Stereo to mono...

[mcelaj]

I tried hooking up the two outputs out of my gainclone into one speaker and it would distort (clip I guess). Is there a way to do this without causing the distortion, perhaps attenuate the signal? Perhaps the signals should be combined before it gets to the amplifier, or pre-amp (phono stage), which would entail putting together a monoblock, which I don't mind undertaking. Any help on a stereo to mono conversion would be most appreciatred.

 

[anatech]

Hi mcelaj,
You must be very careful about hooking amplifier outputs together. Normally this can not be done. When it can, the amp is either bridged or it's a tube amp and it may be in parallel. There is normally a switch to allow for this.

You almost let the magic smoke out of the box, and you wouldn't be the first to do this, this way.

-Chris

 

[rabbitz]

You have to do the mixing at line level prior to the power amp or bang and smoke.

Have a look here for a simple circuit using 2 resistors which I used on one amp with a switch to use stereo or mixed mono. Very handy also for sub inputs from line or speaker level but the speaker level has to be attenuated first with a voltage divider.

http://www.tkk.fi/Misc/Electronics/circuits/linesum.html

I'll add the speaker attenuation circuit as well.

http://www.tkk.fi/Misc/Electronics/circuits/speaker_to_line.html

 

[mcelaj]

Fortunately I didn't get the puff of smoke as I tried it from my gainclone into a Decware Radial speaker. Would have been a shame to lose them. Thanks for the response guys.

 

[amt]

So Rabbitz,

Are both these circuits essentially what are used in a sub plate amps?
Ive been thinking of building a sub amp, using an inexpensive car audio electronic xo. Would adding both circuits, allow for either speaker level signal use or line level, such as found on most all powered subs?

thx amt

 

[BobEllis]

does your circuit look something like the PA-100 in this app note? http://www.national.com/an/AN/AN-1192.pdf - the point when it comes top paralleling chip amps is to use a series reistance between the chip outputs. If the DC offset of each is significantly different you may want to consider a servo like that shown in the BPA200 circuit in the same note.

 

[amplifierguru]

Use 2 speakers! One amp per speaker - works for me. Or antiphase one for bridge if the speaker Z is high enough.

 

[anatech]

Right on amplifierguru. That's the best way since you now have lower voice coil temps. Efficiency goes up. Amps stay cooler and excursion may be lower.

-Chris

 

[rabbitz]

So Rabbitz,

Are both these circuits essentially what are used in a sub plate amps?
Ive been thinking of building a sub amp, using an inexpensive car audio electronic xo. Would adding both circuits, allow for either speaker level signal use or line level, such as found on most all powered subs?

thx amt

Basically it is all they use. Built a P101 sub amp with a sub processor which has an attenuation circuit and then a mixer. I've got it set up so I can use line or speaker level with a switch selecting either.

Stereo Speaker level> attenuation > mixer to mono> processor
or when switched
Stereo Line level> mixer to mono> processor (chosen by a jumper)
LFE> processor (chosen by a jumper)

 

[amt]

Excellent! I just so happen to have two P101 boards here and just waiting for Mosfets to arrive.

 

[Rickets]

Stereo to Mono

I have joined this DIY because I was interested in the discussion going on about converting a stereo output into mono output.
I have a day care that has 4 rooms with one speaker in each room. One room gets the right channel on speaker "A", the other room gets the left channel on speaker "A", still yet, a third room gets the left on speaker "B", etc.
I want to put in a newer CD player/amp, but they only have a stereo speaker output terminal on the back for 1 set of stereo speakers. No pre outputs like on a component system.
I know just enough about Audio electronics to know that I don't have a spare can of smoke to recharge the amp if I just connected the outputs. I also know the Z must remain at 8 ohms. I read the previous posts that talk about low level dividers. Do you have any suggestions for a "speaker level" divider with 4 speaker switch system.
Regarding a HIGH level (or speaker level), will the circuit below work without the need for the can of smoke?
Or can you recommend a redesign of this for use with speaker out levels?

Speaker output -----+-----------\/\/\/\-----Disconnect Switch-------
AMP | R1 10K SPEAKER 1
--------------+------------------------------------------------------------
(shields) | |
| |
| +----------\/\/\/\------Disconnect Switch------- | | R2 10K SPEAKER 2
+------------------------------------------------------------
| |
| |
| +----------\/\/\/\------Disconnect Switch------- | | R3 10K SPEAKER 3
+------------------------------------------------------------
| |
| |
| +------------\/\/\/\----Disconnect Switch-------- | R4 10K SPEAKER 4
+-------------------------------------------------------------

I can build a robot, but I can't wire a speaker output!
I am also not smarter than a 5th grader either!!!

Thanks,
Rickets

 

[mummyjohn]

Neither of the links on the first page are accessible - when I click on them, the page simply says "403 Forbidden, you don't have permission to access (filename) on this server."

So far, this page is the ONLY lead I've found in being able to make a circuit that goes from stereo to summed, phased mono.

 

[Twaksak]

Dear MCRLAJ, what I would do is to put a mixer before the power amp. I don't know if this is what you are able to do but that would sort out all your problems. Then connect 2 speaker in series, the other two in series and then the 2x2 in parallel giving you 8 ohms speaker load.

Hope you will sort it out
Chris