One-Bottle Preamp

[skipwave]

Nice work, Kiira. Using that Newcomb input TX, aye? :wink:

 

[kiira]

[quote author="skipwave"]Nice work, Kiira. Using that Newcomb input TX, aye? :wink:[/quote]

Thanks Skip! yup, newcomb input and Edcor wsm line and output. Worked all day yesterday (between shopping laundry and cleaning :razz: ) making the front panel.



Kiira

edited for mis-thinking

 

[kiira]

oops just want to make sure before I turn on my iron...

the lo Z DI goes into the grid of the 5879

the balanced line-in goes into the grid of V2B ... or V2A?

I'm switching them both with switching jacks.

Kiira

 

[NewYorkDave]

Here's the answer--if I understand the question, that is.

Sorry for the sloppy sketch, I'm pressed for time today.

We're up to 20 pages now. Wow!

 

[kiira]

[quote author="NewYorkDave"]Here's the answer--if I understand the question, that is.

Sorry for the sloppy sketch, I'm pressed for time today.[/quote]

Thank you for taking the time to answer.

Yeah that's how I had it but I didn't have the additional 1M resistor to ground after the 1.0 cap and before the 100k pot.

We're up to 20 pages now. Wow!

I might finish this soon! wow also! That would be great because one of the band guys where I work asked if he could borrow my angevinlay dvc and I told him hey I have something better now. rawk. acourse I can't use any of the front end stuff I build because my neighbors call the cops on me... it's pod city from here on. :sad:

Kiira

 

[NewYorkDave]

The Pod? Oy! There's got to be a better way :wink:.

Here's an idea: a low-power (5W or less) tube amp through a 100-watt (nominal) variable L-Pad. Mount the L-pad in a ventilated metal box. It does mess with the tone to an extent but not necessarily in a bad way. I've been using just such a set-up with my 2-watt amp and it works well for getting a good tone at a very low volume. As a matter of fact, for overdriven tones, I think this particular amp sounds better through the attenuator.

NB: despite the 100W rating of the L-pad, I do not recommend using it with an amp of more than, say, 10W rating. That's because the L-pad will get too hot otherwise. Also, the action is not altogether smooth at the lower end of the rotation, and sudden jumps in volume are not as jarring with a lower-powered amp :wink:. Since I find myself using the L-pad mostly at the lower end of its rotation (greater attenuation), I'm thinking of adding a fixed 10dB L-pad, built from suitable power resistors, in front of it.

I'm going to start a thread over in the Brewery for those of us who record in apartments or other lo-noise situations. We can swap tips and war stories.

 

[Consul]

I still need to work out a layout for my one-bottle. I'm still worried the 6x8" bud box I got is too small, but I'll make it work. I'm just waiting for the output trafos from EDCor now. That, and I need to get a few caps still.

Dave, the Zobel that follows the transformer, will I need that with the particular input trafos you sold me? Will I want to experiment with some different values?

Again, thanks for the assistance, and the design.

I'm getting a small basement with a 7' ceiling to do my recording in. I'll probably end up wallpapering it in OC705 to make it usable for anything, but at least noise isn't too big a factor.

 

[kiira]

[quote author="Consul"]I still need to work out a layout for my one-bottle. I'm still worried the 6x8" bud box I got is too small, but I'll make it work. I'm just waiting for the output trafos from EDCor now. That, and I need to get a few caps still.[/quote]

Hey Darren that's exactly the size of the box I started with, 1U too. If you are making a mono one-bottle it might work, depends on the size of the rest of your parts I guess. I am working on the two-bottle and I could have made it all fit with one less tube. It would have been cramped still and I would be concerned about hum, but with my power transformer and ps it did fit. Mine would have all fit if I had smaller input and output xformers as well, but I used Edcor too for line and output. The box I transferred it all to is almost 2U and more like 175x250. It is still compact but much much easier to build inside, and not nearly as frustrating.

good luck,

Kiira

 

[kiira]

[quote author="NewYorkDave"]The Pod? Oy! There's got to be a better way :wink:.[/quote]

ha ha I know. How about a pod into a tube DI onto my Tascam 38? I do like my pod, actually I have a bear inker v-amp pro rack mount, even if only for 2 am playing with headphones. $125 and it is built pretty well, metal not plastic and it really has a lot of I/O choices.

Here's an idea: a low-power (5W or less) tube amp through a 100-watt (nominal) variable L-Pad. Mount the L-pad in a ventilated metal box. It does mess with the tone to an extent but not necessarily in a bad way. I've been using just such a set-up with my 2-watt amp and it works well for getting a good tone at a very low volume. As a matter of fact, for overdriven tones, I think this particular amp sounds better through the attenuator.

I never knew those type of pads existed... I thought you needed a power soak or some other expensive box. I'd be totally into trying that! I no longer have my 5 watt hi-octane though (took it apart to build a Lightning clone). So I would need to build an amp... 1 or 2 watts I think but it would have to be P-P. I just don't like single ended sound. :? That would be fun but I have to finish the Lightning, the LA-2a, the Neve, what, NYDave EQ channel strip first. ha ha :razz:

NB: despite the 100W rating of the L-pad, I do not recommend using it with an amp of more than, say, 10W rating. That's because the L-pad will get too hot otherwise.

okay. I'd love to be able to use something on my deluxe reverb it sounds pretty good cranked up. I think I've seen schematics for higher power type pads or power sinks. Oh... Kevin O'Conner I think has somwe ideas about power attenuation. I have one of his books.

I'm going to start a thread over in the Brewery for those of us who record in apartments or other lo-noise situations. We can swap tips and war stories.

That would be fun. You should do that I hope.

thanks for the info Dave!

Kiira

 

[Consul]

Yeah, I wanted to try to fit the power supply plus two one-bottles into this box, but it may not happen. I do, however, have a separate small aluminum box I can build the PS in. I may end up doing it that way. Then I'll just need to solve the problem of cabling the power over to the pres.

I guess I should've bought the 8x10. :wink:

 

[Kingston]

Hey cool! It didn't occur to me (as I'm quite the beginner still) I could insert a line level input right after the 5879, similarly to the DI input before it.

Migh have to do that, too. Heck, since I've already added all the basic options to it, might as well make it a true swissknife. I'm thinking of variable input impedance option to this one similar to the G9 mod in the other thread. Or maybe I'll save that for the next project, since I haven't got the transformers for it yet..

*sigh* the german PSU transformer is stuck somewhere in their labs still. Sucks to have to wait with the otherwise completed two channels.

 

[cannikin]

Can you gurus help me? I always get the wrong Power transformers. :?

I'm building two -- One Bottle Pre's and want to use one Power T. (of coarse) Which hammond will fulfill my needs?

Also NYD: can you shoot me another schematic of the One bottle with DI option (LineAmpE ?? I think?) cannikin AT mac DOT com

Thnaks

 

[NewYorkDave]

This power transformer is perfect for two channels of One-Bottle:

http://cgi.ebay.com/STANCOR-PS8416-NIB-PS8416_W0QQitemZ7578107814QQcategoryZ97184QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

(It's misidentified in the listing as a "9V, 400mA" transformer. But it's 250VCT/25mA with a 6.3V/1A filament winding).

NB: It's just a hair too big to mount in a 1RU enclosure, if that was your plan.

 

[AnalogPackrat]

[quote author="NewYorkDave"]This power transformer is perfect for two channels of One-Bottle:

http://cgi.ebay.com/STANCOR-PS8416-NIB-PS8416_W0QQitemZ7578107814QQcategoryZ97184QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

(It's misidentified in the listing as a "9V, 400mA" transformer. But it's 250VCT/25mA with a 6.3V/1A filament winding).[/quote]

I would clarify with the seller that the pictured item is what is for sale--otherwise you might just get a wallwart...

 

[cannikin]

How about this Hammond

Part #: 261C6
VA 17.5
Secondary: 250V C.T. @ 45 ma
Filament : 6.3V @ 1A

 

[kiira]

[quote author="NewYorkDave"]This power transformer is perfect for two channels of One-Bottle:

http://cgi.ebay.com/STANCOR-PS8416-NIB-PS8416_W0QQitemZ7578107814QQcategoryZ97184QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

(It's misidentified in the listing as a "9V, 400mA" transformer. But it's 250VCT/25mA with a 6.3V/1A filament winding).

NB: It's just a hair too big to mount in a 1RU enclosure, if that was your plan.[/quote]

hmmm... I am using one of them and it just fits into 1U for me if mounted sideways.

Kiira

 

[NewYorkDave]

Kiira: Heed CJ's warning in this thread.

AP: In that same thread, Charlie mentions that he contacted the eBay seller already and it does indeed sound like they're selling a PS-8416, despite the inaccurate description.

I'm planning on using a PS-8416 myself, when i get around to making a two-channel One-Bottle.

David: That Hammond sounds fine, as long as it works out space-wise. But that Stancor I linked is probably cheaper if the dimensions are not a problem.

 

[skipwave]

I always thought it was best to mount the transformer on the back outside of the box. That's how it was done on the old Altecs like the 1566a and other vintage pres. This way, too, you can take advantage of the full height of a rack space, not just the inner dimension.

Any possible negative side effects? Does the transformer have to have shielding on it to do this?

 

[NewYorkDave]

Mounting it on the rear of the box is generally the best way, if it works out mechanically. It's good to keep the power transformer away from the audio circuits, ya know.

 

[cannikin]

Hey NYD

I'm building 2 stereo units of your two Bottle and I have a 2 pairs of input and 2 pairs output transformers.

I'm wondering what your opinion is in regard to choosing the transformer configuration.

Input: 2 UTC A-11 1:10 and 2 Beyerdynamic input 1:15
Output: 2 Cinemag CM-9589 (10k/600) and 2 Edcor WSM10K/600

UTC and Cinemag?
Beyerdynamic and Edcor?

Just curious.... One of these units is going to a friend, so I want the 2 channels to match.