What would you choose between Zener and IC regulator for the preamp section and why? I read that zener regulated power supply is unstable, but then, would that make the amplifier feel more "organic" and "touch responsive" compared to the IC regulated one.

My goal is to build an amp with TL072 or TLE2072. The power supply would be +-15-18V. I want it to be as clean as possible, with as low noise as possible, because I will be using it for jazz. So, the greatest concern for me for now is how to regulate the power supply for a maximally clean and quiet preamp, but then again, I don't want a sterile Hi-Fi amp sounding either.

I am thinking about using a choke for the power supply of a TDA7293 amp as a means to filter out all that DC ripple. The amp would be running at +- 32-36 Volts. What would be the specs of the chokes that I need?

Also, can I use chokes for the preamp section, which is built around two TL072 chips, or the ones used in the power amp supply would suffice?

Thank you! One more question, not exactly related to the preamp section of the forum, but yet related to my amp building plans. What do you think of this design?

http://redcircuits.com/Page123.htm

It's really simple, I hope its not too simple. But it's a single supply and  that would suit most the preamps in the previous posts. Also what exactly is the purpose of the bipolar transistor there, and can it be replaced with a fet or mosfet transistor?

After awhile, I am thinking about building a new solid state amp, that would suit my needs. The reason - my beloved tube amp is oh so gentle, and go into rattling snake/tamburine mod after a year or so! So, there are three paths I'm considering:

1. Building the "Blackface" preamp from RED circuits and  making its power supply switchable from 30 to 12 volts.

2. Doing the same thing with ROG's "Umble" preamp.

3. Maybe even doing them both as switchable channels.

My questions:

- What are your opinions on these circuit designs?

-  Can I increase the Umble's power supply, without doing any harm. Also, I read that the circuit is a bit noisy, is there a way to fix that?

Hi! Until now, for my projects I've used mostly pre-designed PCB's. Lately I've been thinking about building some stuff on a perfboard, so my question is - should I pay attention where I lay the parts regarding things like oscillation etc.? Can I just replicate the schematic on the perfboard, for example, on the top I put the +V, on the bottom the ground, on the left side Input and on the far right the Output?

I've put this question in  "Preamps and Effects", but the same goes for other circuits like power amps etc...

Thanks!

Somewhere around 7.5V. Just the amp turned on.  But that was without playing the guitar. Thing happens when I play it.

Here's something that i copied from another forum:

"Zener diode "shares" current with the load; the more is drawn by a load the less goes through zener, and that is one reason for not very stabile voltage regulation with zeners. On the other hand an IC voltage regulator draws from power source a bias current which is almost constant regardless of the load and input voltage and in most cases is negligible."

I'm not that good in science, but maybe it's something about the current, I don't know...However, it's clearly audible.

When searching for a solution for my problem, I found this online calculator something:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/zenereg.html

Do you think its accurate?

Well yeah, I always get confused with that +- V thing   The secondary coils of the transformers are center tapped, and from one end to the center it measures 18 (22)V.

About the preamp, well, let me describe it in few words, coz I don't have the schematic on my hard drive, and I don't have a scanner. It's a preamp that have two TL 072 op amps in it (input stage with the overdrive circuit, buffer, EQ, buffer) and add to that  two more TL072's from the Condor cab sim that I'll build for the Line out section.  In the original schematic says that I should use +-12V for the preamp. However, when experimenting with zener diodes, I found that on a lowered voltage the preamp got really interesting sound, with more harmonics, and kind of touch sensitive(OK, I won't use the buzzword ). I think that that also has to be somehow related with using Zeners instead of IC regulators, since the Zeners aren't quite stable, and that maybe attributes to that compressed sort of squishy sound I guess. Yeah, and the clipping is done with assymetrical diode clipping circuit. So all in all, when I play lightly, it's almost clean, but when I hit harder, it get's overdriven and compressed.

Now, I have this preamp built together with a TDA 2030 chip for the power amp, and it sounds good to my ears, but I'd like to make it louder, a project that intended to do a long time ago, but never really had the time for it before.

About the 15V, together with that underpowered squishy preamp, I'd also like to have the option for more headroom from time to time, so that's why I'd like to go with the optimal maximum voltage according to the TL072 datasheet, since it can be supplied with +-18V tops, if I remember correctly.

Hi! This is not exactly a schematic question, but maybe a question related to a part of schematic, Anyway, I apologize if post the thread on a wrong place.

I need 15V regulated dual supply, and I've decided to go with Zeners instead of IC regulators. So I have two questions:

- what would be the value for the resistors in series with the Zener diodes?
- I'd also like to have switchable 7.5V dual supply; can I use some DPST switch which would switch on and off the 7.5 Zener diodes in parallel with the 15V ones, and also, what would be the resistor value for the 7.5 diodes?

The transformer would be +-22V or +-18V.

Thanks in advance!

Huh, then I won't need those, definitely  I thought that it might have something to do with hum or something...

Thanks guys, you've been a great help!

Thanks for your replies. Actually, I already have built an opamp pre, but wanted to build one more channel for versatility I guess, and I read this stuff that FET transistors act similar to tubes and what not, but then again, I decided to stick with this one channel that I have already, which is built around two TL072 chips, and I actually like how it sounds.

However, reading this topic http://www.ssguitar.com/index.php?topic=1885.0  on the following schematic I saw those two diodes 1n4148 right in the very input, which are connected to the supply:



Could please someone explain  what is the purpose of those diodes, and how would they affect the sound if I put them in my preamp?

Thanks!

Hi! I found this interesting circuit : http://www.redcircuits.com/Page120.htm, which I would like to use as a preamp for a power amp with TDA7294 chip. But the power supply needed for TDA7294 is dual, and for the RED circuit is single. Is there any way to convert the RED circuit into a dual supply, and how?

Well, I have three transformers that are center tapped. One is already in the amp with 2030, its 2x9(18v, 1,7A), then 2x18(36v)- that would be suited for LM3886 eventually, and 2x22(44v) which would go with TDA7294. In this TDA2030 amp that I built I have a 10" speaker in it, so lately I'm  considering just swapping the 2030 for 2050 and removing the two 9V zener diodes that I put in to stabilize the supply to 18V, because after the filters it goes up to 24V, which would do well for the TDA2050 and give me some 25W rms- nice little practice/recording amp. But still curiosity eats me about that TDA2050/BD249-250 combination
Now, for the TDA2050 vs LM3886 thing- I've heard that although 3886 eats 2050 in output power, some think that 2050 sounds a bit better, and I must admit that I really like how this TDA2030 sounds. I had the preamp running another amp, and when I put it with 2030 it really came to life somehow, with well pronounced mids in a certain way, and I' d like that sound, but a bit boosted...

Thanks for the sugestion J M! Actualy, I had the LM3886 planned for another project in which I'd include that FET blackface preamp, and I'm still hesitating between the LM3886 and the TDA7294 for the power amp section. As for the amp mentioned in the first post, here is the schematic for the original version with TDA2030+BD243A/BD244A. The file is of really poor quality so I'll write the values down, starting from left to right:
C1=2,2mF(16V); R1=47kohm; R2=1k8; D1,D2=1N4148; R3=47kohm; C2=47mF(16V); R4=1k8; R5,R6=2,2 ohms; C4, C5 and C6=100nF; C7,C8=22mF(40V), R7=1ohm;C3=220nF, and protection diodes are 1N4001.  Simple circuit, but since I.m not very familiar with designing and what not, I thought I could use a second opinion