Fender Twin Preamp Frequencies?

Dennis Detweiler · From: Solon, Iowa, US

Does anyone know the bass, middle, treble and presence frequencies on a Fender Twin? Did these frequencies change throughout the years?
Thanks
Dennis

Gino Iorfida · From: Pittsburgh, Pennsylvania, USA

Not exactly cut and dry... if you move the mids, the treble peaks at a different frequency etc... in other words, the centers of any knob (bass, mid, treble) are affected by the level of the other tone knobs...

however, to answer your question, the tone stack on twin reverbs is virtually unchanged from the early blackface until the latest silverface... other circuit changes cause the different tonalities of the different amps.

Dennis Detweiler · From: Solon, Iowa, US

Brad Sarno anylized the session 400 frequencies at bass:50hz, mid/shift:movable, treble:2700hz and presence:??
I was hoping someone might know the same for the twin?
After using a Furman PQ-3 for several years, I've found the bandwidth of each frequency setting can overlap into other frequencies unless the bandwidth is narrowed to zero. It seems amp frequencies have a wide bandwidth, but still are electronically set a a certain frequency.
Thanks
Dennis

Brad Sarno · From: St. Louis, MO USA

Dennis, being a tonestack design, the Twin EQ is sort of interactive, BUT generally the bass is at 65Hz, Mids are at about 500, and treble is a high shelf above 1.5kHz. That's why I modded the Twin EQ to move that 500Hz mid control to about 800Hz. As Gino said, this type of EQ curve is interactive and isn't as describable as one like the Session. But generally it's what I listed.

Brad Sarno

C Dixon · From: Duluth, GA USA

The question is difficult to answer. Here is why. UNLIKE the tone and equalizing controls on a Peavey, Fender did NOT "center" the pots. That is, the pot did not use a +/- system of design.

I will explain. On a N400 each tone control has no affect on the tone of the amp, WHEN in the center position. IE, when at 12 o'clock, they are affectively OUT of the circuit. When you go left the center frequency is attenuated, when you go right the center frequency is amplified.

NOT so on any Fender "stacked tone" control circuitry. To add further, Leo Fender was very preferential in HOW controls "felt". Remember, he was probably one of the most incredible marketing geniouses the musical world has ever known.

He litterally catered to how the player's minds worked. So just about everything Fender came out with, many many many players simply equated with. And of course would pay any price to have one.

So he had his engineers design each control so MOST of the change occurred during the first few degrees of the knob. Thus, why a Fender volume contol does little after about 3 on the knob. Same for the bass, treble and mid controls. This instant "gratification" was the secret that other manufacturers never understood.

This caused players to perceive that Fenders were more powerful because Gibsons, Ampegs, etc had to have their controls set on 7 or 8 (typ.) to sound as loud. Even though at 10, both amps (equal rated power) was the same.

I said all the above to say that the center frequency of Fender tone controls are really nebulous with respect to say a Peavey amp, because there is NOTHING similar in the way they are designed; or work.

carl

Dennis Detweiler · From: Solon, Iowa, US

"anylized" ??? Too early in the morning for spelling? Now I'm awake....analyzed

Thanks guys. I'm trying to narrow down the duplication of tone controls into a Genesis 3. The "blackface" model. The session 400 settings on the blackface didn't sound on target to me. I brought the 50hz up to 60 and that seemed better. So I guess I wasn't too far off from the 65hz. The mids seemed more familiar at 500, but toward 800 seemed better for steel. I couldn't narrow down a treble frequency. So, I'll give the 1.5 a shot.
Programming the frequencies seems to open up more choices in spker cabinet selections also. The 57 tweed 12 still seems best for steel. I'm toying with a few other options by adjusting cabinet resonance and frequency changes on the bass, mid and treble.
Thanks again,
Dennis

Ken Fox · From: Nashville GA USA

http://www.duncanamps.com/tsc/

Download the above and you will be able to see the Blackface circuit graphically as well as be able to interact with it. It is a great tool! I have used it when tweeking Fender amps.

Gino Iorfida · From: Pittsburgh, Pennsylvania, USA

Ken,
When you see the fender tone stack, try this:
set the bass and mid capacitors (c2 and c3) to .02uF (22n), then change R1 to 56k. Now run the bass and treble up around 7, and the mids down below 5.... Try this on a twin etc and elt me know what you think, (i.e. see if we agree here

Greg Derksen · From: Alberta, Canada

Interesting topic, My 69 Super Reverb, is the closest thing to a perfect EQ, I can set
everything on 5 and its close, give or take,
bright switch on,
On Nashville 400's, the bass, treble and
presence, are generally okay around 5, but
the mids always must be cut around 800,
That is a nasty nasty frequency, most rental
400's I've used are set very similar, so I'm not alone,
I think the 400 is a good amp, but IMHO the
mids around 600 to 900 could be cropped in a little wider EQ sweep,
The Boogie PreAmp , seemes quite similar to
the Super, in that it sounds good, everything
on 5, maybe treble up, mids down a bit,
The funny thing is I've played steel amps
that EQ wise are right, no ugly mids, but feel stiff and tight, jump back on the old super, and it feels like home again, Greg

Ken Fox · From: Nashville GA USA

Gino, I tried that same idea with the tonestack calculator about three weeks ago. I was temped to try it, but did not at that time. Other than a little different rolloff on the lows, I think it would be great for steel. The rollof may not even be noticable. Next amp I get on the bench will be tested with that. Have you tried it yet? Interesting, I saw those two .022 caps in an early tweed amp schematic, if I recall correctly.

[This message was edited by Ken Fox on 05 November 2003 at 02:11 PM.]

Jennings Ward · From: Edgewater, Florida, R.I.P.

Fellows, a lot has been said about tone, but no one has mentioned how well we HEAR, volume and TONE wise. It is a known fact that we do not all hear the same frequenccies at the same level and time. I learned early on to Use good test equipment, an audio generaqtor and an oscilloscope when working on the tone circuits of and amp. If you dont , your hearing is subjective and the accoustics will play tricks on you. Cause you to hear things that are not there, and miss those that are.. there is no such thing as perfect accoustics, and due to this fact response wave form can be missinterpited...All of that to say this, A deaf person can not get a good tone out of a fiddle, no matter how well he can play.....Reguards, Jennings

------------------
EMMONS D10 10-10 profex 2 deltafex ne1000 pv1000, pv 31 bd eq, +

C Dixon · From: Duluth, GA USA

The entire world of sound is subjective. It is all perception and many many different factors go into what an individual hears.

Some facts:

1. Humans perceive level changes logarithmically.

2. Humans perceive tonal changes linearly (unless the level is real low).

3. The human ear was designed to listen to sound at average levels of 1/8 of a watt at 1KHZ.

4. It takes 10 times a level change for most humans to perceive the level has doubled (or halved).

5. If you wish your tone control to give a "boowah" affect, change the normal linear tone pot to a log taper pot using the same value.

6. Leo Fender had his engineers design their amps so the amp would produce the same level of output at a volume setting of 3 as other amps (with the same wattage rating) at a setting of 9.

7. If you connect the same make and type speaker (but of different impedances 4, 8 or 16 ohms) to an amp with am 8 ohm output, most players can only tell a small difference (if at all) in sound level.

8. The tone cutout switch inherrent on most all Emmons' PSG's, does not give the guitar more power (when off) as has been repeatedly stated. It simply sends more of the highest of the highs to the amp when the tone control is at maximum treble.

9. In double blind tests, players fail the test every time of a volume pedal "changing tone" as it changes level. Incidently, an inactive pot pedal DOES attenuate the highs to a very infinitessimal degree when it is not at maximum, but players in the above "tests" cannot prove it. Their answers vary all over the place including saying opposite things with the same pedal.

10. Many players (AND technicians) confuse gain for power. They are two distinctly different attributes of any amplifier. They have nothing to do with each other. A 10 watt amplifier can have a gain of 60DB while a 500 watt amplifier can have a gain of 55DB, etc.

11. 100% of all the great musicians used as "testers" during the early stages in the development of musical instrument amplifiers, felt that an amplifier with 100% flat frequency response did Not sound as good as one where the frequencies around 800HZ were attenuated. To date this remains a mystery, nevertheless very true.

12. Impedance has nothing to do with resistance, yet BOTH are expressed in ohms.

13. A straight length of wire has NO impedance (at audio frequencies). Yet if you form that wire in to coil loops, it does have an impedance at any given audio frequency.

14. Yet in 12 and 13, the resistance measures the same!

15. Audio power and impedance is always measured at 1KHZ unless otherwise specified. Therefore a microphone with a rated impedance of 600 ohms, may measure 2000 ohms at 10KHZ!

16. The only power that is considered 100% true according to most audo engineers is "True RMS power". IE, the continuous power output of a given amp driven to its maximum level using the amps OWN power supply at 1KHZ.

Ironically this almost always comes out to be the lowest power rating of the many ways a manufacturer can determine power.

In other words, manufacturers can take a 50 watt true RMS amplifier and claim it as putting out 550 Watts "peak to peak" music power!

It is NO wonder the US Gov't made them stop this utter chacanary! Yet before they did this, the entire audo industry was guilty of out and out fraud! NOT one was stating power using true RMS power measuring.

(there were some that did use Peak power. But none used true RMS)

With that I am going to bed. May Jesus bless you all,

carl

Brad Sarno · From: St. Louis, MO USA

Carl said:

"11. 100% of all the great musicians used as "testers" during the early stages in the development of musical instrument amplifiers, felt that an amplifier with 100% flat frequency response did Not sound as good as one where the frequencies around 800HZ were attenuated. To date this remains a mystery, nevertheless very true."

I'd like to offer a suggestion as to why this is true. One time at the ISGC I got to meet Bill Lawrence. He, being an expert in magnetics and magnetic field theory, gave me a very long dissertation on why pickups have certain tonal characteristics. After a lot of trig and calculus, he finally came to a simple graph that was a line showing the typical frequency response of a magnetic guitar pickup. Whether it was a 12string steel pickup or a 6-string guitar pickup, there were some commonalities. The main two factors were that there is almost always a high power range that averaged around 710Hz based on his math. There is another resonant peak up around 2.5kHz. I believe that this large hotspot around 710Hz is the main reason that guitar amps over the years have been designed with a "voicing" or a midrange dip in this region. A Webb or Fender will have a dip around 500-550Hz. A Sho-Bud amp will tend to dip up closer to 1000Hz. Most Peavey steel amp users tend to dip at around 800Hz. I think that this EQ dipping is actually so that the pickups response can be made smoother, flatter, bringing out the full range of the music in a more balanced way. Often times an amp's treble control will address the higher peak at 2.5kHz. I think our ear wants to hear a balanced sound so if the pickup is hot at 800Hz, then it only follows that we'd like our amp to dip at 800Hz to compensate.

Just a theory,

Brad Sarno

Tom Gorr · From: Three Hills, Alberta

Brad,

That is a very interesting theory - I wish I had a better sense of the physics (electro-magnetism) that makes that so. I've always been intrigued by the fact that in "blind tests" where I dial out the most disturbing frequency on my steel amp - that it is always within a few Hz of 800 Hz - and the fact that 99% of PSG'ers dial out 800 Hz, too. There has to be something more to it than arbitrary "personal preference".

Why, though, does a six string humbucker need the 300-500 Hz dialed out?

Forum Index > Electronics		Next oldest topic :: Next newest topic

All times are GMT - 8 Hours	Jump to: