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#1 2011-04-11 14:45:46

Robstr01
Member
Registered: 2009-08-05
Posts: 23

Modify V4 into V4B ?

I havent been able to find this using search... Is there a simple component change to give a V4 the low end frequency responce of a V4B? Thanks  --Rob in Austin.

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#2 2011-04-11 19:57:57

teledeluxe
Member
From: Chicago, IL
Registered: 2008-09-24
Posts: 467

Re: Modify V4 into V4B ?

Here:
http://stonemarmot.com/rants/?p=38

The easiest and biggest change you can make is by replacing the .01uF capacitor with a .1uF in C3 or C6. Actually, just adding a .1uF in parallel with the .01uF would be super easy and sound vitually identical.

Last edited by teledeluxe (2011-04-11 20:20:18)


2 wrongs don't make a right, but 3 lefts do!

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#3 2011-04-23 23:03:35

chabby
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Registered: 2010-06-08
Posts: 37

Re: Modify V4 into V4B ?

and completely eliminate the reverb section because reverb eats power.

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#4 2011-04-24 07:49:49

hangman
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From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: Modify V4 into V4B ?

reverb eats power?

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#5 2011-05-05 21:26:27

chabby
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Registered: 2010-06-08
Posts: 37

Re: Modify V4 into V4B ?

what-i-meant-was-the-additional-drain-of-the-reverb-section-takes-away-from-the-circuit-and-yes,-it-drains-power-for-lack-of-a-better-term.plus-v4b's-don't-have-reverb-i-thought.
its-the-same-reason-the-normal-channel-of-almost-every-fender-ever-built-is-louder-than-the-reverb/trem-channel.

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#6 2011-05-06 01:32:22

hangman
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From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: Modify V4 into V4B ?

ah,  a bit of a tone suck... yes agreed.

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#7 2011-05-06 14:56:16

teledeluxe
Member
From: Chicago, IL
Registered: 2008-09-24
Posts: 467

Re: Modify V4 into V4B ?

chabby wrote:

its-the-same-reason-the-normal-channel-of-almost-every-fender-ever-built-is-louder-than-the-reverb/trem-channel.

The LDR tremolo circuit in those Fenders is typically what makes the reverb channel quieter. That's the reason a lot of people turn the pull boost on later ones into a tremolo bypass -- to completely remove it from the circuit giving it a huge volume boost.

Granted, Reverb does bleed some signal to ground so it is a little lossy. I've read that replacing the 3.3meg resistor that's in parallel with the 10pF cap in the reverb section of a Twin Reverb might correct the volume drop somewhat. Evidently the larger the resistor, the bigger the tendency to drift way out of spec over time.

Last edited by teledeluxe (2011-05-06 15:11:41)


2 wrongs don't make a right, but 3 lefts do!

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#8 2011-05-06 17:03:47

hangman
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From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: Modify V4 into V4B ?

I've never thought the reverb "loss" was much of a loss.

especially since you get reverb out of the deal.

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#9 2011-05-16 03:58:34

ddbass
New member
From: Athens, GA
Registered: 2011-05-16
Posts: 9
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Re: Modify V4 into V4B ?

hangman wrote:

I've never thought the reverb "loss" was much of a loss.

especially since you get reverb out of the deal.

My thoughts exactly.


B-15N,R-12R, G-15, V4B, V4

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#10 2012-05-21 03:14:09

jamesvermillion
New member
Registered: 2012-05-21
Posts: 1

Re: Modify V4 into V4B ?

I just bought a 1976 v4 and am wanting to mod it for a bass. I understand that this "distortion" model is a bit of a different beast that the earlier v4s. do you have any suggestions as to some caps that I can replace to make the lower lows a little more pronounced like a v4B? Or would changing the same caps work on a 1976 too?

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#11 2012-05-21 14:00:42

Robstr01
Member
Registered: 2009-08-05
Posts: 23

Re: Modify V4 into V4B ?

I ended up doing the cap replacement as described here...
http://stonemarmot.com/rants/?p=38
Even with 6550 power tubes it didnt make much difference.

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#12 2012-06-04 18:53:43

Liquids
Member
From: CT
Registered: 2010-08-01
Posts: 491

Re: Modify V4 into V4B ?

It shouldn't make much difference, the cutoff frequencies are below audio in the guitar circuits, and they are 1 octave further below audio for the V4b.  Where the volume control is 1 MEG in both and the bass uses 100n and the guitar 10n for coupling cap, the bass has 100k in series with the 1MEG pot so....that evens out the cutoff frequency there.

Reverb channel tone difference in a fender is also due to 3.3MEGs of series resistance between the output of one tube and the input of the next tube with the reverb side-chained there. That causes volume drop and affects the sound a bit.

To compensate, an additional tube stage is added in the reverb/vibrato channel, for more gain as lost by that circuitry...a subtle affect, but hard to say, as many do, that it's clear 'non reverb fenders soudd better than their reverb counterparts.'  For one, I like reverb, for two, none of the reverb circuit and associated commpensations/tonal compromises are present in the normal channel of a fender with reverb, but few people seem to say the NORMAL channel sounds better than the VIBRATO channel in fenders! Just me =^)  Maybe everyone just likes reverb.  I guess some people do mod their fenders so the normal channel has reverb too...?  But invariably you're back to a re-voice of the normal channel in giving it the reverb circuitry and modding it to do so.

I have a V4b and use a used TC electronics rack unit that is high quality but not the newest and greatest, so it came cheap.  Previously I had the cheapest available lexicon unit for the same thing.  Both sound friggin' good and their reverb (let alone the variables to tune in how you want the reverb) sounds are amazing. 

I use the rack units mostly rfor everb and delay.  IF you're like me and want multiple reverb and delay options, you can control it via midi - it's like having a hundred reverb units at your disposal simultanously, but only takes up a rack space.  The TC is preferable because a change in patch doesn't cause a mute of all sound like the lexicon did. It just transitions from one arrangement of affects to the other (reverb and delay trails remain and the new settings hit the inncoming signal after switching, with the dry signal maintained throughout.)

Going rack  is a jump for most pedalboard guys, but I think it's worth it after never feeling I had enough reverb or delay options, let alone the improvement in sound quality.  The boss DD-3 is a good unit I will say, however, but outside of tap tempo, it's got one programmable setting for mix and feedback - the knobs.  Two pedals gets you two presets...no experience with the boss reverb unit.  Not to impressed with the belton 'brick' based reverb pedals either.

Spring reverb is nice, and unique and classic and all, but the cheapest lexicon unit offers awesome sounding reverb (And delay).  Just be sure you feed rack units a well buffered signal or else your high frequencies will be sucked out by the 20k input impedance of most rack units (by comparison, the ampeg has 5.6MEG input impedance.  I think the TC unit I have is made for guitar and can be programmed or out of the box had standard 1MEG input impedance would you be so silly as to plug your guitar right into it...even though it doesn't have distortion (?) so, it's really meant as an 'effects' unit like I use it, rather than a 'all in one' for guitars.  Even still, a buffer that's always on is a wise way to get your guitar to play nicely with all this kind of stuff thoughtlessly.

You have to be a little techie and be willing to spend a few hours learning and then tweaking/programming patches when you use such a unit, but after that (at least for me) you've got as many ambient sounds at your disposal as you'd like, foot-switchably, and there's no 'tone sucking reverb' inside your amp for extra mojo bragging rights ;^)

You also get the option of a stereo output for a mono input, which can come in handy too, as a side benefit, assuming this is the last thing in your chain before your amp.

Last edited by Liquids (2012-06-04 19:03:06)


Matthew

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#13 2012-06-04 19:32:56

hangman
Banned
From: Seattle Washington
Registered: 2006-09-04
Posts: 1848

Re: Modify V4 into V4B ?

Everybody always talks about the tone sucking reverb and tremolo ciruits.   All I have to say is this:  who cares?

Digital reverb will never fully replace the sound of tube driven spring reverb,  the end.   
Technically you lose tone in the eq circuit too.   Just get a line6.   Then you dont have to worry about those pesky analog circuits sucking up your tone.

It seems so pointless to me to own a twin reverb and cut the reverb circuit out.   You do know fender made an amp called the bassman right?  Get one of those.

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