Hi,
I am experimenting and wish to create an audio saturation device to run my instruments through and get that transformer saturation sound.
I got 2 of these transformers 119DA rated at 12w.
Hammond Mfg. - "Classic" 600 Ohm - Speaker Matching Transformer - Hammond P/N 119DA
And got this:
Permalloy Audio Signal Transformer 600Ω: 30K, 7 times boost boost signal, frequency response 23Hz ～ 36KHz -3DB
Buy Products Online from China Wholesalers at Aliexpress.com
And i have a 2 channel 140w amp outputs 8 or 4 Ohms, that i can use to power the transformers.
My end goal would be to saturate the transformers and step it down to live level to record it.
I ran a 50Hz sine wave input to the amp, and hooked up the secondary 8 Ohms of the 119DA transformers to the hi-level out of the amp. The signal is amplified from 25v max to 60v max. (I measure the ACV with a multimeter)
I haven't hooked up the other 600:30k pair yet but i can't seem to saturate the transformer, the sine wave somes out clean.
Any ideas on what to do to achieve saturation?
Thanks,
Mike
I am experimenting and wish to create an audio saturation device to run my instruments through and get that transformer saturation sound.
I got 2 of these transformers 119DA rated at 12w.
Hammond Mfg. - "Classic" 600 Ohm - Speaker Matching Transformer - Hammond P/N 119DA
And got this:
Permalloy Audio Signal Transformer 600Ω: 30K, 7 times boost boost signal, frequency response 23Hz ～ 36KHz -3DB
Buy Products Online from China Wholesalers at Aliexpress.com
And i have a 2 channel 140w amp outputs 8 or 4 Ohms, that i can use to power the transformers.
My end goal would be to saturate the transformers and step it down to live level to record it.
I ran a 50Hz sine wave input to the amp, and hooked up the secondary 8 Ohms of the 119DA transformers to the hi-level out of the amp. The signal is amplified from 25v max to 60v max. (I measure the ACV with a multimeter)
I haven't hooked up the other 600:30k pair yet but i can't seem to saturate the transformer, the sine wave somes out clean.
Any ideas on what to do to achieve saturation?
Thanks,
Mike
To easily saturate a transformer you need to run some DC through it. It will probably take some experimenting to get the sound you want out of it. In order to get symmetrical soft clipping you need two, biased in opposite polarity but fed/ mixed in phase. You will have to be careful not to exceed the current capability of the winding.
I was able to saturate a Hammond 149 series by biasing a single ended D40K darlington through it at 25mA. With a little more easily saturable transformer you could do it with less current and a 2N3904 or op amp driving it. If you don’t want the stage gain, just configure the driver as a current source and cap couple the signal in.
I was able to saturate a Hammond 149 series by biasing a single ended D40K darlington through it at 25mA. With a little more easily saturable transformer you could do it with less current and a 2N3904 or op amp driving it. If you don’t want the stage gain, just configure the driver as a current source and cap couple the signal in.
Both of those transformers have a low end bandwidth extending to around 30 Hz. Try input signal frequency which is lower than that. As you may know, saturation is frequency dependent so amplitude for saturation is lower the lower the signal frequency.
I reckon your transformers are simply too "hifi" and powerful to saturate with ease.
As you may have noted, transformer saturation with common mechanisms (not e.g. biasing the coil with DC) is much rarer occurence than commonly thought. It may require signal amplitudes that do not appear in conventional applications or use or signal frequencies close or below low end human hearing range.
I reckon your transformers are simply too "hifi" and powerful to saturate with ease.
As you may have noted, transformer saturation with common mechanisms (not e.g. biasing the coil with DC) is much rarer occurence than commonly thought. It may require signal amplitudes that do not appear in conventional applications or use or signal frequencies close or below low end human hearing range.
Which would be?
Transformer saturation has been stated to be a large part of "tube amp sound" and so somewhat desirable.
I have never seen a solid justification for that.
Yes, tube amps have output transformers and they saturate under certain conditions, but it´s a lowest frequencies and DC phenomenon, not sure how it affects "normal" Audio frequencies in a desirable way.
In my view the desirable saturation comes from tubes and how they react to signal dynamics at high power; transformers just "happen tobe there" and get unjustified/unproven praise for no reason.
You seem to have SS amps so you are missing the main "desirable saturation" mechanism and as you are finding, transformers by themselves do nothing of what you expect.
I suggest you FIRST find and show us an example of successful/desirable transformer saturation effect on sound and then we´ll try to analyze it and help; but so far we are chasing shadows.
Hi,
I am aware of the fact that their main utility was to drive tubes but transformer core saturation can happen in the audio spectrum without the tubes.
i think there are a lot of sources regarding audio transformer coloration and saturation.
This book has a lot of info i found useful, https://www.jensen-transformers.com/wp-content/uploads/2014/08/Audio-Transformers-Chapter.pdf
Analogue Warmth
A lot of new (and old) pro audio equipment have transformers in their signal path just to get that character/coloration, without the tubes.
A few examples are
The famous Neve 1073 that has been known for its transformer color
Neve Style Preamps: Imitation in the Sincerest Form: | Tape Op Magazine | Longform candid interviews with music producers and audio engineers covering mixing, mastering, recording and music production.
SSL Fusion
Fusion | Solid State Logic
TB12 transformer based preamp
TB12 Black | Warm Audio
TransDrive
https://avedisaudio.com/transdrive/
and so many others, the list is endless.
https://www.sweetwater.com/store/search.php?s=transformer+preamp
https://www.sweetwater.com/store/search.php?s=transformer+equalizer
Popular audio transformers known for their color are carnhill, cinemag, jensen to name a few.
In this video there are many audio examples of when engaging the transformer in the signal path, starting at 5:50:
https://www.youtube.com/watch?v=3sVYqhhEeLQ
I am aware of the fact that their main utility was to drive tubes but transformer core saturation can happen in the audio spectrum without the tubes.
i think there are a lot of sources regarding audio transformer coloration and saturation.
This book has a lot of info i found useful, https://www.jensen-transformers.com/wp-content/uploads/2014/08/Audio-Transformers-Chapter.pdf
Analogue Warmth
A lot of new (and old) pro audio equipment have transformers in their signal path just to get that character/coloration, without the tubes.
A few examples are
The famous Neve 1073 that has been known for its transformer color
Neve Style Preamps: Imitation in the Sincerest Form: | Tape Op Magazine | Longform candid interviews with music producers and audio engineers covering mixing, mastering, recording and music production.
SSL Fusion
Fusion | Solid State Logic
TB12 transformer based preamp
TB12 Black | Warm Audio
TransDrive
https://avedisaudio.com/transdrive/
and so many others, the list is endless.
https://www.sweetwater.com/store/search.php?s=transformer+preamp
https://www.sweetwater.com/store/search.php?s=transformer+equalizer
Popular audio transformers known for their color are carnhill, cinemag, jensen to name a few.
In this video there are many audio examples of when engaging the transformer in the signal path, starting at 5:50:
https://www.youtube.com/watch?v=3sVYqhhEeLQ
As stated previously, the more expensive and hi-end the transformer is, the less "transformer sound" you'll get. Try something like this:TY-250P Triad Magnetics | Mouser or even cheaper transformers 10Pcs Audio Transformer 600:600 Ohm Europe 1:1 EI14 Isolation Transformer DIY | eBay
We don't really know inner details of how those "transformer overdrive" devices operate and what they actually mean with the phrase saturation. AFAIK the transformers of revered Neve preamps were rated 1% THD @ 20 Hz with usual input signal amplitudes so for audio I'd label them quite transparent, which I believe was the original intention. They were preamps not signal processors.
Most transformer overdrive devices seem to feature a rather lofi transformer for actual distortion generation. Some more likely rely on circuit topology with preferred distortion characteristics rather than actual saturation. Some just introduce a LC filter based emphasis of which the transformer is part of. In practically all cases we're discussing of very subtle effects.
Most transformer overdrive devices seem to feature a rather lofi transformer for actual distortion generation. Some more likely rely on circuit topology with preferred distortion characteristics rather than actual saturation. Some just introduce a LC filter based emphasis of which the transformer is part of. In practically all cases we're discussing of very subtle effects.
Part of the 'warmth' may be a low bass note that is by itself not very audible, but it's effect may well be to modulate the mid-band signal distortion, and hence be noticeable.
If you had a capacitor coupled mid-range speaker, and could adequately attenuate any low frequency signal used for modulation (so as not to damage the speaker), then that may be interesting. Or better still make it a preamp stage using as you say 600 ohm style coupling transformers. Sort of akin to an LFO modulation used for tremelo or vibrato modulation effects.
If you had a capacitor coupled mid-range speaker, and could adequately attenuate any low frequency signal used for modulation (so as not to damage the speaker), then that may be interesting. Or better still make it a preamp stage using as you say 600 ohm style coupling transformers. Sort of akin to an LFO modulation used for tremelo or vibrato modulation effects.
This is the second pair i have which seem to be very similar to what you are suggesting:
Permalloy Audio Signal Transformer 600Ω: 30K, 7 times boost boost signal, frequency response 23Hz ～ 36KHz -3DB
I was able to get some saturation, but i am not sure if this is coming from the transformers.
I connected the amp to the 600 Ohms side of the Hammond, then the 8Ohms is connected to the 600Ohms side of the smaller transformers (600:30k) and the 30k goes to the headphones/multimeter.
Here is a photo:
Imgur: The magic of the Internet
When i raise the volume of my amp at about 65% it starts to introduce harmonics/distort and the output volume increases slightly when reached 100%. So, from 65%-100% it saturates/distorts more.
The interesting thing is that I can find easily a spot where distortion is not too much, from 65%-75% volume is the range of added saturation to an instrument or sound would be acceptable, more than that it sounds like a guitar amp.
Btw, I sent an email to Hammond Electronics to ask what voltage their 12w transformer would saturate. They replied "Saturation will occur at 93V applied to the primary at 30 Hz". So, with my 25v i highly doubt that i am saturating these.
The output of the amp is 25V when max. Connected to 600 Ohms
So (25v x 25v)/600Ohms = 1.04w
The output from there is about 2v, connecting to 600Ohms.
(2v x 2v)/600Ohms = 0.006w
The output from these transformers is about 0.6v when i max the amp, which is ok for line level in, a bit low but ok.
If i apply DC to the Hammond transformers, wouldn't this need some sort of rectifier diode to not allow current to be fed in my amps output? Any suggestions on using DC to saturate the Hammond 12w transformers?
Thanks much for all the suggestions/info.
Ohhhh ok. I guess this means i would have to take apart these transformers and add the additional winding?
I have the same impression.
For example: I have two Fender amps with very similar power amp sections, one an inexpensive Super Champ XD, the other a '65 Princeton Reverb reissue. Both use almost identical output stages with a pair of 6V6 beam tetrodes, driven by a cathodyne phase-splitter, driven by an ordinary triode gain stage. Power supply voltages are not identical, but not that different, either.
On visual inspection, the noticeable difference is that the more expensive Princeton Reverb uses a larger and heavier output transformer, while the SCXD uses a much smaller one - probably the cheapest one that Fender Corp could find to do the job.
When you play through both amps and listen critically, the sound of the SCXD gets "thinner" (less bass) as you turn up the output power (loudness). The Princeton doesn't have the same characteristic.
I'm almost sure that what's happening is this: as you turn up the output power, the smaller output transformer in the SCXD starts to saturate at the bass frequencies. This means that the transformer stops "transforming" at those low frequencies, and so we hear less bass from the speaker as the volume goes up. (This is going to also put a heavy strain on the output valves, as a saturated transformer will not present a proper load to them.)
In other words, the transformer saturation acts pretty much like a bass cut tone control, one that cuts more bass as you turn the amp up louder and louder (and tortures the output valves at the same time).
IMO this doesn't sound musically wonderful in any way; it's a fairly minor effect, and not of much musical significance at all.
It's true that having less bass from the guitar will often make it "sit better in the mix", since there is less unpleasant interaction with the bass guitar and drums and the keyboard player's left hand. But, of course, you can achieve the same thing from the Princeton much more effectively - and without stressing expensive output valves - simply by turning down the bass control - no need for an undersized, saturating, output transformer!
-Gnobuddy
Power amp sections of the those amps are indeed very similar, except for little detail of RC coupling hi-pass filter of the input/driver stage, at which point Princeton Reverb Reissue provides considerably deeper bass extension than the Super Champ XD.
Maybe. Or you could be jumping to too early conclusions. First, we don't know exactly how DSP of the XD treats volume control dial (there could be a built-in "loudness" compensation or "bright cap", etc.). Secondly we need to acknowledge deeper bass extension of PRR. Thirdly, we must ponder if a guitar, or guitar preamp, can even output low enough frequencies to saturate the amp's OT. So, one must also be open to other explanations of that audible difference besides actual OT saturation.
We must heed that, when saturated, the transformer indeed stops transforming. Entirely. At all frequencies. So saturation is not just a hi-pass filter. We would hear less of everything and this would manifest itself as very distinct distortion as saturating OT would "chop away" considerable portion of the signal, and not in a "nice" fashion, (nice as in ordinary peak clipping). We must also heed that saturation, when occuring, is a rather abrupt effect and very little saturation is required to skyrocket harmonic distortion.
By the way,
with a bit of googling one can likely find a few oscilloscope screen capture examples of what audio transformer saturation actually does to the signal. (There are few people who actually took the time to arrange tests of the subject and post their results, instead of just making assumptions and guessing what saturation might cause). These examples are very, very scarce (which I always consider highly suspicious when topic is something quite popularly discussed), and I suppose that this is due to reason that reality about effects of audio transformer saturation's isn't exactly corresponding with self-perpetuated myths about the phenomenon.
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You mean 25k and 100nF? The corner frequency (-3 dB frequency) of that combination is about 64 Hz, which is well below the lowest frequency you get from a normal 6-string guitar in standard tuning. It has no effect on the sound of the guitar.
You also forgot about the acoustic high-pass filter caused by the small open-back guitar cabinet; neither the Super Champ nor the Princeton Reverb has any significant audio output at these very low frequencies.
Finally, and most important, a fixed-frequency RC filter cannot produce the effect that I heard: a high-pass filter with a sliding corner frequency, that increased with power delivered to the loudspeaker.
That's certainly possible. At the time, I did not have access to audio testing equipment to make objective measurements, and I was more interested in improving my abilities as a guitarist, than in doing potentially expensive experiments that pushed output tubes and output transformer hard in an amplifier that was very dear to me.
A good hypothesis, but I can eliminate this possibility; I heard the same effect (bass gets thinner at higher power to the speaker) whether I used the volume control on my guitar, or the volume control in the SCXD. The effect was dependent on output power, not the position of the SCXD knobs.
I should also mention that I observed this effect on the clean channel of the SCXD. While I did not have the ability to take FFTs and look at spectrograms at the time, by ear, there was very little harmonic distortion on this channel, and what there was, appeared to come from the actual vacuum tubes, not the DSP.
I, and many others, bought this amplifier because the clean channel sounded like a little Blackface Fender tube amp, at one-third the price. It was, by far, the least expensive way to get a taste of the sound of a good tube amp.
To be clear: even on the clean channel, the DSP was certainly in the audio chain. In this amplifier, volume, tone, and onboard sound effects were all implemented in DSP. However, on the clean channel, there was no audible evidence that the DSP was also implementing harmonic distortion (tube emulation).
By contrast, on the SCXD's "drive" channel, the distortion from the DSP was not subtle; it was relatively harsh and unrealistic on all settings, and did not sound much like a good overdriven tube amp.
The PRR always had deeper bass, at all volume settings. But the signature effect in the SCXD was a sliding bass characteristic, with less bass at high output powers; I heard nothing like this from the PRR.
Certainly. And this would depend on how small the OT was. The OT in the SCXD is noticeably smaller than the OT in the PRRI, though both are nominally 15-watt amplifiers with nearly identical output stages.
In other words, at the same output power, magnetic flux density in the SCXDs output transformer would be higher than flux density in the PRRIs output transformer. Transformer saturation would be more likely to occur in the SCXD.
Agreed. My hypothesis: the most plausible alternative explanation has to do with the smaller, cheaper loudspeaker in the SCXD. Almost certainly it runs out of linear excursion sooner than the speaker in the PRRI. Since bass signals have the largest amplitudes, this would produce the same audible effect as an OT starting to saturate at bass frequencies: bass SPL would not keep up with higher-frequency SPL as the output power is turned up, and the amplifier would sound thinner at higher output power.
Well, no! Saturation is not a digital effect that's either on or off. The magnetic hysteresis loop has a higher slope near the origin, and the slope falls as you approach full saturation. Moving the point of operation gradually towards the saturation limit progressively reduces the slope of the curve.
So if the very lowest frequencies are pushing the transformer core momentarily into these regions of lower slope, the effect will be to lower the transformer coil inductances, filtering out the deepest bass in a way that tracks output power. Higher frequency signals of much smaller amplitude would still get through, as the transformer is still functioning, albeit at reduced magnetic coupling (mutual inductance).
Agreed. Just like the popular discussions about why red Teflon-insulated wire sounds better than blue Teflon-insulated wire in certain overpriced tube guitar amps.
IMO: From a big-picture perspective, it's easy to get 10% THD from a triode, 10% - 15% THD from a loudspeaker at bass frequencies, and 25% THD from a pentode/beam tetrode. That being the case, it's hard for me to believe that an additional 1% - 5% THD from the onset of transformer saturation plays a significant role in the sound of the amplifier.
The transformers contribution to distortion is far smaller than the contributions from tubes and loudspeaker, and would be largely swamped out by them. At best, its a minor effect.
However, if more people believed this, Mercury Magnetics would lose a lot of money and go out of business, so the myths will continue to be sustained by advertising dollars, and continue suck lots of money out of guitarist's wallets. Contrary to the popular belief, what you don't know can indeed hurt you!
-Gnobuddy
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