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Let's talk mixer EQ - specifically improving the EQ in mine
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Regebro



Joined: Sep 12, 2004
Posts: 60

PostPosted: Mon Oct 05, 2020 2:37 am    Post subject:  Let's talk mixer EQ - specifically improving the EQ in mine Reply with quote  Mark this post and the followings unread

I want some ideas and inputs on what makes a good EQ, because I don't know. It is just the frequencies and Q that does it? How does a good EQ look, really? Are there any EQ circuits out there that are Real Good but doesn't use tubes or millions of parts?

Explanation:

I have a Tascam M-2524, and the M-2500 series EQ usually gets comments from "It has an EQ" to "It zuuuuuuckkkz", and since I have very little experience with mixers that has more than "bass" and "treble", I didn't have much opinion of my own on the topic.

However, I do feel that it's not super-useful, and when seeing videos of real classic high end classic vintage mega EQs, I kinda get it. It seems that with something like a Pultec, it doesn't matter what you do, it just magically sounds better.

So I mentioned to a friend that I might sell the Tascam and get something else, I don't like mixing in the computer, and he just "You can find somebody that can mod the mixer and make it better!" and that's an intriguing idea. Can I?

If all that's needed to make it better is changing the frequencies or Q values, then heck yeah, I just need to find an example of a good three-band EQ and mod the tascam to have similar values. But if I need to replace the whole EQ circuitry, then obviously, that's not doable.

Opinions, insights and information, please!
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Airlock



Joined: Apr 06, 2007
Posts: 258
Location: Calabash, NC USA
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PostPosted: Sat Oct 10, 2020 4:05 pm    Post subject: Reply with quote  Mark this post and the followings unread

OPINION: Not worth the trouble or expense.
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Regebro



Joined: Sep 12, 2004
Posts: 60

PostPosted: Sat Nov 07, 2020 1:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

Maybe not. Let me hear your opinion. Listen to these quick and shitty tests for example:

https://soundcloud.com/regebro/mixer-eq-mod-version-3-vocals
https://soundcloud.com/regebro/mixer-test-eq-v3-cheap-techno

I like the modded EQ better. It seems to me I can make things sound better with it. And this is with crap caps I had lying around, and supposedly better capacitors can also make a difference. We'll see.

Turns out the expense isn't too bad. Parts are costing around $150, and that's high quality parts for 24 channels and changing a LOT of caps. Trouble though? Maybe not. There's going to be a LOT of soldering. Smile

It would also have been a lot more trouble if not Calibrio on gearslutz would have been kind enough to do the designing for me. I don't know much about filter design at all.

Full thread: https://www.gearslutz.com/board/geekslutz-forum/1328083-could-i-improve-eq-my-mixer.html
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Airlock



Joined: Apr 06, 2007
Posts: 258
Location: Calabash, NC USA
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PostPosted: Sat Nov 07, 2020 3:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

I guess it all comes down to application: do you really need a 24 channel mixer w/EQ? The 8 busses is nice in post, but unless you are tracking a live band most people don't need that many channels. That's was a nice mixer in '90s, if it all still works I'd leave it alone and use a plug-in EQ in the DAW.
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Regebro



Joined: Sep 12, 2004
Posts: 60

PostPosted: Tue Nov 10, 2020 4:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Airlock wrote:
I guess it all comes down to application: do you really need a 24 channel mixer w/EQ? The 8 busses is nice in post, but unless you are tracking a live band most people don't need that many channels. That's was a nice mixer in '90s, if it all still works I'd leave it alone and use a plug-in EQ in the DAW.


I don't like mixing in the DAW one little bit. So yeah, a 24 channel mixer with a nice EQ is going to be great. I just ordered a a Cymatic 24 in/out interface to go with it.
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dk



Joined: Feb 12, 2019
Posts: 108
Location: Europe

PostPosted: Wed Nov 11, 2020 8:18 am    Post subject: Reply with quote  Mark this post and the followings unread

Another opinion: not worth the expense.

For the $300 you paid to buy it + $150 you'll spend on mods, you could probably already buy something better. Toss in the amount of time you spend working on it instead of making music (if that matters), you can definitely find something better. Even with the mod you'll end up with something that's at best mediocre, as even a newer Mackie, Behringer... pretty much anything newer will match or outpace it. And we won't even get into the magical "N" word (Neve) that you keep mentioning on Gearslutz, which is desirable pretty much only for tracking and for the sounds of its amplifiers and inductors, not it's EQ curves (which is a bit too limited for mixing).

Of course, if you're going for it just for fun, knock yourself out Smile

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Regebro



Joined: Sep 12, 2004
Posts: 60

PostPosted: Wed Nov 11, 2020 1:31 pm    Post subject: Reply with quote  Mark this post and the followings unread

dk wrote:
Another opinion: not worth the expense.

For the $300 you paid to buy it + $150 you'll spend on mods, you could probably already buy something better.

Well, certainly I don't suggest people buy a Tascam M-2524 in order to mod them.

And the expense for me still is $150. Sure, if I bought something else I could sell the Tascam, but just packing it for shipping would be similar amount of work to modding it. Smile

But to be honest, I doubt I could get anything much better in any case, I took a look at eBay now, and only thing I found that would be better was an Allen & Heath ZED 428 for £700. For $450, at least in Europe, the best you can find are what looks like heavily toured Mackie SR24's...
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L´Andratté



Joined: Sep 23, 2012
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Location: Hamburg, Germany
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PostPosted: Thu Nov 12, 2020 5:22 am    Post subject: Reply with quote  Mark this post and the followings unread

I would prefer older Soundcraft over Tascam anyday, always liked EQ---
https://www.ebay.de/itm/Soundcraft-Spirit-Studio/184519185693?hash=item2af633551d:g:czwAAOSwTSdfeblM

Do you need mic pres? Do you need 24 channels?

Another option- the Tascam has inserts? So instead of modding you could build a box of a couple of cool outboard EQs, it has not to be complicated, a quad opamp, 4 lin pots two dual rev.log. (can be found easily here and now) and a couple of resistors, caps, build 8 channels, power it with 2 9V NiMH batteries until you have something better working bom

PS:friggin ebay found something really tasty (for me) no money though Confused
https://www.ebay.de/itm/Soundcraft-LM1-Broadcast-Vintage-Mischpult-1-spare-Canal-f-Filmton-12-kanal/224226487421?hash=item3434f0ac7d:g:WSwAAOSwaAdfp8fX


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dk



Joined: Feb 12, 2019
Posts: 108
Location: Europe

PostPosted: Thu Nov 12, 2020 7:39 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
But to be honest, I doubt I could get anything much better in any case, I took a look at eBay now, and only thing I found that would be better was an Allen & Heath ZED 428 for £700.


Sure, but then you'd have your conversion as well. I'm guessing the Tascam + the convertors you just ordered will end up costing roughly the same?

Mackie VLZ1604's go for about $300 used in Europe, and pretty much anything in the VLZ series will compare very favorably to the Tascam, both in sound and in maintenance. Again, if you're after the fun in modding it, enjoy, but sonically it's not even going to beat out newer 'budget' desks unless you completely rip out the insides and put something else in there.

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Regebro



Joined: Sep 12, 2004
Posts: 60

PostPosted: Wed Nov 18, 2020 4:55 am    Post subject: Reply with quote  Mark this post and the followings unread

dk wrote:
Quote:
But to be honest, I doubt I could get anything much better in any case, I took a look at eBay now, and only thing I found that would be better was an Allen & Heath ZED 428 for £700.


Sure, but then you'd have your conversion as well. I'm guessing the Tascam + the convertors you just ordered will end up costing roughly the same?


No. I already own the Tascam, and as mentioned, the parts for the conversion is about $150. And I bought extra fancy "audiophile" capacitors, and change everything in the signal path, which I'm not sure makes a difference, I haven't checked yet (I will), and if you don't do that the components will probably just be $50 or so.

Now, I ended up actually making circuit boards for it, which cost me another $40. But it's still cheaper. The cost is definitely not the issue here, this solution WILL get me the most bang for the money, if I don't include the work.

Quote:
Mackie VLZ1604's go for about $300 used in Europe, and pretty much anything in the VLZ series will compare very favorably to the Tascam, both in sound and in maintenance.


?!? Maintenance on this thing is zero. I fixed some broken pots that broke in transport, and I cleaned the contacts with contact cleaner. Other than that I've had it for 15 years+ with absolutely no issues. It's built like a tank.

A VLZ1604 has only 16 channels. The EQ can also only sweep the mids, which might still make them better than the default EQ on the M2500, but certainly not better than my improved ones.

Quote:
Again, if you're after the fun in modding it, enjoy


It is fun, which is why I'm not counting the work. Smile

Quote:
but sonically it's not even going to beat out newer 'budget' desks unless you completely rip out the insides and put something else in there.


Sorry, but you are wrong. There's nothing in this desk that destroys the sound, which you seem to think. The preamps are lovely and it has a lot of features.

Seriously, the only drawback with it is that the EQ isn't that great. Otherwise it's a really good desk.

Now I don't need the 8 busses. And the tape inputs only save me one patch bay, so no big deal. I don't think I ever used all four sends, only three. But a Mackie 1604 doesn't even remotely cut it.

Last edited by Regebro on Mon Dec 07, 2020 11:48 pm; edited 1 time in total
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Regebro



Joined: Sep 12, 2004
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PostPosted: Wed Nov 18, 2020 5:05 am    Post subject: Reply with quote  Mark this post and the followings unread

L´Andratté wrote:
I would prefer older Soundcraft over Tascam anyday, always liked EQ---


Yeah, I believe you there. But that was completely out of my budget when I bought the Tascam.

Quote:
Do you need mic pres?


Well, not 24 of them. Smile That is a bit overkill.

Quote:
Do you need 24 channels?


Yes. 20 might do.

Quote:
Another option- the Tascam has inserts? So instead of modding you could build a box of a couple of cool outboard EQs


That's an interesting idea. It would be very awkward to work with, having the EQ somewhere which isn't the mixer, but yeah, it would work.

Quote:
PS:friggin ebay found something really tasty (for me) no money though Confused
https://www.ebay.de/itm/Soundcraft-LM1-Broadcast-Vintage-Mischpult-1-spare-Canal-f-Filmton-12-kanal/224226487421?hash=item3434f0ac7d:g:WSwAAOSwaAdfp8fX


Cute!
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Ricko



Joined: Dec 25, 2007
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Location: Sydney, Australia
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PostPosted: Sun Mar 07, 2021 10:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

I read there are three relative weak spots for thst TASCAM mixer.

1. EQs are too sharp
2. Crosstalk
3. Noise

The first may be improved by different resistors. If you gave the skills, look at the schematic, figure out what kind of EQ cuicuit it is, find an online calculator fir that circuit, then substitute resistors for less resonance.


The second is not easy to say.

The third, I would replace all the NJR4565 dual opamps with (sockets and) less noisy chips. Start in the ouput stage. It seems a 5332 would substitute OK. Thus would also change distortion and clarity.

Regarding re-capping, It is a good thing to do. But it wont give much effect while these middling op-amps are in use.

For cost, it is vital to shop around: you may find thst, say, buying 30 or 50 chips in bulk can be much cheaper than buying 10 from the wrong place.
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Regebro



Joined: Sep 12, 2004
Posts: 60

PostPosted: Tue May 04, 2021 3:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Ricko wrote:
I read there are three relative weak spots for thst TASCAM mixer.

1. EQs are too sharp
2. Crosstalk
3. Noise


I haven't had a problem with crosstalk, but then again, I don't have a completely different song playing in some channels, so I don't know how that would ever get to be a problem, to be honest. Smile

I don't find it noisy either, but one thing that should be noticed is that it basically operates with 25dB of headroom. I'm not sure why, maybe that's so that you can max out the EQ boost of both the high bass and the low mids at the same time without clipping or something? But the EQ goes to +15dB, and the nominal input is -10dB, but the headroom is +15dB!

I didn't realize this myself until I read the manual after realizing that the audio interface I bought has a nominal max output of +20dB and I was grasping for solutions to interface with my -10dB mixer. Smile So, turns out it's actually +15dB, giving your 25dB less noise if you know that, and start actually trusting the OL indicators (and your ears).

But yes, I did not like the EQ's, hence this thread.

Quote:
The first may be improved by different resistors. If you gave the skills, look at the schematic, figure out what kind of EQ cuicuit it is, find an online calculator fir that circuit, then substitute resistors for less resonance.


Yes, Cabirio on gearspace helped me with this, and I actually spent this winter implementing it, while also reorganizing the whole "studio".

Quote:
The third, I would replace all the NJR4565 dual opamps with (sockets and) less noisy chips. Start in the ouput stage. It seems a 5332 would substitute OK. Thus would also change distortion and clarity.


I think it's maybe possible to lower the noise that way, but again, all the noticeable noise always come from other equipment, not the mixer, so... I believe the somewhat mellow sound is due to the input stage, and I actually like it. I think the preamps sound great, warm but still bright. Maybe the THD could be improved, but I doubt it, these opamps are pretty linear. And when they clip it's immediately obvious, the clipping is super-hard, almost digital in nature.

Quote:
Regarding re-capping, It is a good thing to do. But it wont give much effect while these middling op-amps are in use.


It didn't, and it likely won't even with other opamps. The THD actually lowered, but I tested plenty of different combination of caps, and there was no difference between the combinations. The difference happened with the new EQ implementation, even with old caps. It seems it just has lower THD for some reason I don't understand.
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Regebro



Joined: Sep 12, 2004
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PostPosted: Tue May 04, 2021 3:44 am    Post subject: Reply with quote  Mark this post and the followings unread

So, final update and conclusion.

Was it worth it? For me, yes. For others? No. Because for me the cost was just a bunch of new caps, resistors, and a few small circuit boards I made. And most of the caps you can skip, the recapping made no difference.

Was it worth all the WORK though? From a commercial perspective, absolutely not, this probably took at least a 100 hours of work. But I enjoyed it, and I learned a lot.

Was the end result better? Oh heck yeah. I find the new EQ (designed by Cabirio on gearspace to have curves a more like a Neve) a lot more musical and easy to use.

I took a song I struggled to mix for days 7 years ago, and remixed it. I got to a place where I felt I wouldn't be able to improve it after a few hours.

See what you think.

* Old mix: https://soundcloud.com/regebro/a-northern-shore-desert
* New mix: https://soundcloud.com/regebro/desert-lullaby-2021

The only difference in gear here is that I have an old budget reverb a dbx 290, that I actually really love on acoustic guitar. The new mix is a complete remix from scratch without caring about the old one at all, so differences is not just EQ, but it just felt better, and I think it sounds better too.


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I made a plaque so nobody thinks it's a standard M2524 if I die. :-)
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Blue Hell
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Joined: Apr 03, 2004
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PostPosted: Tue May 04, 2021 5:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Regebro wrote:
[...]it just felt better, and I think it sounds better too.


I agree, can hear details better .. on the original one the voice being in one ear almost was a bit odd to me .. it being more centered and with a nice reverb sounds better .. it removes some character from the voice as well though, not sure if that is good or bad ..

It is a nice song!

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also .. could someone please turn down the thermostat a bit.
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Regebro



Joined: Sep 12, 2004
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PostPosted: Tue May 04, 2021 6:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks!
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Ricko



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PostPosted: Tue May 04, 2021 10:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

Yes, much clearer?

Do you have a schematic or url for the eq boards?
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Regebro



Joined: Sep 12, 2004
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PostPosted: Thu May 06, 2021 10:54 am    Post subject: Reply with quote  Mark this post and the followings unread

I'll attach the final schematic. The full thread is here:

https://gearspace.com/board/geekzone/1328083-could-i-improve-eq-my-mixer.html


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