Transistor equivalent

[Nikolai Petrenko]

Dross float in the surface must be removed before pour into mould. I realize that clay powder is much better than mix of sand and plaster.
My main switch is screw type. Add binding posts for sub board in the right (rear view)?
How can I mounts jacks, bin. posts in the heatsink has "positive fins"?
Unlike older post has "negative fins" is easy to mount but distance between 2 fins must large enough for switch, jacks, posts's body.

 

[spec]

Dross float in the surface must be removed before pour into mould. I realize that clay powder is much better than mix of sand and plaster.

Are you now happy to do the back panel mould?

My main switch is screw type.

You can use any components that you like, as long as they meet the required specification. One of the main features of the case design is that it allows maximum flexibility and user choice. It also maximises accessability- you can get at all the electronics, especially the amp boards without disassembly. This is one big advantage I can tell you. I have even used the case design philosophy to house test equipment. When the main chassis is completed a top panel can be fitted to round off the amp nicely. I will tell you how, but if you would like to know now just post. The finished amp will impress your audiophile friends.

Add binding posts for sub board in the right (rear view)?

No understand - do you mean you would like me to post a new rear sub panel with the bass sub binding posts shown?

How can I mounts jacks, bin. posts in the heatsink has "positive fins"?
Unlike older post has "negative fins" is easy to mount but distance between 2 fins must large enough for switch, jacks, posts's body.

Machine, drill holes, file etc, as necessary in heatsink to give space for components mounted on rear sub panel- it won't affect the cooling significantly. The rear sub panel is best made of sheet ally but sheet steel would be OK too.

 

[Nikolai Petrenko]

No understand - do you mean you would like me to post a new rear sub panel with the bass sub binding posts shown?

Yes. I also want new front panel. In the front panel I have 5 potentiometers:
+) Master volume control
+) Balance control for right
+) Balance control for left
+) Subwoofer balance control
+) Subwoofer frequencies cut off control (too much???)
I like all LED indicators are blue (not colorful) and light for pot. knobs (like power button in computer case), I think it will make the amp cooler .
Ah, I want to know: is able to convert stereo to quadraphonic? Quad. make better 3D sound effect than stereo.

 

[audioguru]

A balance control for left-right is simply one control, not two controls.
A subwoofer balance control is simply a volume control for it since a balance control must adjust the mains channels plus the subwoofer channel requiring 3 controls.
You do not need a subwoofer frequencies cutoff control (and the opposite frequencies cutoff controls for the main channels) unless you replace the speakers very often. Instead you look at the speaker spec's and select one crossover frequency for the main channels and subwoofer channel.

Quadraphonic or fake quadraphonic? In the "good old days" more than 42 years ago I bought vinyl records recorded with the SQ method quadraphonics and made an SQ quadraphonic decoder with Motorola ICs. It worked well but the records were available only for a couple of years. Of course it needs additional amplifiers and speakers.
My SQ decoder makes an effective type of fake quadraphonics from normal stereo because it has active level attenuators and enhancers. A similar type of fake quadraphonics without active effects is by using the Hafler method which is done by connecting the two rear speakers in series and between the front live speaker wires. The front amplifiers can easily drive the added rear series speakers and the added speakers play the ambience (the difference between the front channels) of the recording space. I use the Hafler method with my TV.

 

[mvs sarma]

An old RED LED is 1.2V
An IR LED is 0.8V threshold
Silicon LED 0.5 to 0.6
Schottky diode 0.1V is best bet, Typical examples are the 1N5711 or BAT41.

SEMTECH makes two types of diodes .
1N60A and 1N60P
the datasheet reads that one type is germanium diode.
1N34A are available on ebay and the O P could get them .
same time he could perhaps try out 1N5711 schottky diodes.

 

[mvs sarma]

An old RED LED is 1.2V
An IR LED is 0.8V threshold
Silicon LED 0.5 to 0.6
Schottky diode 0.1V is best bet, Typical examples are the 1N5711 or BAT41.

**broken link removed** this supplie offers 10lot at 2.5

of course i dont have any links with his business.

 

[spec]

Yes. I also want new front panel. In the front panel I have 5 potentiometers:
( 1) Master volume control
( 2) Balance control for right
( 3) Balance control for left
( 4) Subwoofer balance control
( 5) Subwoofer frequencies cut off control (too much???)
(6) I like all LED indicators are blue (not colorful)
(7) light for pot. knobs (like power button in computer case)
(8) Ah, I want to know: is able to convert stereo to quadraphonic? Quad. make better 3D sound effect than stereo.

(1) done in pre amp
(2)&(3) single balance control in preamp
(4) preset pot on sub amp board
(5) adjusted by changing components
(6) any colour LED you like- blue is fine
(7) never seen an illuminated knob
(8) yes as AG says, a chip can do, but in pre amp

In general this is a power amp, a separate preamp is really required for the functions that you list. The phone amp should really go in that too.

 

[audioguru]

I think since the bass and treble are normal controls then the subwoofer volume control should also be a normal control and not a preset. It will get its signal from the normal volume control. Then you can control the amount of low frequencies depending on the program.
The Motorola quadraphonic decoder ICs were discontinued many years ago. I do not know if there is a fake quadraphonic IC made anymore.

 

[spec]

I think since the bass and treble are normal controls then the subwoofer volume control should also be a normal control and not a preset. It will get its signal from the normal volume control. Then you can control the amount of low frequencies depending on the program.

Good call. My use of a sub would be to set it for the equipment/room and then job done, but I can see that some people might like to adjust the low bass- me when I was younger perhaps. The problem is that pots generate distortion, unless you go for a really expensive type. They also mess up the impedance loading and xtalk. By far the best balance control is the dual concentric type which have friction betwen the two knobs. This elliminates any extra pots from the circuit- but the cost is high. You can do a mechanical coupling between two independent pots though. Be an intresting project for ETO. I have never done it, but have seen it done by a chap who was into model making etc.

The Motorola quadraphonic decoder ICs were discontinued many years ago. I do not know if there is a fake quadraphonic IC made anymore.

Oh dear, didn't know that- isn't quadphonic yesterdays news anyway?

On a general point about this project: the simpler it can be made the more chance of success. The case/chasis has been designed for flexibility so bits can be added later but a separate preamp seems to be the best way for any extra functions, including phone amp. The extra circuitry will require +- stabilised supplies, screening and god knows what to get a decent sound, so it introduces a high risk. The complexity also means that the project will never be built or completed. That is my experience with building audio amps. Where I worked about 100 people started building amps etc over the years, but very few were completed/used. Most of the amps that were built didn't sound that good either- the main problem was earth loops and frequency instability. On one popular kit of parts for an amp I had to completely redo the, PSU, Ov references, screening and transformer screening to get a half decent amp.

Do you have the term 'specification creep' in Canada?

 

[audioguru]

Have you tried the Hafler pseudo quadrophonic system with an ordinary stereo? Simply connect one rear speaker or two rear speakers that are in series to the hot stereo speaker terminals. It provides noticeable ambiance to music.
I like it when spec's creep upwards (get better) not downwards (get worse). The spec's for my local TV stations will creep up soon when they begin broadcasting 4K ultra-high-definition.

 

[spec]

Have you tried the Hafler pseudo quadrophonic system with an ordinary stereo? Simply connect one rear speaker or two rear speakers that are in series to the hot stereo speaker terminals. It provides noticeable ambiance to music.

I vaguely remember hearing stuff like that at a seminar. interesting that it is so simple to do. I have never been too taken with quad.

I like it when spec's creep upwards (get better) not downwards (get worse). The spec's for my local TV stations will creep up soon when they begin broadcasting 4K ultra-high-definition.

I know what you mean but spec creep on a project means a harder and longer job and the engineer normally carries the can. There is never any mention of spec creep when the bean counters get involved.

We had one manager who was a nightmare: whenever we had a meeting with the customer he would gratuitously offer them all sorts of extraordinary things and then leave us to sort the mess. One time he offered the navy a mouse instead of a roll ball- can you imagine a mouse with the ship rolling around in the swell or under gunfire.

 

[spec]

looks like someone is making quad chips: https://www.aliexpress.com/item/New...ssor-original-special-YTYKDZ/32468943593.html

 

[audioguru]

The datasheet for the quad chip says in addition to being an active crossover with pushbutton volume control it can produce "3D effects" but does not say what the effects do. It does not have rear outputs, it has only left satellite, right satellite and subwoofer outputs to feed 3 amplifiers. Maybe it makes ECHOESssss (good grief!).

 

[spec]

Ahh, right. I hadn't checked. Just a quick post before hitting the hay.

 

[Nikolai Petrenko]

Let forget quadraphonic. I have thought carefully.
After what you said I decide to remove frequencies cut-off control pot. because it rarely in use and make more chance the sub hum because long wire. But still 2 pot. for R-L balance control because of many subjective reasons (some of them seem be too ridiculous but they are what I want). Bass volume is necessary because some songs have too heavy bass.

 

[spec]

Let forget quadraphonic. I have thought carefully.
After what you said I decide to remove frequencies cut-off control pot. because it rarely in use and make more chance the sub hum because long wire. But still 2 pot. for R-L balance control because of many subjective reasons (some of them seem be too ridiculous but they are what I want). Bass volume is necessary because some songs have too heavy bass.

Hi Nicolai,

You probably think I am overcautious and a kill joy; that is exactly what I thought when people told me things about my grand ideas. I didn't listen. Of couse you never do when you are young. The result nothing worked and nothing got finished. My first project was an analogue multimeter. It had the best movement available, the absolute best multiway switch- all military stuff from the scrap. To start it was to just measure DC volts. Then when that was designed I decided resistance would be nice, so i designed that. Then AC volts. That was difficult but, after a while, I managed to steal a design from an Avo meter. Then capacitance seemed like a good idea... and so it went on. All I wanted the meter for was for home use to do electronic projects. In the end I had just finished buildingf the meter with just DC vollts, when a reasonably priced digital multimeter chip came on the market from Intersil. Now a new test equipment project started. I spent two years designing various circuits for digital multimeters. Then one day I noticed an ad for a ready made multimeter for a reasonable price- so I just bought that and have used it ever since.

Had I have chosen a reasonable spec and not added and added I coulod have had useful analogue meter within a month and later a useful digital meter within 3 months. The next major project was a lab PSU. One day an old hand in the Lab saw my design and kindly advised me that it had so much gain that it would never be stable. Rubbish I thought. But I soon found out that he was right. So i just built a normal lab PSU. It worked a treat and I used it for years.

I have done a lot of work on this amp project, which I don't mind doing because it intrests me and also after years in management, it is good to get back to electronics. But I can't go on forever chopping and changeing. And also fighting off all the unfounded critisisms I seem to attact every time I post a circuit.

So I am sorry but if you are not going for a single power amp (with L,R & Sub), with just a mains on off switch, I'm afraid I wont be able to help any more- it's up to you my friend. Either way it has been fun and I have learnt a lot from the experience- especially casting ally

 

[KeepItSimpleStupid]

Remember his space constraint? Tony posted a 6 channel amp because that's what people wanted to support the 5.1 stereo.

3 channels can also be handled as a powered sub-woofer.

Equalization is one thing, but then so is sp/DIF and HDMI. Analog inputs are almost out these days.

My crystal ball sees a huge learning experience as well as the building of an antique.

Do the design as:
What would I ultimately want if I had all the money in the world.
What do I absolutely need.
What can I afford now.
What can I add later.
Add the hooks for the "later".

What this generally does is:
Allows the project to progress and prevents "scrap" and re-build.

MY "first" amp had a volume control in an external cardboard box. It used the SE540 and a home wound torroid with a switching power supply. The amp was in a metal box and operated off of 12 V. The year was in the '70's and I was in high school. The pre-amp later was a broken amplifier found at a garage sale. I actually bought the turn table next because I did not want to ruin LP's. The next piece was the tuner. Then the pre-amp.

A "system" predates the "MY stuff". It was an all in one AM/FM tuner amplifier and external turntable and external speakers on a cart.

My take is a 3-channel box isn't a bad idea. The question becomes: how do you support those 3 channels?

With the digital age, your building an antique. That antique is a stereo amp with a sub-woofer, not a 2.1 digital stereo.

 

[KeepItSimpleStupid]

My take:
3 channels
Why? Space

Electronic crossover
Why? To support 2 channel with sub
Crossover points set internal to amp.

Rear panel
Power inlet
Why? Amp needs power

RL Sub Inputs
Why? Amp needs RL & sub inputs

Speaker fuses
Why? Minimal protection

A way to connect speakers
Why? You need them
Choices 4-way binding posts, screw terminals, push in terminals, speak-on connectors or combination,

Front Panel
Power switch
Why? To listen to phones.

Separate L & R Level Controls
Why? Does balance and max before clip (Set and forget)
Volume belongs elsewhere: Think phones

Bass relative Level control
Why? Assume no other equalization

Aside:
Bass can get boomy
Mid generally enhance voice
High generally reduces hiss (e.g. FM stereo)

Crossover on/off
Why? This would basically support 2.1 and channel stereo.

Aside: Headphones
There are 5.1 headphones that accept HDMI inputs to amplifiers with their own volume and equilizers and stuff in between,
Then there is the Stax ear speaker which is exceptional but is priced way up there.

So, a BASS boost control is only included because there is no other equalization.
Two of these devices (slightly different) could support 5.1 stereo. You need 6 amplifiers. 2x3 is six.
The BASS relative level would become center channel volume max.

So, there....My take on requirements. Later... proposed enhancements.

 

[KeepItSimpleStupid]

"Enhancements" - just for the sake of creating them

DC protect
Why? That's the consumer thing to do. They won't replace a fuse with the correct value.
Usually requires some sort of indicator.

Clipping indicator
A good idea in general
left/right/pos clip/neg clip
You can use color to indicate which rail clipped.

Overtemperature indicator
really depends on how well the temperature compensation is designed.

Input & speaker anti-thump
Generally it's part of the DC protect stuff as well.

Reset
Recycle power?

Troubeshooting mode
Some easy way to troubleshoot.
Often overlooked.
Protections sometimes need to be disabled
My amp requires me to remove and extend a connector for power+, power-, gnd, and, speaker out
It also has an RCA jack on the board itself bypassing the external VACTROL
The RC network at the speaker is not connected using this mode
A resistor in series with the line needs to be bypassed.

Displays (bar graph)
Their "cute".
Most of the time they assume 8 ohms.
Definately indicates loudness and even "close to clipping"

Remote ON
Useful because the pre-amp is limited in the amount of power it can switch.
So, you have two power cords.
One is used to enable the power (from the pre-amp). The other goes to the wall.
This **broken link removed** supports a low voltage trigger in/trigger out
signals. This is starting to become more common in home automation systems.

Convienience outlets

With remote on, it's now possible to have switched and unswitched outlets.
They basically remove clutter, but make it harder to remove just the amp.

Surge supression
From RFI filters to slow turn-on to ZNR's across the main filter caps.

Troubeshooting mode
Often overlooked
It's just ways to make troubeshooting easier.
In my amp I have to:
Remove the module by disconnecting a phono input and the connector supporting power and the connector supporting power and the connector supporting the speake
The VACTROL and speaker protection are in the chassis.
I did not make it convient to bypass the AC line resistor or jump it.
As I said before - my protection circuit needs work.

An electronic mute input
Why? An automation control input. Doorbell or phone rings.

Some amount of "always on" power
e.g. Suppose that "trigger" is implemented by AC or some other way.
A microprocessor could also used for power up stuff

Out of all that, what's the most useful?

I would vote:
Design with troubleshooting mode in mind and not mass production
Surge suppression
(A lifetime issue)
Remote power via AC
(Depends on total power: 70*2 and 100 is 240 W. Don't let the pre-amp try to switch it)
Thump - depend son the amp
Slow turn on - depends on the amp
Clip - depends on the amp power and whether one likes high frequencies.
Hi temp - might be useful for an unknown amplifer
Some of the above could be integrated into a microprocessor.

Nearly everything suggested above with the exception of the VU meter is internal.
An extra power in connector (e.g. the 3A version) supports external turn on.
DC triggers would require panel space.

DC LED (e.g. Protect), Clip Left, Clip right, Thermal require panel space.

Even if they don't work, they might be cool.

Thermal without shutting down could be easy. Protect could be part of the anti-thump. e.g. It's on for the short time the speaker relays are open during power up..
Clip is harder.


e.g.
Put labels of
Protect---TEMP--DC-- CLIP on each side of the amp and sub.

Another option is to put protect totally in a different place. e.g. On the front panel, centered in width, a few cm from the top edge or near the power switch.

 

[audioguru]

If you need a clipping indicator then you are deaf and your amplifier does not have enough power to do what you want. Most people blast the low frequencies up to clipping, not high frequencies. Oh, if somebody is VERY deaf to high frequencies then they probably blast them so they are clipping.