Hi Kevin.
Yes, you're right. All ICs - no tube, no tranny's. I myself was also afraid of doing this. :wink: It is well known that tubes and transformers sound good. That seems to be a general fact somehow. And... i learned tubes are sounding better than ICs even if they are overdriven. Tube distortion sounds maybe better than 'IC' distortion made with diodes. But I heard ic/transistors cricuits which sounded much better than bad designed tube preamps. Some manufacturers are putting a tube in their products for the reason they can say.. its tube gear. A mic preamp with an IC for the mic amplification and a tube output stage... don't know if this will produce the sound you want. Although it can sound very good.
I also like the sound or the saturation of transformers. There are transformers out there which are nearly 'unhearable'. But why spending much money for something you can't hear. For input buffering a 20cent IC can work very good. Maybe they need some compensation which makes the IC thing slower but it works good. And why am I doing these pultecs? I can't afford a real one.. or 5 of them. The pultec don't need to have tubes... I'd seen API opamp versions of original pultecs. I think the reason why the pultec was done is to make the filter circuit independent of in and output impedances.
However, I had the chance to compare the IC version with a 'hi end' tube version from a manufacturer who just sells pultec type eqs. There was a difference. But I don't want to spend hundreds of ?s more to make a pultec which can maybe sound like this. And I also wanted to make more than one EQ. I think there is not much difference of making 1 or 5 units.
The costs for one channel... Hmm... hard to tell. I collected the parts over some month and had most of the parts already at home. Take a look at the schematic and you'll see which components are needed. Take a look at the parts-site and you'll know the price for the mechanical parts.
You can make a pultec with tubes and transformers close to the original and you have to pay 700? - or you can do an ic based version for a few ?s.
schematic:
http://www.diygallery.de/DIYsites/eq/Pultecschemo.gif
as PRR mentioned you can also use the 5532 for the gain makeup instead of the BA38x. So you have only one problem... the inductor.
DIY Jedi Steffen has an answer to this also:
:wink:
http://www.diygallery.de/DIYsites/inductor.html
Here is a picture of the inductor. You can also wind this one by hand.