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 Post subject: Re: Your tone recipe
 Post Posted: Mon Dec 22, 2008 11:23 pm 
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Joined: Wed Nov 16, 2005 2:00 pm
Posts: 2962
Location: Scotland
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My blackface Bassman is going to be mainly for gigging. I know some other guitarists, who have had good results with theirs, in playing heavy rock. Considering that the Marshall JCM45 was based upon the Bassman circuit, I'm not surprised.
The JTM45 is based on the '59 Tweed 5F6-A Bassman though, which is a completely different amp. It shares almost nothing in common with the BF Bassman apart from the name on the front and the fact that it uses the same tube types. Everything else is completely different, from the circuit to the transformers to the speakers!

Quote:
I'm still deabting as to whether or not I want to mod a blackface Bassman (no matter how reversible the mod is), or just use an attenuator like a THD Hot Plate.
The PPIMV mod is incredibly simple and doesn't actually involve 'modding' the circuit really, just adding one component (a no-load pot, so it's completely disconnected when turned up full) across the power tube grid feed points. Other than that, I wouldn't mod it though. I know a lot of people do - things like turning the Bass channel into a 'Marshall' circuit and stuff - but in my opinion it's perfect as it is and should be left alone... if you want different distortion tones, use a pedal. The attenuator and MV simply allow you to get the original sound at lower volume. The MV is much less stressful for the amp than cranking it into an attenuator, by the way.

Do please make sure you overhaul it though - I can't stress that enough as most old amps were run until they broke, and then only the dead parts changed - this can lead to much worse damage if you're unlucky... like a blown transformer or at best, melted power tubes. You DON'T need to change the tubes if they're working properly though - in fact, old-production tubes are superior to new ones so if they're still good, leave them alone!

The vital parts to change are the main filter caps, the bias supply cap, the screen and grid stopper resistors (wirewound or metal-oxide flameproof for the screens, metal-film or carbon-film for the stoppers - the originals of both are carbon-comp and degrade due to the high heat levels over the tube sockets), and if you're being really thorough, the bias supply resistor and the rectifier diodes, including the bias diode. All these things can cause other damage - not just the amp stopping working - if they fail.

I would also consider removing the ground switch (which shouldn't be left operational now anyway, along with fitting a proper 3-wire cord if it doesn't have one already) and putting an HT fuse holder in the hole - this will protect the amp much better than the single primary fuse.


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 Post subject: Re: Your tone recipe
 Post Posted: Tue Dec 23, 2008 7:23 am 
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Joined: Mon Feb 18, 2008 9:10 am
Posts: 618
Location: CT
I had a JTM 45 RI. It did sound awesome, a little too much so, and the louder you play it the better it sounds. I had to sell it to protect my hearing for lack of self control.


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 Post subject: Re: Your tone recipe
 Post Posted: Tue Dec 23, 2008 11:13 am 
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Joined: Fri May 05, 2006 8:47 am
Posts: 462
Location: Ohio
I agree with BlueAngel. I would not mod the amp, rather use pedals to get the sounds your looking for. When people mod an amp to make it sound like another amp, I have to think, "Why not just get that other amp?". If you want the Fender amp sound, get a Fender amp. If you want a Marshall sound, get a Marshall. Etc., etc., etc.

I guess I'm being a bit hypocritcal since I had my '68 silver faced Bassman "de-CBS'ed" to a black face, but it was still "in the family" of Fender. I was trying to get rid of the tinkering that was going on in that early silver face era and back to the more classic circuit.


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 Post subject: Re: Your tone recipe
 Post Posted: Tue Dec 23, 2008 3:53 pm 
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Joined: Wed Nov 16, 2005 2:00 pm
Posts: 2962
Location: Scotland
Quote:
I guess I'm being a bit hypocritcal since I had my '68 silver faced Bassman "de-CBS'ed" to a black face, but it was still "in the family" of Fender. I was trying to get rid of the tinkering that was going on in that early silver face era and back to the more classic circuit.
Not hypocritical at all! It's widely agreed that the early-CBS changes were bad, and converting the amp to an earlier version (or even a later one) is totally justified. By common consent, the best version of the BF/SF Bassman is the AA864 circuit or the AB165 preamp with AA864 power section ("the one they never made"), and since you can build these circuits into a later Bassman without changing anything major - and certainly not altering the overall 'character' of the amp - it's definitely justified.

For historical accuracy, there's something you may not know though... the first of the bad changes - the asymetrical bias adjust - was NOT a CBS change, it was done by Leo's own engineers! The first circuit to feature this was the rare AA165, which was made for less than one month in January 1965 (AA864 = August '64, 1st revision; AA165 = Jan '65, 1st revision; AB165 = Jan '65, 2nd revision), and since CBS only bought Fender on Jan 4th 1965 this circuit - and even the AB165, since CBS didn't import their new engineers immediately - MUST have been developed by the existing team. It's true that the combination bias with cathode resistors (another attempt to avoid using matched tubes or having to bias them properly) and the suppressor caps to control oscillation (caused by poor wiring dress due to employing less skilled assemblers), were CBS changes though.

Quote:
I had a JTM 45 RI. It did sound awesome, a little too much so, and the louder you play it the better it sounds. I had to sell it to protect my hearing for lack of self control.
Attenuators are your friend :-).

A lot of people think they spoil the tone, and if you're trying to use one to turn a 100W non-MV monster into a bedroom practice amp the results will be pretty poor - you simply can't attenuate that much and keep the proper dynamics and tone balance. But used to just knock a few db off a slightly-too-loud amp, they work very well. That's why it's best to use a combination of attenuator, master volume and even pedals if you want to get a great tone at low volume - none of them sound all that great by themselves, but if you balance them so each is doing as little as possible, you can actually get better tone QUIETER than with any one method.

Very few of the classic overdriven tones are pure power tube distortion anyway, contrary to popular belief - even with non-MV amps, there is almost always preamp tube distortion as well, and in some cases MORE than from the power tubes.


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 Post subject: Re: Your tone recipe
 Post Posted: Thu Dec 25, 2008 3:22 am 
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Joined: Wed Dec 24, 2008 7:00 am
Posts: 9
Location: Athens, OH, USA
i plug my 481 into a roland JC 120, sparkly and clean.
i use a few pedals here and there.... vintage russian small stone :) .....


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 Post subject: Re: Your tone recipe
 Post Posted: Fri Dec 26, 2008 9:16 am 
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Joined: Mon Nov 10, 2008 11:13 am
Posts: 154
Location: Greenfield, WI
Quote:
I agree with BlueAngel. I would not mod the amp, rather use pedals to get the sounds your looking for. When people mod an amp to make it sound like another amp, I have to think, "Why not just get that other amp?". If you want the Fender amp sound, get a Fender amp. If you want a Marshall sound, get a Marshall. Etc., etc., etc.

I guess I'm being a bit hypocritcal since I had my '68 silver faced Bassman "de-CBS'ed" to a black face, but it was still "in the family" of Fender. I was trying to get rid of the tinkering that was going on in that early silver face era and back to the more classic circuit.


I plan to use my Bassman mainly for gigging. The Bassman heads up to the late 60s silverfaces can still grind pretty good. Listen to Mike Ness of Social Distortion. He's used a silverface Bassman head for over 20 years. He has great tone. I plant to not run mine clean if I can help it. If I wanted to just have a clean power amp, I'd get something like a Twin, or for that matter a Crown power amp, and use a rack mounted pre-amp. I do like my amps to have some grit, to add to the mix. I really don't intend to mod the amp.


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 Post subject: Re: Your tone recipe
 Post Posted: Fri Dec 26, 2008 12:35 pm 
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Joined: Tue Jun 26, 2007 7:20 pm
Posts: 447
+1 on the DA-5 for what it is. My 360/12 sounds great with a little of the built in compression, quite surprising actually. My 330 sounds great on all of the settings once you tweak them in. For a little practice amp you can take anywhere, get great volume at the lowest power setting, have the batteries last a long time, this little amp is hard to beat. At the moment, I'm a cross country semi driver, need an amp to keep in thr truk and blast out whatever Rick I have with me as often as I can.

Ok, for live, 330FGVP through Dr504 Hiwatt halfstack. I've got boxes of pedals and such that all work great with the amp. You never have to worry about cutting through the mix, or being overpowered by your bandmates. I really should get a Rat as iheartricks recommends them so highly. My 4003AFG also sounds great through it.

360/12FGVP sounds outstanding through my Roland JC-120 Jazz Chorus on the neck pickup, and my Vox AC30 for the bridge pickup. Various tweaks to the overdrive on the AC-30, and Chorus/Vibrato adjustments, can really make the 2 amps work sonic wonders.

These settings and equipment are ones that I have found most conducive with what I want to play, and not meant as an insult to those who prefer other setups


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 Post subject: Re: Your tone recipe
 Post Posted: Fri Dec 26, 2008 1:07 pm 
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Joined: Tue Jun 26, 2007 7:20 pm
Posts: 447
As far as modding old amps, I highly recommend against it. Replacing leaking electrolytics or blown componenets is one thing, but why butcher a piece of history? I've seen these destroyed amplifiers brought in by installing the old Torres mods that promised to make the unused channel of you Twin Reverb an AC30 or a Marshall. They sell no such kits anymore,but if you send your amp to them, they wiil do what they do. Now, whether or not they deliver the goods, you are still subject to the quality, but most importanatly. Also, getting someone to fix it will not be cheap, they are probably not cool with giving up the schematic. I'm not attacking Torres,just using them as an example to the kinds of hype people buy in to.If the amp you're looking at does not do it for you 100%, look elswhere untill you find it.

I saw Social Distortion many times in the early 80s, and I could have sworn Mike Ness was using a Marshall halfstack. I know in the studio he records 3 amps simultaneously, one of them being an AC30 with a big muff in front of it, to get his wall of distortion sound.

I would have to check with my old guitar player to get the blow by blow on Ness' equipment, but I'm afraid the thread would get nuked if I continued to discuss this.


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 Post subject: Re: Your tone recipe
 Post Posted: Fri Dec 26, 2008 3:40 pm 
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Joined: Wed Nov 16, 2005 2:00 pm
Posts: 2962
Location: Scotland
Quote:
Ok, for live, 330FGVP through Dr504 Hiwatt halfstack. I've got boxes of pedals and such that all work great with the amp. You never have to worry about cutting through the mix, or being overpowered by your bandmates.
The guitarist in the band I play bass in has just traded his Orange Rocker for a Hiwatt DR103, which he's running with only two power tubes so it doesn't blow up his 2x12" cab. (Although it's still loud!) It sounds fantastic with his 330 - and his Gretsch Duo-Jet and SG, for that matter... and half a dozen pedals. It's an amazing combination of clean and clear, and yet rich and toneful - not at all like playing through a plain power amp.

Quote:
I really should get a Rat as iheartricks recommends them so highly. My 4003AFG also sounds great through it.
I think the RAT is the very best plain distortion pedal ever made. It's very under-rated - a lot of people assume it only does hard distortion, but in fact it will do everything from warm overdrive onwards, you just have to find the right settings (which are quite interactive). They do also sound great for bass - Terry de Castro of The Wedding Present uses two!


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 Post subject: Re: Your tone recipe
 Post Posted: Sat Dec 27, 2008 9:14 pm 
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Joined: Mon Nov 10, 2008 11:13 am
Posts: 154
Location: Greenfield, WI
WhoJamFan and BlueAngel - Hiwatts? Man! I used one of those back in the early 90s for gigging (a DR103). Can you say L-O-U-D? That was during my "I have to sound like the 'Live at Leeds'" phase. You know what Hiwatts are like - once you get past 5 or so, te enter the realm of deafening. There is no such thing as medium volume with a Hiwatt Custom 50 or Custom 100. It was either too quiet, or waayy too loud! Still, it sure was great for a hammering rhythmn tone.

WhoJamFan - I'll keep this brief (I don't want to hijack the thread). As for Mike Ness using Marshalls in the early 80s - yeah he probably did. But from the late 80s until today, he's been using Les Pauls with P90s in them with, through Fender Bassman heads modded by Bolly Zoom (who used to be an electronics tech) of X. Here are a couple of sites that mention this:

http://en.wikipedia.org/wiki/Mike_Ness

go down to the Equipment description


http://acapella.harmony-central.com/for ... ?t=1777736

read BaldGuy's posts since he saw Social D perfrom live in 2006


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