Frequency response

[gbono]

I continually read that soild state amplifiers don't not have the low frequency response of tube designs. WTF is this about? Urban legend? Is this just an issue with certain legacey designs? I guess it's time to fire up the old HP 8903B and make some measurements.

[joecool85]

I continually read that soild state amplifiers don't not have the low frequency response of tube designs. WTF is this about? Urban legend? Is this just an issue with certain legacey designs? I guess it's time to fire up the old HP 8903B and make some measurements.

I've never even heard of that, but certainly it is myth.  There is no reason that a tube amp would have better low end than solid state.  In fact, bass guitarists frequently use solid state gear BECAUSE it can cleanly handle the lows so well.

[phatt]

The Famous Marshalls had a massive drop blow about 80hZ where as a lot of SS power Amps can be almost flat down to 10hZ.
You can of course make a Valve Amp do the same trick,, just go hunting down all the HiFi Valve circuits.

Having very low response in the power stage can/WILL reap you a whole lot of frustration if it is intended for Guitar. 
Phil.

[Enzo]

All the high power subwoofers I have ever seen were solid state.

SOme solid state designs go down to DC.  Try that with a tube amp.

[gbono]

http://johnkvintageguitars.homestead.com/SunnColiseum.html

This web site has a pretty critical review of a Sunn Coliseun bass amp - oddly enough this guy loves vintage Acoustic amps and has posted frequency response plots (using RTA software) of ACC amps - I believe he dosen't have an issue with the frequency response of an ACC320. For reference, maybe he should measure the Fender Studio Bass amp he has on his site?

[phatt]

All the high power subwoofers I have ever seen were solid state.

SOme solid state designs go down to DC.  Try that with a tube amp.

No offense Enzo,, but if you care to point me to an instrument which actually produces a DC response then I'll be interested in the technical details of such equipment.

Meantime us guitar players have no need of such such sub wooffery equipment. 

Cheer's, Phil.

[gbono]

http://aetechron.com/?gclid=CKb31biU66sCFRdlgwodiw6iLQ

Easy to do in the istrumentation world - I've used DC coupled designs with multi octave bandwidths. Can't see why you couldn't use a similar design for a MI application? So what is the low end response that a guitar player wants to see 80Hz?? I see guitar players like Buckethead, Tom Morello, etc generating DC all the time 

[J M Fahey]

In fact there *is* a grain of truth behind the phrase "tube amps have more/better bass than SS ones" ... only that it does not mean "a wider or more extended one", quite the contrary.
Fact is, *terrible* (by Hi Fi standards) guitar speakers have a huge "bump" at the resonant frequency, much worsened by the high "Q" they have.
In layman terms, Hi Fi speakers have low Q which means they are properly designed and built, have proper damping for flatter and extended frequency response; cone mass, voice coil geometry, edge and suspension elasticity (called "compliance") is optimized.
Classic guitar speakers are just the opposite: underdamped, peaky, with too light cones, too short coils,  too hard suspensions, plain cardboard edges ... you name it ... but it´s Rock´n Roll, isn´t it?
A high damping SS amp "damps" (duh !) that resonant bass peak, but a low damping Tube amp enhances it.
It's like having a Graphic EQ with a 6 to 12dB boost at the speaker resonant frequency (usually around 100 Hz)
You will definitely perceive more bass, although a fake, "one note" one.
SS amps fake that by using current feedback, to achieve the same.

Note: funny thing is, classic Guitar speakers (old Jensens, Celestion´s famous G12) were Hi Fi speakers ... in the 40´s.
And tube amps, of course, were meant *not* to distort.
Now introduce a few not exactly rich Chicago Blues players, with 30 or 40W amps in overcrowded Clubs .... and the World changes forever.
We owe most of our Guitar sound to those old dudes.

[joecool85]

Note: funny thing is, classic Guitar speakers (old Jensens, Celestion´s famous G12) were Hi Fi speakers ... in the 40´s.
And tube amps, of course, were meant *not* to distort.
Now introduce a few not exactly rich Chicago Blues players, with 30 or 40W amps in overcrowded Clubs .... and the World changes forever.
We owe most of our Guitar sound to those old dudes.

Thank you Guitar Guys of yore, we salute you.

[Enzo]

Crown DC300, a classic amp if there ever was one.  The DC in the name stood for DC coupled, and the spec sheet says response is "flat to 0Hz (DC)".   SUch response was used in driving shaker tables in labs.

REmove the input coupling amp from a lot of SS power amps, and they will respond to DC.  How long and how much they can hold it, is a separate question, they are not designed for continuous DC into a load.  The DC300 could run DC into a load.

[J M Fahey]

Agree and add: I remember an ad for an amp, don´t remember the trademark, *might* have been a Crown for all I know, where they attached an arc soldering "pistol" (regular English name?) it might even have been a TIG or MIG one, to the speaker terminals, donned the proper mask, and proceeded to SOLDER some metal using the amp output.
I mean soldering heavy metal parts, not a PCB.

[phatt]

I continually read that soild state amplifiers don't not have the low frequency response of tube designs. WTF is this about? Urban legend? Is this just an issue with certain legacey designs? I guess it's time to fire up the old HP 8903B and make some measurements.

Then,,,,I strongly suggest you do exactly what you state ,,, then you will see 2 very different response curves.

The big bottom sound for guitar is coming from the 200hZ ,,ish area ,, not 40hZ.

The big roll off below 100/80hZ is the classic response of the Marshall sound.

Again I ASK?   please point me to an instrument that ***OUTPUTS a DC response.****

To test this just connect a 9 volt DC battery and listen to the MUSIC it produces :duh 0:) :lmao:

Enjoy what you hear
PHIL.

[J M Fahey]

I remember some experiments I made way back in the Disco Music era (no, I didn´t use a white tuxedo, black shirt and white tie to perform them), and "big bottom", "chest thumping" "let´s all move to the rhythm" basslines came out of a (famous for its FAT tone) Mini Moog synthesizer .... producing what basically was 90 to 100Hz frequencies, of course properly triggered and envelope shaped to simulate a "big" bass drum, instead of the dull 90 to 100Hz sinewave oscillator which was the real sound source.
Any deeper and it got "lost" and lacked perceived power.
Speakers just flapped or farted.
The only useful way to add some similarly processed 40 to 60 Hz frequencies was to have them mixed with the around 100Hz zones.
It was real humbling experience as to what *really* are the limits of practical speakers.
And that disgusting one note bass which most "impress the neighbours" car sound systems offer are also in that around 100 Hz area.
Oh well.

[Enzo]

Again I ASK?   please point me to an instrument that ***OUTPUTS a DC response.****

Phatt, again I point out the Crown DC300.  It has response down to DC.  If you put a DC voltage into the input, the output will move to a DC voltage and STAY THERE...into a load even, yes.  COnnect a 9v battery to it, and yes indeed the output will swing over to whatever the gain tells it to...and sit there.  It is not something to listen to, any more than the B+ in a tube amp is something to listen to.  But it is something the amp is capable of.  You expressed an interest seeing in an example in your earlier post

I brought it up as the ultimate in low freq response, and from a solid state amp.  I am not suggesting DC on the output would be musical.  That wasn;t the point.  But if it will handle DC< it sure as hell will handle 40Hz.

DC response has serious applications, just not in audio.  In mechanical engineering labs, they use such an amp to move linear actuators.  Ever see something bolted to a flat surface that then moves up and down to shake the unit under test?  Cars for example?  Military electronics.

[J M Fahey]

I´ve seen films of such actuators flapping a plane wing up and down until it cracked and fell away.
A terrifying sight for anybody who flies regularly.
Why? ... because I have *seen* plane wings flap that way in turbulence. Gosh !!
And what was said actuator?
The mother of all subwoofers.
The voice coil was 1 (one) turn, made out of a piece of copper tube. (it must have been 0.1 ohm or something like that)
The magnet was a *huge* field coil.
Power was around 20KW .
No, not PMPO,    RMS. And we are talking the 60's here.
It had no cone, but a threaded steel bar, which bolted to the wing or any part meant to be tortured.
Frequency was visible, must have been between 1 and 10 Hz.