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What should I buy?? Super Reverb or Deluxe Reverb??
Old 7th August 2020
  #91
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Quote:
Originally Posted by PoundTound View Post
What year is your SR? Original speakers? I’m looking at getting a vintage sr soon.
Hello, mine is a 64. I have tried it with both vintage Jensen ceramics C10R I believe, as well as I set of vintage cts.

My favorite is a pair of each in XY. That’s the one combo that anybody who’s heard it fell in love.
Old 8th August 2020
  #92
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bowzin's Avatar
The Fender reissue Deluxes are pretty meh to me. Kind of good-not-great. Dynamic range feels too small, not nearly as sensitive as the vintage. Can be a good pedal platform amp, and basically IMO it has a high floor, low ceiling kind of thing. High mids take more effort dialing out annoyances elsewhere in the chain, when actually its just the amp. Good for the price though, a safe choice, waaaay better than the old Hot Rod Deluxes and Devilles and lower tier Fenders Ive played in the past (awful), but theres a lot of new stuff in the last ten years I havent tried so im out of the loop I guess. Maybe everything's improved.

The Super Reverb reissue is pretty wild and can be very rock and roll, I like it. It's a 4x10 vs 1x12, and it's loud as all hell, and very heavy to be lugging around everywhere. However cranked up it sounds very dramatic with those 4x10's. The 6L6's and whatever rectifier are in Super Reverbs generally is a tighter, more immediate response and feel but IMO it sounds best when it's cranked up a bit and starts to lose some of that control and get a little wild.

Is it like a vintage Super? Sort of, yeah. The vintage Super's are possibly the best amps I've ever heard in person, absolutely ridiculous amps, whatever the configurations (Ive heard and played a fair number). Smoother, more bell-like, absolutely effortless getting inspiring tones out of it. But overall the reissue is in the ballpark.

But honestly I'm not a good enough player to take advantage of the Supers, IMO they are best in the hands of a player who plays loud and with big control over their dynamics and playing. IMO Deluxes are a little more forgiving than Supers, looser response, more sag/bloom. So having said all that, I'd still pick one of the Deluxe Reverb RI's b/c it's 1x12, and what I'm used to, even though the Super Reverb RI has a lot going for it. It's player dependent, very different amp lines.
Old 9th August 2020
  #93
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Questions regarding impedance....If I buy a new 65 reissue, can I....

Plug in a couple (two) of 300 watt Rumble 1x15 cabs...ie...disconnect the wire to the internal?

Or plug in a 412 angled Marshall cabinet (or two)...either with or without the internal speaker plugged in?

Just wondering as these are cabinets I have....and historically, I've never kept up on the math of what kinds of impedance mismatches can blow things up.

This would all be strictly studio connections. No gigging.

Any potentially interesting tonalities to be had?
Old 10th August 2020
  #94
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enorbet2's Avatar
The Math is easy IF all speakers are the same impedance. Simply put ... Example: - 2 x 8 0hm speakers are doubled (16 ohms) when in Series and halved (4 ohms) when in Parallel. This applies to individual systems (like multi speaker cabs) as well as individual speakers. Things only get real and complicated when you mix different impedances since that's not exactly intuitive. EZ solution? If you don't understand the equation just don't ever mix differing impedance speakers. They will have very different outputs (basically unusable) anyway. Use speakers of the same impedance and it's EZPZ.

On a normal tube output one cannot go higher than the rated impedance, at least without altering the electronics since load impedance affects tube operation which requires Bias adjustment to even get in the ballpark. Real world example: Plugging a 16 ohm load in an 8 ohm tube amp (without at least adjusting bias voltage) won't blow it but it will certainly alter the sound and feel and generally not in a good way.

Also in general, going lower... plugging a 4 ohm load in an 8 ohm tube amp is not dangerous, will generally work OK, but does have a lesser effect (ignoring that it is louder) on tone and feel, not generally a bad effect.

Going different by more than a factor of two, either up or down, is not a good idea at all and is flirting with disaster. So going to 2 or 32 ohms is a No No.
Old 10th August 2020
  #95
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bowzin's Avatar
Thats one potential consideration with Super Reverbs, is the speaker outputs can be a little tricky, cant remember the specifics but I think it's 4 ohms? My friend with a Super Reverb reissue ended up purchasing a Weber Z-Matcher / impedance matcher for this reason. I think it made it easier to use into an 8 ohm Reactive Load box, but please do your own due diligence, just going off memory.
Old 11th August 2020
  #96
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enorbet2's Avatar
Super Reverbs are at 2 ohms. Not really a great idea to add an extension cab to those 4x10s running so low. I guess Fender just figured it was easier than 32ohms (Series) or choosing decent 16ohm speakers for a 4 ohm load overall in parallel or 16 ohms overall in Series-Parallel. The latter would've been my preference.

Running an additional similar 4x10 or 4x12 at 2 ohms would result in an overall load to the output of 1 ohm. At that level the impedance in the speaker connecting wire becomes significant once you exceed around 4-6 feet. By "significant" I mean much of any gain by adding drivers is lost in power being dissipated as heat in the connection. Even losing 10-15 watts is a big deal and that wire will get HOT! Imagine touching a 20 watt light bulb for a rough estimate.
Old 14th August 2020
  #97
Quote:
Originally Posted by enorbet2 View Post
Well, Tweed Princetons' were cathode biased and full Class A because they only had one 6V6 - single-ended. Every Princeton with 2 x 6V6s is "fixed bias", in other words has a B- supply and an adjusting pot on most versions. Those are Class AB, though they can be modded for Push-Pull Class A.

The gain of the Long Tailed Pair of 12AT7s is roughly 12-15 times that of the Split-Phase 12AX7. The effect of that is quite dramatic.
At least some of the brown faced princetons were push-pull, with cathode bias.

Split-phase amps have a PI gain of less than 1, in other words they put out less than what comes in.
Old 14th August 2020
  #98
Quote:
Originally Posted by Yuri Kogan View Post
I was also told that the SF trannies are higher rating because the under-powered trannies in the BF caused a lot of warranty issues for Fender.
Your friend was wrong, at least in part. The first sf trannies were bf trannies. later they beefed up the PT to increase the voltage for more power. I believe the OT remained the same until they went Ultralinear.

The Princetons remained more or less the same - they never did a UL version.

The "warranty issues" thing is utter BS.
Old 14th August 2020
  #99
Quote:
Originally Posted by audioloud View Post
If you want a killer tone AND be able to carry easily I would go for the Blues Jr. or a valve Princeton.
Both are not very expensive and punch above their weight.
If you expect to keep the amp long DO NOT get a Blues Jr.

Badly designed, poorly built using cheap parts. Crap reverb, sh!t tank and a really really cheap ss circuit to drive it.
Old 14th August 2020
  #100
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enorbet2's Avatar
Quote:
Originally Posted by John Eppstein View Post
At least some of the brown faced princetons were push-pull, with cathode bias.
So? I said Tweeds specifically and Cathode Biasing doesn't automatically bring any tube closer to anything bias-wise. The bias voltage at the grid is an implied, relative and somewhat static voltage and whether an actual B- supply or created in reference to cathode voltage doesn't matter to Class of operation. That is entirely due to that voltage difference and can be achieved either way. Example: A cathode biased stage is easily configured to run in full Class B and beyond.

Quote:
Originally Posted by John Eppstein View Post
Split-phase amps have a PI gain of less than 1, in other words they put out less than what comes in.
Exactly... and the Split-phase driver has something of a non-symmetrical effect since the Cathode is never identical in any way to the Plate. Aside from the Less Than Unity Gain compared to gain of 10x-15x there are other differences in this extremely important amp stage.

Here's two solid documents on Driver/Inverter design that most non-techs can easily understand (I think) that will help people making choices between amps of differing design or considering mods.

Note that the first one wrongly reports mu as if it were gain when mu is roughly double actual gain. In practical fact, the 12AX7 listed as having a max gain of 100 (actually it's mu) commonly tops out at a gain of under 40. 30 is very common. 50 is possible but exceedingly rare in audio gear.

https://guitaramplifierblueprinting....seinverter.pdf

This 2nd entry is not specific to musical instrument amps so has to be adjusted since ultra clean is not necessarily desirable. What is desired is the right kind of overdrive envelope and harmonic content. Still a decent explanation of driver differences

http://www.angelfire.com/electronic/...-DB_Heart.html

This may seem a tad OT but it is really important. It is a MAJOR difference affecting how guitar amps sound and feel. Knowing the design will help anyone choose more knowingly as that knowledge with experience will strongly correlate.

Last edited by enorbet2; 14th August 2020 at 09:05 PM..
Old 14th August 2020
  #101
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Yuri Kogan's Avatar
 

Quote:
Originally Posted by John Eppstein View Post
Your friend was wrong, at least in part. The first sf trannies were bf trannies. later they beefed up the PT to increase the voltage for more power. I believe the OT remained the same until they went Ultralinear.

The Princetons remained more or less the same - they never did a UL version.

The "warranty issues" thing is utter BS.
As far as i know , the larger amps were modded with new trannies in the 6. The rest within ~2 years
In any event trannies in my BFs and SFs are different.
Old 14th August 2020
  #102
I would get an amp kit myself, some of them are so good that they're better than the original vintage fenders that the circuit is based on, and you can obviously mod it to suit your exact needs, modulus amps make some great kits, I plan on making several of them, definitely leagues ahead of anything fender currently make, all handwired point to point and you can get them to build it for you if you don't have the soldering skills so it's a win win, would work out a lot cheaper as well.
Old 14th August 2020
  #103
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enorbet2's Avatar
Quote:
Originally Posted by Yuri Kogan View Post
As far as i know , the larger amps were modded with new trannies in the 6. The rest within ~2 years
In any event trannies in my BFs and SFs are different.
Hi Yuri
I'm not certain I understand what you meant but I can assure you that Fender never went to the UltraLinear design OTs on smaller amps like the Deluxe and Princeton. In fact I'm pretty certain that ONLY happened in amps employing 6L6s and not all of those.

That said it is entirely possible that even if a schematic uses the very same Fender part number that it can be actually provided by a different manufacturer and be a slightly different physical design with only the electrical specs being the same. This is a difference, nonetheless and will have some impact on sound and feel but it is really quite minor given the same ratios and orientation. The design requirements from Fender are restrictive enough that only minor variations are allowed to "fill the bill".

As an amp designer I would look to other areas with a much greater impact to match an SF to a BF tone and feel. Bias, coupling caps. and Negative Feedback are much more powerful in that regard not to mention the stiffness of the power supply which is HUGE.

Simply put if one desires a single coil sound for example and will accept NO alteration then really you must live with the noise and actually stick with a single coil pickup. If "close enough" is acceptable and exact duplication is less important than lack of noise other options are possible.

In my experience there are far too many players uneducated in how to affect their tone and feel and will fall back on some knob number that worked for them on a completely different amp as if it were Magick.

FWIW I have had many clients bring me two amps, some even of the same brand/model from different years asking me to "Make A sound like B". They never are exactly identical even when ALL parts are made identical but they can and usually are "close enough" to a very fine tolerance.
Old 14th August 2020
  #104
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Quote:
Originally Posted by John Eppstein View Post
The Princetons remained more or less the same - they never did a UL version.
I checked and both my 74 Princeton and 81 Princeton Reverb have UL Listed stickers.

On the Princeton, I'm fairly sure that it's a 74 - Power Transformer dates to 33rd week of august, and the output transformer dates to 34th week of August. The Chassis stamp is what throws me - all of the databases I see only go up to A15000, which is 1970, and mine is A18003.

If anyone knows a source for dating newer SF Princetons, that would be great...
Attached Thumbnails
What should I buy?? Super Reverb or Deluxe Reverb??-74-sf-princeton-ul.jpg   What should I buy?? Super Reverb or Deluxe Reverb??-81-sf-pr-ul.jpg  
Old 14th August 2020
  #105

Underwriter's Laboratory listed Ultra Linear amps, even!



-tINY

Old 15th August 2020
  #106
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Yuri Kogan's Avatar
 

Quote:
Originally Posted by enorbet2 View Post
Hi Yuri
I'm not certain I understand what you meant but I can assure you that Fender never went to the UltraLinear design OTs on smaller amps like the Deluxe and Princeton. In fact I'm pretty certain that ONLY happened in amps employing 6L6s and not all of those.

That said it is entirely possible that even if a schematic uses the very same Fender part number that it can be actually provided by a different manufacturer and be a slightly different physical design with only the electrical specs being the same. This is a difference, nonetheless and will have some impact on sound and feel but it is really quite minor given the same ratios and orientation. The design requirements from Fender are restrictive enough that only minor variations are allowed to "fill the bill".

As an amp designer I would look to other areas with a much greater impact to match an SF to a BF tone and feel. Bias, coupling caps. and Negative Feedback are much more powerful in that regard not to mention the stiffness of the power supply which is HUGE.

Simply put if one desires a single coil sound for example and will accept NO alteration then really you must live with the noise and actually stick with a single coil pickup. If "close enough" is acceptable and exact duplication is less important than lack of noise other options are possible.

In my experience there are far too many players uneducated in how to affect their tone and feel and will fall back on some knob number that worked for them on a completely different amp as if it were Magick.

FWIW I have had many clients bring me two amps, some even of the same brand/model from different years asking me to "Make A sound like B". They never are exactly identical even when ALL parts are made identical but they can and usually are "close enough" to a very fine tolerance.
I will check. The only SF amps I still have are a Twin Reverb and a Super Reverb.I had a Deluxe, a Bandmaster (?) and a Princeton but all those are long gone. They were nothing like BF counterparts (which i still have) even after the "BF mod". As are Twin and Super, even after all the mods.The ones I kept have the mods but are still very different. Have their original trannies. All that changed in the late 70s to get more output... Hate those.
Old 15th August 2020
  #107
Quote:
Originally Posted by enorbet2 View Post
The Math is easy IF all speakers are the same impedance. Simply put ... Example: - 2 x 8 0hm speakers are doubled (16 ohms) when in Series and halved (4 ohms) when in Parallel. This applies to individual systems (like multi speaker cabs) as well as individual speakers. Things only get real and complicated when you mix different impedances since that's not exactly intuitive. EZ solution? If you don't understand the equation just don't ever mix differing impedance speakers. They will have very different outputs (basically unusable) anyway. Use speakers of the same impedance and it's EZPZ.

On a normal tube output one cannot go higher than the rated impedance, at least without altering the electronics since load impedance affects tube operation which requires Bias adjustment to even get in the ballpark. Real world example: Plugging a 16 ohm load in an 8 ohm tube amp (without at least adjusting bias voltage) won't blow it but it will certainly alter the sound and feel and generally not in a good way.

Also in general, going lower... plugging a 4 ohm load in an 8 ohm tube amp is not dangerous, will generally work OK, but does have a lesser effect (ignoring that it is louder) on tone and feel, not generally a bad effect.

Going different by more than a factor of two, either up or down, is not a good idea at all and is flirting with disaster. So going to 2 or 32 ohms is a No No.
Super Reverbs are 2 ohm amps.
Old 15th August 2020
  #108
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enorbet2's Avatar
Quote:
Originally Posted by John Eppstein View Post
Super Reverbs are 2 ohm amps.
Yeah I stated that in post #96 in this thread. Did you actually imagine I didn't know better than the back of my hand?

Ive actually used that to advantage by using 4 x 16 ohm speakers to provide 4 ohms so I could run the power section in true Class A which requires nearly double the plate load impedance. That reduces wattage to less than 30 watts which allows channel volume settings above "4" to begin to really breathe without creating near deafening SPLs. It's substantially better for small to medium venues and recording than a stock Deluxe. In fact, true Class A Supers (or any similar 2x6L6 Fender amps) remind me of a Matchless King Cobra but Supers have the punch of 4x10s... Glorious!
Old 15th August 2020
  #109
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guavadude's Avatar
What’s involved in running a Super in a class A? One of my better purchases has been an Aracom attenuator.
It’s the only one I’ve ever heard that doesn’t change the tone. Best part is it has in and output settings for 2-16 ohm. This lets me use any amp with any cab at whatever volume I prefer.
Old 16th August 2020
  #110
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enorbet2's Avatar
Quote:
Originally Posted by guavadude View Post
What’s involved in running a Super in a class A? One of my better purchases has been an Aracom attenuator.
It’s the only one I’ve ever heard that doesn’t change the tone. Best part is it has in and output settings for 2-16 ohm. This lets me use any amp with any cab at whatever volume I prefer.
What's involved? Essentially it is just meeting the required conditions that a tube needs to operate in Class A. It may help to realize/recall that all your preamp stages are in Class A and all Single Ended Power sections are as well as they must be biased and loaded to provide a reasonable curve during 100% of the signal wave cycle.

Pure Class B requires/allows a lower output impedance load and higher (colder) bias voltage to only run 50% of the signal. Few tube amps run pure Class B (crossover/cutoff distortion is UGLY) and instead run in some median area referred to as Class AB2, close to Class B but having some overlap to reduce crossover distortion, or AB1 which has substantially more overlap (closer to A) for a bit less power/headroom but a sweeter tone and snappier response..

So specifically most power tubes need ~170% of the output load impedance and a reduced (hotter) bias voltage whether provided by choice of cathode resistor value or an actual B- voltage supply. 200% load, achieved by doubling the output load impedance, works just fine but reduces output a bit further but the tone is extremely sweet, rich in harmonics, and has a very different overdrive envelope... more touch sensitive.

So, TLDR, on a Super like a Blackface, and some later versions, which have a BIAS voltage adjustment pot, it's basically a 2 step proposition - 1) Increase the load, 2) Reduce the bias.

TLDR isn't smart though in this case. This needs to be done properly so the tubes don't red plate. IOW measuring plate current is important and ideally checking under a variety of drive conditions is wise. Many amps require altering the bias voltage dividing resistor to a slightly lower value to get a low enough voltage to achieve real Class A operation. Tube manuals list such conditions and requirements so any tech worth his "heater voltage" will be familiar and have the required tools to do the job right.

If you're really careful you can get a taste of what kind of alterations in tone and feel await you by just reducing the bias a few volts . like from the very common -52VDC to -47VDC on 6L6s, which will get you from AB2 to AB1 and hint at what direction this is headed. The careful part is having your 6L6s easily visible while you play so you can shut it off should it begin to red plate. If you like where it's headed there is a rather major jump in harmonic content and envelop when you actually get all the way to A. Get a proper tech to do that if you like it.

You may still use your attenuator in some environments as even 25 Watts is not anywhere near a 50% reduction in SPL down from 50 Watts... more like 12% less.

NOTE: Tubes don't last as long in Class A as they do at higher (colder) bias and lower load conditions. It isn't ridiculously less though.. still generally measured in thousands of operational hours.
Old 16th August 2020
  #111
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guavadude's Avatar
@ enorbet2
Great answer, glad I asked! Thx
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