Hi, what different sound when I use H2 like a preamp ? I am using single end connect L R GND, can I use H2? Because H2 need 2 RCA connection input.
Hi!
I have some questions about H2 parts. Can I replace LM317 with a little bit lower noise part regulator like LM350 or something better?
What changes are needed to use Q1 with JFE2140 or JFE150 instead of J113?
I have some questions about H2 parts. Can I replace LM317 with a little bit lower noise part regulator like LM350 or something better?
What changes are needed to use Q1 with JFE2140 or JFE150 instead of J113?
Hello all, I have what may be a stupid question, but I am certain this is the place to get an intelligent answer.
I built my H2 Generator Version 2 yesterday and was excited to hear it. I placed it in my system between my DAC and my preamp and I definitely got distortion. Unfortunately not the sweet second harmonic sort. It sounds like I’m hitting the input on my pre with too much level.
My question then is, does it strike anyone that I may have made a blunder in a component value, or do I have a misunderstanding about how to integrate this into my system?
One thing to note, as soon as I powered it up and took the measurement at T2 for the sake of calibrating the potentiometers, the measurement was bang on the money for the value written in the bag of my provided jfets.
This led me to wonder if I’m running a full gain preamp into a preamp and just blowing up my input gain on my pre.
Any advice is extremely appreciated. You guys are my heroes. I love electronics, but my brain just doesn’t work with math.
I built my H2 Generator Version 2 yesterday and was excited to hear it. I placed it in my system between my DAC and my preamp and I definitely got distortion. Unfortunately not the sweet second harmonic sort. It sounds like I’m hitting the input on my pre with too much level.
My question then is, does it strike anyone that I may have made a blunder in a component value, or do I have a misunderstanding about how to integrate this into my system?
One thing to note, as soon as I powered it up and took the measurement at T2 for the sake of calibrating the potentiometers, the measurement was bang on the money for the value written in the bag of my provided jfets.
This led me to wonder if I’m running a full gain preamp into a preamp and just blowing up my input gain on my pre.
Any advice is extremely appreciated. You guys are my heroes. I love electronics, but my brain just doesn’t work with math.
Yes, you need to make the H2 unity gain:
H2v1 w/24v wall wart: R1 = 33.2K, R2 = 7.5K
H2v2 w/12v wall wart: R1 = 22K, R2 = 10K
You will need two of each size resistor for stereo.
I want to build an H2 in balanced form. I know this has been discussed and some of you have done it. I have not built balanced before and basically know what needs to be done but I would be most grateful for a schematic if one exists. I have not been able to find one with search on the threads here.
Difficult to make this as balanced as the 2nd harmonic gets cancelled in the balancing, leaving you with 3rd...
Would transformers work? I was thinking something like a Jensen iso max on the inputs and outputs if you want to throw money at the problem. Or if you’re careful with matching impedances something like the triad ty-250p that Nelson mentioned before at Burning amp could work (FR looks flattest with a 1k load). I don know if the output impedance of the H2 is low enough to get a decent response through the output triad transformers.
Good point Nelson, I thought that might occur but honestly, I am using the H2 as an experiment to learn how to implement balanced connections...it is cheap. My real objective is putting balanced inputs on a Wayne's 2018 that I built last year. I have a Denefrips Ares DAC that I would love to outpput to the Wayne and get the extra 6 db or so of gain that I think I would get using it's balanced outputs. I'm also contemplating a future build of the F5M and might also like to use it with an Okto Research DAC/preamp that only has balanced outputs. I know I can use adapter cords but it would be cool to keep it balanced all the way to the power amp. Olen, if transformers would work I'd like to see exactly how they would/should be implemented, but I will admit I'm a cheapskate which is one of the many reasons I am drawn to DIY 🙂.
I read the white paper on balanced audio at the Jensen site by Bill Whitlock, https://www.jensen-transformers.com/wp-content/uploads/2014/08/an003.pdf, and it helps but leaves me with the question, what is the best method to implement balanced xlr connections. He says transformers, but forgive me if this sounds skeptical but he works for a transformer company. From my other readings I have the impression that Nelson is indifferent to the value of balanced connections. Yet I believe some Passlabs products have them. So when they do it what is the method of choice? Are transformers indeed the way to go?
Try both and see whether you have a preference. Maybe you'll like unbalanced, maybe you'll like balanced, maybe you'll discover they sound so similar that the choice is unimportant.
If you're building DIY gear for your own ears and not selling to other people, the only thing that matters is your preference. What other people like, is immaterial. Do it your way and be happy.
If you're building DIY gear for your own ears and not selling to other people, the only thing that matters is your preference. What other people like, is immaterial. Do it your way and be happy.
I built my H2 balanced using two boards, one board for each channel with XLR pins 1 to audio ground, pins 2 to the input & output of one channel on the board and pins 3 to the input & output of the other channel. I used REW to dial in the H2 to 1%. When I used it with my balanced BA2018 line stage, it made the music fill the room.
I've also used Rod Eliott's P176 differential amplifier module for balanced builds where I want to use single ended inputs and balanced XLR inputs. The board uses a pair of dual opamps. I plan on building another P176 into a stand alone enclosure with balanced and single ended inputs and single ended and balanced outputs for use with REW.
The third method would be with transformers as you read.
However, I prefer positive phase of H2, so the way I build things may not be the best.
It is easy to set the H2 to + or - phase 2nd harmonic. This also allows nulling it altogether, all by setting the operating point.
Same with balanced operation.
Same with balanced operation.
At the beginning, I ask for your understanding because I use Google translator
H2 plays in a temporary housing. For now, I've been checking the reinforcement, how much it needs. To begin with, I checked how it looks in my condition in harmony with the original circuit.I did the measurement with multimeter. The CD source gives a 1khz 0db sine. At the output of DAC I have 1.7V RMS. If I counted correctly, with the oryginal divider it gives 1.5V RMS at the H2 input. The maximum opening of the potentiometer is given at the output of H2 5.4V RMS. If I counted correctly, it's 11dB of gain. I'm not complaining about too little power because M2X only needs 3V (as I understand from the data of this amplifier)
I would like to understand this 3db difference between the documentation and my device. Maybe my calculation is wrong.
H2 plays in a temporary housing. For now, I've been checking the reinforcement, how much it needs. To begin with, I checked how it looks in my condition in harmony with the original circuit.I did the measurement with multimeter. The CD source gives a 1khz 0db sine. At the output of DAC I have 1.7V RMS. If I counted correctly, with the oryginal divider it gives 1.5V RMS at the H2 input. The maximum opening of the potentiometer is given at the output of H2 5.4V RMS. If I counted correctly, it's 11dB of gain. I'm not complaining about too little power because M2X only needs 3V (as I understand from the data of this amplifier)
I would like to understand this 3db difference between the documentation and my device. Maybe my calculation is wrong.
Had a fun random idea: you could build the H2 board into a guitar pedal allowing a guitarist to turn "tube" sound on and off. Might be a fun thing to try.
Korg already has one...based on its Nutube
I know it's not exactly what you wanted but fyi..
https://www.korg.com/us/products/effects/tr-s/
I know it's not exactly what you wanted but fyi..
https://www.korg.com/us/products/effects/tr-s/
@turion64 how would the pedal trigger the box? Seems like it'd be more interesting and practical to put the board in the pedal. You'd need to add a line for the "unfiltered" signal and a switch to switch between the filtered and unfiltered output (which would be a pedal step switch or whatever it's called). You'd probably also want to add a potentiometer so you can adjust how much "tubiness" you put into the signal by adjusting the balance between the unfiltered and filtered signal. Seems like it could be a fun project! (Though probably for someone more skilled than myself, but maybe at some point.)
There's sites that sell pedal chassis that you could use for something like this. The H2 board is small enough that you could probably find a chassis that would fit. Another problem though is that for a guitar pedal you'd probably want it to be battery powered, which means you'd have to configure the board to run off a 9V battery supply.
There's sites that sell pedal chassis that you could use for something like this. The H2 board is small enough that you could probably find a chassis that would fit. Another problem though is that for a guitar pedal you'd probably want it to be battery powered, which means you'd have to configure the board to run off a 9V battery supply.