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Jah Tubby preamp mods continued

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mange View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mange Quote  Post ReplyReply Direct Link To This Post Posted: 20 November 2008 at 9:01pm
Played around a little in Matlab (or actually GNU Octave).
I was using that a square wave can be written as an infinite series like this.

In other words, a square wave can be constructed by summing sine waves of odd multiples of the fundamental freq. from the first one to the inf. one.

In your example with the fundamental freq being 90 you would sum sine waves with the freq.:
90 hz, 3*90 hz, 5*90 hz, 7*90 hz ......, inf*90 hz

what i did was that I substracted sine waves with freq. lower than 240 Hz and higher than 4000 Hz from a perfect square wave. (xover points?)
I ended up with a plot looking like this: [edit - this is one period]


Edit: [pasted wrong plot first]
Comparing this to your plot you can see some resemblance..


But as I said, square waves are rather complex and it would have made much more sense to use a sine wave for this.


Edited by mange - 20 November 2008 at 9:42pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mskeete Quote  Post ReplyReply Direct Link To This Post Posted: 20 November 2008 at 9:30pm
Originally posted by Joseph Redhemption Joseph Redhemption wrote:

My advice is not to push the gain too much because when the led goes on the distortion become audible. This is because of the way this preamp drive the led. The signal is directly taken from the individual xover outs to drive a transistor who in turn drive the led.
It would have been better to buffer with an opamp before driving the transistor.
N.B. This can be a wanted effect to beef up the sounds.
http://www.4shared.com/file/72242105/af49cbbd/THD_Led_on_1Khz.html
 
It's something I call the LED test. The circuit is OK as it is. The problem is due to something else
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DC View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DC Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 10:33am
I didn't say soundmen don't hear above 10k, i said most attenders. People who go stand in the middle of the arena and get harsch tops feeded into the ears definatly loose their high frequency hearing over time.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joseph Redhemption Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 11:20am
Originally posted by DC DC wrote:

I didn't say soundmen don't hear above 10k, i said most attenders. People who go stand in the middle of the arena and get harsch tops feeded into the ears definatly loose their high frequency hearing over time.
 
 
This is where the tubes come in and was the major upgrade to the JTS. The highs goes very high and they are so sweet. But for shure it depends of the driver you use.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mykey Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 11:39am
Originally posted by king david king david wrote:

if u have a preamp and combine scoops, folded horns, midrange horns, tweeters there is no chance for time aligment...
 
i have a jts 3way preamp and its a good unit, it has its limits, and this thread just confirm this...but it works good with a reggae sound cause it has a lot of useful things to colour the sounds and spice it.
 
everytime i play with preamp, sound isnt perfect (sometimes is very good sometimes is just good) but its great for live dubbing. with other equipment i can come close but i feel more at ease with preamp
and u dont see people at gigs doing measurements, they come to dance+have fun!
 
everytime i use the sound as a p.a....i bring out my crossover, equalizer and limiter and the sound is much much better!
 
cheers
ShockedI do it in my head, the same as everyone else.
 
I'm sure if you went round with a questionnaire and asked people to fill it in on the way out, it would be all bad about the sound 
 
I have never been to a dance and been satisfied with the whole sound spectrum, there is always something missing or too much of something else
I have actually heard gaps in the crossover bands
 
most of it is down to the pre'sShocked
 
A selecta should own up and say he 'does not know' how a system work's, this way they could have someone with them who doesWink
 
what sound uses Digital LMS and a pre? would be interesting to find out
 
I know some will say i need to come back and listen, but it looks like I don't need to, seeing as this as cropped up
 
never heard one of yours though mskeeteWink
 
 


Edited by mykey - 21 November 2008 at 11:42am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote king david Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 12:23pm
when i play out and bring the sound i always bring the preamp, it has lots of useful things for live dubbing, i connect to the fx units and since i play lots of instrumental dubs, it works great for wild remixing...people would be much more into listening this wild things+looking at a selecta "working"on the tunes than taking care of missing frequencies
and when i see sounds playing out and they have their custom built equipment, stuff u cant buy in the shops,thats great, and it makes every sound different and not the usual dj thing with 2 decks and pioneer dj mixer and stop...
i know the limits of jts preamp, and u can add eq, other boxes(i tried to add a crossover+15"reflex or folded horns to ahve more lower mids) but theres no chance...use it for what it does dont ask for hi fi sound, if u want that go through normal dj-p.a. equipment.
also the 3 way is 30years old design...i found out it sounds better with roots music than with digital dubs
i have some boxes in my living room now and i'm listening roots and its perfect, it sounds "very reggae and warm" Tongue
 
i dont know about mostec, i just saw king shiloh with a 4way mostec, and the sound was excellent. so big respect to mostec, when i win the lottery i will try different preamps, no money to spend on it now. but really if theres a preamp that can work with different music styles and can give a flat response, while keeping some character of a classic preamp(kill switches, fx, parametric....) it would be perfect!
 
 
i did p.a. for a dub band 2 months ago, they played on my soundsystem, from their mixing desk to my preamp...sounded ruff and powerful but really lo-fi
we did it again 1 week later and used crossover, eq and limiter and no preamp. it sounded excellent!
i would never use the preamp again for a band or p.a. service.but when u come to dance to the warrior charge soundsystem, the preamp is essential!
 
just some random thoughts...


Edited by king david - 05 August 2009 at 11:21pm
http://www.warriorcharge.noblogs.org
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Post Options Post Options   Thanks (0) Thanks(0)   Quote King Simeon Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 12:48pm
I'm glad we're getting a bit more open with the comments. I'll admit to being a traditionalist and even stuck in my ways, but i would not wish to hear roots and dubs played through a clinical/quality sound system... seems pointless/soulless. Most of the old tunes are not high quality made/mastered so what is everyone going on about?? I would love to hear different sounds with different equipment bringing each different character of sound, and hopefully different tunes!!

When it come to other music... well i wouldn't want to hear any of them through a pre. Makes no sense, just as half of the talk makes no sense. I was at SE1 last month and there was some big pa in one area and Tubbys/Aba/Ch.1 in the other. The pa sounded LOUD, but no dimention, the tops squeezed into the sound and the bass was boomy, but no round definition, just overall loud, compressed/crisp. But thats for there music, (Garage/R&B/Urban), they have it how they want it.
 
When Tubbys warmed in it was impressive, got a good few 'woofs' people couldn't help smiling and looking at each other, people banging on tables, like the old days. Nothing fancy, just simple control on sounds. No harshness, just power/sound. Everyone sounded different and all the better for it. Some folks don't run that clear, it is true, some could work a bit harder on there skills... but that is how it runs. All this clinical talk is entirley missing the point.. this is a roots and culture forum. . . . did i miss something?
https://www.facebook.com/KingSimeonSound?ref=stream     
https://soundcloud.com/king-simeon
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DC View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DC Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 1:05pm
When Russ is @ the controls... he make sure it sound good. As said it upto the operator.
I've heard Russ get a real crisp and clean sound from a JTS pre. Steve Vibronics also know how to operate the JTS. But it definatly also got to do with the gear after the pre.
See some people getting an extra xover after a 3way pre trying to make a 4 way sound.
As King David says... use gear what it's built for. Soundsystems are not aiming for the highest soundquality but for a vibe (and some just for bass)
 
Shiloh using speakermanagement systems these days and that improved the sound significantly. It not only upto the preamp.
 
And esides all that... the one tune sound different from the other. Like lots of digital dubs are being mixed straigt in the box and that don't contribute to the warmness of a tune.
As Simeon mentioned.... some producers seek for older gear just for the charater of the sound. For instance i used to have a mackie console and all my mixes were done on that desk but i felt the desk lacked some warmth. Just couldn't achieve what i wanted. Now since june i own an old Soundtracs console..... and made the difference.
So soon come 1st release mixed on that console
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mskeete Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 3:51pm
DC, I think yuou need to give me some pre release mixes of the tunes dem so I can check they sound compatible with my preampsSmile
 
Shiloh were also using a LMS when they had a JTS preamp
I actually think the LMS can cause some headroom issues but that's for another topic
 
got some more comments to add but got to dash
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DC Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 4:10pm
Originally posted by mskeete mskeete wrote:

DC, I think yuou need to give me some pre release mixes of the tunes dem so I can check they sound compatible with my preampsSmile
 
Shiloh were also using a LMS when they had a JTS preamp
I actually think the LMS can cause some headroom issues but that's for another topic
 
got some more comments to add but got to dash
Haha... well them being tested thru your pre a lot and i can tell you ... them compatible.
My only advice for your pre is to use a bit more sturdy kill switches.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joseph Redhemption Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 7:04pm
Are those who satisfy themselfes with a not too bad JTS pre  forgetting the human nature?

Aren't we always wanting better for ourself,family,friends,humanity?

Aren't we folowing the example and teaching of his majesty? Be a better man thru
 education ?
I'm trying to explain - with the help of others -  to everyone what happens in their pre and even show them a way to make it sound better and some of you complain about that!

As Ijahman say - JAH IS NO SECRET.

And same thing apply to sound. There are no secrets. It must be told freely to everyone how to use and make sound with quality to spread the culture.
And as soundmen it is our roots and culture to know how our soundsystems works and the ways to improve it. We always have to give our best when spreading jah words.

I was hoping that people will post ideas to improve further this pre but I'm very disapointed . Anyway InI still continue pushing this pre to the max.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Deadbeat Quote  Post ReplyReply Direct Link To This Post Posted: 21 November 2008 at 7:31pm
If you want to try to see how the transient response is, would running an impulse response help as opposed to your square wave?
Away on extended leave.
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