Handcrafted Tone
Well-known member
I've been talking about a few new projects lately, but due to time and money limitations, most of these projects are not finished yet. I thought I'd let you guys know what I'm working on, and maybe kick around a few ideas to improve.
First up is the Jensen Twin-Servo, that will fit in the API 500 series lunchbox. This pre is amazing. Ultra low noise and distortion, and double the bandwidth of a single stage topology. IT SOUNDS GREAT!
The only problem with this guy is I'm borrowing the metal work from my Eisen Audio preamp, and I'm unsure where I should source this metal bracket.
-edit - I borrowed the dimensions of the DIY500 just for this prototype, only to save time in research. I need to modify the bracket to be used with my design. I'm planning on using a completely different layout, but for ease of use in this PROTOTYPE, I used these dimensions.
The next project spawned from curiosity. Do IC's really suck, or is this another case of audio industry marketing? It turns out they do not suck. They can sound Perty darn good! So I made up two little IC to 2520 footprint converters, one for single-stage, and another for dual stage IC's.
The single stage IS FREAKIN AWSOME. I included a trim to tweak out DC offset, and power supply bypass caps. I tried out the OPA604, AD797, and the NE5534. All three had slightly different characteristics, and all sounded great compared to a JH990C. I used a 312 card to test. I'm not 100% about output driving capabilities, but they drove a Cinemag CMOB-2S with about 25' of cable with no problem.
The dual opamp to DOA footprint converter was a continuation of the previous idea spawned from this Burr Brown APP note: http://focus.ti.com/lit/an/sboa031/sboa031.pdf
It uses both gain stages in a dual opamp to double output drive capability. It sounds fantastic, but it becomes unstable at the highest gain settings. :sad: Does anyone with more experience know why? I'd like it to be a drop in replacement for a 2520. The gain settings that the oscillation occurs is so high that you'd never use that setting, but I still want to find out why it's happening and how to fix it.
You can also see in that pic my attempt at a simple DOA. I used the topology of my Sphere M1200 card, and tried to shrink that down into a 2520 footprint. It sounds really good at low gain, but there is not enough headroom for a mic pre (it distorts really bad). I'll have to dedicate some time to this one someday.
and last for now, a noise gate based on the THAT application note, built around the 4301 dynamic processor chip. I just plugged it in today, and it works great, but there is some oscillation associated with the release control I still have to work out.
There are two other projects in the works, but I should probably finnish up these first.
BTW BIG thanks to Olimex, that processed my pcb order even though I was a day past their deadline (they took the whole month of Aug off for vacation). I didn't realize bulgaria was like 10 hours ahead of LA.
First up is the Jensen Twin-Servo, that will fit in the API 500 series lunchbox. This pre is amazing. Ultra low noise and distortion, and double the bandwidth of a single stage topology. IT SOUNDS GREAT!
The only problem with this guy is I'm borrowing the metal work from my Eisen Audio preamp, and I'm unsure where I should source this metal bracket.
-edit - I borrowed the dimensions of the DIY500 just for this prototype, only to save time in research. I need to modify the bracket to be used with my design. I'm planning on using a completely different layout, but for ease of use in this PROTOTYPE, I used these dimensions.
The next project spawned from curiosity. Do IC's really suck, or is this another case of audio industry marketing? It turns out they do not suck. They can sound Perty darn good! So I made up two little IC to 2520 footprint converters, one for single-stage, and another for dual stage IC's.
The single stage IS FREAKIN AWSOME. I included a trim to tweak out DC offset, and power supply bypass caps. I tried out the OPA604, AD797, and the NE5534. All three had slightly different characteristics, and all sounded great compared to a JH990C. I used a 312 card to test. I'm not 100% about output driving capabilities, but they drove a Cinemag CMOB-2S with about 25' of cable with no problem.
The dual opamp to DOA footprint converter was a continuation of the previous idea spawned from this Burr Brown APP note: http://focus.ti.com/lit/an/sboa031/sboa031.pdf
It uses both gain stages in a dual opamp to double output drive capability. It sounds fantastic, but it becomes unstable at the highest gain settings. :sad: Does anyone with more experience know why? I'd like it to be a drop in replacement for a 2520. The gain settings that the oscillation occurs is so high that you'd never use that setting, but I still want to find out why it's happening and how to fix it.
You can also see in that pic my attempt at a simple DOA. I used the topology of my Sphere M1200 card, and tried to shrink that down into a 2520 footprint. It sounds really good at low gain, but there is not enough headroom for a mic pre (it distorts really bad). I'll have to dedicate some time to this one someday.
and last for now, a noise gate based on the THAT application note, built around the 4301 dynamic processor chip. I just plugged it in today, and it works great, but there is some oscillation associated with the release control I still have to work out.
There are two other projects in the works, but I should probably finnish up these first.
BTW BIG thanks to Olimex, that processed my pcb order even though I was a day past their deadline (they took the whole month of Aug off for vacation). I didn't realize bulgaria was like 10 hours ahead of LA.