Would using (2) 10k ohm resistors in line with headphone outputs tied together at the opposite
end provide sufficient isolation/mixing to feed a mono amp?
Code: Select all
Right---10k--\
|--- mono input
Left ---10k--/
Thanks,
CeaSaR
Code: Select all
Right---10k--\
|--- mono input
Left ---10k--/
C2 is shown connected backwards.CeaSaR wrote:Geez, just when I thought I was done with this, I come across this circuit.
I would use a cap closer to 10,000uF. With only 1,000uF there will be as much bass signal wasted across the cap as on the 8 ohm load. A 1,000 cap has an impedance of about 8 ohms at 20Hz.CeaSaR wrote:So using the 1.4 rule, I would need a 26 V transformer to get 35 V using a bridge rectifier and, say, a 1000 uF cap
for filtering. Do I have that right?
Better change those 2N3055's to 2N3773. You have a +-35V supply. During peak output voltage excusions, 70V will appear across the output transistors' from C-E. 2N3055 is only good for 60V max. Use 2N3773's, good for 140V. Make sure all of your diodes, transistors and caps are good for the voltages that they may encounter.CeaSaR wrote:What I am thinking of is trying a revised version of this circuit using 2n3055's for output. With a +-35 V supply, it has the potential to put out around 65 W into 8 ohms. With beefed up predrivers, it should be able to get around 120 W at 4 ohms. This is a heck of a lot more efficient than anything I have found on the net. And that is with an input of 300 mV! BTW, quiescent current is 20 mA.
With the series cap in front of the load? With the 8 ohm speaker connected?CeaSaR wrote:If this is correct, then the amp is flat from 20-20kHz +-~0.25 dB! At 10Hz it is only down 1.9 dB! WOW!
Robert,Robert Reed wrote:Caesar
Now that you are thinking in terms of high power, have you considered the "Losmandy Amplifier".
This is beauty in simplicity, low distortion and DC to 25 KHz flat response.It uses very few parts and one Op-Amp. The amp has a builder choice gain of 1-10. But of course any gain or frequency juggling could be accomplished with the other half of a TLO82. Also uses 2N3055s in the output stage.Can be built with single or split supply. Split supplys do not seem to be in vogue these days, But I really prefer them as it makes design and construction so much simpler. It also gets rid of that big hunkin output capacitor.
Bob,Bob Scott wrote:I would use a cap closer to 10,000uF. With only 1,000uF there will be as much bass signal wasted across the cap as on the 8 ohm load. A 1,000 cap has an impedance of about 8 ohms at 20Hz.CeaSaR wrote:So using the 1.4 rule, I would need a 26 V transformer to get 35 V using a bridge rectifier and, say, a 1000 uF cap
for filtering. Do I have that right?
Better change those 2N3055's to 2N3773. You have a +-35V supply. During peak output voltage excusions, 70V will appear across the output transistors' from C-E. 2N3055 is only good for 60V max. Use 2N3773's, good for 140V. Make sure all of your diodes, transistors and caps are good for the voltages that they may encounter.CeaSaR wrote:What I am thinking of is trying a revised version of this circuit using 2n3055's for output. With a +-35 V supply, it has the potential to put out around 65 W into 8 ohms. With beefed up predrivers, it should be able to get around 120 W at 4 ohms. This is a heck of a lot more efficient than anything I have found on the net. And that is with an input of 300 mV! BTW, quiescent current is 20 mA.
You'll need a big heat sink. Check the power dissipation of your driver transistors. The may need cooling too.
Look here for all the ways to hook up a power transformer. See pages 11-12:
http://www.hammondmfg.com/pdf/5C08.pdf
Note that a choke input design is rarely used anymore. The choke costs Buxx and the circuit needs a bleeder resistor with a minimum load for proper regulation (ie: to keep the voltage down.)
With the bridge rectifier designs, just wire your CT to ground to split the output voltage. That is the design most commercial amps use, bridge rectifier and a CT transformer, two outut caps.
Yep, 2200 uF. Here's the plot:Bob Scott wrote:With the series cap in front of the load? With the 8 ohm speaker connected?CeaSaR wrote:If this is correct, then the amp is flat from 20-20kHz +-~0.25 dB! At 10Hz it is only down 1.9 dB! WOW!
I know, it's typically known as quasi-complimentary when a low-power complementary pair is used toRobert Reed wrote:... two 2N3055s being used,this is not complimentary ...
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