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-   -   Grounded Grid w/ remote volume (http://www.diyaudio.com/forums/tubes-valves/47685-grounded-grid-w-remote-volume.html)

ultrachrome 14th December 2004 03:40 AM

Grounded Grid w/ remote volume
 
Took the plunge and ordered the LiteAudio V03 kit from diyclub.biz along with the matching A28 preamp case. Shipping from HK to Washington was steep (by air), about 1/3 of the total cost.

I mounted the tubes on an improvised o-ring suspension inspired by one of the Morgan Jones books (don't remember which one). Wiring needs some tidying up and I need to sanity check the earthing scheme but it's so darn quiet I should probably leave it the way it is.

Here are some pics:

http://www.brainwatch.us/images/gg2_front.JPG
http://www.brainwatch.us/images/gg2_back.JPG
http://www.brainwatch.us/images/gg2_above.JPG

I'm very pleased with the remote kit despite being sparsely documented. Direct selection of source, mute, 99 volume steps, and balance. The relays are kind of loud but I don't find it bothersome. Although I might have a stubborn relay or something as the volume balance gets out of whack for a handful of the quietest volume settings.

fdegrove 15th December 2004 02:42 AM

Hi,

Quote:

Direct selection of source, mute, 99 volume steps, and balance.
99....??? Really?:cool:

All that with relays...
Good ones used to be expensive (mercury wetted stuff and all that, reed realys etc.)

I'm using a 24 (23 + stop) Elma switch and almost never go beyond pos. # 10-11.
A remote is nice to have unless you have a TT, you have to get out of that rocking chair to flip over the record anyhow.

Anyways, if you allow some observations: (your post was sitting rather lonely here, so)

Just looking at the PRB tag board used with the tubes mounted vertically; a piece of L-plied aluminum stock would have done just the same.
If worried about microphony (line stages shouldn't be upset by this), a rubber grommet put between the mounting surface and the bottom plate is quite effective already.
I usually mount the boards vertically with the components facing the front panel.
So much easier when you want to try a new cap, for instance.

The multi-colored wire (telecoms?) used for the inputs/outputs is probably tin-plated, if so strip it and shorten the signal path wherever possible making sure both channels share equal cable lengths.
Sounds better that way and the wire won't oxidize easily anyway.

As for the noisy relays, are they bypassed with a cap?

Cheers, ;)

ultrachrome 15th December 2004 06:48 AM

The wire is telephony but unplated.

The wire was intentionally long while I was trying to figure out how everything would fit. I'll clean things up shortly.

I was going to mount the tubes horizontally but I saw I could implement the suspension trick from Building Valve Amplifiers and not have to drill any holes. I may later settle with a grommet scheme such as you suggest.

99 steps is definitely overkill. It can take a while to get from one volume setting to another. When holding the volume up or down key, it first steps slowly then quickly. I wish it was a little faster.

The relays do not appear to be bypassed. The switching noise really only stands out at low volume leves.

garbage 11th April 2005 09:14 AM

Re: Grounded Grid w/ remote volume
 
Quote:

Originally posted by ultrachrome
Wiring needs some tidying up and I need to sanity check the earthing scheme but it's so darn quiet I should probably leave it the way it is.

hi ultrachrome

i got the same thing as well, but without chassis.
care to share your grounding scheme?

my monoblock is not grounded to safety earth, when connected to this as a passive pre, i get major ground loop problems.

i did hook up the output of the vo3 to safety ground (earth), and it magically quietened the whole thing, but unfortunately, i was not able to replicate the same thing again... it was a one-off thing... strange.

here's a pic with the outputs ungrounded. everything is floating. i noticed that your regulator pcb is grounded to somewhere, but could not tell from the image.
http://img219.exs.cx/img219/7369/vr3connected6ng.jpg

ultrachrome 11th April 2005 03:08 PM

I don't have much to share. I really didn't know what I was doing. I think I was lucky as I have no hum issues. I still intend to go back and reassess the layout.

Which regulator are you referring to? The one powering the V03 boards is floating I guess. The EI transformer powering it has an electrostatic screen that is tied to chassis ground (yellow wire but not connected in picture). You can see the V03 is tied to chassis ground.

The regulated heater supply is grounded to a star point in the middle of that rat's nest of an HT supply at the bottom of the picture. The output grounds from V03 and the output jack ground all meet at a star point on the tube board. This then goes to a second star point where a couple of resistors and a cap meet. Then that runs back to the HT star point. Finally, the HT star is run back to the chassis ground point.

garbage 13th May 2005 03:54 PM

just wanted to update that i got it working w/o ringing or buzzing.

i use separate ground for inputs and outputs connected back to the relevant pads on the pcb.

for the below, grounding the pcb common ground pads to safety ground was the final touch to making it not ring.

http://img80.echo.cx/img80/9325/vr3separategnd5pw.jpg

ultrachrome 13th May 2005 04:00 PM

Good news. Hope you didn't lose too much hair figuring it out.

jleaman 19th November 2005 06:17 PM

Id like to buy one of these.. WHat did yuo guys pay for it. How do you like it ? does it come with remote ?

J'

ultrachrome 19th November 2005 07:00 PM

Parts:
- steel chassis (w/ milled aluminum front panel, all jacks and feet but oddly no fuse holder)
- V03 volume control (control board, volume/source boards, power supply, remote control)
- small EI transformer
- mounting kit for V03 kit (misc standoffs and screws)
$142

Shipping (air):
$75

Shipping is the killer. I could have save $25 by no choosing the air method but I'm glad I did. It arrived in 7 days.

I'm very happy with it. There was some fit issues with the front panel buttons and the power switch mounting had to be modified but it was only a minor inconvenience and easily remedied.

Having 99 volume steps is a little overkill. Most listening is in the -60 to -50 range. For movies I have to crank it up to -35. You have to hold the volume button down for a little while to get it that high.

jleaman 19th November 2005 07:09 PM

Does it have a remote ? I think i shal get one of these.. it looks nice..


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