Picked up a `71 Maverick guitar amp... got questions

capnjuan

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Hi Rick; ok ... so ... you already know how to cut component leads too short and burn your fingers and nearby insulation with your soldering iron.... :wink: If you rebuild V1 and you still have grunge, then you'll know what it isn't but will have put a little sparkle in your tone. Good luck. John
 

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BTW, you'll need a hot iron to solder to that buss wire. cj, I changed the power tubes, but I don't think I needed to. I didn't notice much of a change. I think the CTS 10"s in there are not the match of Webers.
 

capnjuan

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... I think the CTS 10"s in there are not the match of Webers.
No ... not much chance of that ... I have a matched pair of Nused Sylvania 7591s that are waiting for the U305R to spontaneously fix itself ... Thanks to the recent troubles in Haiti, voodoo men are easier to come by around here ... I've been putting out some feelers ... I like the workmanship in the Mavs ... they were really taking it seriously. I bet a pair of new 50w 10F150s would really tighten the amp up nicely.
 

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Weber 10F150(T) would make it bark real good. I had a `71 Vibrolux with a pair of 25 watt 10F150T (not as warm as the 50 watt version) and they sounded great. For about 30% less cost, Eminence has some really nice speakers. I tried a pair of Rajun Cajun's in the same amp and it sounded huge. It's a very sensitive (loud) speaker, with a big bottom. I have a 2x10 partial open back cab with a RC and Lil' Buddy (Emi hemp cone) that I use for my Allen Encore head (hot rod Vibrolux circuit). It's a pretty good mix. The RC tends to be brighter, where the LB is a darker, smoother speaker. My Classic 10 sounds really good through this cab, too. The Copperhead is a really nice 50 watt speaker, too (very balanced). That's what came in my C10 combo kit. I bet a pair of CH's in the Maverick would be very sweet. If you're on a budget, the Weber ceramic Signature series speakers can't be beat ($30). That's what I have in the Maverick, now (smooth cone). I haven't tried any, but I've read really good reviews on the Warehouse "Veteran" 10" ($41). They have more of a British flavor to them.

RV
 

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capnjuan said:
...I bet a pair of new 50w 10F150s would really tighten the amp up nicely.
Hi capn:

Those Drells really lay down a groove, considering they're reptile-like and all...
Sorry for the veer...but all these years I was thinking a Drell was merely a word that rhymed with Bell! :wink:
 

capnjuan

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fab467 said:
capnjuan said:
...I bet a pair of new 50w 10F150s would really tighten the amp up nicely.
Hi capn: Those Drells really lay down a groove, considering they're reptile-like and all... Sorry for the veer...but all these years I was thinking a Drell was merely a word that rhymed with Bell! :wink:
Hi Fab; no apologies necessary ... yes, some very groovy ... eh ... cats. Any chance you remember what their 2nd hit was? :wink: And ... in case it got lost in all the uproar ... Compleanno felice!
 

capnjuan

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Ahhh, speakers! Easier to hide from the wife than a new Marshall stack. :lol:
Yes; many people hide ... uh ...sorry ... I mean put speakers in a cabinet ... The alnico 10A150 is available at 50 watts. "What this country needs is a really good five-watt amplifier." Paul Klipsch

KlipschPaul_f.jpg
 

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capnjuan said:
fab467 said:
capnjuan said:
...I bet a pair of new 50w 10F150s would really tighten the amp up nicely.
Hi capn: Those Drells really lay down a groove, considering they're reptile-like and all... Sorry for the veer...but all these years I was thinking a Drell was merely a word that rhymed with Bell! :wink:
Hi Fab; no apologies necessary ... yes, some very groovy ... eh ... cats. Any chance you remember what their 2nd hit was? :wink: And ... in case it got lost in all the uproar ... Compleanno felice!
Grazie mille Capitano Giovanni!

Really liked 'Tighten Up' and owned the single (single?) but can't recall any subsequent hits. Attained one-hit-wonder status, at least in my somewhat compromised memory.

Wiki to the rescue! Interesting stuff I think. :)
 

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OK... I pulled the chassis this evening and started checkin' things. All resistors seem to be within range, with the exception of the two 5 watt resistors in the reverb circuit (68 & 120 ohm). They are both registering around 45-50 ohms. The four 32 uf caps (bypass?) are all showing signs of wear (bulging). Those will be replaced, along with the 10uf in the reverb circuit. The 32uf caps (in the schem) are actually 40uf in the amp. I've found another discrepancy with the little disk caps on the bass pot. The schem shows .0033 & .033, but the pot has .01 & .001. All these caps look original to me.

I was playing around with the amp, before I pulled the chassis. There's one other issue that I noticed with the bass pot. All the pots seem to work smoothly with no crackle or scratchiness. The bass pot, however has a very slight "drop" when turned up the last few degrees (98% of the way up to 100%). It's barely noticable, but I can hear it. I left it wide open and turned the volume up a little and noticed a different kind of distortion. This is more like a crackle, break up. If I back the pot off just a tad, it sounds OK. Could be to pot? Maybe the disk caps on the pot?

I got some pix, but I haven't figured out how to attach JPG files to this message.

RV
 

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RickV said:
45-50 ohms. The four 32 uf caps (bypass?) are all showing signs of wear (bulging). Those will be replaced, along with the 10uf in the reverb circuit. The 32uf caps (in the schem) are actually 40uf in the amp. I've found another discrepancy with the little disk caps on the bass pot. The schem shows .0033 & .033, but the pot has .01 & .001. All these caps look original to me.
This is more like a crackle, break up. If I back the pot off just a tad, it sounds OK. Could be to pot? Maybe the disk caps on the pot?

I got some pix, but I haven't figured out how to attach JPG files to this message.
Yeah, they're bypass caps. The 2 stacked 275 mf caps in the voltage doubler powercircuit as probably waving goodbye as well. The 40x4 cancap is out of stock most places, so you might have to get clever to match the values.
Pot dirty at that (untraveled?) section?
caps on the bass side are probably stock. Guild made a lot of undocumented changes in their amps.
 

capnjuan

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fab467 said:
... Really liked 'Tighten Up' and owned the single (single?) but can't recall any subsequent hits. Attained one-hit-wonder status, at least in my somewhat compromised memory.
It was popular just before I went into the service. I was hoping you'd know their next hit ... that way it would seem like I knew there was one and you'd seem like you had Archie's waterfront covered ... so much for the best laid plans ... :( :wink: Thanks for the link ... and I thought 'Dance' songs had pretty much died with Tighten Up until ...
 

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OK... got a few parts in. I replaced the four 32uF bypass caps (had 40uF in it) and the one 10uF in the reverb circuit. Didn't do anything with the trem, yet. I also changed the 68 ohm 5 watt resistor in the reverb circuit. Used two 33's in series. When I fired it up, I got a loud pop with the standby switch (didn't get that before I changed the parts). It seemed to sound OK in the second input, but when I plugged into input #1, I got lots of loud static and white noise. I double checked everything and all looks good to me. Default mentioned needing a hot iron for soldering to the buss wire. The hottest I have is only 40 watts. It took a long time to get the old ones off. I went back on tried to re-flow the connections, particularily on the buss. That seemed to help. The pop on the standby was a lot less, but still there. #1 input sounded OK, but I could hear some faint noise. After a few minutes, it started to develop a lot of static and microphonic feedback. Could all his popping, static and stuff be a product of my lousy soldering (I'll blame it on the iron)? Would it be worth it to get a 100 watt iron for buss connections? I'm thinkin' (hoping) that's all it is. I didn't have any of these symptoms before I started changing the bypass caps.

Thanks,
Rick
 

capnjuan

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Hi Rick; I think you answered your own question about the power of the soldering iron you need; at least 75watts or better. The ground buss conducts heat just as easily as electricity and when you heat it with an iron that can't put a lot of heat in one spot, the heat is conducted away from the joint (not that kind of joint) you're trying to make. One bad solder joint on the buss will send weenkie wonkie to everything tied to it ... including the standby switch.

This is how the standby in that amp works; in its later amps, Guild usually grounded out the signal on standby. The magenta is the signal path going left to right. The green leads to the standby switch which is drawn in the 'on' position. You can see that if it's in the 'standby' position, the signal path is connected to a leg to ground that offers no resistance ... the signal is grounded out; the output stages see no signal to amplify.

But if there's an intermittent on the ground buss, then whatever electrical trash present there will travel the buss, find the standby switch leg in the 'standby' position, flow across the contacts, and travel to the next stage and out the speakers ... so .... don't forget to squirt some contact cleaner on the standby switch. Good luck with your amp.

BrettMaverickstandbyc.jpg
 

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Yup... that did the trick. Went out and got a soldering iron that pulls so many watts, the house lights dim when I pull the trigger (I think I caused an area wide brown out...)...LOL. The Maverick seems to be quite and stable, so I'll play around with it for a while, before I open it back up and get the tremolo working. Can't wait to gig with it.

I really appreciate all the help (and encouragment).

Maybe I'll change my login name to "Grasshopper".

RickV
 

capnjuan

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Hi Rick; glad you got it straightened out ... any change in the 'verb and trem? CJ
 

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Actually, the verb was working up until I opened it up this last time. May need to touch up a connection to the bypass cap I changed. The verb sounds good, if I turn it up just a touch. It's an unusual sounding verb (nothing like Fender). The tube seems a little microphonic, but from what I read, those tend to be by nature. I like it, even though I rarely use verb. I like it dry. I got new caps for the trem, but will give the iron a rest for a couple weeks (vacation).
 

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Look at the reverb tank and see if it still has the standoffs intact. If it's screwed directly to the cab, you'll have problems with the tank resonating.
 

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I gigged the mighty Mav for the first time last night. I killed! I never got around to getting the trem working, but I would only use it on one or two songs, anyway. The socket for the reverb tube shorted out (never seen that happen before) a month or so ago, so I just took it out and taped up the wires. I also pulled the pan, so it wouldn't rattle around or get damaged. I usually don't use any verb either. Someday, I'll get these two circuits back up and running.

I'm running an Emi Ragin Cajun and Lil Buddy (hemp cone). Both are very efficient speakers, with a lot of thump. We played an outdoor patio, behind a biker bar in Arlington last night. I was very surprised how loud this amp was at about half way up in the high input jack. I grabbed my LP Classic (w/Classic 57's) and an Ibanez Artstar (w/Super 58's). Played both (two sets each) and both sounded wonderful through the Maverick. The bass player keep coming over to my side of the stage to hear it when I was soloing. My pedal board if fairly straight forward TU2>Tone Press>Route 66 OD/comp>Nobels ORD 1 (overdrive)>MXR Carbon Copy. I set both OD's with low to medium OD. If I want heavier OD, I just kick them both in. Same for the two compressors... not a lot, just a touch from each. Works great.

The Mav has great note definition, clarity, and a very different tone (not like anything else I've heard). I think this may be my main gigging amp for a while. I'll bring my Allen Encore head along for a backup (now,that's a real statement on just how good this baby sounds!).

The only thing left to determine is it's reliability.

Rick
 

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Thanks for the 411 on the speakers! The top CTS blats when it's turned up, (on mine) so they"re probably due for replacement. I would probably go with something less efficient for my basement concerts though. :oops: :wink:
 
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