M-Pulse 600

[MoJ]

Hi,
new to the forum so hi to all fellow Mesa users!

Just bought myself a 2nd hand M-Pulse 600, and I think Ive finally arrived at the sound Ive always been looking for. These things are awesome, even the rest of the band think so too (a 1st for one of the guitarists to be happy with the sound!). And they're **** loud too!

Only snag is, Ive been using it tonight for the 1st time (only took me 4 hours while it sat at work taunting me) and Im getting really nasty crackle/hum and spluttering type noises, that get louder. The manual came with a nice sheet the states that a lot of problems can be narrowed down to valves, however, it seems to stop for a while if I waggle the lead in the input socket. Anyone able to tell me if this is still valve related and if so, would swapping one of the two out help me, or would resoldering a new jack socket help?

Ive also found that the passive socket doesnt work, and something I found on one that was recently lent to me, though this was a newer one so it was a toggle switch but the passive mode was still quiet as a mouse.
Oh, and the para EQ on the far right, for the highest frequencies appears to be not working.
Apart from all that, I love this thing already! Seriously, Im in tone heaven

Does it sound like I need to send it back to the shop I bought it from (3 months warranty), or are these (except the EQ problem) things I could do myself, given that Mesa suggest due to the layout some things are simple to do yourself?

Apologies for such a long 1st post here, but I dont wanna have to send her back if I can help it as I have a gig next Saturday I was hoping to have it for

Andy

 

[THB_bassman]

I'd almost rule out a valve problem just based on the fact that when you wiggle to cable in the jack, it gets better. The noise could be as simple as the input jack dirty, or a bad connection somewhere. You could try some electrical contact type cleaner, and check to see if you can otherwise make it a better connection with the instrument cable. If that would get you through the gig, great. You might not even need the EQ frequencies that aren't working.

If you had a backup amp to use for now and if the shop you got it from is qualified to work on Mesa gear, heck, I'd make them fix it all under warranty. Without knowing how inclined you are to handle this stuff, that's just my opinion. Plus, if you should open it up and something needs replaced, parts to get, or maybe they'll say the warranty is void because you're not a certified repairman...I don't think I'd want to take the chance.

Good luck with it.

 

[MoJ]

Hi THB,
thanks for the reply.
I tried the contact cleaner tonight at practice and sadly it hasn't made it any better. There's still the horrbile crackle and the passsive input still doesnt wanna know.
What's odd is the noise got more bearable throughout the course of rehearsal. It took about half an hour to an hour, but after that Im left with a nasty hum that progressively gets louder until I turn the amp off or at least take the lead out, but by the end of the night it's less noicable. It's still there at the end of the night, but better.
If only I could leave the amp on for four hours before a gig!

Ive spoken to the shop I bought it from and they seem very happy and willing to get it sorted for me. Ive got a gig next Saturday so Im hoping the amo will do me till then. Not doing many gigs where there's no pa backup and would be awesome to be reliant on the Boogie for this.

Thanks again for your help THB.
Andy

 

[MoJ]

Just one more thing. Could anyone suggest if a power conditioner is liekly to stop or reduce the noise Im getting? Not really sure what one does and what would be best/afordabkle to get, but Im wondering if it's a power thing...
Andy

 

[THB_bassman]

Try looking through this. Lots of information.
http://www.talkbass.com/forum/showthread.php?t=387567

 

[MoJ]

:lol: Fair enough!
I think the general consensus there is that they're a waste of money and time unles you pay big money, which Im not able or preapred to do. Nice to hear from Bill Fitzmaurice on there too. Someone who's opinion I respect.

What I am going to do at some point is upgrade to decent patch cables for my pedal though, whether or it solves some of problems at the moment, I think it needs to be done.

Thanks THB!

Andy

 

[THB_bassman]

Good luck, Andy. It would be nice to have that amp put back in totally functional condition. I don't use one, myself, but I've heard many folks rave about them. I like my GK, but it's not for everyone.
Best wishes
Mike

 

[MoJ]

Thanks for the support Mike.
This WILL be in fully functional operation one way or another. When it's working properly it sounds unbelievable. I've finally found an amp that I need very little tweaking on to get the sound I want, which leaves EQ left over to compensate for room/stage dynamics.
All this makes for one happy bass player! I WILL have this head!!

Andy

 

[Guitarzan]

Rhonda Smith uses these live!

 

[THB_bassman]

Thanks for the support Mike.
This WILL be in fully functional operation one way or another. When it's working properly it sounds unbelievable. I've finally found an amp that I need very little tweaking on to get the sound I want, which leaves EQ left over to compensate for room/stage dynamics.
All this makes for one happy bass player! I WILL have this head!!

Andy

I went through an amp-test-driving period a couple years back, and never got to a m-pulse 600...I used a 400+ for a while and wasn't happy with it. Ashdown ABM really had a sound I liked but it broke twice and spent too much time in the shop. I settled on my GK 800RB and my 73 SVT for amps.

Darn it, Andy! Now, based on your (and others) opinions on that amp...I'm gonna have to check one out!

 

[Boogafunk]

i play a gk800 also. that's my money maker right now. i have auditioned an m-pulse 600 and was pretty impressed with it, but it's quite a bit different from the gk sound. softer attack, more bottom, and a very tubey gooey sound, vs the gk's agressive middish voicing, and tight attack. you can get in the ball park of the m-pulse with the gk by cranking up the boost,and cutting the highs a bit, but it just won't quite do the "sweet" sound of the mesa. conversly you can run a little less gain on the mesa, cut the low bass a bit and you can get close to the gk sound, but you'll have a hard time getting the agressive grind that the gk does so well. the m-pulse just seems to have smoothness built in. a great sound, no doubt, but not for everybody. of course, gk's aren't for everybody either.

btw the mesa built in compressor is a fantastic circuit. it is also addictive and makes you dial in more than you need, further cintributing to the smooth factor.

 

[MoJ]

I went through an amp-test-driving period a couple years back, and never got to a m-pulse 600...I used a 400+ for a while and wasn't happy with it. Ashdown ABM really had a sound I liked but it broke twice and spent too much time in the shop. I settled on my GK 800RB and my 73 SVT for amps.

Darn it, Andy! Now, based on your (and others) opinions on that amp...I'm gonna have to check one out![/quote]

Do it!
You owe it to yourself as a bassplayer Mike.
Ive not tried the 400+, and Im just put off by so many valves. Not sure about the USA but that's gonna cost in the region of £300 just revalve. Ive heard the 400+ also only really does one sound, but I digress.
As Boogafunk mentions, the M-Pulse is a sweet sound. I dont find it overly harsh in the uppermids, and I can get that aggresive growl if I need to (but then I do use a valve overdrive pedal before my amp for a which gives me a whole lot more grind when I need it). The lows are just so big and warm its nuts. You can dial pretty much any sound in you want, and that's just from the initial bass/mid/treble controls, let alone the para EQ. I find it's all voiced just right. For me anyhoo...
I havent tried many amps, certainly not the likes of Ampeg or GK, but though I like the Ampeg sound, it's not for me. The M-Pulse is the best sound Ive heard IMHO.
Ill put it to you this way: my singer even commented on my sound yesterday at practice, and the only time she says anything to me reagarding my bass is to turn down! Apparantly it sounded more 'woody' (I dont care what it sounds like, I love it).

I just bought some nickel wound strings for the 1st time just to tide me over, and I find that I can leave the bass and treble flat, rollback the mid between midday and 3 o'clock and that's it, thats my sound.

Oh, and yes, the compressor is reeeally good too. So smooth, punchy and most importantly natural I've got rid of my custom valve compressor in my pedal board.

Sorry for the long post. Please indulge me in this, as Im uber impressed by this amp, and I also want to convey how good this amp is and why you should feel bad for not trying it when you did! :wink:

Andy

 

[MoJ]

Mike,
would you know if (and I know I asked this in my original post) the hum Im getting, is that likey to be due to a bad preamp valve? The nasty carckle doesnt happen if I leave the lead alone now, but the hum at points will just keep getting louder and louder until I pull the lead out or turn the amp off, (which I have to do 5/6 times over a few hours) until eventually it will be quiter and remain at one level, but it's still there.
I still want to get the passive jack fixed and the fact it crackles any way, but for this gig on Saturady I just want a quick fix to get me through. I have a spare 12AX7 though it's not a Mesa.
From what I can see I should be able to unscrew the front panel and gain access to the preamp valves. Just not sure if this sounds like 'normal' problem valve behaviour.

Andy

 

[THB_bassman]

Cool, Boogafunk---GK amp and mesa/boogie diesel cabs are my sound...which cabs do you use?

Hey Andy, I won't pretend to know enough about your problem, sorry- so I think you'd be better served maybe by calling Mesa themselves, or maybe Boogafunk or someone else on this forum knows. I have been noticing that there doesn't seem to be many bass players using this forum, though. At the risk of alienating the moderators here (I hope not) I would suggest the talkbass forums. It's huge, and there's many, many knowledgeable folks there who'd be happy to point you in the right direction....but I'd appreciate if you'd post your findings right here so I can learn from this.
Good luck...

 

[MoJ]

Thats cool Mike, no problem.
Ill certainly let you know soon as I do what the problem is and how Ive got it fixed.

Thanks
Andy

 

[Boogafunk]

right now i'm using blackwidow 15's for most of my gigs. however i am in the process of building a couple of bass cabs right now. these will be test models for a new possible line. i really don't want to say much about it cause the mods have rules about that sort of thing. anyway i'm really loving the gk, and i have used quite a few amp/cab combinations in my time. (eden, peavey, gibson, swr, tech21, groovetubes, sunn, schroeder, ampeg, preamp/poweramp gigantic rack, and probably a few that i've forgotten) the 800rb gives me the best balance between slap and fingerstyle that i've experienced so far, i switch techniques frequently so it's important that i get a sound that will work for everything without tweaking. i have a feeling that the m-pulse would give me that as well, but i haven't gigged one yet. it is on my short list though.

as far as the m-pulse probs, i am not an amp tech (more of a speaker guy) but ime the crackle says bad imput jack or soulder joint on said jack, while the hum kinda suggests a bad cable or a microphonic tube. try narrrowing the field by testing the amp with known good components (new cables all the way around, different bass, etc..) and make sure the prob lies with the amp and not some sort of issue with your bass or other gear. also try it in different locations in case you're getting some funky power out of the wall. hope that helps. whatever it is it sounds like a simple fix and any competant tech could track it down in short order.

 

[MoJ]

Thanks Boogafunk.
On that basis Im putting it down to microphonic noise, as I tried various different leads the 1st night I got the amp when the noises 1st arose, directly into the amp as well, so that I could rule out anything on my pedal board and it still made the noise.
My drummer's just got a Roland SPD-S, and Ive had him turn that off and it still makes the noise. The only other things left would be the guitar amps, and as much as Id love to have them shut up for a bit (!), it's not practical for gigs!
Other than that, I only have one bass and my previous rig wasnt make that noise and that had a valve preamp too.
Im giong to see if I can pop the front off the M-Pulse next practice and replace either of the 2 valves in the M-Pulse and see what happens, but it's only so I can get through the gig Saturday. Im going to send it back after that and get the original shop to fix the rest (and the hum if it's not a valve thing).
Much appreciated for both you guys opinions and help.

Oh, Im going the self-build cab route after xmas as well, though it's not my own design. I wouldnt have a clue. Ive bought plans from a guy called Bill Fitzmaurice. Really looking forward to hearing the M-Pulse through some decent cabs. Sounds f***king A through my Trace 2 x 10's right now!

Thanks
Andy

 

[Boogafunk]

bill fitz is the man. compared to him i am only a pretender. i have his cd and have built a titan39. one of these days i will build a few more of his designs. which models are you considering, perhaps i could advise you. as i know just a bit about them.

 

[MoJ]

Yeah, Bill really knows his onions!
Ive nit been on many other self build sites but the ones I have don't seem anywhere near as comprehensive, though possibly sophisticated but as simple either. Bill's a definite authority on efficient sound managment!

After uming and ahing for some time, and spending far too much time on his forum, Ive decided to go for the new(ish) Omni 15TB, as it seems like for the ease of build the best build for me, a complete woordworking dunce. To me it has the flattest/widest response which should be easier to EQ (especially with the M-Pulse). I know some people will argue that flat response isnt actually great in live settings for bass, as you dont neccessarily need certain frequencies on stage to hear yourself, but Id argue that surely flat response is the best place to start to hear your instrument and amps natural sound. From there you can EQ to a room much more easily surely?

I was tempted by the T39 and an O10.5 for a top, as the wiring seems a bit easier, but comparing the charts the O15 seems slightly more efficient in the low bass (80 hz and under) on a one cab basis. And also an easier build.

As for advice, would you know anything about the compression driver vs piezo debate? Ive order some piezo's but at only a few quid a go there's not much lost if I dont use them, but would be harder to retrofit either should I not like my initial choice.

Would very much like to hear about your cab designs though. If only what you intend doing (reflex, radiator?) and what the results are. You can always PM me.

Andy

 

[MoJ]

Just a quick update.
Im now hum free, for some reason. Turned up at practice on Friday and the drummer decided on a slightly different layout in the room, and that was about he only difference. I was all prepared to take the front off and replace the valves systematically, but couldnt find an allen key the right size and gave up. Maybe I frightened the amp into submission!
Luckily it held out for the gig Saturday too so now all I need to do is get the active and passive inputs sorted, and I think Ive found that one of the speaker jack sockets doesnt work.
Other than that, I can now finally enjoy the awesome sound that is the mighty M-Pulse 600!

Thanks for all your help guys.

Andy