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Re: wattage vs volume


 
7/25/2000 11:42 PM
Brian
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Re: wattage vs volume
Don't get in my car GW!  
 
:)  
 
I like clean tight bass-- Not a big power tube distortion fan when it comes to bass guitar. (Chris Squire of yes is about as distorted as I would ever play)  
 
Then again I love the old jack bruce (cream) fuzzy stuff, but that is totally different.  
 
But, alas - I hate being too loud esp. when rehearsing. I just like to have the power there.  
 
BT
 
7/25/2000 2:57 PM
Ken Gilbert
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quote:
"solid-state power section for cost reasons"
 
 
wuss. :D  
 
steve, what kind of output are you looking at? anything fancy? what kind of zistors? tube VAS?  
 
do you need heatsinks? i've got a nice pair of sinks (hafler OEM) already drilled for 6 to-3's each... they are easily configured for use as a cooling "tunnel" with a fan at one end. i've been looking for a use for them for about 3 years now. they should fit in a 3u or greater rack case, and i got them for like 20 bucks, so it wouldn't pain me to donate them.  
 
ken
 
7/26/2000 11:29 AM
Stephen Conner
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Hi KG,  
 
quote:
"steve, what kind of output are you looking at? anything fancy? what kind of zistors? "
 
 
I intend to use the sziklai pair (aka CFP) output stage because it's more efficient than the normal emitter follower (and thermal compensation is easier) To get the power I'm using 4 pairs of Motorola MJ15024/15025 transistors (these are 16 amp 250V TO-3 units) each one with its own driver transistor. The whole thing runs off +/-85V and is basically one of Douglas Self's blameless amps on steroids.  
 
Thanks for the offer of heatsinks, but I had one in my collection already, a huge mungus thing 8" square by a foot long. I've already bolted all the transistors on.  
 
quote:
"tube VAS?"
 
 
No way, the VAS has to pull its collector (plate?) right to the rail for maximum efficiency. I thought about using a dual triode in the LTP input stage, but it would probably play havoc with the DC offsets. It'll be solid-state throughout with a twin-tube preamp (probably one EF86 and one 12AT7)  
 
Steve C.
 
7/26/2000 1:42 PM
Ken Gilbert
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the cfp is the way to go, as far as i've learned. it's more linear (not like that's a design goal at this point, but still) and pretty elegant in design. i've been reading the Self book quite a bit (it's next to the throne) and he IS quite the engineer. sometimes the more anal-retentive the better.  
 
i DO wonder just how many of those graphs included in the text are SIMULATED as opposed to measured... he relies on SPICE quite a bit as far as i can tell. naturally the problem with simulations is that they're only as good as the models.  
 
+/- 85V, eh? that's a good rail voltage. are you going to running into high Z loads a lot?  
 
what kind of preamp are you thinking of? i would certainly think about including one of your parametric eq's in there... it could be really useful with a bass.  
 
like i said, i've got these heatsinks and i'm itching to use them. i've just got to build a SS amp first. ;) maybe something like a monitor amp, mono.  
 
btw, thanks for the kind words about the posted mp3's. it's pretty nice to know your jams can be heard 1/3rd of the world away.  
 
ken
 
7/26/2000 4:58 PM
Stephen Conner
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quote:
"i DO wonder just how many of those graphs included in the text are SIMULATED"
 
 
They all are, except the Audio Precision analyser printouts (recognisable by the AP in top left corner)  
 
quote:
"+/- 85V, eh? that's a good rail voltage. are you going to running into high Z loads a lot?"
 
 
Nope... that's just what it takes to generate silly power into normal loads, once you factor in sag and volt drops in the output stage. I'm aiming for around 400 into 8 ohm and 600-650 into 4 ohm, continuous. If I'm lucky I might be able to top 1kW into a 2 ohm load in intermittent service.  
 
quote:
"what kind of preamp are you thinking of? i would certainly think about including one of your parametric eq's in there"
 
 
That's exactly what I'm going to put in there :D I'm using a pentode as the first stage (to use up some of my NOS Mullard EF86s) then a gain control, then a dual triode limiter, one half wired as a CF driving the grid of the next half a la mosfet follies. Next comes another gain control, a SS equaliser, a soft clipper, the master volume, and then the power section. If I decide I need compression I'll connect some kind of vactrol thing to the pentode plate to vary the AC load resistance.  
 
quote:
"it's pretty nice to know your jams can be heard 1/3rd of the world away."
 
 
Yes, well you will use such a big amplifier. The MP3s are nice too.  
 
Steve C.
 
7/25/2000 3:29 PM
JM
I thought like any instrument the bass is about tone and playing something interesting that that works within the context of the song and with the rest of the band. I stand corrected and will begin building some very large amplifiers so I can damage peoples hearing and make their chests hurt as soon as I can locate some output transformers that can handle a 1000watts or more.  
 
JM
 
7/26/2000 12:05 AM
Brian
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Cut it out dude. Quit pouting. I do respect my ears. And that is just it-- They are MINE.  
 
Ever tried to keep up with a cranked AC30 with a 100W solid state bass combo?  
 
YOU CAN'T DO IT- BECAUSE YOU START TO DISTORT AND YOUR TONE IS CRAP. Bass is all about headroom.  
 
a 1000W solid state power amp for bass is not that extraordinary, especially if your guitarists use Stacks and stuff.  
 
This wasn't supposed to be a flame, but please stop judging people who are "too loud". You have never heard us, so you don't know.  
 
Peace;  
BT
 
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