Joined: 04 Mar 2006 Posts: 200 Location: Cleveland, Oh
Posted: Tue Jul 17, 2007 3:46 pm Post subject:
Actually this is true. I had forgotten about it until I saw this post. When I was at the shop a few months ago to have my my Mod100 repaired I got the story from Bruce. If I remember correctly, his kid still uses one of the prototypes in his band. He did design the amp although I'm not sure it is, or even supposed to be public knowledge. I think Bruce has had his hands on alot of things that we are not aware of.
Bruce is the master of creating good tone. I've jammed thru a B-52 at GC and it does sound very good for a "budget" amp.
Whoa! That's real cool if that is the case. I had an at-100 for some time and that head sounds like a much expensier amp when cranked up and correctly retubed/biased. Excellent tube head for the money.
I post over at the B52 forum and some of the folks over there we're talkin about Bruce designing a new 4-channel tube amp for B52 a couple years back. That never happened, and while everyone was still waiting for it, the Egnater Tourmaster hit the shelves.
Been thinking about picking up one of those AT-112s for a while just for the hell of it since they're so cheap right now _________________ ? Soldano SLO100
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Joined: 29 Jun 2008 Posts: 642 Location: Chicago, IL
Posted: Fri Jan 09, 2009 3:04 pm Post subject:
Interesting, I never knew this.
Been thinking about picking up one of those AT-112s for a while just for the hell of it since they're so cheap right now
yeah the AT-100s aren't too bad actually.
Also says designed by egnater op the back just like the RM series does. _________________ RM50 Bface,1086(Gigmod) -Blackstar HT5- RG100ES
Randall MTS R212CB X 2
ESP Eclipse - Fender Strat Plus - Jackson Kelly KE3
The B-52 AT-100 is actually the amp that led me to get into the Randall MTS series. I first bought the AT-100 as a little fun project amp, and a back up. Soon I was using it non stop it sounded so unbeleivably awesome. I did some research and found that Bruce Egnater designed the amp for B-52. That triggered my memory that Bruce did the modular series with Randall as well. No I have a B-52, and an RM100 so I guess I am Bruce Egnater Fan. Some other interesting things about the B-52. Alot of people in my area call this amp the "poor mans mesa" in reference to a dual rectifier. I have had 5 rectifiers in the last 8 years (you could say I am an addict). I love Triple Rectos. But, the AT-100 is quite different. The tone stack circuit is about as Marshall as it gets. It reminds me more of a hot rodded JCM900 (this is a good thing) more than a rectifier. It is true that the AT-100 uses a tube rectifier, but that does not make it a Mesa clone by any stretch. The AT-100 sounds very good for high gain, medium gain, blues, and clean - what more do you need? It sounds great in Drop D at high gain, but does not really pull off the Rectifier sound for the more modern tone. (Again, the preamp is closer to a Marshall). Another unbelievable feature is the contour control. It really works and allows you to dial in the midrange just perfect. this is really my favorite feature of the amp. If a Dual Rec had this feature, i woud still have one! Another great and overlooked feature is the foot swtichable effects loop. the footswichable effects loop allows you to jack in an offboard pre-amp (like and RM-4!) to the effects return jack, and then use the effects loop footswitch to switch between your offboard preamp, or your internal preamp. This turns your 3 channel AT-100 into a 7 channel amp if you are using an RM-4. Great stuff and makes the amp even more flexible. I have modified my AT-100 quite a bit just trying different things and it has been a ton of fun.
The only downside to the AT-100 to my personal ears is that it is a little bright in general. Especially the high gain channel. With a Randall MTS cab, I have the treble set at about 3. I also had a 1 x 12 AT-112 for a while and while it sounded cool, it wieghed 68 lbs. A 1 x 12" combo that is almost 70 lbs? I could not deal with it. I would rather carry my 4 x 12" - at least it has 2 handles!!! So I send the 1 x 12" back, and was disturbed that B-52s product literature stated that it only weighed 45 lbs. That is a bit more than a misprint in my book.
Posted: Fri Dec 04, 2009 5:39 pm Post subject: update
This is an update to my last post about the AT-100. Man, what a cool amp. I guess I look at things a little differently that other people might. For the money, such a solid performer. I see this amp as having alot of potential.
As I mentioned, I bought this as a project amplifier. Since my last post, I continue to make little changes here and there, most of which are in the preamp. But, i also changed the bias ckt so that I could run E34Ls. This amp LOVES E34Ls. So I am running JJ E34Ls with an old RCA 5U4GB recifier tube for a bit more sag. I have come up with a pretty good set of preamp changes that gets this amp closer to the rectifier sound.
I am not promoting modifying anything, actually, you don't need to. This amp sounds great stock as a rock. As mentioned, the only issue that I see with this bad boy is that mine is pretty bright. I have kept the treble control dialed back pretty hard to avoid it being too bright, but that has bothered me a little because i feel like I am loosing some of my "crunch" when doing so. I have done a little circuit bending and fixed some of that, but ultimately I think finding the perfect speakers will be the trick keeping the highs from getting out of control. G12T-75s are simply too bright for the amp I have, even though they help in getting to the rectified type "crunch" zone. I tried some Eminence Texas Heats thinking the 2" voice coil would help, it didn't so my next attempt will be a mix of 2 Vintage 30s and 2 Eminence Swamp Thangs. The Swamp Thangs will help give this amp a little low end too. I do not use the Resonance Control. i like the power section as loose as possible and adding damping does not really do it for me. i would rather sacrifice the low end (or get it from different speakers instead) than turn the Res control up.
Anyway, fun little amp. Not sure if I would take it on a world tour, but for my practice room, it makes me feel like a rock star. I think Bruce and B-52 provided exactly what they intended to with this one. A great sounding, versitle amp and is easy on the wallet.
Once I get the speaker issue sorted out, my next plans are strictly cosmetic. I am going to make a new front panel with more of a vintage wheat look, similar to the Black Palomino RM100. I am also planning on having my machinist mill a new black front panel, and I will run cream knobs with that for the typical "Egnater" look.
Posted: Thu Apr 08, 2010 9:21 am Post subject: More B-52 stuff
Well, since my last update, I have tried about 35 new circuits or modifications to this amp, and I have aquired a second one as well. So now I am rocking two of them.
My expereince has changed quite a bit since my last post. For starters, running E34Ls in this amp became a problem for me. I did the conversion correctly, modifying the bias circuit, jumping the proper pins on the tube sockets to accomodate the E34Ls, upgrading the screen grid resisters, etc. But I started having trouble red plating tubes. I initually thought it was because the added current of the E34Ls were causing doides to reach thier threshvold voltage and fail, but to be honest, I am really just not sure. I was going to try to run KT-77s instead for the similar sound with less current draw, but then I thought better of spending big bucks on new tubes when I have tons of 6L6s everywhere. So I went back to the drawing board, re-installed the stock Sovtek 6L6s, and then just tuned the preamp to get a similar sound to the E34Ls but with the stock tubes instead. That ended up working out great, now I have a killer sounding amp, with the stock power tubes which are about half the cost of E34Ls.
Some of interesting items of note: As mentioned, through pspice modelling, tuning by ear, and just personal experience, I have tried about 35 changes to this amp, both in the power secion and the preamp section. Some of those changes were entire new circuits, some of them were just component value changes, and some were "system" changes - meaning changing several complonent values based on a model to produce a desired result - the general idea might be changing everything possible to get the correct vaules so that the frequency response "should" match that of a desireable amp like and Engl or Uberschall. Well, of all of these changes, I have reversed all but three of them, in both of my amps. I find that modelling a circuit in a computer program is cool, but still does not usually match up to what you are trying to pull off, because I am not familiar enough with modelling at this point to capture nuances like compression based on plate voltage, etc. Mostly just frequency response is what I use modeling for. Anyway, the point is, I have tried lots of different things, but in the end, the stock circuit topology has produced the best results, with just 3 small exceptions.
1) I added a high frequency roll of circuit, just like I do to just about every bright amp I have. But, this circuit has evolved. I used to just use fixed vaules and break it out on a switch, but I now control it with a potentiometer so it truly acts like a presence control. This amp NEEDs this circuit and greatly benefits from it.
2) I added a little low end through some component value changes in the preamp.
3) Gain 1 on this amp sounds different from Gain 2. Gain 1 is thinner sounding, and more classic rockish with humbuckers. Gain 2 is thicker and more modern sounding, but also sounds great at low gain with a strat for thick blues tone. Gain 1 was just too thin to run single coils through to my ear, so I really wanted Channel 1 to sound just like Channel 2 (thicker) so I could kind og assign channel 1 to be my "strat" channel, and channel 2 to be my "Les Paul Hi Gain" channel. If I can make the channels close to identical, I would still have the Gain control for each channel to dial in the tone I wanted. So, I made a modification to get these channels to be the "same", which involves the same optofet that Bruce employed in the design of the MTS modules. THis made a big difference and gave me the thickness I needed in Gain 1, but I still came up a little short. The channels are 40% more identical than they were stock, but not exact yet, so I think I am still missing a gain limiting resistor or something somewhere that is different between the two channels. Actually, they are not really channels, they are more like 2 modes within the same channel.
Outside of these three circuit changes changes, both of my AT-100s are back to stock (except tubes - running JJs in the preamp and a NOS RCA 5U4GB rectifier tube in one, and a NOS WInged C 5U4G in the other). I play them everyday and love them. They meet the spec for me, which is, the amp must sound great for texas style blues with a Strat, and high gain stuff with a Les Paul. This amp delivers. I would like to someday invest in an upgraded output transformer for one of them, but I just can not justify the cost since i just use these amps as fun projects and learning tools.
Other items of note:
It has been a struggle to get more low end out of this amp without totally reworking the entire power section and filter caps. I have tried to "open up" the preamp to let as much usable bass pass through as possible, but I think the power section is the bottleneck, especially since this amp only uses one rectifier tube. Alot of people would disagree with me on this due to the "Low Res Control", but that controls damping and "stiffens things up" when adding more low end, so I try to keep the res control set to 0 to keep the amp as loose as possible. It sounds so good loose, and tube rectified, but you sacrifice a little low end in doing so. I have corrected this to 90% satisfaction with just small preamp changes, but one of these days I might add some real low end to this sucker, without leaning on resonance control.
I notice that Madison Amps are almost an exact clone of the B-52. I have never actually heard one, but I can tell due to the layout - it is the AT-100 in a different skirt. I see that the Madison also sports EL-34s. Anyway, interesting.
B-52s are pretty good sounding amps with nothing more than a tube change and a few good knob adjustments. It's hard to go too wrong with a tube amp. _________________ ?The true sign of intelligence is not knowledge but imagination.?-Albert Einstein
Joined: 17 Mar 2011 Posts: 171 Location: South Easton Massachusetts
Posted: Tue Jan 31, 2012 2:05 pm Post subject:
These are awesome amps and mod friendly. Mine has had a gain mod done to it now the amp is a beast very tight great cleans very nice gain channels as far as price these amps cant be beat _________________ Good deals with:x2 alowerdeep Mr Marcus Skyze JadedFaith Detroit ABA RADE01 ibenhadx2 Anomaly Mattfig Packman
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