Adding VU meter on crack, will it affect sound quality?

[ghost_rider]

Hi everybody,

I am very new to the bottlehead community. I was reading about the crack for a few months now and finally ordered one few days back . Recently I found a very exciting new thing, a tube VU meter,aka "magic eye". There are many kits of them available online. I found a cheap one that i like and I was thinking if i could connect it with the crack somehow, 1 for each channels. It would be nice to watch a bar on a tube jump up and down with music

I was planing on connecting "magic eye" PCB's audio in with Cracks headphone output as parallel. but I am concerned if it will affect the sound quality of the crack? I plan on using two 6E1P - EM80 tubes with the PCB VU meter. I am also attaching the picture of the pcb board,I got very little knowledge about the circuits so it doesn't make much sense to me

Somebody please help on what is the best way to connect two of these with the crack

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi62.tinypic.com%2Fwl4qit.jpg&hash=b4c32856334bd8526e0a88283ade53c60245c02d)

 
 

[ghost_rider]

anybody?

[2wo]

Well, it has a 3.5mm jack. You could run back to the output of the crack. Maybe there is some kind of 'Y' cable you could find or make to connect it and your phones to.

No idea what it will do to the sound...John

[Grainger49]

The answer depends on the input impedance of the circuit board. If it is something like 100k Ohms it should not affect the sound quality from a loading standpoint. 

[mcandmar]

I would assume they are for use with line level signals so you could connect your DAC to the Crack and to those boards by using splitters.

Keep in mind those boards will each require a beefy power supply, DC 9-15V @ 0.5-0.9A. Its not clear if those are included in the auction, and although the blurb lists AC there is no rectifiers on the PCB shown so it will need a DC power source.

More importantly there will be 1-200v on that circuit board so treat them with the same respect as the internals of the Crack, just because its input is only ~12v doesn't mean they cant hurt you.

[ghost_rider]

I would assume they are for use with line level signals so you could connect your DAC to the Crack and to those boards by using splitters.

Keep in mind those boards will each require a beefy power supply, DC 9-15V @ 0.5-0.9A. Its not clear if those are included in the auction, and although the blurb lists AC there is no rectifiers on the PCB shown so it will need a DC power source.

More importantly there will be 1-200v on that circuit board so treat them with the same respect as the internals of the Crack, just because its input is only ~12v doesn't mean they cant hurt you.

Thanks for the reply. I will be careful,infact I plan doing everything with a help of a friend who has alot better soldering skills than me.
 
I plan on running a 12v 1-2A adapter and spit it to both thos connectors to power them. I was thinking if I could make the housing the crack little bigger(a custom made wood housing with some extensions on the front( or back or both sides for one on either side) and then put these two underneath so only the two tubes on both sides are visible. Then solder a connection from cracks headphone out jack to these two PCBs input.

That way nothing from outside will be visible,meaning now split,not Y. will connect Xonar U7 (My dac) --> Crack via RCA connectors --> HD650 through cracks headphone out. I play the music and tubes jump around with the beats

That was the plan, will it work? I am concerned if it will interfere with some sound noise or any other lose of sound quality? 

[ghost_rider]

The answer depends on the input impedance of the circuit board. If it is something like 100k Ohms it should not affect the sound quality from a loading standpoint.

I am very new at the whole circuits thing but I think i can ask the seller for the input impedance. Would you please tell me how to measure it and what range do I need to be if I dont wana lose any sound quality?

[Paul Birkeland]

It looks like my response got lost, sorry.

That PCB appears to have a buffer for each channel, so I would feel reasonable confident that it won't load down the output circuit appreciably. 

[ghost_rider]

It looks like my response got lost, sorry.

That PCB appears to have a buffer for each channel, so I would feel reasonable confident that it won't load down the output circuit appreciably.

Meaning I will not lose any sound quality if i connect it inside the crack? by the way one PCB has 1 channel and 1 tube,right? I need two PCBs with 2 tubes for both channel. Correct me if I am wrong.

[Grainger49]

PB answered your impedance question, you are good to go.

I think you are right, even though it has a stereo input, there is only one tube output.  You need two circuit boards.

[JamieMcC]

While on the subject of vu meters I saw these on ebay  they also sell a selection of  illuminated vu meters to go with it.

DUAL VU METER DRIVER BOARD   US $16.49

http://www.ebay.co.uk/itm/160642268294?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi823.photobucket.com%2Falbums%2Fzz154%2Ftubeshunter2%2FDSC04670.jpg&hash=3dd6ddf6530164395867fb3dc0d37abb648a4903)

[STURMJ]

The big question is, how much RF or EMI will this board give off, and will that effect the crack?  There is only one way to find that out, try it.

[mcandmar]

In relation to the meter the OP posted about, i just couldn't resist getting one to play around with, which meant i had to put it into an enclosure, and then a bit of tube rolling had to be done in the name of science

Just using the stock microphone it works very well, and i found it useful to know when people are shouting up the stairs at me when in my own little world with the headphones on.  The line in i'm not so keen on as one channel gets tied to ground and the other feeds into an IC so i dont bother using it.  With speakers it works great just using its inbuilt Mic.

Pics are the stock 6E2, Mullard EM84 which is basically the same tube but better made, and a Telefunken EM800.  The EM800 is my favorite as its a single bar from bottom to top vs the two bars that meet in the middle. It is ~€14 for the tube which is more than the whole meter cost in the first place, but hey its cool so worth it. The other types of tubes are only a few quid each, and there are at least half a dozen different styles that will work in it.

I'll give it a 10/10 for novelty value, but 4/10 for actual usefulness.

[JamieMcC]

Mark, neat post I could do with one connected to down stairs also so I know when the door bell or phone rings when the cans are on there is very little chance of me answering.

I still have the ebay analogue vu meters and driver board booked marked, every now and then my finger hovers over the buy it now button!