stratum wrote:Old radio speakers that were in those old synths are still in use in guitar amps. They were intended to be full range speakers for their time but their upper frequency range is actually around 5khz and then it starts to roll off. That is probably one source of warmth associated with old analog gear. There are probably others, like a similarly band limited output transformer in a valve amp, harmonics added by the valve circuitry, their gentle overdrive character etc, but I have built a few such amps and withnessed first hand that this gentle overdrive character is not gentle at all without a properly band limited speaker cabinet.
I generally go for "clean as possible" but a lot of folks like the sound of synth run thru a guitar amp with the cheap output transformer and band-limited high-distortion speakers. Though so far as I can tell, "low distortion speakers" are vanishingly rare. So far as I know, speakers below 2 percent distortion over the audio spectrum are quite rare, and perhaps speakers below 1 percent distortion over the audio spectrum are nonexistent. For instance--http://www.neumann-kh-line.com/neumann- ... term=THD+N
Ideally the lower the harmonic distortion, the cleaner, or more transparent, the loudspeaker will sound. Less than -30 dB (3%) at low frequency and less than -40 dB (1%) at mid-high frequencies is normally considered to be good, lower values than these is of course better.
So if that is a "high fidelity studio monitor" distortion level, then PA speakers or guitar speakers probably lots worse on average.
Some of the more popular guitar speakers have presence peaks in the upper mids before they start rolling off in the highs. The upper-mid boost can be "ear candy" like with celestion greenback or old stiff-cone "classic" speakers. A combination of the high frequency rolloff, presence boost, and several percent of distortion.
Maybe running computer synths thru a guitar amp set for "clean" and re-miking back into the song would make them sound "fatter" or "older" or whatever.
Low-level coupling transformers are another thing that adds distortion while still sounding "fairly clean". Maybe a box with a few coupling transformers could be used in an interface loopback to "warm up" computer synths. I looked into it awhile ago, but can't recall details of which ones to look for.
The "highest quality" coupling transformers are rather clean and wideband, so looping back thru premium high-fidelity transformers probably wouldn't make much audible difference. On the other hand, a 2 dollar telcom 1:1 600 ohm coupling transformer might just sound crappy rather than subtly sweetening the signal. Or maybe it would be nice. Dunno.
Some of the coupling transformers of yesteryear, in expensive studio gear were prized for the sound, but they were not "near ideal" low distortion devices. I think there are new-manufacture transformers also designed to be "hifi" but with warts like that.
So far as I know, a good quality saturating transformer would tend to add a little distortion / saturation to bass frequencies while remaining clean at mids and highs. Also I believe heavy saturation of the bass ought to intermodulate the mids and highs, though the "hifi sweetening" probably is with "just a little bit" of bass saturation and everything else clean.