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Re: Open back array [message #24016 is a reply to message #24013] Wed, 07 November 2007 13:04 Go to previous messageGo to next message
tolits is currently offline  tolits
Messages: 21
Registered: May 2009
Chancellor
Posted my reply to Linc. A tube(12ax7) limiter before the power amp that drives the midbass.



Re: negative going signal [message #24017 is a reply to message #24015] Wed, 07 November 2007 18:23 Go to previous messageGo to next message
Tom R. is currently offline  Tom R.
Messages: 51
Registered: May 2009
Baron
I have never heard of doing this before. Is there any documentation on the web that we can look at? If not, can you post further information on what you are doing? Schematic? Line / block drawing?


Please advise,
Tom R

limiter operation [message #24018 is a reply to message #24015] Thu, 08 November 2007 07:53 Go to previous messageGo to next message
lcholke is currently offline  lcholke
Messages: 73
Registered: May 2009
Viscount
Hi Lito,

What order xover are you using?

This method is very clever. It looks like the limiter limits the current surges/peaks to the speaker. I wonder if the energy being limited is made of frquencies outside the mid band.

-Linc
--------------------------

Aphex 1788 mike preamp description:
"Microphone Output Limiter - All preamps have a maximum input level. Once that level is exceeded, there is no way to remove that very unpleasant distortion. In order to avoid that occurrence, many engineers set the preamp so that the expected peak level at maximum sound level is still at least 12dB below the clip point. While this provides some insurance against the preamp clipping, it causes a loss of noise performance and, in the case of digital, a loss of resolution. The Model 1788 has a unique limiter (patent pending) in the front end of the preamp which limits the output level of the microphone by as much as 20dB, hence the name 'Microphone Output Limiter'. This allows the engineer to get maximum noise performance and also allows maximum resolution for an analog to digital converter, all without worrying about crashing the preamp."

Re: limiter operation [message #24019 is a reply to message #24018] Thu, 08 November 2007 18:51 Go to previous messageGo to next message
Tom R. is currently offline  Tom R.
Messages: 51
Registered: May 2009
Baron
I may be wrong, but I do not think this is what Lito is doing…The microphone output limiter attenuates the entire signal. If I read the posts correctly, he is using a 12AX7 tube before the amplifier to reduce the negative portion of the input signal to the amp, and then to the speaker, so the driver only reacts to the positive portion of the signal. That’s what I have interpreted. Not sure if that is correct, waiting on Lito’s response


Tom R

Re: limiter operation [message #24020 is a reply to message #24019] Fri, 09 November 2007 08:28 Go to previous messageGo to next message
lcholke is currently offline  lcholke
Messages: 73
Registered: May 2009
Viscount
Hi Tom,

I read the same- tube before the amp.

I asked a EE friend of mine about the operation of a std limiter, and he replied that it eliminates the signal peaks by acting as a variable gain stage. The low level signal recieves more gain and the high level signal less gain. This is often used where a mike is to loud and then to quiet as the singer moves about.

-Linc

Re: limiter operation [message #24021 is a reply to message #24018] Fri, 09 November 2007 13:47 Go to previous messageGo to next message
tolits is currently offline  tolits
Messages: 21
Registered: May 2009
Chancellor
Hi Linc,

48 db LR

Lito

Re: negative going signal [message #24022 is a reply to message #24017] Fri, 09 November 2007 14:02 Go to previous messageGo to next message
tolits is currently offline  tolits
Messages: 21
Registered: May 2009
Chancellor
Hi Tom,

Here is the limiter I have been using.

http://picasaweb.google.com/bernardo.lito/Array/photo#5130946822579695378


Negative signal applied to RS 8 [message #24039 is a reply to message #24008] Fri, 16 November 2007 13:43 Go to previous messageGo to next message
JPH is currently offline  JPH
Messages: 20
Registered: May 2009
Chancellor
I own a pair of RS 8 from Selah Audio Rick Craig's now discontinued design !!!!! and I also complain of the unnaturalness of the mid's and lack of openess and transparency,Rick redisigned the crossovers but in vain . I use 8 Daytons RS 180 and 8 Fountek ribbons , unfortunately I am not good in electonics so I dont relly have the ability to mount a negative reducing circuit , but I wonder if there is anything on the market that is ready to plug in and could do the same job ???
I've also used DCX buy with little improvement.
I am tempted to think that the Daytons are not a good option ? but maybe reducing the negative signal woul do the miracle happen.
Any suggestions are welcome
JP

Re: Negative signal applied to RS 8 [message #24040 is a reply to message #24039] Sat, 17 November 2007 13:31 Go to previous message
tolits is currently offline  tolits
Messages: 21
Registered: May 2009
Chancellor
Hi JP

I don’t think there is any thing in the market that would accomplish the
negative limiting signal.I am sending you a copy of the schematic I am
using. It is very simple to make and maybe you can ask a friend who can
make it for you. Remember , I tried this with the open back arrays
wherin the effect is pronounced. You can try it with closed back and see
if it works for you. Anyways, I play with the adjustment via the
variable resisitor until it sounds right adjusting too the level of my
DCX. To my ears, I get a setting that is very pleasing to my ears and
sounds right.To me it’s like MAGIC. Don’t forget to maintain the correct
polarity to the speakers they are driving.If the polarity is reversed,
it becomes a positive going limiter. I think too that the daytons are a
lot lot better than what I am using.Good luck. I hope it will give you
the same pleasure I get from listening to them. By the way ,I am using
too a subwoofer and my NEO8 are open back too.x’over is at 754hz.It
sounds better with the subwoofer handling 100hz down.I also found out
that due to the sheer nos. of the drivers the importance of breaking in
the drivers before getting the max. result. I guess an array with so
many drivers makes every thing very pronounced. It is like a magnifying
glass.

Lito

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