Bringing down the gain on a studio pre?

[EOengineer]

Does anyone have any experience using lower gain tubes in a studio preamp in order to bring the front end gain down a bit? I generally find that the preamp cascades quite quickly into high gain, and I would like to explore the mid-gain potential a bit more.

I am not using pickups that have a ridiculous output, so I have to believe that its a preamp tube that is supplying all the gain. Anyone use a 12aT7 in the first gain stage to clean it up?

 

[chode7]

I just did yesterday. I did not like it in V1 at all. I tried an EH12ax7, Sovtek 12ax7LPS, and EH 12at7 all in V1. I did not like the 12at7 at all. It was brighter than either the Mesa or EH. I did however like the Sovtek best. More low mid emphasis and not as fizzy. A bit darker to my ear.

 

[axisman5150]

Another tube option is a JJ 803s. http://www.eurotubes.com/euro-e.htm


I have the gold pin 803s in V1 and it sounds good.

 

[EOengineer]

Im curious about the added "brightness" that the 12aT7 added. I think it is quite easy to produce a fizzy character on this preamp, though I have to believe that it can be dialed out with careful tweaking. The other option might be to put a lower gain tube in whichever stage the lead drive circuit recieves its gain. Have you tried that?

I like the sound of the clean channel, and I think that has a great tone, so maybe I should swap more on JUST the lead drive stage. Anyone know which stage that is? Im guessing V3?

 

[axisman5150]

yeah, it's V3.

 

[EOengineer]

Thanks axisman. I appreciate your input. I just checked out the 803S gold pin and its a pretty basic description on the site. What were your findings after switching to that tube in comparison with what you were using? Did it clean the preamp up a bit?

I should not that I am not as clueless as I seem here. Im an audio engineer, but just getting into tube swaps and still learning this studio preamp. My ears are fully functional, so feel free to toss around some tone slang ; )

 

[axisman5150]

I've only had mine for a few weeks so I'm still learning about the Studio Pre as well. My ears are fully DISFUNCTIONAL after all the years of playing and tweaking, HA!! :lol:

Yeah, the description is brief but to the point on that site. The JJ803s does have a thicker rounder midrange and not as harsh/fizzy on the top end as the JJ83s.

Another tube to consider is a 5751. I haven't used that one yet on the Studio Pre but I do have one in my Rocktron Piranha. It has 70% of the gain as a 12ax7. I put that in the V1 slot of the Piranha which was the tube for the clean mode and it sounds great! It broke up sooner than a 12ax7 but felt more bluesier and more dynamic, Fenderish.

By the way, I'm running both of those preamps together at the same time in stereo through a VHT 2/50/2 and they compliment each other very well.

Here's a photo of the tube layout for the Studio Pre.
http://www.tubefreak.com/studio.gif

This helps figure out what each tube does in the gain stages.

Tube swappage can be never ending it seems, but it's what us tweakers love to do! [/img]

 

[EOengineer]

You're the man axis. I will eventually check out the 803S, but I just ordered an NOS Mullard CV4024 and an NOS JAN 5751. I am going to try those and I will let you know how things sound.

 

[axisman5150]

Nice choice of tubes! 8)

I found this site (http://kcanostubes.com/content/Default.asp) after a google search for the Mullard CV, I never heard of that tube before. Yeah, I liked to hear what you think of those.

Maybe try one in the V1 and the other in the V3. V1 controls the gain on the volume knob on the far left(input Vol.) which coincides with the gain on the lead channel as well, I think, correct me if I'm wrong.

 

[JT_Marshmallow]

Before I bought the Studio Pre, I read all 100 reviews on Harmony Central to get an idea of it. I saved a few in a text file that had some good info that I might use later, and one review talked about how he did just what you're asking about. Here it is:

I play a 1994 prs ce 24. My main point for posting this review is to give others who are looking for cleaner sounds out of this unit a couple tips. I wanted to reduce the gain, so I retubed the 3 main gain stages with nos rca tubes. I used 12at7's in the first two stages and a 12au7 in the lead drive gain stage. It has worked out beautifully for me. Now, the whole range of gain on the clean and dirty channels is usable for me. Someone who is looking for a little less gain reduction might make all three of them 12at7's. I'm getting some really good sounds out of this thing. Glad I bought it.