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#26 2010-09-22 05:51:03

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

It does change the sound,  but its doesn't change the character or overall tone of the amp.  that all stays the same,  only your lows are more round,  and highs sweeter and less abrasive.   
i think i said it early on in this thread that i was never totally satisfied with the tone of the ampeg.  my main complaints were these:

1. Wanted more highs but didn't like the way the treble sounded when boosted,  and the ultra high was just plain unusable

2. bass always seemed lacking,  even when boosted.  seemed out of focus, or undefined.   

I still played the amp and loved it,  but these things were just always in the back of my mind. Not anymore.

ultimately I can imagine some people might prefer the sound of ceramic caps.... but I haven't met any people who have ever said that.   
we are talking about so 4 caps total in the mod... its not like all of the caps in the ampeg are ceramic just those in the tone circuit.  And originally (pre v-series) ampeg didn't use the PEC wafer,  they used discrete components.  it was only after 1966 or so that they switched to circuit boards and the integrated tone circuit, mainly to reduce costs.

So my opinion is that the mod is worth doing.  everything I liked about my vt-22 is still there,  only better.

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#27 2010-09-22 14:53:08

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I'm really curious about this and your comments, Steve.  I'm not a fan of ceramic caps (though am somewhat of a skeptic about tone cap mojo), but my experiences with these amps has been so different than yours.

I have a V-4b in some disrepair, mind you, but with all the switches 'disengaged,' the amp is just flat/muddy/middy with everything near flat. Same thing with a fixed up V4 I tried at a store in the first place, though the V-4b I have seems to be 'bigger,' which I attribute to C3 and C7 being 100n rather than 10n as in the V4.  I was pushing the bass more and cutting the mid less on the V-4, than I am with the V-4b. But pot tolerances can really vary, especially given 30+ years, I've found. so tone settings should be given at least 20% in general when comparing. 

Anyhow, with either amp, it's needed a lot of mid cut (9 o'clock to 7 o'clock) @ 300hz to sound distinct and clear like a Fender. At that point, it's got the fender mids, but a HUGE bass with tons of low end.

In fact, it's got so much low end, in a live situation I fear it would be create a sub bass "mud bath," though the bass is huge but tight (unlike a Fender, where when the bass gets 'big' it gets muddy/indistinct).   I'd have to turn the bass down around 10 or 9 o'clock on the V-4 for it to be where my 68' fender SR's bass content is ideal, at best. It's fun to turn up the bass when playing alone though. It's almost exaggerated, but stays tight and distinct before it overwhelms everything else.   It's one of the only amps I've ever felt like the bass control had real range, rather than needing to be set just right aurally, somewhere between 'no bass' and 'just mud,' though honorable mention to a DR Z I tried.

The high control has been friendly - I like it boosted a bit if not flat, and I've *always* tended toward a dark tone - balanced at best - think Larry Carlton clean and Robben Ford dirty.  I can only imagine turning the treble pot down for a jazz gig, maybe, especially with the mids set near flat.  Treble All the way up is extreme but it has lots of useful settings, and seems to avoid being harsh more if not altogether, compared to any other amp I've played.  And I've never been a fan of bright caps, but it's got that tone available, if you like that sort of thing, for crunch or cut.

I can only wonder if it's your speakers?  My SR's 4x10s sound great, it turns out I've found they really drop off those sub lows the Ampeg is capable of, and don't do it justice compared to the 2x12 I recently acquired.  When I first read your mod and comments, to be honest I thought it was all mojo (as a lot of audio/amp stuff can be), but I know you've repaired and heard a lot of these amps.  Is this also your experience when you take in other similar amps and A/B different speakers, heads, etc?

As a side note, do you use the stock 330n value for C11 or C13?  I imagine that could have an effect?

All that said, I'm interested to get rid of the ceramics at some point, but I'm less anxious to do so since I'm not hearing what you are with mine stock!   And I'd also like to try (or hear your take) on comparing your tone stack 'mod' with the good caps you like vs newer cheap ceramic caps, just for fun.

Last edited by Liquids (2010-09-22 14:59:38)


Matthew

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#28 2010-09-22 16:11:29

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I too like the V4's EQ set realtively flat. I typically roll off the bass some, nudge up the mids a little on the 1000Hz setting, and leave the treble totally flat.

FWIW: I come from an extensive Fender amp background (silver, black, blonde) and have always wanted a little more mids than traditional Fender sound.


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

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#29 2010-09-22 18:27:52

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I don't think the mod boosts the bass response at all... as I said it simply clears it up a bit. its a matter of imaging. which might even solve your dissatisfaction with the bass response of your amp.   perhaps our issue is one of semantics. 

as for the treble,  I found it impossible to turn the treble up before the mod simply because it was so harsh. perhaps you would find if you did the mod that you would actually turn up the highs.  I tend to use the ultra high switch now even though I never did before.

I have done this mod to amps with jensens, eminence, celestion and altec speakers... I don't think it is the speakers.

I think with all matters of tone,  everyone has a preference, and people hear things differently. 

as for the cap mojo... I think you're probably correct.  a lot of the boutique cap market is snake oil. 
But I do like the sound of tubular film caps, i've a/b'd them with ceramics and orange drops... and i just prefer them.
I like sozos because they sound good, and they're american made. 
I'd pay 50 times what a chinese ceramic costs just on principal.

I'd suggest that as a couple of skeptics, you volunteer to be test subjects.   I'm curious to hear what you think.    I promise that the bass wont be louder,  and the highs wont be quieter.   its all in the imaging.

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#30 2010-09-22 19:56:54

rob
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Registered: 2008-10-28
Posts: 171

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I suggest that some of the older amps that have excessive bass or muddiness are in need of filter cap change. It is very common that these caps drift way up in value causing this problem. The tone controls all appear to be very effective on these amps when they are in good repair. I think this mod is a great idea that makes good sense. I have not had my v-4 apart in a while (it has been very reliable since the major overhaul), but if I need to get into that area of the amp for any reason, I will probably do it.

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#31 2010-09-23 00:54:54

ROBO
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Registered: 2010-01-26
Posts: 134
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Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I did this mod on my V4B and SVT when each was being overhauled and I like it. It pretty much did just as Steve said. The core sound of each amp is still there but the eq's are much cleaner and more usable. I'm a fan.


Less talk, More rock

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#32 2010-10-19 15:03:38

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Anyone mess with the cap values?

I've been doing some spice modeling.  I see some other Ampegs use 47pf/470pf on the treble side. That looks too extreme to me - however, I still don't find my V4-b harsh - if anything I find it dark. It's the least buzzy amp I've ever had - even with the bright switch on (500pf), where I just found it cuts nicely, even though that's not my sound.

Anyhow, playing around last night, I found various settings useful - but tend toward boosting the highs at least slightly no matter what and cutting the mids somewhere, at least a little bit. Anyhow, as I boost the treble I get more clarity, but what I hear, from being a sound man, is that the treble control is too expansive in what frequencies it affects, and has too low of a corner frequency to my ear - 'too much 1k' when I'd rather it be boosting highs starting more around 2K or 3K and beyond.

I find that cutting 1K is nice, sure, but I more so need some cut in the low mids, like 300hz, or it's a mud bath...and have to pick one frequency or the other with the mids.   Putting the treble at 4:30 and bass at 3:00 yields a nice low mid scoop in it's own right, and then cutting 1k a bit is more reasonable, though the bass is pretty overwhelming...using the duncan TSC tone stack calculator (changing the values to match the ampeg), or simulating with Spice might make this all clearer...I can send some of my spice files if that helps anyone.

Anyhow, from my spice/TSC sims and the tone stack, it looks like making the 470pf treble cap to 220pf or even 100pf, and making the 4.7n treble cap to 2.2n or 1n would make boosting the treble have less affect on the 1k region when turned up, which might be my ticket.  I'm Not going to be able to screw with this anytime soon, sadly, but any takers?  big_smile

I'm going to do the mod myself ASAP...but I've been having trouble (And a bit scared) of getting at the pot board, other than spraying the pots, as the screws on the toggle switches have seemed a bit too hard to remove, so I can't get at that board properly yet and have other work I'm trying to get to and evaluate at the same time!

Last edited by Liquids (2010-10-19 15:07:14)


Matthew

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#33 2010-12-10 15:58:42

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

As I mentioned in another thread, I've successfully done this mod (sooner than I thought), and like it.  It's easy to tinker and get what you want from the tone control/high end with some tinkering.

I feel I prefer the values I settled on currently (150pf and 1.5n on the treble side) over the stock values, as best I can tell.  But it's also comparing apples to oranges in terms of parts (ceramic caps and ? resistors vs poly caps and metal film resistors) and I may continue to try out other values for the ones I like the most.

Since the board I put is in there and I'm using the smallest values I'd ever want for the treble-side caps, it would be easy to parallel other caps in and try out other larger values fairly simply, even without solder, and then audition it in the right environment.

I have a TSC screen shot of the range of the treble pot with the bass set flat, using 4 different values stock 470pf/4.7n, 330pf/3.3n, 220pf/2.2n, and 150pf/1.5n.

http://www.aronnelson.com/gallery/main. … alNumber=1

http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=44067&g2_serialNumber=1


Matthew

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#34 2012-10-23 01:42:43

Pilbromatic
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Registered: 2012-10-23
Posts: 1

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Hi all, I know this is an old post but is anyone able to email me the photos that are missing off the first page? rmahoney@paradise.net.nz I'm trying to find out the original values for this circuit and I'm a bit confused. The last post was very useful but I'm not sure if they're correct or not...? Thanks! smile

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#35 2012-12-22 20:19:06

Redwood
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Registered: 2012-12-10
Posts: 19

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I can't seem to get to any of the links in this thread and I'd really like to study up on it.  Have the photos been moved elsewhere that they can be accessed?

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#36 2012-12-22 23:18:14

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

My apologies,  I had all of my photos hosted using my .mac account and apple closed down the site.  I still have all the pictures,  but need a new way to host my own photos/files online. 

Any recommendations?

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#37 2012-12-22 23:28:29

Redwood
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Registered: 2012-12-10
Posts: 19

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Imageshack is free and pretty easy.

http://imageshack.us/

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#38 2012-12-25 03:58:30

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I will work on getting the pictures back up after the 29th. 

I am out of town and the photos are on my computer at home.

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#39 2013-01-02 17:07:28

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

One thing I've found with the tone circuit - if you tweak the values just so, you can kind of 'control' where the break betweeen bass and treble are by the set 120k resistor.  This may be quicker and easier way to tinker than changing cap values since it's one component if you're working on your stock amp, and want to hear a difference. 

You could also make the value big, and use an existing hole like the 'death cap switch' to switch in parallel resistors to get two or three variations.  Just a thought.

Or you can build it all from scratch the way you want and make it a pot or something and change whatever you like, as I'm hoping to get around to finishing in the next 12 months or so =]


Matthew

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#40 2013-06-01 01:05:38

greengoblin
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From: FL
Registered: 2009-05-14
Posts: 54

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I performed this "mod" on my early v4b.  Really have to give Hangman big props on posting this info...  I like running the individual components!

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#41 2013-06-02 02:51:38

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I am glad you dig the Mod.  It's so much better with discrete components

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#42 2013-07-24 00:57:16

Dan56
Member
From: RI
Registered: 2012-09-02
Posts: 37

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Hello,

Does anyone here have the pictures that went along with this thread that they could send me?  Or maybe some of your own of the before/after and board you set up?

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#43 2013-07-24 04:43:52

Dan56
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From: RI
Registered: 2012-09-02
Posts: 37

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Steve was kind enough to send me the pictures of this mod.  I would like to know of a good source on line to purchase the parts where there is no minium order?  Also, what voltage (I'm assuming 600V) and wattage for the resistors?  I ask because I would like to order the parts before I take the amp apart.

Thank you.

Last edited by Dan56 (2013-07-24 05:12:17)

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#44 2013-07-24 19:29:45

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

The silver mica caps are 500v the rest of the caps should be 400v or higher.  I would use 600v or 630v

These resistors in the mod only need to be 1/4 watt,  but you could use 1/2 watt too.  (That's what I used in the pictures I sent)

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#45 2013-07-25 17:58:24

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Comment/Question...
Since there is a coupling cap before the tone stack, my thinking is there wasnt any DC on the tone stack caps, and so long as the caps could handle the AC swing, lower voltage would do.  I have 50v/63v caps if I recall.  They're smaller. I've had no issues.

One benefit of that is the caps are smaller, and cheaper, so they're easier to fit and make look nice. Not that anyone sees them once it's buttoned up. Though one may not need to use insulation over the part leads, where one may need to do that with such physically large caps.

Of course, silver mica caps have a certain mojo, and I don't know they make them in anything but 500v+, though they're not that large.

*In general,* won't high voltage caps have higher ESR?  ESR may not be the only tonal difference between cap choices (harry bissell has an interesting article on caps for audio), however, it may be a noteworthy difference in the "sound" of the tone cap mods, if so...or not.

Last edited by Liquids (2013-07-25 17:59:38)


Matthew

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#46 2013-07-25 18:46:22

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

I go 400v or higher as that is what ampeg used before the PEC wafer was used. 
The caps in the tone circuit will not see any dc voltage.  But somehow I am comforted by the thought that if the coupling cap started leaking or shorted,  that I wouldn't have to worry.   Perhaps that is going overboard, but I figure overbuilding in this case isn't going to hurt anything.

As for the sound of a 50v cap vs a 600v cap,  If you hear a difference go for it.  The point of the mod is to make your amp sound better but at some point we get to splitting hairs.

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#47 2013-07-25 19:17:54

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Definitely agreed about splitting hairs, and I get your thinking on using the high voltage caps, for certain.  I was, more than anything, anticipating someone stating that the HV caps "sound better."  And really, maybe they do.  I don't care enough to do the work to find out!

"At some point..." indeed!: While I aim to use stuff that is not cheapo, while I've spent the time to even select my frequency curves on the treble pot more precicely, and all that, sure, I'm interested in the best sound....but, after at a certain point, I button up the amp and get it to produce audio! =]

And even then, I can tweak to make things sound "better," to me, in realtime by turning the tone knobs different, and/or tweak how I appoach the strings and play the notes to make things sound "better," rather than only dreaming about a different capacitor with the mojo I can't seem to tap.  =]


Matthew

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#48 2013-07-26 00:05:56

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

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Yeah, I regardless of the voltage rating of the cap,  if you use quality caps the amp will sound better.  Beyond that... Not worth it.

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#49 2013-08-06 16:17:37

Dan56
Member
From: RI
Registered: 2012-09-02
Posts: 37

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Just an update.

I have completed the rebuild of the tone circuit along with the other caps for the mid switch, treble boost and the reverb.  I used the orange drops.  Little large, but made it all fit.  I went to my local electronic store (not Radio Shack) to get the resistors for the mid switch as the Spragues I had ordered were physically to large to fit.  I changed the treble boost values to those suggested by Steve.

While at it I changed the indicator lights as mine were real dim.  Fired it up to test it all and don't you know the standby light is not working. Dang!  I think it's the 180K resistor.

However, I hooked it up to the speaker in my Princeton and everything else is working.

I did some video sampling of the amp hooked to my 4 X 10 bottom and will get some after video then post it all on youtube.  I'll post the link when that is up.

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#50 2013-08-26 10:14:42

MarkusBass
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Registered: 2013-08-26
Posts: 2

Re: Tone circuit upgrade Mod for V-4s (And other Ampeg amplifiers)

Can someone post a list of components used? It's looks like posting the pictures is to difficult and almost all links posted previously are incorrect.

Mark

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