simplest EQ and compressor?

[kiira]

[quote author="Viitalahde"]How about the NewYorkDave EQ (which I'm starting next week) ? Could be made to be as complicated or simple you wanted it to be. Two bands would probably do..?

http://www.groupdiy.com/index.php?topic=4107&highlight=nyd+eq[/quote]

That looks nice - I would like to do the three band version. I'm not really sure about the schematic and the parts though. It's all passive? So you would need an input stage and makeup gain. I would like to power everything in this box off of one power supply but that will be hard with the vari-mu since it uses only 100 volts. Most mic pres need 250 to 350 volts.

If you do work on this could you share the design? It would be better than building a Pultec I think.

Kiira

 

[kiira]

[quote author="Viitalahde"]How about the NewYorkDave EQ (which I'm starting next week) ? Could be made to be as complicated or simple you wanted it to be. Two bands would probably do..?

http://www.groupdiy.com/index.php?topic=4107&highlight=nyd+eq[/quote]

That looks nice - I would like to do the three band version. I'm not really sure about the schematic and the parts though. It's all passive? So you would need an input stage and makeup gain. I would like to power everything in this box off of one power supply but that will be hard with the vari-mu since it uses only 100 volts. Most mic pres need 250 to 350 volts.

If you do work on this could you share the design? It would be better than building a Pultec I think.

Kiira

 

[NewYorkDave]

Variations on the theme have been explored but here's the "official" version:

http://electronicdave.myhosting.net/miscimages/passive-eq1.gif

http://electronicdave.myhosting.net/miscimages/passive-eq2b.gif

...and one possible application:

http://electronicdave.myhosting.net/miscimages/passive-eq4.gif

As noted on the schematic, driving impedance must be kept very low. The last illustration shows a stepdown input transformer being used to this end (with the penalty of added insertion loss).

 

[kiira]

ok... I'm sorta beginning to understand. I need inducters. :-(

Can I do this... can I put the eq in between the first and second stage of my mic pre? I'll build something with lots of gain to compensate for the 10db loss. If so, would I still use a 4:1 Xformer in front of the EQ? I have a 4:1 Haufe coming, an a-24.

Kiira

 

[Svart]

How about this, start with a list of things that you HAVE to have on this device, then start a list of things you would LIKE to have on this device. write down all of the different choices of EQ, input, etc.

If you let 20 people on the forum give you ideas, you will have 20 DIFFERENT ideas.. :green: So it's best to decide what you want first then start to work it out!

you could also assemble different schematics and start sourcing some parts from each to see important things like how much and how many ..

just a few ideas because it can get super confusing really quickly!

:thumb:

 

[Bauman]

I'm going to a 3 band EQ, 12 frequences each to cover all the range. Q will be selectable between narrow/broad. 90% sure I want it passive with make up.

:guinness:
Fabio

 

[kiira]

urk... I don't understand what the chart means or anything.

I'll build a Pultec and stick it in between preamp stages and hope it works. The vari-mu will be last. I'll build a tube output so I dont hafta make a circuit board for the op-amps. I'll have to use a 2U box too.

Kiira

 

[NewYorkDave]

A unbuffered tube plate is gonna be pretty unhappy trying to drive a Pultec filter section. Expect low output and massive distortion. :wink:

 

[kiira]

[quote author="NewYorkDave"]A unbuffered tube plate is gonna be pretty unhappy trying to drive a Pultec filter section. Expect low output and massive distortion. :wink:[/quote]

But, but... I like distortion!

Ok.... so even if I use a cathode follower on the first stage the Pultec input will be unhappy? How about if I used a 4:1 transformer in between the output of the cathode follower and the input of the Pultec?

I want to integrate the EQ nto the pre so I don't have to build another make up stage. I m thinking of the suggestion Joe Malone made to put the eq in between the two op amps of the jmr99v ... but I'm just gonna build my own pre instead. I'd love to use a jlm99v but I can't afford it.

Kiira

 

[NewYorkDave]

Basic cathode followers using typical preamp tubes cannot drive 600 ohm loads directly. The Pultec filter presents a load of 600 ohms or less depending on the setting of the controls. A cathode follower driving the Pultec filter through a 4:1 stepdown xfmr would work. But then you're adding 12dB of loss to the ~20dB of loss inherent in the filter section.

I know you want something fancier; but for a tone control to be inserted between tube stages, it's hard to beat the old "James" design and its variants:
http://www.schmarder.com/radios/tech/tone.htm

You might recognize this circuit from Ampeg guitar amps as well as a number of hi-fi amps. Its main virtue for this application, in comparison to a Fender tone control, is that it's approximately flat (relative to 20dB insertion loss) when the pots are at 12 o'clock. The components can be scaled to values of impedance high enough to be driven by a tube plate. In tube circuits, you usually see 500K or 1M pots used.

Fancy EQ is sexy; but if the program material requires more than a little bass or treble lift or cut, it's probably time to move the microphone around instead :wink:

 

[kiira]

[quote author="NewYorkDave"]Basic cathode followers using typical preamp tubes cannot drive 600 ohm loads directly. The Pultec filter presents a load of 600 ohms or less depending on the setting of the controls. A cathode follower driving the Pultec filter through a 4:1 stepdown xfmr would work. But then you're adding 12dB of loss to the ~20dB of loss inherent in the filter section.

I know you want something fancier; but for a tone control to be inserted between tube stages, it's hard to beat the old "James" design and its variants:
http://www.schmarder.com/radios/tech/tone.htm

You might recognize this circuit from Ampeg guitar amps as well as a number of hi-fi amps. Its main virtue for this application, in comparison to a Fender tone control, is that it's approximately flat (relative to 20dB insertion loss) when the pots are at 12 o'clock. The components can be scaled to values of impedance high enough to be driven by a tube plate. In tube circuits, you usually see 500K or 1M pots used.

Fancy EQ is sexy; but if the program material requires more than a little bass or treble lift or cut, it's probably time to move the microphone around instead :wink:[/quote]

Well it's also usefull, in addition to being sexy. I'm a Ampeg fan... I've been using a V4 since 1984. What we need is some eq to help place the guitar in relation to our singer etc. I would really like to try and build something unique and which will be really useful at gigs.

Kiira