Monitoring section

[fuzzbox]

very cool stuff but the dact. 4pole for balanced stereo is 433$
any other good quality attenuators you could use for this box?

By the way I'm Rob. Green newbie who's been lurking and is just about ready to DIY.
This is a great forum and has inspired me to get off my ass and try and learn how to do all this very cool stuff.

 

[Kev]

Hi Rob,

yeah sure, there are other attenuators out there. Even a simple dual layered pot can be used. The four layer stuff gets a little harder. Stacked rotary switches from other manufacturers with resistors soldered buy you is a good balance between cost and quality.

The four pole switch can also be a rotary. The Lorlin switches are pretty popular with many of us DIYers. There is a three position 4 pole and also a 12 position one pole that we often use as a single channel attenuator.

The beauty of a project like this is that you can start with very cheap components and a get a unit operational ... then set about building a new version with all the expensive and enhanced parts. You can choose to spend as much or as little as you like.

I personally think that a unit like this could be built with relays. At first that might seem over the top but it has to do with the clutter at the work position. I don't see it as a good thing to have all the speaker and link cables to come to the desk top and then away to the various bits of equipment. I'd prefer to see equipment in the rack and only the control cables come to the desk top. This desktop control cable and unit may be changed and added to as you make more monitoring devices and change you ideas. shut up Kev - perhaps another time...

 

[NewYorkDave]

[quote author="Kev"]The beauty of a project like this is that you can start with very cheap components and a get a unit operational ... then set about building a new version with all the expensive and enhanced parts. You can choose to spend as much or as little as you like.[/quote]

That's a very wise statement. I'm often surprised at how DIYers will blow big bucks on "premium" parts to build up a circuit they haven't even breadboarded yet. My policy is to always breadboard with cheap stuff; and, if I like the outcome, then I'll consider upgrading the components if I have good reason to believe it'll make a difference.

 

[NewYorkDave]

By the way, somebody asked about US distributors for ELMA and I don't believe his question was ever answered. Anyway, I'm pretty sure you can buy direct from ELMA in the USA. I know that I was talking to them about some 24-position switches a while ago.

http://www.elma.com/us/

 

[Kev]

relays vs switches
:roll:
both have advantages and dis-advantages
if you want remote then you have to use relays or active circuits
don't worry about this question yet

A Vu-meter, in the passive path is not impossible and might have much to do with the meter itself. We would need to know about the meters and if you replaced them it could upset the balance of the circuit. Generally I think it could be worked out ....
HOWEVER ... the first issue is the VU is likely to be ready to operate tat +4dbu /dBv ... lets not do this now .... back to the point ... if we end up unbalanced it is likely we are already 6dB down. The passive VU meter is already to low.

This is likely to need an active meter driver.

OK,
where in the chain do you want this/these meters ??

Cable quality for the internals ?
... again , don't worry about this part for now and for the prototype. Just use a good general hook up cable. I have cable in the resistor colour code and some stripped cables beyond the first ten.

 

[poomka]

I would like these Vu-meters just before the attenuator...
I don't have them yet.

Could you tell me what's a "good general hook up cable" ?
I'm really starting from nothing in DIY...
Could you give me a ref ?

 

[poomka]

fuzzbox

The dact. 4pole for balanced stereo is about 200$ in the shop I bought my 2pole, I'm sure you could get it for much less than 433$

 

[Kev]

Meters,

you want the meters before the attenuation so this pretty well spells that you want it right at the output of the 192.

Here is the rub and also where most people lose the plot with digital versus analog.
I don't want to start another 0 db level thread.
Digital has 0dBFS ... full scale and everyone knows were this is ... that is to within 1 dB depending on physical units.
Lets not start another 0 dBbFS thread.

:sad:
for those of us that have been on forums a long time some things can get a little boring and half the time people are arguing the same thing ... just from a different start position.
:roll:

People should get a pair of hand held passive VU meters with a couple of preset levels and a termination switch. They would learn so much.
I must get around to writing that web page that is bouncing around in my head.

Back to the point.

192 has a max output of say 24 dB give or take. I am guessing here as I haven't read the spec and I don't have one yet so I don't actually know. If you put your passive meter on the end of it where will you set the zero position.
Lets say you set it for a typical VIDEO world -18dbFS and mix into that. We will have healthy metering on the VU and PT will have some headroom. Now place a MAXIM or L1 plug on the end and do the top 40 squeeze .... the VU meter will soon be pinned.

I can explain later and it would be much easier if you did have at least one VU meter to play with.

You are new to DIY so I can't see any reason why you should just go out and get a couple of cheap VU meters right now. A large crappy . cheap plastic box to put these and the switches in.
This will be a sacrificial box so it only has to be big enough to fit every thing. When you have a working model, you can scrap the box and make something nice.

One suggestion is to make a pair of Y cords so you can feed that signal to the amp and also to the passive VU meters ... spend an afternoon playing some sessions and watch what you have on the meters.
Then we can talk.

I'll see if I can find time to knock up a schematic for a suggested circuit using the switches you already have.

 

[poomka]

Once again Kev thank you very much for your precious answers, I will bought the VUs and make some tests.

 

[Kev]

total rush ... no time
:shock:

http://www.diyfactory.com/data/passive_monitor_01.PDF

tell me what I've done wrong ...
if someone does spot something please say so

must go

 

[Mark Burnley]

Kev,

It all looks good to me!

:thumb:

Mark

 

[poomka]

Thank you so much for your investment Kev, I will try your schematic as soon as possible.

 

[Kev]

I've changed the extension to lower case :

http://www.diyfactory.com/data/passive_monitor_01.pdf

and I've added a VU meter circuit idea :

http://www.diyfactory.com/data/passive_vu_01.pdf

This might cause some trouble as the VU is looking across hot and cold ( 2 - 3 ) of your main DAW output.
So the method of de-balancing and phase reverse might need to be modified to a DPDT switch in the normal phase flip method like we used in the Green-Pre output. This may also give us more level through the passive monitor unit as it is 2-3 instead of 2-1 and 3-1 for each phase choice.

... does this make sense ?



oops

 

[Kev]

thanks kubi

... should have checked what was on the clip board before the cntrl V

 

[NewYorkDave]

Regarding the "vu meter in a box" concept, here's a sketch I just made of the classic implementation:

The bridged-T attenuator usually has several steps ranging from "off" to zero attenuation. The attenuator is designed in the normal manner, in this case for an impedance of 3900 ohms. The usual 3600 ohm series resistance is replaced by a 2K fixed resistor and a 2K trimmer, to allow fine adjustment. The circuit has an input impedance of 7500 ohms at all settings; and at minimum attenuation, 0VU = +4dBM. You could add a switchable 600-ohm termination, as Kev did in his box.

Note that this is NOT my circuit; this has been around since the Bronze Age, at least :razz:

The attenuator and series resistor were often packaged together in one case and sold as a "VU multiplier" or "range extender." Sometimes the series resistor was made up of two fixed resistors with a tap that allowed you to shunt one of the resistors with a pot for fine adjustment. Here's a couple of photos of such a multiplier made by Langevin (from a recent eBay auction):
Photo1
Photo2
...and lastly, here's some catalog info from Langevin about their range extenders:
82kB jpeg

 

[Kev]

The kev meter is different and for a reason.

I can explain if you want ?? :?

 

[barefoot]

[quote author="Kev"]Thomas,
no bulding required , just suggestions. I'll get back to you with some ideas ... but in the mean time , can you think of any budget 2 way speakers that caught you ears as being better in the top end and mid than their competitors. A very square and flat fronted box might suit my plan better than some sculptured units. [/quote]

Kev,

What do you think of something like this? http://www.madisound.com/vifastudio.html

Thomas

 

[Kev]

yep
I do like it
and it seems to have one of the newest funny tweeters so it makes it topical and interesting.

I still think that IF a company has a ready built unit that is better than the sum of the parts then it would make life better.
It would mean that we would ALL have the same mid high and therefore some comon ground.

A full kit/DIY is still great and this vifa combo looks as simple as the usual Vifa stuff.

Peerless have a funny mid that looks interesting.
I'll see if I can find a link.