Luny Tune
Well-known member
It's been discussed many times and I don't have very much new to add. However, I dabbled with cap values and thought a lot about what I wanted and which values would give me that. I'd just like to share with the community that brought me so much. I owe a debt of gratitude to Jakob Erland for providing the projects and for kindly letting me benefit from his knowledge and experience when advising me on these things.
Here's what I did:
I needed a stereo eq before my GSSL on the 2-buss. I had just fitted the GSSL with a couple of OEP trannies in the output which resulted in a killer mixbuss comp but I still needed an eq as well.
I think it was NY Dave who had already shared a design for a passive eq and I was also advised to build a passive eq as that would be perfect for that specific application. I found out that the eq filter on the Pulec EQP1A was completely separate in the schematic and with a little help I found out that I could easily make it a stereo eq and actually add functionality by using 2x6 switches and split the Low Frequency selector in two so I have Low Boost and Low Cut separated. Rather cool for 2-buss application, actually!
I built it in with the GSSL because it was perfect since the GSSL has (before the latest revision!) a very sensitive threshold and plenty of gain. That matches the passive eq brilliantly because the eq drops the level by 21 dB. The GSSL appears to have a less sensitive threshold and the gain makeup takes care of the loss of level.
I should say that I haven't found the best way to handle the bypass function but I may never get around to that because it actually works fine for me as it is. If someone would like to built this thing they might like to handle the bypass issue somehow. An idea could be to use a hafty switch of some kind and let it short the 4 points necessary in the eq section and the point in the GSSL simultaneously. Refer to the Pultec schematic.
Here's how it ended up looking outside and inside:
...and the mess inside. I was kinda prototyping the thing so it's pretty messy. But it works and sounds great!
The below schematic is just an edit of the schematic for the Pultec project. (Click for larger picture!)
Here's how the chosen cap values work for me.
Lo Cut:20-25-30-40-60-80 Hz
Lo Boost: 30-40-60-80-100-240 Hz
Hi Boost: 1-3-7-10-12-18 KHz
Hi Cut: 5-7-10-12-18-20 KHz
Now, the values may not correspond exactly with the desired frequencies but as far as I can hear it's pretty close. At least close enough! The eq is pretty "wide" and since I removed the coils to make the Hi Boost shelf instead of bell curve it's even "wider" than the Pultec...
The eq is not as silky smooth as the Pultec project because the tube and the rest of the gain stage is not there, but instead it's really crispy and every single customer I've had has commented on how crisp and tight my mixes and/or masters are. I contribute this to the nature of the eq as well as to the GSSL and the Lundahl trannies in the input and the OEPs in the output of course. The crispyness is very much thanks to the eq, though...
What I aimed for and what I got exactly without having to change anything afterwards was that for the Hi Boost the 18 KHz gives the very airy high end without really affecting the material. The 12 KHz also affects shakers, overheads, hihat, line bells and sources like that. The 10 KHz reaches down and grabs the vocal's s'es and f's and the general top of the vocals. 7 KHz starts to affect the top in guitars and other mid range oriented instruments. 3 and 1 KHz can really open up a dull mix if they really lack hi mids and hi end.
It's EXACTLY what I was looking for and anyone who needs something like this should just do it! Almost everything with regard to the eq filter is mounted on the switches. Easy! And GREAT sounding! :razz:
Here's what I did:
I needed a stereo eq before my GSSL on the 2-buss. I had just fitted the GSSL with a couple of OEP trannies in the output which resulted in a killer mixbuss comp but I still needed an eq as well.
I think it was NY Dave who had already shared a design for a passive eq and I was also advised to build a passive eq as that would be perfect for that specific application. I found out that the eq filter on the Pulec EQP1A was completely separate in the schematic and with a little help I found out that I could easily make it a stereo eq and actually add functionality by using 2x6 switches and split the Low Frequency selector in two so I have Low Boost and Low Cut separated. Rather cool for 2-buss application, actually!
I built it in with the GSSL because it was perfect since the GSSL has (before the latest revision!) a very sensitive threshold and plenty of gain. That matches the passive eq brilliantly because the eq drops the level by 21 dB. The GSSL appears to have a less sensitive threshold and the gain makeup takes care of the loss of level.
I should say that I haven't found the best way to handle the bypass function but I may never get around to that because it actually works fine for me as it is. If someone would like to built this thing they might like to handle the bypass issue somehow. An idea could be to use a hafty switch of some kind and let it short the 4 points necessary in the eq section and the point in the GSSL simultaneously. Refer to the Pultec schematic.
Here's how it ended up looking outside and inside:
...and the mess inside. I was kinda prototyping the thing so it's pretty messy. But it works and sounds great!
The below schematic is just an edit of the schematic for the Pultec project. (Click for larger picture!)
Here's how the chosen cap values work for me.
Lo Cut:20-25-30-40-60-80 Hz
Lo Boost: 30-40-60-80-100-240 Hz
Hi Boost: 1-3-7-10-12-18 KHz
Hi Cut: 5-7-10-12-18-20 KHz
Now, the values may not correspond exactly with the desired frequencies but as far as I can hear it's pretty close. At least close enough! The eq is pretty "wide" and since I removed the coils to make the Hi Boost shelf instead of bell curve it's even "wider" than the Pultec...
The eq is not as silky smooth as the Pultec project because the tube and the rest of the gain stage is not there, but instead it's really crispy and every single customer I've had has commented on how crisp and tight my mixes and/or masters are. I contribute this to the nature of the eq as well as to the GSSL and the Lundahl trannies in the input and the OEPs in the output of course. The crispyness is very much thanks to the eq, though...
What I aimed for and what I got exactly without having to change anything afterwards was that for the Hi Boost the 18 KHz gives the very airy high end without really affecting the material. The 12 KHz also affects shakers, overheads, hihat, line bells and sources like that. The 10 KHz reaches down and grabs the vocal's s'es and f's and the general top of the vocals. 7 KHz starts to affect the top in guitars and other mid range oriented instruments. 3 and 1 KHz can really open up a dull mix if they really lack hi mids and hi end.
It's EXACTLY what I was looking for and anyone who needs something like this should just do it! Almost everything with regard to the eq filter is mounted on the switches. Easy! And GREAT sounding! :razz:
