One-Bottle Preamp

[NewYorkDave]

No. The wiring for 6.3V heater is
4+5
9

 

[3nity]

yes, that sounds ok (6.3V between pin 9 and 4&5 connected togeither)
So your tube is heated and it glows ?
I would check B+ at the differents points showed in the schematic on page 1
if all is ok, then I would check sound input/output connections

Yeah the tubes glows very nice. All voltages checked and are fine.

Gonna recheck my input/ouput connections.

input transformer is an OEP 262A3C

 

[raysolinski]

I said I was sorry ...not enough coffee yet this morning...

Cheers,
Ray

 

[3nity]

:thumb: me too i need one!

 

[Phazinhead]

Hi everybody !

I just would like to know how does sound that kind of "one bottle" preamp ? I mean, is it really capable of having fat and coloured sound, or should it be only used as a simple preamp, without anything special?
And as a DI box ?

sorry for my stupid questions if it is :green:

 

[3nity]

geez..i only get a big hum now! it increases when turn the gain pot.??

 

[3nity]

Problem solved! Rz and Cz was in series instead of parallel.!!!
yeah i only listen for a few seconds but i got to go back!!!!!!!!
sounds good!!!

thanks to all the guys and NYDave for the tips and design!

 

[pstamler]

If Cz and Rz are the Zobel network, they're *supposed* to be in series. Normally there's also be a load resistor in parallel with the Zobel.

Peace,
Paul

 

[3nity]

geez RL and CL, sorry, stupid me

 

[3nity]

one issue...i'm using JLM Go between boards. PAD is using 2x 470R and 1 120R....now when using the pad the gains changes drastically.....should i change them to 200R and 1k?

 

[Kamel]

i plan to try, after building this pre, to use a 1:30 beyer tranny :shock:
the idea is to use low level signal mics, ribbons and dynamics.
the secondary Z is 180k, so what do you think about this configuration?

 

[rafafredd]

I use 180R and two 820R for my pads.

 

[APMA]

Hi
I turned on my two bottle for the fisrt time today and had some smoke coming from the power transformer, so I turned off the unit and dissconected the PSU from the circuits. Before I shut it off I measured 302-3 ish off of the B+, nothing coming from the heaters (could have had the DMM on the wrong settings?) and measures 117 going into the transformer. Any tips on what to check for? tomorrow I will take the whole PSU out and check everything but I will only be guessing. Any tips will be very much appreciated.
Are my problems likely to be from the mains, fuse, switch to that side of the tranny or within the PSU circuit?

Thanks
Aaron

 

[khstudio]

[quote author="APMA"]Hi
Any tips will be very much appreciated.
Are my problems likely to be from the mains, fuse, switch to that side of the tranny or within the PSU circuit?

Thanks
Aaron[/quote]

YES, Check ALL your wiring until you find it.
Your B+ (or High voltage secondarys) could be touching each other or ground.
OR your filements could be touching each other or ground OR on the wrong pins.

The 1st thing I would do is get a 100 watt light bulb & wire it in series on the AC power cord. When you first turn on the unit - IF there are any shorts or bad connections -the bulb will light & give you time to turn off the unit before any major damage occurs.

On a 3 prong AC cord there is:

GREEN = GROUND
BLACK = HOT
WHITE = NEUTRAL

Cut the black OR white (only one) & wire it so it goes thru the bulb.
This has saved me many times!!!
:wink:
Take your time & good luck.

 

[khstudio]

BTW... you MAY have already burned up your power tranny if it WAS smoking :sad:

 

[khstudio]

:!: :!: :!:
If your NEW to high voltage Tube equipment BE CAREFUL & DISCHARGE ALL LARGE CAPACITORS AFTER UNPLUGGING THE UNIT - BEFORE WORKING ON IT.
:!: :!: :!:

 

[APMA]

Thanks KHStudio
I think the biggest thing thats losing me is the physical connections. http://sound.westhost.com/psu-wiring.htm I wired up from the tranny to the mains socket exactly as shown in the physical connections pics on this site. Would that be correct for this project. From the tranny to the PSU, I am now trying to figure out Nedeges PSU layout (are only the thick black lines connections and the thinner ones nothing?, are all connections out of the tranny being used, originally I had the CT closed off? and where is the bridge rectifier on this layout)
I know these are some obvious questions to most but any advice will help out a lot.
Thanks Again
Aaron

 

[khstudio]

Reposted PM

[quote author="APMA"]Hey Thanks for your help.
How do you discharge the caps ? just wait a day or so?

Stupid question but just to be sure, the light bulb goes between the mains and my unit. I'm very shaky as to when I turn the mains on or not and how much testing can be done with out it on. The light bulb would put me at ease so I would like to be 100% on how it work, you wouldn't have a picture of this would you.
Thanks again for your help.
Aaron[/quote]

Please ask in the forum so more people can help & learn too.
Also, Me, nor anyone else, can walk you thru every step ESPECIALLY when it come to HIGH VOLTAGE TUBE GEAR = You can KILL yourself if you don't know what your doing :!: :!: :!:

Discharging caps is an important & basic ABC/123, Bread & butter thing you "Should" know before working on this stuff... these kinds of questions scare me. :?

PLEASE BE CAREFUL.

I haven't built this YET so I can only help so much :sad:

 

[sonicmook56]

here is a page on the light bulb current limiter. I always use one when powering up something for the first time. The bulb will glow very bright if you have a major problem, saving expensive parts and the trouble or replacing them.

http://www.repairfaq.org/samnew/tvfaq/tvtslbt.htm


here is my ghetto backup one.

Use a low value, high watt resistor to move the electrons, "de charging" the caps. Hold it with pliers cause they can heat up fast.

If you don't know what your doing with high voltages, you can really hurt yourself. I've been working with electronics for years now and still get a bit uneasy around HV stuff.

Maybe you should choose a project that won't kill you.

~B

 

[APMA]

Still trying to figure why I had some smoke. I was looking at the PSU's for the One bottle compared to the Mila. The line that's coming off R3 and R4, is it as shown or should it be going to the + side of the diodes (as in the Mila). Here are links to the two schematics. I'm sure the schematics are right it would just narrow my search if by chance there's a mistake.

http://i261.photobucket.com/albums/ii49/aaronmoore82/NYDpsu_p01.jpg

http://i261.photobucket.com/albums/ii49/aaronmoore82/MILA1-Updated_p03.jpg
Thanks