Music Man HD-130 and Ampeg cab review

[drbassman]

Thanks guys, I'm feeling better about modding these cabs.  So, two key questions.  What should I be looking at for contemporary 15" speakers?  Second, what material should I use for damping and where should it be placed?

I did forget to mention that the speakers seem to be fine, but they really were distorting with volume.  Really not up to the bass I was pumping through them.

[amptech]

Thanks guys, I'm feeling better about modding these cabs.  So, two key questions.  What should I be looking at for contemporary 15" speakers?  Second, what material should I use for damping and where should it be placed?

I did forget to mention that the speakers seem to be fine, but they really were distorting with volume.  Really not up to the bass I was pumping through them.

First, although the JBL is a fine speaker, using both cabs call for similar speakers - in my opinion that is.
I know people who likes both biamping and even using brighter 15"s for the top cab, but then you have to trial and error a lot,
as these cabs are somewhat - uh.. different.

Anyway, with two 115RH's I'd either look up something with similar specs as the EVM15L. I know that EV does not make cast frame 15"s
anymore, at least not for instrument reproduction. Talk to the speaker factories, they usually gives good advices.

Current production 15"s for bass, well, I've been through several standard ferrite/ceramic ones from china, italy, etc (various brands, jensen etc)
in the 100-200w range that are similar sounding and OK but nothing special- in another cab they might be great.

I only use the EVM15L these days, when it comes to 115 cabs, exept for a small ampeg cab with a stock china 15" that sounds OK at it's best.
If I had to replace my EVM for some reason, I'd check out the Celestion BN15-400(S) neodymium. It is the same series as the 12"s i bought for my
212RH, and they are really givin' me a good time. They were recommended to me by celestion.

Remember that neodymium, being a rare earth material, might be tougher to find in years to come. Prices have gone up, and neo speaker prices
are expected to be tripeled now - so grab 'em while you can!
When they first came around, many wouldn't touch them - and I agree that it doesn't look good in the back of an old open cab guitar amp.
Maybe in 40 years neo speakers of a 'certain vintage' will be worth a fortune.

As we all know, it happened to alnico in the 60's, they are available now of course - but are still high priced.
Both neo and alnico are very good speaker magnet materials, and similar sounding though neo is way more powerful.
People have different opinions and taste here, but a good bass speaker can be made of anything if the design is good and it fits the application.

Now, what do you call that dampening material? Good question, don't know! Have to check my encisclopheediac.
It's sort of a foamy, white blanket that is used both for HiFi and furniture building.
Didn't measure any resonance, stick your head in - when you can say HO-HO loud and it sounds pleasant, it's fine really!

[Dave W]

Are you talking about Acousta-stuf?

[Granny Gremlin]

First, although the JBL is a fine speaker, using both cabs call for similar speakers - in my opinion that is.

This is a valid opinion, though I disagree.  There is plenty of precedent for 2 different drivers even in the same cab if not rig (see people who run a 2x10 + 1x15 bass rig or boutique guitar 2x12s with 2 differant drivers in them).  

Integration is not really that big an issue moreso than if the drivers were identical - that's already problematic due to Freq overlap and multiple distant sound sources (not single point source), having 1 brighter speaker will not really create more of a problem there.

This is not a hifi system, and there's no crossover so integration is nearly a nonissue IMHO.  The only thing is whether you like the combo in the end or not and whether the new driver(s) work well in the reflex horn design.

I don't have any specific speaker recommendations other than I find that EVs work well in these cabs and in terms of general specs.  If distortion-less handling of bass freqs is desired (clean, tight, thumpy) then definately go for something cast frame and either a heavy cone (as every bass guitar speaker typically has - this will give you the typical 15 incher sluggishness) or a lighter cone but overall power handling that is 3x more than required given the amps output wattage spec (this will give faster transient response and more detail - my EV SP15a for example takes 300 watts, but my amp is just a pair of 6550 giving about 50-60 watts RMS).

Other brands/models to look at:
- Another JBL d or k or e140 (the E being the least desirabble and heaviest, but also slightly cheaper)
- BEYMA 15MI100 (the JBLs are no longer made; these are supposed to be a really close match and available new; not cheap though and I haven't tried them myself)
-  EV EVM15L as per the original factory upgrade option (safe, but not available new - plenty available used and reconed - I can get them easily here locally for $150 +/-, freshly reconed)
- EV SP15a (modern not vintage; previously mentioned caveats etc)
- Peavey Scorpion (yes really; tight and thumpy as all hell, but maybe a bit lean in the top - coupled with the JBL in the other cab, and depending on your tastes this might be good or too dark).

You will also likely need to replace the stock driver mounting screws with longer ones (my EV has a very thick cast frame vs the thin stamped steel of the original driver - I had some really bad resonances due to the driver vibrating in place because it wasn't secure enough until I put in longer screws that I could really crank down).  Also, this gives room for you to add a gasket between the frame and cab which will also help clean things up a lot (if you do nothing else, do this!).  I use cork (cut my own out of 1/4" sheet); you can buy them readymade (I really recommend the more expensive cork ones vs the hard compressed paper ones) from any speaker supply or reconer or DIY out of any of the same materials listed below for lining the interior of your cab.

As for stuffing, fiberglass insulation will do but is not ideal acoustically as well as safety-wise.  I recommend long hair 'roving' (raw unprocessed, just washed) wool (also sometimes called 'batt' - like a big ass cotton ball basically).  This is available from any knitting supply store (e.g. where they sell yarn) but tends to be expensive and comes in relatively small quantities (I usually buy in quantity from whatever local Sheep farmer I can find instead, like by the garbage bag vs a lb at a time from knitting shops).  There are synthetic options such as Acousta-stuff (which is second best to wool apparently, but I never used it) or polyester pillow stuffing (better/safer than fiberglass) which is the easiest to find.  Before stuffing, you might want to just try lining the interior walls of the cab as this will change it's properties the least while still helping with internal resonances (and as mentioned, reflex type cabs aren't supposed to be stuffed, but yes, this isn't a straight up reflex and rules are made to be broken - if it sounds good to you, it is good).  For this you can use anything absorptive that can be easily glued or stapled to the inside such as: 1/4" cork sheet, thick felt, sheet foam, or any number of panel deadening products designed for car audio (usually asphalt based, sometimes rubber/butyl/neoprene, with an adhesive back .... not that I advocate silly things like 500 watt subs in cars).   If you find lining is not enough, you can always stuff afterwards (without removing the lining) even if you use a completely different product for stuffing vs lining.  Also just line/stuff the main enclosure and not the horn part.

I actually can't remember what I used on mine - it's been quite a while, I should have a look in there.

[drbassman]

Thanks for all of the great input and advice.  I am toying with the upgrades, but I always have a problem modifying vintage equipment that hasn't been molested already, even cabs.  I might just put them away and buy something else to use with the head.  I think I should keep the two cabs and amp as they sure are a nice set.

We'll see, gotta think about this some more.

[Granny Gremlin]

Fair enough, but changing a driver/rubber feet/gasket/stuffing are pretty easily reversable with no damage done (you can use one of the metal corner mount screws to attach the rubber feet.... or get an Auralex gramma/DIY one).

[drbassman]

Adding everything up for the exterior changes, damping, and a high quality driver comes out to $300 or more per cab.  Not sure I want to spend that much.  Leaving them vintage, or as is, might be a better option. 

[Psycho Bass Guy]

I would disassemble the cab and put Locktite on all the joints and in all the screw holes except the driver mounts, where I just install some screw collets. If the driver were actually distorting from being overpowered, it would happen immediately, so that means it's either a vibration problem with the cabinet or the amp is getty dirty as it gets warm.

[Granny Gremlin]

Or that he just didn't turn it up (either gain or bass EQ) as much the first time.

IIRC these cabs (or at least mine did when it came to me) have the drivers mounted on T-nuts already (I prefer bushings/collets/threaded inserts personally, but if they're already there I'm not gonna change em out).

I guess not everyone has wool/insulation and cork sheet lying around all the time like I do, but I'm sure it can be done for less than $300 per cab (not including replacement drivers, but like I said, there's no point changing out the JBL unless it's not your cup of tea, but selling it off will easily fund a replacement... and the Eminence might actually be OK if not the sole driver taking the load and some damping, gasket especially, is added.... the cone can also be stiffenned to reduce breakup distortion , aka fartiness, by painting it with Puzzcoat or watered down white/wood glue.... this will, cause a loss of some top end, but increase low end extension by lowering the cone's resonance point; might be worth the risk to try on that $40 Eminence - common mod in hifi circles).

[jumbodbassman]

my 115H cab has a reconditioned EVB  which now is 400 watt 4ohm and it sounds great.  no rattles,  farts,  I did add some sound deadening when i put the new speaker in.  my 212 needs some help.  not sure mixing neos and magmake sense but maybe in this situation.....the jbl should sound great but is more of a 150-200 watt speaker IIRC

[amptech]

Adding everything up for the exterior changes, damping, and a high quality driver comes out to $300 or more per cab.  Not sure I want to spend that much.  Leaving them vintage, or as is, might be a better option. 

There is certainly possible to get good deals on celestion neo's, especially those on the way out of the market now (or at least out of stock).
Damping should be easy to find as well at low prices.

PBG's post as well, about the amp getting warm- check it out. Didn't you have another working HD130? A/B the cab's to rule out the amp.
And glueing / thightening the cab is a must in any rattle situation - anybody here who have played ampeg combo's of recent vintage would be experienced cab thighteners I guess...

[drbassman]

Lots of good suggestions.  It looks like the rehab of these cabs is going to take more time and money than I had expected.  As for A and Bing the amps, we did try that and ruled out the amp after all.  The amp performed well with the Mesa/Ampeg cabs.  The main issue was high volume speaker farts and massive cab rattle.  I already have so many projects going, I'm going to have to think about my timing on these.  I'm spending the entire weekend just organizing my shop to produce my basses and amp mods weren't on the radar!  Not to mention several part time job offers to consider now that I have retired.  Geez.

If everyone thinks these things will sound good with tightening, damping and new speakers,  I'll probably go for it when I can squeeze it into my schedule.  Probably won't be till September or after.  The summer is really busy and going way too fast!!!!

[drbassman]

Update.  Last night at practice, I played through a 4x10custom built bass cab using my "newer" MM 130.  It was so nice!  The amp finally showed what it could do with a high quality cab to drive.  I literally played an entire 2 hour practice through it and the volume and tone were super.  I was surprised that the cab was not overly high freq, but had a nice across the range sound to it.  So, the verdict is the amp is fine, it needs good cabs.

After an hour, I hooked up my Y box and ran both amps, one with the 10s and the other with the two 15s.  Now I have the dispersion of bass I was looking for and excellent range of lows thru highs.  I have two outdoor gigs coming up and this setup should really cover things for me.  I'm going to keep using the 4x10 cab for awhile and decide later what to do about the MM cabs.  No big rush.

[Dave W]

You can never have too many cabs.

[drbassman]

You can never have too many cabs.

Amen.  It's all about moving air!