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Currently I am playing jazz through a Fender Twin 65 Re-Issue, it's about six years old, and generally speaking the sound is very clean with a somewhat warm tone. However, I am looking to make changes to the amp to get a warmer tone especially in the mid and high ranges.
It has been suggested that there are some modifications that can be done to modify the tone; change the valves/tubes, change the transformer and/or change the speakers, from what I understand changing either the speakers and/or the transformer will have the biggest impact on the tone. Or buying a new amp.
In any event does anyone have any thoughts, views, experience in making these kinds of modifications and if so do you have recommendations on tubes, transformers, speakers.
Input is appreciated
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02-18-2016 09:35 PM
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Unless you have a special attachment to this amp I'd sell it outright and find another Fender say the newer Michael Landau Hot Rod Deville. Or go another route even Quilter Aviator which is very Fender like w/out the weight or tube hassles. Modding can be a lot of fun but quite expensive unless you have the knowledge already yourself.
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Sell it and buy a silverface fender, it's easier.
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I have a Fender Super Twin Reverb and I added a Skyliner preamp circuit and "Deep," "Rock/Jazz" and "Mid Boost" switches. I put in a ODS distortion circuit and Preamp Boost circuits also (replacing the C610 for a 12AX7). The clean side sounds nice with an archtop guitar on the "Jazz" mode. I didn't change the speakers or mess with anything after the phase inverter or the transformers.
Last edited by icr; 02-19-2016 at 06:05 PM.
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First thing I would do is to look for good tubes/valves. Second, I would have a tech bias it properly; properly biased it should have a warmer tone. Third, and please take this with a huge pinch of scepticism since it comes from me, check out some speakers with hemp cones such as the ones from Weber or Eminence (Cannabis Rex) since clean sound and not distorted is your priority.
The stock transformers are good. I won't change them out for boutique ones. Based on what Fender did with the 68 Customs I would also ask the tech to lower the negative feedback a little to give it better sensitivity and a warmer response. It may increase the hiss on idle though. There is an 820 ohm negative feedback resistor; increasing its value decreases the amount of negative feedback applied.
I would also change the V1 12AX7 to a 12AU7, 12AT7 or 5751 for a lower gain preamp stage which stays cleaner in the middle of the pot.
There is Rodgers Cabs in Florida which could replace the stock cabinet for one made out of pine with a floating pine baffle. Pine imparts a warmer tone than plywood and a floating pine baffle has a natural resonance to it which is consonant with a rounder fatter tone. Or just replace only the baffle with a pine one from Rodgers, keeping the stock birch plywood cabinet. Vintage Exact Cabinets .
The other suggestion is to send the amp to someone like Rick Hayes of Vintage Sound Amp in Florida and have him replace the PCB with a turret-board and hardwired components, then bias it for a warmer sound. Cost is about $600. Rick could also beef up the power supply capacitance at the same time.
Don't attempt any of these things yourself unless you are a trained technician or electronics engineer.
Just my suggestions. The other folks replying made very good alternative suggestions.Last edited by Jabberwocky; 02-19-2016 at 08:02 AM.
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The choice seems clear; get rid of it and buy something else. It will be cheaper than trying to transform it into something else. Plus, you won't know what it's going to sound like until after you've spent the $. To boot, if you sell it after modding, you'll never get your money back.
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First of all: the Twin Reverb is an iconic jazz amp and all the greats - Burrell, Montgomery, Green, Martino – have used it at some point getting great tones out of it. But the Fender Blackface - and also the Silverface - circuit has scooped mids by design. To get a more flat signal try this: put your mids on 10 and treble and bass on 0. I recognize your desire for more mids and upper-mids, and I bet you'll like this tone setting (or a milder variation of it, as long as you dial in more mids than bass and treble).
I went even further with my Twin Reverb: I put the reverb and tremolo on both channels and I modded the normal channel's tonestack to that of a 5f6-Bassman/early Marshall, more or less like Fender did with the 68 Custom-series (although I did not the touch the negative feedback). This involves changing one resistor, two caps and a pot-meter (costs in parts maybe $5). I did this in my Guyatone Twin Reverb clone that has a much more accessible PCB-board, but I also changed the tonestack of my Blues Deluxe with the vulnerable modern PCB-board, so it very possible in your 65 RI Twin as well. If you can't do this yourself, any capable amp tech should be able to do this in less then an hour of work.
So now my Twin Reverb has a Fender BF/SF-channel and a more Tweed-like channel with bigger and rounder mids. I use the 'tweed channel' with my P90-guitars. For humbuckers I like the original Fender-channel best.
Of course changing speakers and tubes all have their impact on the tone - speakers act like an EQ-filter and are quite effective to change your amp's tone, but are much more expensive and you change the overall tonal color of the amp, while my mod makes the amp very flexible. A good set of tubes and a proper bias is always advisable, but that won't radically change the tone of your amp. Jabberwocky is right to not change transformers: those are expensive and will only slightly change your tone - if at all. To experiment with different tubes in V1 and V2 is also a very nice suggestion, I like to use a 12AY7 sometimes.
Lastly: you might like the sound of the amp being pushed to it’s limits more than the all-clean-powerful-sound. (I don’t mean an overdriven sound, but just more gain and being pushed.) Only problem with a Twin is that to push the amp you have to increase volume to ear-shattering levels. But there’s a trick to push the amp on lower volume levels: you can pull two of the four power tubes, thus reducing the amp’s power to around 40 watts (you will have an impedance-mismatch with the speakers, but it will not hurt your output transformer). It will compress (‘sing’ or ‘bloom’) a little earlier on the volume dial. Important: if you do so, pull either the outer or inner pair of tubes (A and D or B and C, not AB or CD). To further ‘push’ the amp you can change the 12at7 phase inverter tube (V6) to a 12ax7, it will make the amp sound a bit looser and warmer. (If you don’t use the normal channel you can use the 12ax7 of V1 and put it in V6.)
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I doubt that will bring TS much; they are essentially the same amps and many like the Blackface circuit (that the 65 RI also has, just a PCB-layout instead of an eyelet-board) better.
Originally Posted by vintagelove
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I only partly agree; the Twin is somewhat of a Swiss-army knife. I suggested some mods that cost nothing or are very cheap and all completely reversible that can change the amp's characteristics quite a bit. But of course there's a chance that TS will like a different type of amp(-circuit) better. He should than try out either a Polytone (or any amp with baxandall tone-stack) or a Tweed-circuit. Originally Posted by whiskey02
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Get a tech to swap the 10k ohm mid pot for a 25k ohm pot. Also the cap that feeds the mid pot from a .047 to a .033 or .022
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Yup, that's what I did in the normal channel, I changed both caps for .022. I also changed the slope resistor for a 56k. Originally Posted by abelljo
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My super twin is responsible for my right arm being twice the size of my left (visualize a fiddler crab) , several trips to the osteopath, one broken toe, ringing in my ears, and neighbors that HATE me :-) Originally Posted by icr
Seriously it's THE behemoth of an amp with the sweetest EQ of any Fender, its only failing is no reverb... and the damage it causes to me if I move it. I'm surprised you needed to do anything to it. As usual the Fender OEM GINORMOUS speakers were crappenzola but that was easily solved.
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What tone control settings have you tried?
The Fender Twin Reverb tone stack is designed for a very scooped midrange. The frequency response is nearly flat with the Mid knob at 10 and the Treble & Bass near zero. On my Twin, I start there then dial the bass up slightly to taste and finally the treble.
The final settings depend on the acoustics of the room and the other instruments I'm playing with, but they are usually pretty low. With low treble and bass settings, the volume knob needs to be set higher than you might be used to, but it will still get plenty loud.
Once I discovered this method I fell in love with the amp. (Unfortunatly, due to its weight it usually stays at home!)
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The RI amps are brighter and more aggressive than their vintage counterparts in my experience. A good test would be trying a vintage one, if possible - this way you can know if you don't like Twins or you don't like RI Twins.
Messing with the circuit is the easiest and cheapest step. Just messing with the mid pot from 10k to 25k or 50k and maybe changing the resistor from 47n to 22n will add a lot of mids (the higher pot will alternate between scooped at 0 and incresed mids as you turn it up).
One other decisive factor in how warm an amp can sound is the bass knob (paradoxically), specially in fender blackface circuits like the RI. These circuits can produce A LOT of bass which can make us run the bass too low and loose depth / warmth. A good solution is adding a passive low cut filter which allows you to run the bass higher but cut the boomy sound (very common technique in the studios when recording guitars).
Another option is changing speakers - stock Jensens can be bright (both new and vintage). Some speakers have very sweet treble but can increase too much the bass for archtop use (say Cannabis Rex), which can (again) be easily solved with a low cut filter.
Changing tubes, cabs, transformers is too expensive to make it worth imo and will not yield a significantly different sound.
Bear in mind your will amp you loose value and will be harder to sell in the end if you mod it so... it might be best to get a new one. Silverface Fenders are cheap, easier to service (ptp vs pcp) and sound better imo.
Good luck!
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I've never understood the logic of designing/building and amp (much less an entire product line of them) that is specifically missing an entire sonic neighborhood. Rather than simply turning a dial to remove B, M or T you want rid of, you just don't get any mids ? To me, Fender amps come with 2/3 of what I want available to me.
Last edited by whiskey02; 02-20-2016 at 11:23 AM.
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The mids are there -- you just need radical tone control settings to get the bass and treble in balance. One could modify the tone stack instead, but turning knobs is much easier.
The original logic if the Fender tone stack was to make the country players happy. For country (and rock) a smiley-face frequency response is thought to help "cut through the mix".Last edited by KirkP; 02-20-2016 at 11:40 AM.
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I don't get the 10k mid pot on blackfaces honestly... you turn the knob up and down and it's just a poor gain control. With a higher pot you can get scooped (mids at 0) and fat (mids up).
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