Downgrading them to lesser quality colleges?
just gonna hire my son into the family business. No college tuition then lol. And I get the write off
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An inexpensive audio transformer with DIY projects
- Thread starter boomertech
- Start date
just gonna hire my son into the family business. No college tuition then lol. And I get the write off
We don't even know if they're college material.Downgrading them to lesser quality colleges?
- Feb 16, 2008
- 21,240
- 23,636
- Disclosures
- John K Custom Basses
I always wanted to build a Sunn 200s or Sunn 2000s preamp emulator (and I have nothing against it using Jfets for the tubes, and would actually prefer to use them).
I actually started drawing one up about a year ago but never got around to finishing it.
I actually started drawing one up about a year ago but never got around to finishing it.
That would be so awesome! Especially if it wa sin the style of some of those Chracter series/Joyo pedals.
Stop it John......I just bought the correct sound custom sunn beta
- Feb 16, 2008
- 21,240
- 23,636
- Disclosures
- John K Custom Basses
I've looked at those too. I just prefer the old tube Sunns. the 200S/2000S amps still are some of my favorite bass amps of all time.
If you guys have some extra PCBs left over, and don't mind sharing the schematic, I would potentially be interested in trying to DIY one of these Trans Boosts. I've been toying with the idea of building an efx pedal for a while, and this is sick! That being said, I don't want to take away from the hard work you guys put in here, so if you are planning on just selling finished units, I totally understand!
(I also can't help but wonder what these would be like with a 3 band eq and driving a power amp lol)
Cheers!
(I also can't help but wonder what these would be like with a 3 band eq and driving a power amp lol)
Cheers!
I'm broke even before getting a Trans Boost!
The next project needs to be the TalkBass Loan Company.
The JohnK/Frank Alchemy pedal. You feed it a low B signal, it spits out molten gold in stereo.
Well, you guys did a pedal that emulates a pushed SS power section, then you guys used a transformer. The only logical next step is yo use some sort of tube.
That would seem to be the logical next step. Maybe something like a DIY tube/tranny DI box. I haven't seen a tube/tranny DI box that doesn't require you to sell organs on the black market to afford.
-Frank
I know they are not cheap, but maybe something that employs subminiature tubes like the 6112 that Coopersonic uses in their clean tube booster/buffer pedals. I think Effectrode might use that in some of their pedals as well.
And, yeah, that DI idea would be amazing.
This thread has been a great read. I have also been investigating and experimenting with transformers. I stumbled on this thread while looking for a chorus pedal. It was hard to follow because all of the early schematics were deleted. I had to read through until I found the schematic, the re-read the whole thread again to figure out what was going on.
Referring to post #166, low end rolloff. I can see that changing C8 to 10 uF helped some, but there still is low end rolloff.
You guys are hitting the transformer pretty hard. I suspect that you may have a DC bias on the transformer. This causes early low end saturation, which rolls off the low end.
My application is a lot more subtle. Not a problem for me since I play jazz on a 4 string, but the low B guys may want more oomph on the fundamental.
Anyway, I am not criticizing, just trying to be helpful. I will try to dig up some transformer DC bias curves. The bright side is that if you get it rolled off just right, you also have a nice HPF.
Referring to post #166, low end rolloff. I can see that changing C8 to 10 uF helped some, but there still is low end rolloff.
You guys are hitting the transformer pretty hard. I suspect that you may have a DC bias on the transformer. This causes early low end saturation, which rolls off the low end.
My application is a lot more subtle. Not a problem for me since I play jazz on a 4 string, but the low B guys may want more oomph on the fundamental.
Anyway, I am not criticizing, just trying to be helpful. I will try to dig up some transformer DC bias curves. The bright side is that if you get it rolled off just right, you also have a nice HPF.
This strikes me as an open source project of sorts. It would interesting to see those with knowledge and skills continuing to change/modify/improve/tweak the existing circuit. Especially since I haven't commissioned my build of this design yet.
The circuit had really evolved from its initial concept into something totally new, so the earlier schematics were deleted to eliminate the documentation that was no longer relevant.
Here are measurements of the TY-250 transformer frequency response at different input levels. You can see that the low end at 20Hz is approx -1.5dB for all of the plots.
Link Removed
The DC bias at the outputs of primary drivers (U2a and U2b) will only be the opamp offset error times a gain of 1, which should only be a few mV at max... definitely not enough to cause core saturation.
Here is the TY-250 with large input signals:
Link Removed
You can see from these measurements, that even with hitting the transformer with large input signals, that the low end roll-off is fairly consistent with a -3dB dip at 20Hz.
The earlier plots that John made with a lot of low end roll-off (post 166 to post 185) was mostly due to the input impedance of his sound module/sound card in combination with the output coupling capacitor of the circuit (C8). When he increased the size of C8 to 10uF along with the size of C5 and C11 to 4.7uF the frequency response changed to this:
You can see that the blue trace is approx -2dB at 20Hz, it's pretty much the same as the TY-250 frequency tests from above. IMO, For an effect pedal, this circuit has an outstanding low frequency response.
-Frank
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This strikes me as an open source project of sorts. It would interesting to see those with knowledge and skills continuing to change/modify/improve/tweak the existing circuit. Especially since I haven't commissioned my build of this design yet.
That is a nice thought, but too many cooks isn't always the best course.
It has been said that a is a camel is a horse that has been built by committee. These guys built a race horse. Don't make it cross the desert.
The circuit had really evolved from its initial concept into something totally new, so the earlier schematics were deleted to eliminate the documentation that was no longer relevant.
Here are measurements of the TY-250 transformer frequency response at different input levels. You can see that the low end at 20Hz is approx -1.5dB for all of the plots.
Link Removed
The DC bias at the outputs of primary drivers (U2a and U2b) will only be the opamp offset error times a gain of 1, which should only be a few mV at max... definitely not enough to cause core saturation.
Here is the TY-250 with large input signals:
Link Removed
You can see from these measurements, that even with hitting the transformer with large input signals, that the low end roll-off is fairly consistent with a -3dB dip at 20Hz.
The earlier plots that John made with a lot of low end roll-off (post 166 to post 185) was mostly due to the input impedance of his sound module/sound card in combination with the output coupling capacitor of the circuit (C8). When he increased the size of C8 to 10uF along with the size of C5 and C11 to 4.7uF the frequency response changed to this:
You can see that the blue trace is approx -2dB at 20Hz, it's pretty much the same as the TY-250 frequency tests from above. IMO, For an effect pedal, this circuit has an outstanding low frequency response.
-Frank
Thanks for your clarification. I did not see any mention of the low input impedance of the sound card. You did a great job on the pedal.
Triad makes nice transformers. TY-250 looks pretty good. I am using a different triad in another application. I may use the Ty-250 in the future.
I never said that the frequency response was not outstanding. The blue line shows a very good response.
I was only commenting that the steep rolloff of the purple line would make a nice HPF if it rolled off at 30 Hz instead of 50 Hz. Low B on a 5 string is 30 Hz, so you don't need to go down to 20 Hz. But if an HPF is not part of your needs, that's cool.
There wasn't any mention of the input impedance of his sound card. It was more like... I changed this capacitor to 10uF, now look at this awesome response and let's wrap this thing up.
At that point we quickly finalized the circuit and stopped analyzing it. I was the one that came to the conclusion that his sound card input impedance was the culprit. I didn't mention it in this thread because it doesn't really matter and John and I were anxious to put this to bed.I just realized that the first plot of the TY-250 is from the shunt attenuator test that I made while working on another project. On that plot, the input remained at 0dBu and the violet plot is the unloaded secondary output. All of the other plots on that graph are for various shunt attenuator values across the secondary output. (details are on the first page of this thread)
You said "...but there still is low end rolloff", "...the low B guys may want more oomph on the fundamental.", "Not a problem for me..." and "Anyway, I am not criticizing...". So I wanted to clarify that the frequency response was really good and that you may be looking at the wrong measured response, because it is only down approx -1dB at 30Hz. I hope that you can see where I could read your comments as that the frequency response was lacking in the low end, even after the output capacitor was changed to 10uF. I have read your post several times and I still come to the same conclusion, which led me to believe that you were looking at the wrong freq plot. This is one of the reasons that John and I were trying to clean up irrelevant documentation along the way.
Just to clarify for everyone that comes across this thread: The frequency response that John measured is 20Hz to 20KHz (-3dB to -1dB) when using the 1KHz measurement as the reference... that's in the range of decent HI-FI consumer products.
As for using the TY-250 as a HP filter (sub-sonic filter), it could be a very simple circuit. I am thinking input buffer with a series capacitor and resistor feeding the transformer primary coil. You would need to size the resistor and capacitor for the proper resonance bump at the corner freq, but the frequencies below the cut-off should drop like a rock. You may not even need an output driver, just feed the raw secondary output to the amp or next pedal. Something to think about......
-Frank
