Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #86858  by redbeard
 Thu Sep 16, 2010 10:56 am

Just trying to figure out if what I'm thinking about would work. I just picked up a vintage 1972 AIMS Tube AMP, 120W, with a cabinet with 6 10'S. The head has an external speaker out, a 5 ohm out and a Preamp out. Now, I know that the ideal situation for running the SMS Jerry Preamp is to go into a power amp and then out to a speaker box. Trying to determine if there is an effective way to use the Preamp with this amp and still get the benefits of the tone. I plan to build a box and get a Power Amp at sometime in the future, but I would really love to try and use this amp combined with the preamp if possible--I just don't know enough about the higher end of specialized gear like this and would like to figure out if it is doable before buying one. Could I go from the preamp out into the SMS Pre, and then out from the Preamp out to my speaker cabinet? I'm assuming the problem with that would be to have the signal going from the head into the pre, since the speaker cabinet is meant to go out from the head. Obviously my understanding of the inner workings of these things is in its infantile stages. Any help is appreciated,

 #86859  by jeffm725
 Thu Sep 16, 2010 11:03 am
you would always want the SMS to be the first thing you plug into after your guitar and your effects. Now that being said, some tube amps have a Power amp IN junction (like my Boogie for instance) where it bypasses the Boogies preamp section and hooks into the amp at the power amp section.
If your amp had a Power amp in jack, then you could use the SMS with it. Or You could have a good amp tech put a Power amp in jack in your amp.
 #86867  by redbeard
 Thu Sep 16, 2010 12:43 pm
Thanks Jeff, thats what I was thinking, now just need to find a good amp tech here in Denver. Any thoughts on using the 6 10"s cabinet rather than the typical 2 or 3x12"s? Its a nice cab and the speakers are new, just trying to make what I have work better in order to get the band going in order to justify the next step, the Mac and E120's, etc. As it stands we are a long way from needing that kind of power, as it is I run my AIMS amp with a master volume of 1! Thanks again,

 #86870  by jeffm725
 Thu Sep 16, 2010 1:45 pm
redbeard wrote:Thanks Jeff, thats what I was thinking, now just need to find a good amp tech here in Denver. Any thoughts on using the 6 10"s cabinet rather than the typical 2 or 3x12"s? Its a nice cab and the speakers are new, just trying to make what I have work better in order to get the band going in order to justify the next step, the Mac and E120's, etc. As it stands we are a long way from needing that kind of power, as it is I run my AIMS amp with a master volume of 1! Thanks again,

The speakers are fine as long as they meet the following criteria:

1)The cabinet matches the ohms rating needed as specified by your amp (and it sounds like this is head/cabinet combo so they SHOULD match I think) .
Be careful getting different cabinets to go with that amp, as with 6 10's it may have a non standard impedance rating.

and a Most important factor
2) YOU dig the sound of the speakers. It does not matter what kind of speakers they are , what size they are or how many you ave, IF YOU like the way they sound.
 #86892  by JonnyBoy
 Fri Sep 17, 2010 8:34 am
That is true about speakers, I find that some amps sound better with different speakers. JBL's sound great with vintage Fenders, but not so good for other applications sometimes. I put a JBL straight to a modeling amp one time and it was way worse than the special design eminence stock speaker it had. But when it was preamp'd through the mac, it sounded a lot better the way it should.

You can't deny if it sounds good, you probably will waste a lot of time and money trying to make it sound better. If it sounds bad, then it won't be so hard to get it better. I have learned the hard way when it is sounding good, leave it alone despite the brand names or configuration. Like Jeff said, if the cab was for the amp in the first place, its good to go. You won't regret an SMS to set the tone.

Those 10" speakers probably sound killer. I love some 10" speaker tone. I just got my new Gdec patched into my mac as a 3x10 in total. the Gdecs Fender special design on one channel and the MC250 pushing a K110 2x10 cab from another separate channel out. Whats cool about that, I can make sure the tone from the amp (or preamp in this case) is coming out right through the mac without too much coloration. In other words, make sure the tone is the same for the 2x10 by using the amp to go by.

So many ways, so little time. - JB
 #86898  by tigerstrat
 Fri Sep 17, 2010 9:38 am
Is it something like this?

 #86905  by SarnoMusicSolutions
 Fri Sep 17, 2010 12:15 pm
Bear62 wrote:I may have missed this, Brad can you tell me what tubes you use in the SMS. Thanks

For about a year or more I've been using the premium selected Shuguang series 9 12AX7's. These are chinese tubes. I never thought I'd allow it, but after years of testing and returning literally hundreds of european tubes for failure or bad microphonic issues, I finally took the cues from audiophiles and boutique amp makers such as VHT/Fryette, Fuchs, and others and gave these a shot. They're actually quite good, they have a good and solid clean tone, and generally have been holding up better than the JJ's and the Soviet tubes (Sovtek, EH, Tung-Sol reissue, Mullard reissue, etc.). These premium Shuguang tubes are also marketed under the brands Ruby, Groove Tubes, Tube Amp Doctor, Penta, and a few others. The chinese Shuguang factory has been refining their 12AX7 since the '80s, and now on their 9th generation of refinements and tweaks, it's become a pretty well respected new tube. You will surely find people who will automatically dis these tubes because they're Chinese, as I did for years. But in reality, they're good.

Now when it comes to use in preamps designed for overdrive, I can't make any claims about these tubes. My intended use is for clean with high headroom, and NOT delving into the issues of tone and harmonics when clipped and overdriven. That's a whole other realm.

Now that being said, I think it's always a nice idea to consider an upgrade to a good old or NOS (new old stock) 12AX7 by RCA, GE, Sylvania, Tung-Sol, Mullard, Telefunken, etc. Lots of really great tubes out there from the old era of when tubes were really made to last. They're pricier, but can be found. Personally, in my rigs, I'm using these Shuguangs and amp perfectly happy with them.

 #86913  by Bear62
 Fri Sep 17, 2010 2:43 pm
Thanks Brad. Clean is EXACTLY what I am concerned with. I have a 12 yr old Holland 4x10 that had 1998 Sovtek 12ax7 wxt+ preamp tubes which at least one has finally died. I found some Sovtek 12ax7a tubes locally, replace all three and they sound pretty good so far. I had tried the EH 12ax7 and found them to be very brittle and not much midrange. Peace, Gregg PS. I will try your recommendation next time around. I am saving up my pennies for one of you preamps and am thinking of running it into the Amp In on my Fender Blues Deluxe 1x12. One less peace of rack gear, plenty of power and cool tweed cab. Will have to upgrade the stock speaker. Thanks again!
 #86944  by SarnoMusicSolutions
 Sun Sep 19, 2010 8:53 am
One thing about fresh tubes is that you shouldn't judge them yet. The EH is a decent tube, but when it's fresh (within the first 50 hours or so), you can't really judge it. Like capacitors, speakers and other components, you just can't judge them when they're new. It's not till they've settled in and been at high voltage with audio passing thru them for dozens of hours that they find their real sound.

Even a brand new electric guitar takes hundreds of hours for the vibrations and harmonics to make the wood resins settle into place and then the guitar will take on its tone. So maybe let those tubes burn and work for a while before you decide what they sound like.

But I can say that right out of the box, I do prefer the tone of these Shuguangs over the EH or Sovtek's, and they do warm over and settle in very nicely. With tubes, the upper treble is the first thing to mellow as they break in, but the "tone" of a tube lives in the midrange, how boring or lively or 3D sounding in the midrange is what I look for. Also the bass is something to listen for. Some tubes get a gushy-mushy bass, and others get a stiff, firm bass. For these Jerry pre's, I go for a real rich and complex and vibrant midrange and a hard-tight bass. The treble is not a huge issue for most tubes once broken in, and seems manageable with quite a few tubes I try.

It's interesting to compare short-plate and long-plate tubes too. JJ makes the ECC803s which is their sort-of clone of a Telefunken long plate 12AX7. Nice sounding tube, but can tend to be a bit microphonic. More of an issue in a combo than a separately racked preamp. Also Sovtek does make their long plate 12AX7 which is a good sounding tube. I recommend people compare short plates (JJ ECC83s) to medium plates (Shuguang, TAD, Ruby, Sovtek, etc.) to these two long plate types. The trick is to buy the tube and commit for a few weeks so they can break in and then you can really judge.

For what it's worth, Dan Healy once told me that he really loved to use original 60's Tung-Sol 12AX7's in the Dead's gear. If anyone grabs a nice NOS Tung-Sol, let us know what you find.

 #86968  by redbeard
 Mon Sep 20, 2010 6:44 am
That image is the amp exactly. The company folded the next year after that ad, and then becaome Randall, who still exists today. Its been treating us pretty nice, rehearsal last night was great, even with the master volume only on 1. My drummer can still hear clear as day at that low of a volume. Preamp section leaves something to be desired for my ears though, not quite enough clear high end. Going to try and find an amp tech to see how much it would cost to add a PWR IN like you mentioned. Only paid 400 for the whole thing, so ideally it won't take much to get that jack in there, I love the sound of the speakers but I know it would just sing if I could bypass the preamp and only utilize the power and speakers, combined with the SMS. One other hesitation is that the cab is a beast to move around, not sure how long down the line I will want that obligation. I figure for $400, I can probably at least pull that much out of it sometime, or at least sell the tubes for a good portion of it. I really want to get into building cabinets sometime here, so we'll see.

My bottom-line assumption, then, is that there is really no use in running the SMS Pre into an amp without a way to bypass the amps own preamp section, hence the recommendations to run the SMS into a Power Amp and out to speakers, that about right?