From: JaySG (jaysg@xvb.net) Date: 7/25/2000 6:19 PM Subject: Steve: Dumbell questions I've got a 77 architecture/97 values dumbell channel up on my '83 Fender Concert. I have fairly symetrical distortion coming out of CL2 and OD1, but the OD2 output is asymetrical. Is that the way it should be? I have not implemented the plate to cathode 350pf's on OD1 and OD2. I don't have any oscillation problems -- are these part of the "sound". I noticed they're not on the skyliner. Is there a "correct" range to set the 100k OD trimmer, with a 100k in front of it? Lastly -- the sound. Right now I'm so stoked, I can't believe it. What I don't know is what it should actually sound like. Any dumbell cloners in the San Diego area? (I know Gil is up in LA.) START NEW THREAD REPLY PREVIOUS LIST Read 130 times From: Gil Ayan (ayan@earthlink.net) Date: 7/26/2000 1:59 AM Subject: Not Steve.... I've got a 77 architecture/97 values dumbell channel up on my '83 Fender Concert. I have fairly symetrical distortion coming out of CL2 and OD1, but the OD2 output is asymetrical. Is that the way it should be? Hmmm... that is kind of strange. What actually happens, is that each tube will clip the top portion of the input signal, so after 1 stage you should be asymmetrical, then the signal gets inverted and you clip the other side, etc., etc. In the end, the last waveform in any amp I have seen is not symmetrical. Of course, this applies to overdrive only. If the amp is set pristine clean, you will get a perfectly symmetrical waveform throughout -- until you hit the PI, and then it may get out of whack some. Is there a "correct" range to set the 100k OD trimmer, with a 100k in front of it? [Note: the 100K pair you describe belongs to old amps, as far as I know. Later versions increased the fixed resistor by quite a bit... and maybe even the trimmer got smaller.] Sure... whichever sound best to you! Figure out the amount of overdirve you like and then zero in on it tweaking the trimmer. Also, there is a bit of a psychological factor: do you like for the OD channel to start off burning? Cranl the trimmer... Do you prefer middle gain settings? Try lower settings... Do you prefer middle gain when both the input and the drive control are pegged up? Then set the trimmer only as high as you need to get the signal strength you need. I have not implemented the plate to cathode 350pf's on OD1 and OD2. I don't have any oscillation problems -- are these part of the "sound". I noticed they're not on the skyliner. The puffs take off the "edge" from the signal. You have to play around a bit there, no puffs and to me the sound it a bit buzzy and piercing. You can also try bypassing a plate load resistor (I prefer the last OD stage) and you will get similar results. Lastly -- the sound. Right now I'm so stoked, I can't believe it. What I don't know is what it should actually sound like. Any dumbell cloners in the San Diego area? (I know Gil is up in LA.) Dunno... Gil START NEW THREAD REPLY PREVIOUS LIST Read 114 times From: Mark Abbott (abbottmark@hotmail.com) Date: 7/26/2000 9:55 AM Subject: Gil's Favorite D_Clone? Gil What is your favorite circuit, the modded 77 or the 97 Skyliner? Was the 97 Skyliner much harder to build? I take it from a previous thread that you used aluminium for your chassis, do you think it makes that much difference, and why? Yours Sincerely Mark. START NEW THREAD REPLY PREVIOUS LIST Read 105 times From: Gil Ayan (ayan@earthlink.net) Date: 7/26/2000 4:43 PM Subject: Re: Gil's Favorite D_Clone? Gil: What is your favorite circuit, the modded 77 or the 97 Skyliner? Mark, I assume that by 77 you mean the one with all 100K plate loads and 1.5K/5uF cathodes? IF so, yes, I did build that first (you can clearly see those component values in the pictures of my first amp), and I didn't really like it. It was kind of harsh sounding in overdrive mode, so I quickly departed from that. Then, the "Skyliner" schematics are close to what I built as "Sky." That is a great sounding amp, a nice clean sound and a lead sound that is, inevitably Marshall-esque. I do have one of those amps -- had two, more on that later -- and I like it a lot. Needs to be played loud though, else it sounds sort of lousy. Then, there is another amp which uses the "77" architecture but different component values. That is what my first amp morphed into and the sound is great, and what I always say is that "it sounds like what *my* concept of the Dumble tone is." What about the third amp? Well, originally it was a Sky, with the three-control tone stack at the back of the overdrive an all. Tweak it as you might, the thing will always retain its British vibe; not bad, actually great, but I liked the way the other amp was "easy" to play. The Sky is kind of like a Plexi on steroids, so youget an idea... Very sensitive, but think fat, but not singing like my other amp. So, I ripped out the little tone stack board out of that amp and substituted another board in which I put a little volume control and tone control (treble gate). Didn't change anything else in the amp, and that alone made a huge difference. The "easy feeling" returned to the amp and it is asinging machine. Of course, now it doesn't crunch anymore! So, if crunch is your thing, go with the tone stack after the OD. If singin is your thing, then I would suggest you try removing the second TS and listen. In the end, my "hybrid" amp is the one I'm more enthused about today. It has the great clean sound of the Sky, and a singing lead tone which is more refined than the first amp... Weird, and sure, I amy change my mind tomorrow. I still think all three amps are great sounding. I take it from a previous thread that you used aluminium for your chassis, do you think it makes that much difference, and why? I have no idea, Mark. I know the real thing uses aluminun, and that I was going to need to drill holes for the transformers and wires, so I didn't want to mess with stainless steel. That's why we decided to have 1/8" thick aluminum chassis made -- and yes, they are extrmely beefy at that thickness. Gil START NEW THREAD REPLY PREVIOUS LIST Read 89 times From: Gil Ayan (ayan@earthlink.net) Date: 7/26/2000 4:51 PM Subject: PS: Yes, it was a little harder to build... Was the 97 Skyliner much harder to build? And the reason being that in my first amp I build a single eyelet board with the preamp and power suppyl on it -- anyone who has seen Mark Norwine's (Carlosn Amplification) "Turbo Pup" will see what I mean. I got the idea there, and it was easy to build. I later retrofitted the bias supply board and relay board with PCBs, but originally they were all eyelt boards (and the pictures you have seen are old, so you see the G10 eyelt boards everywhere). When I started the second amp, I wanted to learn something new and decided I would go full steam and copy the blooming thing as best as I could. So I built the intricate power supply PCB, with all those funky radial caps, and built everything other than the preamp board on PCB as well. That alone makes it harder... and there was a bit of a learning curve there as well, since I had never built PCBs before. I think just looking at the amps gives you a pretty good idea of which one was harder to build. :) Then, all of the little tone controls were sort of a nightmare to tweak at first. So I spent quite a few hours there as well. Obectively speaking though, I would say the Sky takes a little longer, only by the amount of time required to build a little tone stack board and connect it to the main board. :) Gil START NEW THREAD REPLY PREVIOUS LIST Read 88 times From: JaySG (jaysg@xvb.net) Date: 7/26/2000 5:30 PM Subject: Re: piercing Gil, I remembered you talking about the basic tone being a bit piercing and that it works best playing in a band. With what I've built up, there's nothing piercing to the tone. That's why I'd like to compare with the real thing. (It wouldn't hurt to know where I'm going.) The amp('83 Fender Concert) is blackfaced on the clean channel, so I have stock fender values for CL1 and also from the Reverb return ckt out to the speaker. I'm not using the dumble clean path or the dumble PI/Output/Feedback/Presence. The speaker is a Celestion V30. There are two tone stacks loading CL1 -- the clean and the distortion, which may be rolling off highs a bit. LDRs, not relays. I'm very glad I did this. I think so far it's cost less than $15 and a few hours of planning. There's a cleanness to the distortion that is unique. That's probably what's been described as smooth. I have to hit a chord or go back to the clean channel every now and then to remind my brain that I'm listening to distortion. START NEW THREAD REPLY PREVIOUS LIST Read 86 times From: Jim S. (jsalman@fiam.net) Date: 7/26/2000 7:35 PM Subject: Re: Gil's Favorite D_Clone? Then, there is another amp which uses the "77" architecture but different component values. That is what my first amp morphed into and the sound is great,... Gil, Would you mind telling us which components you changed and what their values are? Thanks. START NEW THREAD REPLY PREVIOUS LIST Read 88 times From: Gil Ayan (ayan@earthlink.net) Date: 7/26/2000 8:29 PM Subject: Re: Gil's Favorite D_Clone? Gil, Would you mind telling us which components you changed and what their values are? Thanks. Jim, not being the 'owner' of that information, what I can say is that the schematic that's out there labeled as skyliner is not that different from the "missing link" amp (the one which evolved from the old ones, and has no tone stack after the overdrive). Furthermore, I probably like the sound of the sky without the tone stack better than that of the missing link. Hope this helps some, Gil START NEW THREAD REPLY PREVIOUS LIST Read 90 times From: Gil Ayan (ayan@earthlink.net) Date: 7/26/2000 8:32 PM Subject: Re: piercing Gil, I remembered you talking about the basic tone being a bit piercing and that it works best playing in a band. Piercing bright yes, but that doesn't mean buzzy. If I turn the presence control to 10 in my amps, they will take your ear drums out, but the sound will not be buzzy. Maybe that clarifies that? :D The amp('83 Fender Concert) is blackfaced on the clean channel, so I have stock fender values for CL1 and also from the Reverb return ckt out to the speaker. I'm not using the dumble clean path or the dumble PI/Output/Feedback/Presence. The speaker is a Celestion V30. There are two tone stacks loading CL1 -- the clean and the distortion, which may be rolling off highs a bit. LDRs, not relays. So what is Dumble about that amp? I am slightly confused now... Gil START NEW THREAD REPLY PREVIOUS LIST Read 86 times From: Jim S. (jsalman@fiam.net) Date: 7/26/2000 10:47 PM Subject: Re: Gil's Favorite D_Clone? Yes, that helps quite a bit. What about the basic volume/tone circuit you replaced the post-OD EQ with in your "hybrid"? I assume that the volume and tone pots are wired just like passive guitar volume/tone controls (tone pot has wiper to cap to ground). Is this the case? Why did you include the little volume control -- was it to compensate for the added gain and to prevent the front panel OD master volume from getting too loud too quickly? What pot and cap values did you use? (Sorry to be pestering you with all these questions!) Thanks, Jim START NEW THREAD REPLY PREVIOUS LIST Read 81 times From: Jim S. (jsalman@fiam.net) Date: 7/26/2000 10:57 PM Subject: Re: piercing It sounds like the only thing "Dumble" about his converted '83 Concert is that its lead channel now consists of a Dumble-inspired 2-stage overdrive section that is being fed by a Fender-style 1+1 set of gain stages. (The stock Concert lead channel consists only of a total of three gain stages, not four.) The '83 Concert is a great platform for building a Dumble clone. Lots of knobs and the ability to have independent channels, each with their own EQ. Also an effects loop which I believe is already very similar to a Dumbleator in circuit design. If I were him, I would go all the way and "Dumblize" the rest of the amp. START NEW THREAD REPLY PREVIOUS LIST Read 58 times From: Gil Ayan (ayan@earthlink.net) Date: 7/27/2000 5:20 PM Subject: That I can tell you.... Yes, that helps quite a bit. What about the basic volume/tone circuit you replaced the post-OD EQ with in your "hybrid"? See, this I came up with myself -- well, anyone that has a Fender guitar knows this circuit too! -- so here it is: Right out of the second overdrive stage, I have a .02uF coupling cap which feeds a 150K resistor. From that node, there are two paths. The first one goes to a 220K trimmer wired as a voltage divider (which is the "internal" volume control). The second path is to another 220K trimmer, wired as a variable resistor, which feeds a .02uF cap and from there it goes to ground, and this is of course the trivial tone control. The output of that goes to the "lead master" pot, just like in the web's Skyliner schematics. I put the little control on the board for a number of reasons, one of which was to lower the output impedance of the overdrive channel. It also allows you to throttle back a little bit on the lead channel volume, otherwise you might find yourself turning the OD master on the panel way down. You may laugh, but the way I set the little volume control inside is such that for my typical gain settings, both the clean and the OD master controls are at about the same mark. :) > (Sorry to be pestering you with all these > questions!) No problem. I've said all I can though, so I'm dried out. :( Gil START NEW THREAD REPLY PREVIOUS LIST Read 55 times From: JaySG (jaysg@xvb.net) Date: 7/27/2000 5:25 PM Subject: Re: what is dumble about... Gil, The new 2nd channel starts with the skyliner tone stack, executes CL2 as the recovery stage, into OD1 and OD2 per the Hybrid Rev A schematic. I used the rear panel Hum Balance hole for the OD trimmer. The rest of the front panel supports the functionality well. It seemed like a good way to find out whether or not I wanted to build a dumble from scratch. I've seen comments to the effect that the dumble clean sound is not the creation of genius that the distortion is. Also, I've seen comments that there is nothing amazing about the design starting at the PI input. Wrong? I am in the dark on this stuff. What is great about the stock Concert as a platform, is that there's an unused 12ax7 section(V4b), which means I didn't have to add much, besides some solder lugs I riveted in for the extra components. Sorry about being confusing. I often leave other people confused. I'm hell in meetings. As to the piercing tone question, yeah, the thing has enough bright with the presence up. I'm still looking for a dumble or clone locally so I can benchmark the sound. Thanks again for the inspiration. That goes to everyone on this board. START NEW THREAD REPLY PREVIOUS LIST Read 45 times From: JaySG (jaysg@xvb.net) Date: 7/27/2000 5:41 PM Subject: Re: piercing Jim, Clarifications: My modded concert/dumble lead signal path has all four triode stages. Note that the stock effects loop is neatly switch-bypassed when not in use and does indeed look a lot like a dumbelator. I don't have the Master volume control that effects both channels, however, I don't see why I would want it. The BF clean doesn't really cook due to the solid state rectifier. I sort of doubt that the dumble clean cooks either. I have yet to implement the boost switching. I have the parts for a front panel pull switch, but adding a footswitch...I'd have to steal the Reverb On/Off. There's not a lot of room on the rear panel. My only sonic inspiration has been listening to Robben Ford clips on amazon.com. His settings are on the japanese dumble site and in this month's GP. (Anybody else notice the Westone earplugs?) START NEW THREAD REPLY PREVIOUS LIST Read 40 times From: Jim S. (jsalman@fiam.net) Date: 7/27/2000 8:30 PM Subject: Thanks I've said all I can though, so I'm dried out. :( Thank you very much for the tips. I'll now let you rehydrate yourself! Jim START NEW THREAD REPLY PREVIOUS LIST Read 44 times From: Gil Ayan (ayan@earthlink.net) Date: 7/27/2000 11:20 PM Subject: Oops: Minor Correction I've said all I can though, so I'm dried out. :( Thank you very much for the tips. I'll now let you rehydrate yourself! Jim Shoot, I was dired out and made a mistake. The tone control cap connected to the 220K variable resistor is .01uF, not .02uF Gil