ideal steel amplifier

[andrew]

Hi
I have been talking with a company who want to develop an amp specifically for steel and who asked me what my 'wishlist' would be for a steel guitar amplifier. As an inexperienced steel player I thought it best to throw the question open to those with more experience and who perhaps have more specific requirements / ideas on the subject. I am also posting this question in the lap steel section as I am guessing there will be other ideas there. So, any ideas anyone?
thanks, Andrew

[JoeMagnifico]

A great reverb and lots of power (headroom) for starters...

[Ross Shafer]

TUBES!

[richard37066]

Without actually having seen the schematic diagram of the Nashville 112, I suspect that Peavey have included a rather broad-band parametric equalizer with the capability of shifting the center frequency of the band and adjusting the level of the selected frequencies. To my way of thinking, it is a step in the right direction even though it still doesn't satisfy my needs.

In general, I should think that someone would carry this concept a step further and take a lesson from the audiophile folks by incorporating several such parametric equalizer filters into any new design. My best guess would be that three such filters would be the absolute minimum required - which would roughly and crudely mimic the NV112's range of adjustment - while five to ten such filters would give one the opportunity of tailoring the response more closely to ones liking. Said filters - of narrower bandwidth - would have fixed center frequencies with only the gain to be adjusted. In so doing, Peavey's "low", "mid", "shift" and "high" controls would be eliminated in favor of 5 to 10 level adjustment controls keyed to the center frequencies of the bandpass filters.

Sound familiar? It should. 31-band equalizers with sliders to boost/cut bands of frequencies have been around for decades.

Lest anyone be misled by this idea, be it known that an entire recording studio of electronic equipment will NOT create harmonics and artifacts not found in the guitar, itself. The inherent sound of the instrument "is what it is" - the electronics only amplifying that which is detected. A downside to this suggestion is that the player would have to become intimately familiar with the bandwidth of the steel guitar and translate a given "level knob" into corresponding frequencies of given notes upon the neck. The manufacturer could provide a table of such-and-such a note at such-and-such a fret which corresponds to such-and-such a level control. It would take much of the thinking out of the process.

I'm mindful of the fact that Peavey - once apon a time - incorporated a digital delay into one of their amplifiers. Using current DSP technology, one could closely mimic that of the ubiquitous spring delay module in addition to affording the digital effects that most are familiar with and use. In addition, the "norm" seems to dictate the inclusion of such things as "high-gain in", "preamp out", "power amp in", "preamp gain", "master gain", blah, blah, blah.

There - you have an "all-in-one" amplifier on one circuit board and in one box.

I don't even want to think about the cost.

Richard

[Georg]

My "ideal steel amp" reference is roughly as follows.

Solid State power stage...
~200Watt in 8ohm
~350Watt in 4ohm
~450Watt in .5ohm
Peak current: > 100Amp
~1000VA trafo
~100.000uF reservoir

Overall amp data...
Freq response: DC to 50KHz - 3db
Signal/noise: >100db
THD: 0.01%
Input level adjust: -30 - +10db
Input impedance: 20Kohm bal/un.

Equalizer/effects...
Have no need for built-in eq and effects, and if there is any it must be possible to bypass these stages completely.

Speaker/cab, to go with the above...
Freq range: 40Hz - 18KHz -6db
Phase distortion: < +/-20deg.
Sensitivity: >96db/1Watt

[richard37066]

Georg -

Sounds like you're asking for a class-A audiophile amplifier to be used in the reproduction of recorded material.

Couple of nit-picks: - Why the 50KHZ bandwidth? The output of the highest detected harmonics in the steel don't begin to approach this.

Who makes a 0.4 ohm speaker? Never heard of it.

That 20Kohm input impedance would load the heck out of any pickup.

To clarify something for the members: - If I remember correctly, you and I had a conversation some time ago in which your desire was for a guitar whose tonal characteristics were inherent within the instrument - not needing a room full of compensating electronics to produce the final, desired result. Hence, the dead-flat, quiet, distortionless, high-powered beast that you describe. I FULLY AGREE WITH THIS. Thus, the finger is pointed directly at the efforts of those who would improve the breed - to CONTROL the characteristics of the instrument, itself. It is in this direction - I believe - that the impetus should be applied. Sadly, it would appear that the major builders are not disposed to such effort.

In the interim, then, an all-inclusive, compensating amplifier seems to be in the offing - a lesser effort to solve the "problem".

Sorta like "putting the cart before the horse", Eh?

Richard

[Georg]

Richard,

Audiophile amp ... not really but at least quite a bit closer to one than the steel-amps I have tried so far.

I think maybe you need better "detectors", as I get/measure signal up to and above the audible range for a steel. And, if I roll the top off at say around 18KHz I can hear the filter-drop and phase-shift even though my ears are not very sensitive up there anymore.
Any and all amp-stages become somewhat phase-non-linear close to roll-off and changeover points. Thus, 50KHz with the required THD is not very high if non-linearity down into the audible range is undesired ... an octave higher for the 3db roll-off point would be even better.

No single .5ohm speakers on the market AFAIK. I think around 1.5ohm would be a practical limit - two 4ohm in parallel, but it is always good to dimension an amp to handle heavy load at full power without running out of breath and/or fail.

~20Kohm is ideal input impedance when steel-PU is buffered / fed through active VP and/or other pre-stages, which I always use since I don't want long cables (worst case: no longer than 1 meter) between PU and buffer / first stage.


You remember correctly ... ... little to no eq, little to no effects, and definitely no tubes anywhere in the sound-chain. IMO, a good steel sounds best uncolored by electronic gismos, and if a steel doesn't sound "right" uncolored it should be fixed - not "corrected".

I do of course have no problems with what others want or actually put in their sound-chains - between steel and audience - to produce their sound, but it also doesn't mean much when I write my wishlist.


None of what I have written is of course relevant if the OP just want responses about what players want in "another steel amp made more or less along the same lines as the old/existing ones", as I don't want or need one of those.

[sheffield steel]

A WEBB ! IMHO

[michaelm]

Since this topic has managed to resurface, Andrew, I just have to ask: Has anything more come of this amp project?

And since I'm jabbering away, I might as well throw in my two centavos worth on amp design. How about dripping oodles of spring tank reverb, four or five active tone controls, effects loop jacks, external speaker jack with switchable output impedance and ... all solid state design but no hokey DSP effects. There must be more, but that's all that I've got now.

[andrew]

I believe an amp has been built - I don't know the details yet but I think I may get to see it in a couple of weeks - I'm exhibiting at a guitar show in the north of England and the guys who make the speakers will also be there. Difficulty is that I may be on my own in which case I will not be able to check out the other gear as well as look after my own stall, but I'll report back as soon as I have had chance to check the amp out.

Andrew