****JGR's 6SL7 preamp proto is done!***

[JGR]

Thanks folks!



Coming along well so far.

[JGR]

Got the tube mounting bracket fabricated and all the sockets w/shock mounting installed. The Belton sockets are great - insanely tight fit, no worries about the tubes coming loose. Sockets are secured with nylock nuts. I put additional vibration isolation between the bracket and chassis when it is installed. Seems to do a pretty good job - on the proto, I whacked on the bracket with the back end of a big screwdriver with the amp on/at high volume, and hardly and noise or ringing came through. I was worried about microphonics and such with the 6SL7's, but so far it hasn't been an issue.

[JGR]

Here's a couple of clips through Sliderbass's 15/6/1. Tweeter is off. Great tone with everything flat - I thought the cab sounded nice and balanced.

First link is the 6SL7 preamp
http://youtu.be/W0ktbbo1lGI

Second link is a continuation with the 6SL7 pre - camera batteries conked out during the first one.
http://youtu.be/di_KjtKwseQ

[Fuzzbass]

So, I visited Sir Reiner today to pick up my JGR Mk I pre, outfitted with the final tweakages. Of course I was dying to hear the Mk II version. We tested it with my Sadowsky MM and Benavente 51-model P-bass (with J-style pickups in the 70's location), through JGR's 15/8 cabs and of course his Berg NV610.

Short and sweet: the new pre does have all the JGR tubey goodness, but it's a little cleaner, and I'd also say smoother because it's a little bigger in the lows, and/or a little less present in the mids and highs. The differences are subtle. I almost told Jonathan that I liked the new pre a little better, but we were demoing in the basement and playing live I'd probably prefer to have more mid/high end presence, especially with the NV610.

But again, they are far more alike than not, and I'm sure I'd be 100% happy with either.

[Fuzzbass]

P.S. It was like having second Xmas up there. He fixed my hot rod Benavente '51 P-bass: replaced the cheesy jack (bent) with a Switchcraft, and replaced the preamp battery for good measure (a minor pain in the butt, given there was so little room to work). He also gave me some chrome dome knobs for my vintage Benavente '51 P (not present), to replace the non-vintage looking black ones.

Icing on the cake: he gave me a spare (but really nice) 4" leather strap after I explained that I haven't been playing the Benaventes because their non-chambered 1/4"-radiused true-slab bodies made them significantly heavier than my chambered 1/2"-radiused Sadowskys that have the standard arm bevel and belly cut. He really wants me to play my hot rod Benavente again, so I told him I definitely would, starting with my New Year's Eve gig.

JGR has the coolest bass-man-cave I've ever seen, and it's always a great hang.

Pix of the Benaventes. Despite the weight (relative to the Sadowskys) they are cool basses, and I'm really happy to have the hot rod working again.

[Sliderbass]

Ken, sorry I missed you. We need to plan better next time!

The professor has apparently done it again. I've loved the gen-1 preamp and the new mods are really cool, but then he goes and builds this thing! Damm you! :-)

I've always been more of a clean player and the new preamp is really calling me. Think I need to visit again and spend more time with it.

Also just my luck that I bring a babyied fearful 15/6/1 and the woofer decides to crap out. My big cab (1515/66/1) lives in a trailer, gets knocked around and got drenched over the summer and no issues.

So here's the question..... Jon, can I get one?

If he says yes, who would like dibs on his first gen preamp? Serial number one!

[JGR]

Great seeing you Ken - I always feel like its been an hour or two, then I realize four hours has gone by! I think the look/vibe of the old tele basses is hands down the coolest style on the planet, and hot rod flames seals the deal! I've always admired Ken's hot rod bass, but it's been out of commission for a while do to the aforementioned output jack, so I was thrilled to be able to bring her back to life! Ken has an extremely nice stable of Sadowskys, but I have to say the tone of this Benevente is my favorite so far. I may be biased due to the purple flames, who knows... Looking forward to hearing the other Bene as well - the new knobs WILL make it sound better!

Ken was gracious enough to let me shoot a couple of clips while we were messing around with stuff. One is of him playing his Sadowsky MM style 5'er through the 6SL7 pre into my rock cabs, and another with the resurrected Benevente into the 12ax7 pre into the rock cabs. All good stuff! Ken tunes 1/2 step down as I do, and I loved hearing the low B through the cabs. There is some whomp on hand running into both cabs with the PLX3402 running bridged...

Here's a clip of him playing the MM into the 6SL7 pre into my rock cabs.
http://youtu.be/IaY8gh4DY6Q

Here's the second video of the Benevente into the 12ax7 pre into my rock cabs.
http://youtu.be/8h6RlCjKDho

[JGR]

Frank, great seeing you as well, and as with Ken and my other preamp buddies, time always flies! I really enjoyed playing though your 15/6/1 despite the woofer problem, and look forward to hearing it fully healthy! Sure, I'll build you one... at some point... damn the day job getting in the way of the important work!

[Sliderbass]

I'll wait.....

[JGR]

Soldered for 457 hours today.... just finished this.

[Foz]

Ya know, I heard that some of them FedEx stores is open 24 hours... just saying.

[Sliderbass]

Originally Posted by Foz

Ya know, I heard that some of them FedEx stores is open 24 hours... just saying.

The will most likely deliver tomorrow!

Just trying to help….

[Sliderbass]

Originally Posted by JGR

Soldered for 457 hours today.... just finished this.

ITS ALIVE!!!!!!!

[5StringPocket]

I see a PLX amp in the picture but I'll bet this 6LS7 pre racked with an IPR3000 with the digital HPF would be a sweet rig. Nice work.

[Foz]

No.

That unit will drive half an an iTech 6000 into a fEARful 1515/66.

Duty cycle and headroom as long as your arm [longer actually].

[JGR]

Got everything finished, letting it simmer for the day. I was just listening to all of the outputs on my AKG K271's which are pretty nice for picking up any weirdness going on that I might not catch otherwise. I have to say, I really like the "speaker compensation" I put on the post side of the DI out. When listening through headphones, it just makes the top end sound sweeter compared to the raw full range outputs. The intent was to keep any nastiness out of the PA in a live situation or when running direct to the board in a recording environment. It only filters out the very top end harshness - there isn't a lot, and its subtle, but I think it is worthwhile and very effective. It's most noticeable if you are really digging in with a pick or when cranking the gain way up. There isn't any noticeable loss of top end if running clean (sounds very, very close to the pre EQ DI signal), so I don't see any drawbacks.

I like the chassis because there is a ton of ventilation on the top and bottom - everything stays nice and cool, and it feels extremely solid once it's all buttoned up.


All tidied up. Changed some of the mechanicals from the intial prototype for the mounting of the DI transformer and associated circuitry which should add mechanical robustness.




Here it is snotted up with silicone.

[JGR]

Originally Posted by 5StringPocket

I see a PLX amp in the picture but I'll bet this 6LS7 pre racked with an IPR3000 with the digital HPF would be a sweet rig. Nice work.

Thanks!

I run the 30Hz filters on the QSC just because they are there, but I don't notice a difference with them on or off - I spend a LOT of time in the design phase making sure things sound full and balanced, but not get flubby downstairs, even when cranking the bass up. No need for a HPF to keep your tone intact, but certainly not a bad thing as an added measure of insurance - just not a necessity with my preamps.

I only play four strings, but Fuzzbass was here the other day with his active 5'ers and we were cranking pretty good with the QSC in bridged mode, no issues on the low end. I would have cranked him louder but it overloads the camera, even on low sensitivity, so it's pretty loud! Here's proof:

http://www.youtube.com/watch?v=IaY8gh4DY6Q

I went from a CA9 to the PLX 3602 only because I wanted something shallower to fit on my cabs. Only other amp I was looking at was the Crest Pro series, but the QSC had some nice additional features and better input sensitivity. The IPR stuff seems nice for the price, but it's not in the same league with some of the aforementioned amps IMO.

[Fuzzbass]

Great... GAS again! The finished product looks as cool as it sounds.

And due to my subpar PC speakers it's impossible for me to tell how well the videos represent the live sound, but as JGR said, there was no shortage of low end when playing my active fivers, not even down low on the Bb string (they were detuned a half-step).

[JGR]

Thanks Ken! I think the low end in the videos translated quite well - makes the PC speakers on my desktop rattle but in a good way!

The pretty unit in the picture above is now on it's way to Foz.

[Foz]

Yeah!