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Disadvantages to a preamp/power amp

#61
I mentioned earlier that depending how you did your shopping, a component system might be less expensive. I did my shopping on ebay. My Bmax and a DCM600 came out to about $500. Yes I prefer a cleaner, well-defined sound. My gear won't raise fur, that's for sure, but it works for me..
 
#63
vene-nemesis said:
Where exactly do i have to look if i have matched both the pre and power correctly? And what am i looking for?
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Assuming they give you specs, and assuming the specs aren't outright fabrications *cough*behringer*cough*, you want the output level on the preamp to be equal to or larger than the input sensitivity of the power amp.
 
#67
seanm said:
Volts (hopefully RMS)
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No, if expressed in volts for a preamp it's usually NOMINAL output - what it could be expected to be putting out on the average when pre and post gain are decently set.

For power amps it's a sensitivity figure - how many volts at input it takes to drive the amplifier to full RMS at the output side.

The nominal preamp output figure should be at least as much as the power amp sensitivity figure.
 
#68
seanm said:
Assuming they give you specs, and assuming the specs aren't outright fabrications *cough*behringer*cough*, you want the output level on the preamp to be equal to or larger than the input sensitivity of the power amp.
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Already too much thinking for me ;)

BTW, this +4db thing is apparently what made Demeter get such a big Nashville following. It was something everyone knew and could work with, so all the big session guys bought Demeters. And they all started sounding the same as a result, which apparently is just what Nashville producers (the vast majority I consider idiots) want. Man, country music used to be so good back in the 50's and 60's...what happened?
 
#69
JimmyM said:
BTW, this +4db thing is apparently what made Demeter get such a big Nashville following.
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It's beyond me why any of these other companies would even design a supposedly "pro" bass preamp that can't drive any downstream pro gear fully. What good are they if they can only drive a select few amps - like ferinstance only the ones that they themselves make ; }

Power amps are practically commodities so it takes about one squintillionth of a second to realize what's required, by any bass-oriented company's R&D dweeb who actually cares.
 
#70
Right now I have both a Mesa Bass 400+ and an SWR Studio 220/Crown XLS 602. I like having the head for smaller gigs where I wouldn't need lots of power, as bringing my 1680 watt rig would be disgustingly loud.

One option that doesn't seem to have been mentioned yet is to find a head that sounds great for your needs, has enough power for small to medium sized gigs AND has a preamp-out or line-out (preferably both) built into it. You can use the preamp part of the head with an external power amp for more volume.

A major disadvantage for my setup is how to keep things cool in the rack. The SWR only has bottom and top heating vents with no cooling fan, and it's sharing a snug 4 space SKB rack with the Crown. So far I haven't had any major problems with it, but it seems to be a rather stupid approach to design a rackmountable amp that doesn't have front and back cooling vents to keep it cool while in a rack. This isn't usually an issue in a head, as they're designed with cooling requirements in mind.

The other thing that makes me nervous about the pre/power setup is matching the power amp output and ohms to your speaker cab(s). My Crown puts out almost 1700 watts, but my Megoliath 8x10 can only handle 1200 watts max. At the time, the GC salesman said that I needed more watts than my cabinet could handle to prevent power amp clipping and potentially damaging the speakers. I don't know if that is true or not, but if you're not careful you could end up blowing your speakers at a loud gig due to your cabinet limitations.

Sorry for the ramble, but these are things that I wish I knew before I got my rack setup...
 
#71
A lot of people seem to be able to blow speakers no matter WHAT they are using. That's no different with a megawatt power amp than it is with anything else. You still have to use the brain and the ears and the gain knobs.

I've routinely used huge amps with speakers with low continuous ratings.
 
#72
greenboy said:
I've routinely used huge amps with speakers with low continuous ratings.
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Me too. I routinely push 2000 watts (1600 RMS) into an Aguilar GS 212 rated for 600 watts and an Epifani UL-410 rated for 1000 watts. Also 1600 watts (1280 RMS) into an Aggie DB 115 rated for 400 watts. These speakers suffer no damage. Why? Because I listen carefully for signs of distress and don't expect the cabs to be louder than their design limitations. If I want noticeably more volume, I add more cabinets. To my ears, the real advantage of big watts seems to be that it makes the single cab sound 'bigger' (paint a larger sound picture), not necessarily play 'louder'. :)

M. M.
 
#73
blowinblue said:
Me too. I routinely push 2000 watts (1600 RMS) into an Aguilar GS 212 rated for 600 watts and an Epifani UL-410 rated for 1000 watts. Also 1600 watts (1280 RMS) into an Aggie DB 115 rated for 400 watts. These speakers suffer no damage. Why? Because I listen carefully for signs of distress and don't expect the cabs to be louder than their design limitations. If I want noticeably more volume, I add more cabinets. To my ears, the real advantage of big watts seems to be that it makes the single cab sound 'bigger' (paint a larger sound picture), not necessarily play 'louder'. :)

M. M.
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Out of curiosity, how many amps have you blown before you could recognise those distress sings??????
 
#74
I must have lucked out on the Output to input thing. Got scared when I read that post and went to check. Whew! My setup works fine and sounds great but my amp is only 180watts at 8hms. I add a sub to get it to 360 at 4hms but still barely enough for any club over say 75 people. I need to add another 4-10 or something to get it to 2hms for 900 for "larger" venues but thats a lot of gear to haul.:rollno: AND don't know how the amp will react even though the back plate lists it as "OK"
 
#76
In your average rock band, I don't think many combos really cut through a drummer unless you are pushing a tone with lots of midrange. 2 10 inch speakers or 1 15 or 1 12 are only going to put out so much volume before crapping out.

When a speaker cab starts making farting noises and/or sounds like stuff is flapping, then you need to turn down/reduce bass content. It's quite noticeable, but can be hard to tell if you have a drummer and two guitarists banging away loudly. So definitely try the rig out yourself at high volumes and remember what to listen for in the future.
 
#77
bassman.bob said:
Forgot to ask if anyone has or has used a MarkBass Combo. I played through one at a store but without the drummer in you ear how can you tell?
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I used to own one of those little 112 Markbass combos. Believe it or not, it easily held up in any band I ever played in, even the louder ones, but I decided to go for 115 B-15 cabs that have a little more oomph on the bottom so I sold it. Great for a 112, though. Wouldn't play metal with it, but for most kinds of music, it'll definitely do the job IMHO.
 
#78
Thanks for the input. May Your Tone, Taste, and Groove be ever better.
I've been on line for day's trying to see ALL the "higher" powered "Portable" rigs out there. Even the High $$ stuff. (even though I'm just semi pro and can't afford them) and I must say there are a lot of amp builders out there. Other than trying to go to all the different stores that carry the "Flavor of the month" stuff and not one person who works there knows ANYthing about any of them. It's really frustrating. Then I look over some of your profiles to find a bunch of other stuff I've never heard of....:hmm: Now I see a post about building your own amp. Well I built my Bass so why not?
 
#79
bassman.bob said:
Thanks for the input. May Your Tone, Taste, and Groove be ever better.
I've been on line for day's trying to see ALL the "higher" powered "Portable" rigs out there. Even the High $$ stuff. (even though I'm just semi pro and can't afford them) and I must say there are a lot of amp builders out there. Other than trying to go to all the different stores that carry the "Flavor of the month" stuff and not one person who works there knows ANYthing about any of them. It's really frustrating. Then I look over some of your profiles to find a bunch of other stuff I've never heard of....:hmm: Now I see a post about building your own amp. Well I built my Bass so why not?
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Building an amp requieres a lot more knowledge than building a bass and is more expensive than buying an already made one. I thought i could build myself a 1000W amp and soon found out that experience and several hours research are requiered and sometimes even with the proper background you can fail too.
 
#80
bassman.bob said:
I've been on line for day's trying to see ALL the "higher" powered "Portable" rigs out there.
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Here are a couple of links for you:
http://www.talkbass.com/forum/showthread.php?t=442966 30 light weight cabs,amps, combos

http://www.talkbass.com/forum/showthread.php?t=475615 1 Happy with my rig
http://www.talkbass.com/forum/showthread.php?t=455442 2
http://www.talkbass.com/forum/showthread.php?t=537446 Micro-rigs of doom
http://www.talkbass.com/forum/showthread.php?t=280571 1 Mini-rigs of doom
http://www.talkbass.com/forum/showthread.php?t=347456 2
 

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