Fully Parametric Tube EQ (with gyrators) - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd April 2013, 06:33 PM   #21
diyAudio Member
 
Join Date: Dec 2009
Nice work on the Sim, Jaz. That program looks a lot more logical. I looked into using a Voltmeter component on LTSpice, but it appears there isn't one! (not like TINA, anyway). When i try to run the sim, it's saying the potentiometers are invalid subcircuits. Oye! Will keep trying...

I did come across that one by Steve Conner - (i did a ton of searches on this before hand) and it looks useful, but a lot of power supply requirements and still using ICs, so I kept on looking.

I am confused a bit, were they not using fully-parametric EQ's in the studio back in the tube days? Cause I haven't found hardly anything along these lines in terms of schematics.

Hey Ian - glad to see you on here, I've been following your tube mixer project with the fella in Italy and also read thru your site, too. Impressive!!
  Reply With Quote
Old 22nd April 2013, 06:58 PM   #22
diyAudio Member
 
Join Date: Dec 2009
Just downloaded demo of TINA and am going to give it a go.

By the way, Jaz: Does the wiper of P3 (the .25M and .5M pots for bass freq) not need to go to ground?
  Reply With Quote
Old 22nd April 2013, 08:10 PM   #23
diyAudio Member
 
ruffrecords's Avatar
 
Join Date: Jun 2007
Location: Holt, Norfolk
Quote:
Originally Posted by Gonecat View Post

Hey Ian - glad to see you on here, I've been following your tube mixer project with the fella in Italy and also read thru your site, too. Impressive!!
Thanks for the kind words. I have not heard from the guy in Italy for quite some time so I don't know if he ever finished his mixer.

Cheers

Ian
  Reply With Quote
Old 22nd April 2013, 08:34 PM   #24
diyAudio Member
 
Join Date: Dec 2009
Super cool project, though. Kudos to him for trying and you for helping! Hope it finishes up with some pix an sounds...
  Reply With Quote
Old 22nd April 2013, 11:05 PM   #25
diyAudio Member
 
jazbo8's Avatar
 
Join Date: Jan 2011
Location: In Transient
Quote:
Originally Posted by Gonecat View Post
Just downloaded demo of TINA and am going to give it a go.

By the way, Jaz: Does the wiper of P3 (the .25M and .5M pots for bass freq) not need to go to ground?
Both sections of the LF frequency pot are connected to ground... Anyway, I think this particular design is not what we would call a parametric equalizer, it is more like a HF/LF shelving equalizer with adjustable corners and Q's.

As pointed out in the MEF thread, the tube-based studio parametric equalizers were just passive equalizer sections with tube buffers, while a gyrator is an ACTIVE device, i.e., it uses the gain of some type of active stage and capacitor to simulate the inductor.

Jaz
  Reply With Quote
Old 22nd April 2013, 11:29 PM   #26
diyAudio Member
 
Join Date: Dec 2009
Thanks for summing that up, Jaz. Before I swallow the sadness of this down, I was wondering if you would mind posting a few other response curves - just to kind of show off the range of what this thing will actually do in its present form. (I built this in TINA but it says the Demo won't allow me to run such a large schematic!)

I once built a BPF with a pentode and at first i thought it was useless, then i tried it on a drum buss and it was incredibly cool, so it's not to say i won't build this thing anyway (just as a color on the palette), but would be great to get an idea of how versatile / non-versatile it is in advance.
  Reply With Quote
Old 23rd April 2013, 02:07 AM   #27
diyAudio Member
 
jazbo8's Avatar
 
Join Date: Jan 2011
Location: In Transient
Quote:
Originally Posted by Gonecat View Post
Thanks for summing that up, Jaz. Before I swallow the sadness of this down, I was wondering if you would mind posting a few other response curves - just to kind of show off the range of what this thing will actually do in its present form. (I built this in TINA but it says the Demo won't allow me to run such a large schematic!)

I once built a BPF with a pentode and at first i thought it was useless, then i tried it on a drum buss and it was incredibly cool, so it's not to say i won't build this thing anyway (just as a color on the palette), but would be great to get an idea of how versatile / non-versatile it is in advance.
Click the image to open in full size.
HPF and LPF Corner Frequencies

Here are some more plots for your reference, I also connect the middle pin to ground on the HF frequency pots (missed it earlier, sorry about that). Anyway, you can see the responses are just peaks, you can't get dips (not as currently configured). If you are still interested in the idea of a tube buffered parametric EQ, here is one for you to try, you can have as many sections as you want, by adding more gyrators in parallel. As mentioned earlier, all this could be done much easier with ICs/FETs

Click the image to open in full size.

Jaz
  Reply With Quote
Old 23rd April 2013, 02:43 AM   #28
diyAudio Member
 
Join Date: Dec 2009
Thanks Jaz. So i don't see much 'range' in those two, is this thing really that limited?

On that hybrid you posted, i only see one pot (boost/gain i guess?). Any ideas on adding Q and frequency?

I am fine with doing a hybrid, especially what i am hearing about doing it with tubes. Just looking for fully parametric (with the tube gain part if possible!)
  Reply With Quote
Old 23rd April 2013, 03:09 AM   #29
diyAudio Member
 
jazbo8's Avatar
 
Join Date: Jan 2011
Location: In Transient
Yup, not much range at all and no cut only boost... wonder what it was designed for?
Sorry about the schematic, R3 (Q) and R5 (Freq) are suppose to be pots not resistors, you should be able to sim this in LTSpice or TINA. As currently configured, you got about 33dB of gain when in the "flat" position, which might be a tad too much already (anyway you can always add another pot either at the input or output to set the overall gain).

Jaz
  Reply With Quote
Old 23rd April 2013, 07:04 PM   #30
diyAudio Member
 
Join Date: Dec 2009
Thanks for the post, Jaz.

So would r3's wiper go to r2? and would r5 be wired as a rheostat or..?

I wonder if another tube might be good for reducing that high gain a bit, maybe a 12au7 or something.

Did you find this schematic online or did you create it? Looks like a great option.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Parametric EQ project ianmgreen Construction Tips 12 2nd April 2011 11:21 PM
How to calculate capacitor values for fully parametric EQ? diymixer Analog Line Level 2 20th November 2010 09:03 PM
Tube Parametric EQ - Idea looking for clarification joelap Tubes / Valves 2 9th October 2010 07:12 PM
Modifying 4-band semi-parametric to fully parametric with shelving? diymixer Construction Tips 3 5th July 2010 06:38 AM
semi parametric eq reap461 Parts 5 4th December 2008 08:56 PM


New To Site? Need Help?

All times are GMT. The time now is 11:46 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2