for a practice session? That might give you a bit more subjective data to decide on whether a 1x10 would work. If your cabinet has enough volume and is tuned properly, the BP102 should have more bottom than the O10.5.
 
#8
Yeah, the GK through my 10.5 (both of my Omnis have 2510s) can get plenty loud, and sounds fine enough, and I've used the two at rehearsals, and am totally satisfied. The idea behind this combo, though, is to have something smaller and more portable. I was looking at Invalid Link Removed, and going by charts for each cab/driver setup, I'm probably going for the "Larger Vented 1x10." I'm totally clueless when it comes todrivers and cab design, but I look at these charts and see 50hz @ 0dB with a max. acoustic power of 120dB. I don't know what that means, but it sounds impressive. :rollno:
 
#9
Unless someone knows of a good 4-ohm 12" driver, I'm going with the single 4-ohm BP102, but before I finalize that decision, does anyone have any comments on a 2x8 setup, particularly with a pair of Eminence Alpha-8s?

I compared the data for the BP102, a pair of Alpha 8A, and a Delta 12-LF using WinISD.
Here's what I've concluded (and keep in mind that I know little about cab design and what these pretty charts mean):
- The Delta and BP102 cover the same frequencies, but the Delta is louder.
- The pair of Alphas take the dB prize, over the single Delta and BP102, but can't get the lows that the other two can.
- A pair of Beta-8s simply won't do.
- Out of curiosity, I threw in a single Delta 15 and found that it would outdo them all, but would require a large cabinet.

winISD_charts.gif
 
#10
Well, it took the seller forever to ship the amp. Apparently, he had some issue with eBay or PayPal, or maybe he just didn't have the money on hand, or perhaps he's a liar and needed the amp for a gig or something, that kept him from shipping the amp for a full two weeks. I wasn't in any hurry, though, so it's no big deal.

Anyway, the amp arrived. It was a little more beat up than the picture and description showed, but it's for a project anyway. All I care about is that everything works, and everything does.

Quite well, actually. For $86, I got a decent amp. I played it through my Omni 10.5 (single 10" horn-style cab) and for 80 watts (140 @ 4 ohms), it's very loud and has acceptable tone. I can't ask for more! The only complaint I have is that it's still heavier than other people lead me to believe. One guy said it was about the same weight as his jazz bass. This definitely weighs more than any jazz bass I know of, and I happen to own a very heavy jazz bass. I set it atop the 10.5 and picked both up, and it's fairly lightweight, but I'd still like something lighter. The Omni cabs are a little heavy, anyway, since they've got all the bracing and horn and whatnot.

To sum up, though, I think this will make an acceptable combo for practices and jam sessions.
 
#13
Yep. Ordinary screen door material. I wanted something that would protect the speaker while showing it off a bit. It's not very durable, though. I was laying on the floor doing homework one night and accidentally pressed my foot into it, stretching it. I'm thinking about replacing it with a metal grill, or perhaps some black cloth, as I've done with the Omni cabs I've built.
 
#15
No sites used - just my existing woodworking and cabinetry knowledge. Made from 1/2" 5-ply sanded pine around a poplar frame. The amp cost me $86, wood was probably $20, driver was $60, feet were $3, carpet and everything else was about $20, stainless steel screws and whatnot were maybe $10, adhesive was $12. I'll let you guys do the math, but I'd quickly estimate a total cost of around $200. Not bad for a small, lightweight, 140w combo. :smug:
 
#19
I did the same thing afew years back with the same head.

I've also done it with the older Ampeg B1R single rack space head + 15.

I originally built the Hartke 1400 combo out of 1/2" plywood with a 4 ohm 10. It was a simple square combo.

I rebuilt it about 4 months ago and turned it into a wedge monitor style that will sit either upright or kicked back.
This time I went with an 8ohm 12 because I already had a couple. It turned out well, though I haven't yet carpeted it, just sprayed it black.

I'll try to remember to post a pic of it when I either get near it (with my phone) or find the pic on my computer at home.

I've done the same thing with the head out of a Fender combo and built a 2X8 combo, but after using it for a while, I didn't get enough low end out of the 8s and put the combo back together and sold it.

I recommend it if you got the skills.

Kenny
 

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