Anyone ever built a tube di?

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Yes i use the G9 as a tube di for bass. And i really love it, much better than my Trace Elliot bass preamp.
So i really can recommend it as a tube di. Oh and you get a mic preamp with it :razz: :wink: It's just way too good to not have one :green:

I haven't used it for guitar as i really like to mic an amp. Sounds much better than direct recording since 99% of all the stuff i record is distorted.

Flo
 
Kev is preparing a countryman DI page at GroupDIY. At least, that´s what I´ve heard. Just be patient, I bet it´s on it´s way.
 
alembic f2b.
really good sounding, although the first time out I screwed up my power supply a bit so it was humming badly, but the tone came through, seriously large bass.. more or less this is the 12ax7 circuit Byacey mentioned above, with a nice eq section.

sleeper
 
yeah, I'm rebuilding the PS today actually, so I'll have the hood open.

I'll look and see what the specs are on the transformer and exactly what I did. I also had some questions for the pros around here on that one,

I've never been able to figure out when how and why to terminate the output transformer. I'll have to draw something up and post it. expect something tommorrow.

sleeper
 
[quote author="Sleeper"]I'll look and see what the specs are on the transformer and exactly what I did. I also had some questions for the pros around here on that one...[/quote]
Yeah, I've gotten several different responses (from folks more knowledgable than myself) when I mention that I'm intersted in adding a transformer balanced output to the Alembic (to mod it into a tube DI). Some talk about impedence (matching?) issues. Adding an additional cathode follower output stage into the output transformer also been suggested to me. Not really sure what makes the most sense. So, I'm interested to see what you did. Also, would be interested to hear others thoughts about this.

Thanks
~ Charlie
 
I've been using the G9 this weekend as bass DI. Sounds superb - really impressive. I've also built & tried the Altec clone mentioned above but preferred the G9 for this app.
 
I just wired the output transformer directly after the .1uf cap.
much as I had seen done with the hamptone preamp.
http://members.cox.net/soma/hamptone.jpg

my transformer is actually a 15kohm to 600ohm transformer and the step down wasn't a problem from an audio standpoint. Either way the alembic sounds very good and I'm not hearing any wierd rolloff between one or the other.

I used the direct unbalanced line out into the line in on my mixer OR (not and) the transformer out into my mic inputs.

I know I'm getting a gain loss here, but I used what I had. I'll have to try a 600 to 600 transformer and see what happens... probably this way I could take the mixer out of the picture and go straight into my convertors.

Anyhow, out of my depth here.
the plate resistance of the 12ax7 is 62,500 ohms according to the data sheet, but I don't know in theory what the .1uf output cap followed by the 1m resistor to ground are doing in terms of the impedence that is seen by the trasformer

hope this helps.
sleeper
 
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