EDIT: THE AMP IS A '72. I wasn't too fussed about the year yesterday when I set up to shoot the video and I misread the upside down reverb transformer date code.
When the V6 phase inverter is changed from 12AT7 to a 12AX7, the amp reaches distortion in the phase inverter stage before it reaches distortion at power tubes, whereas stock it reaches distortion in the power output stage first. Distortion in the power output stage sounds smoother and more pleasing, less ear-fatiguing to most. Also, that tube-switch-around cuts the clean watts output some as well, which may be a good thing for some folks, as you can then reach output stage distortion (with preamp stage distortion) at somewhat lower loudness. Further, this phase inverter tube change AND pulling V1 can be done to all original black-face and all early silver-face amps.
Edit: this amp is a ‘72. You can’t hear the level increase with phone speakers but it’s very apparent with headphones or real speakers. It’s about a 3dB increase with the amp volume staying just over 3. A real playing test would involve turning the volume up and hearing different overtones etc but that was outside the scope of this video. The owner will probably do a final playing video and we can do that kind of fun stuff then.
It’s interesting that so many didn’t get the message of your video and are pushing the idea of using pedals or they’re more concerned about the exact year of the amp. Maybe I’m weird. I was appreciative of seeing the easy way’s of getting more gain. Thank you.
Me too. I play on a live radio show where there’s a lot of movement on stage and not room for big pedal boards. Been looking for a edge of breakup tone at lower volume so this helps a lot.
Great video. I've borrowed a number of Fender amps for gigs. But one of the best I played was Princeton that was owned by a venue I would play in the mid to late 80s. I would plug my Yamaha SG 200 into it and run a fuzz pedal through it like a Rat and a Boss Chorus. I got more than enough gain for a good classic rock tone. I've owned a lot of Marshalls but Fenders like this just sound like home to me. I prefer good pedal platform amps to high gain amps. You can't beat the warmth of a Fender. The last Fender I owned was a Bassbreaker which was good but too Marshally for me.
great video Lyle. customers always ask me to mod their vintage amps and Im trying to tell them "dont do it" the amp is doing its job. get a boost pedal if you want more gain. please dont ask me to try and improve an already great design.
I have 2 different boost pedals (a Les Lius clone and the Supro Overdrive) sound natural enough that don't change the character of my Blackface Deluxe to make me even think of modifying the amp, I cherish that amp because it's sounds so good on its own.
Have any-one heard or used a little plug-in box called an "Ice cube" it used to plug in to the reverb send / return on the back and this added an extra gain controlled by the reverb knob but you lose the reverb but it was "Epic" !
anyone old enough to remember when most amps had tubes will be aware that, within the lifespan of tubes, there was a ‘peak period’ of performance where they would absolutely sing in warm, rich tones; beautiful, clean sustain that you wished would never end (though, sadly, it did) I would change all my tubes if one went bad so they would all be the same age…my all time favorite tube amp I owned was an original Supro 40 watt…I had no idea what it was but my father, a guitar teacher, used to buy and sell all kinds of gear and picked it up for $50 (in the mid ‘70s) all I knew was that it sounded incredible when full up…I used it exclusively until it blew up onstage in the early ‘80s…let’s quote the bible according to Keith: “The right guitar through the right amp; throw your pedals away” amen (at 65, I now use a 5 watt Bugera)
I experimented with pulling tubes and dropping the preamp voltage and changing the bias of preamp and power amp etc. In the end I accepted that I liked the base tone of the AB763 as designed and anything I tried moved just far enough away from that so as to sound "different". I think the problem is that one-amp-guys want it all. We want amazing clean (so cool bias, tight speaker), the "advertised" Fender chime, we want amazing edge of breakup (hotter bias, celestion style speaker) and we want ballsy overdrive. Its a hell of a rabbit hole. In the old days I would do what the Old Timers did: turned the amp up to 7-8 and use a 8-9k (and microphonic PAF style pickup) Les Paul with 50's wiring (so pickup loading which preserves treble response when you turn down). This involved positioning the amp off-stage, turning it round and latterly using deflector screens to handle the volume peaks. Now I use a treble bleed equipped Fender or a 50's wired LP in to an always-on "transparent" overdrive like a JHS Morning Glory (lower gain V2) or the Bluesbreaker (reissues are great for Fenders) and a mix of lower MU in V2 and higher MU (V4) preamp tubes. The Phase Inverter tube in an AB763 is were most of your overdriven sounds are fundamentally shaped. So getting that one right is vital. I like a NOS Mullard in there. I find the small bottle 5881 style power tubes grind WAY more than the big bottle 6L6's in the bigger amps. The final ingredient being the speakers. I like a bit of speaker breakup and I find that modern high power speakers don't get in to their sweet spot at usable volumes so can sound dull or "flat" while simultaneously being hellishly loud. So I deliberately use 40w speakers in a Twin or 15w speakers in a Deluxe etc. The other option, especially if you record a lot or stream, is to get an UA Ox. Kid Anderson often uses one of those with a silverface twin and headphones (he uses an IR and no live speaker in the room). Covers everything he does. Sorry for the essay! 🤣 FWIW in my opinion the best and only thing anyone ever needs to make every kind of music is a Deluxe Reverb equipped with a JBL D120F. Just drop the money now and thank me later. 🤣🤣
I understand the owner doesnt want to use a pedal. But those that do. An EQ pedal is the best way i have had luck with clean boost. Nice job with your video.
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Great video! I think that amp is late 1969 (they dropped aluminum trim away) to 1970....'71 if that faceplate is original. There reads "Deluxe Reverb -Amp" That "Amp" word dropped ~'71. Also Fender logo is what they used till early 70s.
But it has a glued in baffle. I didn’t look closely, just saw the baffle and a ‘66/‘76 date code on the reverb transformer. Doesn’t matter as to the point of the video.
Nice video. I did your bias cool down mod for my blues jr it sounds as good or better than stock high bias. What bias range do you recommend for the 65 deluxe reissue? Thanks!
$100 Bugera PS1 Power Soak on my ‘68 DRRi. I *_can_* turn the amp volume to 10. But pedal overdrive is much more pleasing than a cranked Deluxe to me. I’m now of the mind that the Wampler Pantheon is the perfect pedal for my amp.
Very nice. Gives that little breakup at low volume! I have heard this before, been reading about it but am scared to try on my super twin reverb with 6x l6. Don't know which ones to pull or switch.
Have you thought of doing show/episode on the different PI stages used by the pre 80’s Fender amps? There was a noticeable change from the tweed PI stages to the Brown PI stage, to the Blackface PI and then the silver face PI.
I have always done the pull v1 truck for my deluxe reverb (66 and 67). And I’ll have to try the phase inverter trick too. Any tips like that for a blackface Princeton?
I've watched a few of your repair vids recently....I'm suprised all the common problems the Fender Hot Rod and 68 Custm Reverb have sheesh....is there a smarter built amp brand you prefer compareable to these level Fender amps and there price range? My Hotrod Deluxe 4 is in the shop....do you like the Peavey Delta Blues at all? Thanks
Great video! Recommended mods for sure. One question, If I remove 2 power tubes on a 4x6L6 amp and disconnect one speaker to match the impedance, do I need or is it recommended to readjust the bias?
Yeah, make sure the bias is still in a safe good range. Some companies switch without a change in bias but they build in a “safe window” (often with tonal compromises).
@psionicaudio this simple mod interests me, but I had a question. Would this be the same result as bridging the two channels together with a patch cable and/or using an ABY switch into both channels simultaneously. I believe it has the same gain increasing effect, but I was curious as to if the pathways dramatically differ. The fenders(and others) have some interesting plug and play mods on the fly for certain sounds for sure.
Love your videos- you’re such a pro. Question- How is this amp so quiet (noise floor)?? Maybe you have something filtering out the noise through your mic? I have a 76’ DR that’s been serviced and the noise floor certainly improved but it’s nowhere near this quiet running.
Thanks. I put a small bit of room removal on my voiceover mic but never do any gating etc on the amp mics. Not even EQ or compression. You hear what the amps sound like. I do videos in 4K so YT uses less compression on the audio so you get a more realistic idea of what the amps sound like. Including noise floors.
@@PsionicAudio Gotcha- so maybe how my amp is running is normal then? Again it’s not terrible, just kinda hissy especially when the reverb is on and I get up to 4, 5 and onwards on volume
Hey, I was wondering; during Nirvana MTV Unplugged show Kurt used a Twin Reverb for his 1959 Martin D18e as a monitor, to have more gain on low volume apparently his guitar tech used a 12au7 in the PI / V6 and replaced the 7025’s with 12AX7’s. What are your thought on this? And how would you approach that show with a Twin Reverb as monitor?
I have to admit we pedal lovers have it way easier. We want more gain, or change of eq, compression, etc. We just slap a pedal in front and our problems are easily solved and away we go. Because in the end nobody else gives a poop. I have tried listening tests with a Line 6 in Vox settings and an actual Vox - and nobody could tell the difference. This stuff only matters to the actual player
Speakers always play a role. This one has a very efficient ET65. But the owner plays this amp up way above 3, while I had it on the bench at ear level for filming purposes. At his actual stage volumes the ET65 is a great choice. There will be a real playing demo of this amp when the owner gets back from a European tour. It will get loud…
Hi, that is an awesome tip. Great video, I'll give this ago later. Can I ask you a Q? Have you ever made a video on amp Vibrato issues you could link? I have a 65 Deluxe Reverb Reissue and if I engage the Vibrato circuit I hear an audible low freq ticking (without any guitar input). It's not very loud but it's annoying. It also remains when the guitar is being played. Thanks.
I set a TC Spark on top of my amp and use it to push the OD circuit. The Spark is a very transparent gain pedal. I don't love pedals. But using that 1 pedal, gives me a lot more gain AND I can turn it off in a second to get my sparkling clean tones back. AND I can do the same for my Princeton Reverb too. For pickers that are searching for their signature tone, this vid is definitely the way to go. For those of us that are trying to mimic tones from numerous different songs, probably not the best way to go. 🤔
I was always wondering when you do tubes swaps like these, is there a risk of blowing a resistor because the current draw increased? Or maybe that's only when you switch from a 12ax7 to a 12au7 if you want less gain (cough peavey cough)...
I seem to recall another "mod" involving connecting the reverb out directly to the reverb in, and then using the "reverb" control on the front of the amp as another gain stage. Of course, you loose the reverb effect, but it is easily reversible (arguably easier than pull tubes). Thoughts?
I had a device back in early 80’s called an ice cube small blue ice cube looking plastic device that plugged into the reverb tremolo foot pedal jacks it really upped the gain Not sure how it worked but it did
I have the same. Still in the reverb phono jacks of my silverface Twin. There’s some circuitry (buffer?) in it that allows a clean pretty powerful boost depending on your REV knob’s setting.
Lyle, I thought Fender stopped using the underlined logo on their amps after 1972. I know that is true for Princetons (I have a 72). Did the different models stop using the underlined logos in different years?
I don’t know. I didn’t open this amp up again, just saw a ‘66 or ‘76 date code on the reverb transformer, saw the glued baffle and lack of black lines on the panel, so thought “‘76 or ‘77.”
I am confused how it is possible to have more gain (or volume) by removing a tube ? Wouldnt that reduce the gain ? (but at the same time also reduce headroom in the preamp , creating breakup at a lower bolume ? )
What about plugging into both inputs? I do that on both mine to get a pretty big boost. But I don't own any Fender amps so I don't know if they work the same.
Are you sure that the amp is a late 70's Deluxe Reverb? From the Fender logo with the tail on the grill and the fact it says "AMP" on the front panel, I would think it is an earlier model. Perhaps the transformer was changed at some point. My 77 Deluxe Reverb does not have the tail on the Fender logo , and also does not say AMP on the front panel. But you certainly have more experience than I do with these amps.
I've heard that this was something SRV did to his Fender amps. It seems like every Fender amp needs all the help it can get in terms of the available gain on tap. Great video Lyle. Thanks for sharing
Another trick is pulling the V5 if you don´t use the tremolo anyway. This will give you also a little bit more tone. This three tricks pulling V1, changing the V6 with an AX7 and pulling V5, I have done to all my fender amps and enjoy their sound now even more :D
Maybe , see if there are other brands with tricks. You can decipher schematics and would be great content. Marshel, Peavey,EVH, MESA, etc.... start a series of content. Thanks ( i have 67 Fender BF but man its OG and I hate to hurt a OG tube lol)
What would be comparable "mods" on a Princeton? Can you pull the 12at7 in V2? or even a 6v6 power tube with no issues? If you pull a power tube I would think it would need to be re-biased.
There aren’t any comparable mods on a Princeton. And never pull odd numbers of output tubes in any Class A/B amp (and only pull even numbers after much research).
@@PsionicAudio I wasn't planning on it - just curious. I know sometimes people will remove 2 of the power tubes in a Twin. Princetons get fairly gainy around 4-5 with humbuckers anyway.
You can on my 68 custom DR but I don't think you can on the original ones. I think it's because the two channels are in phase on mine but not on the early ones.
@@robertbrown2728 I was curious because the Marshall is a rip-off of a bassman. My 65 Princeton reverb is just one channel and all my Marshall's are newer. So I've never even done it. Just seen it done
Why is it the amps are always set with treble and midrange about 5-6 and bass about 4-5? Wouldn't there be more and better tone, if the treble and mids were up about 9 or so and the bass about 6-8, therefore providing more tone?
You’d have more signal but less control over the frequencies. Don’t sweat it - there’s an additional gain stage after the tone stack to maintain plenty of signal even with the insertion loss of the tone stack.
Those two gain stages come after the volume pot, so how is that a better way of increasing gain than simply turning up the volume pot? I suspect the answer is that you have introduced more distortion by “deoptimizing” the two stages from what would ordinarily be considered best for fidelity. If that’s the case I’d view the increased gain of those two stages as a byproduct, not the main objective. If the customer prefers that type of distortion to simply turning up the volume pot or adding a boost pedal, all is good. A comparison to those alternatives would be useful.
Hey Lyle, I just tried this with my ‘66 Pro Reverb and it sounds like the amp is clipping with a really harsh and bright sound that is NOT present when I have v1 inserted and a 12at7 in v2, any idea why that would be? It’s not a pleasant clipping sound- it’s a ‘something is definitely not working properly’ clipping sound.
Could be you have a bad V2 that is working so long as that cathode is shared. In a healthy Fender circuit pulling V1 only makes V2 have a very minor gain increase.
Thanks for the reply Lyle, I appreciate your time. The 12ax7 in V1 and V2 are both new JJs. I tried swapping some different 12ax7s in V2 with no change. However if I Pull V2 instead of V1 and run into the normal channel the issue doesn’t happen. Is it possible the cathode itself needs replacing? Sounds like a fast crackling/ scratchy sound, and is louder than the amp sounds normally.
That’s unusual behavior, points to an issue with your V2B circuit. The grids of V1B and V2B both affect the bias as the circuit is intended. If V1 is absent and there’s a problem with the V2B grid leak (volume pot) the bias may be thrown off. Have a tech take a look.
@@PsionicAudiotaking the amp to a tech this weekend. Very frustrated with my Pro at the moment. Now I’m noticing ghost notes when I have the amp around 5 or higher ( or if I use an OD pedal with the volume lower), that seem to resonate a 4th below the note I’m playing. Makes the amp sound gritty and like it’s gurgling and messy. I had the amp totally gone through and recapped after I got it, and then had to take it back twice for other issues. Hopefully 3rd time is the charm and we can sort out whatever is still causing these issues. I feel like a pain having to call my tech about it so much, but the amp is not reliable for gigging with the issues that keep popping up. Any advice for amps that need repeat service like this? The amp in question was a totally stock ‘66 pro reverb that was sounding good, but hadn’t been serviced in decades- I just wanted it recapped, and serviced for reliability and replace any bad/ too out-of-spec components.
You can’t really hear it with phone speakers. For headphones, I use Beyerdynamic DT770 Pro 80 ohms and Sony MDR-7506s. It’s very apparent on them and on Yamaha HS-7s. I made sure the back to back clips didn’t have the leveling everything else had, and turned them down a bit so YT wouldn’t compress them heavily. But it’s a tricky medium for minutia…
Input 1 = designed for LOWER output signals (single coils and some P-90s). WARNING: pretty sure this contains 60 cycle hum. So even when you're not playing and you leave your volume on, say, 3-10 on your guitar, you will hear something coming from the amp. Input 2 = designed for HIGHER output signals (humbuckers). Using this input lowers the decibels by 2-5? Somewhere there, but decibel readings are NOT linear, they're logarithmic. Goes into distortion faster and sounds a bit darker. To me, "darker" means a little muffled. Same notes/chords being played but with some layers of bed sheets in front of the speaker. Someone please correct me if I'm wrong.
Hot Rod deluxe has a gain channel. And if you want distortion from the clean channel, you could connect a volume pedal to the effects loop and drive the preamp. You can’t do that on a Deluxe reverb. Very different circuit
@@marcospintor1333 Yeah, I'm not fond of the Gain channel on the HRD and I don't know anyone who is. I am aware of the volume pedal trick. Just always looking for other options, if they exist. Thanks for the response. Cheers.
@@PsionicAudio I figured that was the case otherwise its such an easy option. I have the current 64 custom handwired DR and bridging the channels works great, but it has verb and trem on both channels.
Just sayin', but you should NEVER connect those silent plugs to the input of your amplifier. Those are designed to connect to a guitar output. They can damage the amplifier badly. If you google the neutrik silent plug webpage you can find info on it.
I don’t use them, and I don’t see the value in them. It basically halves the input signal. This isn’t great as it lowers the signal to noise ratio on the amp. Ideally you want to attenuate the signal after the first stage.
Well, that’s kind of my point. We moved the amp’s behavior slightly without any permanent mods. It’s still a stock DR inside. It can go back to the stock tube setup quickly and easily.
