In the article listed in the link below
http://home.jps.net/~shiloh/jaes.pdf
Though the article refers to the Quad 405 the current dumping and bridge arrangements are applicable to the 606/707/909 etc
on page 12 in the 3rd paragraph reference is made to changing the construction of the bridge inductor from a single wire to one of many parallel strands and of the improvement in balance achieved. Has anyone tried replacing the inductor in the 606 with a parallel constructed one
Stuart
http://home.jps.net/~shiloh/jaes.pdf
Though the article refers to the Quad 405 the current dumping and bridge arrangements are applicable to the 606/707/909 etc
on page 12 in the 3rd paragraph reference is made to changing the construction of the bridge inductor from a single wire to one of many parallel strands and of the improvement in balance achieved. Has anyone tried replacing the inductor in the 606 with a parallel constructed one
Stuart
Hi,
Regards to the 47uf cap, i think it is for bootstrapping the lower driver transistor T8.
This is intended to increase the impedance looking into the driver base at signal frequencies reducing current demand on the class A stage T7.
The output of the amp will follow the input of the driver in phase (T8 output is taken from the emitter) this is fed back through the cap making the voltage at each end of R30 (560R) equal therefore no potential difference, therefore no current flow and therefore it appears to be a very high impedance not just 1K1 but retains its stiffness at the base as if it was still 1K1.
So the output of the amp almost helps to drive itself.
Thats my understanding but i am only a college student so it might be a load of #### .
Regards
Craig
Regards to the 47uf cap, i think it is for bootstrapping the lower driver transistor T8.
This is intended to increase the impedance looking into the driver base at signal frequencies reducing current demand on the class A stage T7.
The output of the amp will follow the input of the driver in phase (T8 output is taken from the emitter) this is fed back through the cap making the voltage at each end of R30 (560R) equal therefore no potential difference, therefore no current flow and therefore it appears to be a very high impedance not just 1K1 but retains its stiffness at the base as if it was still 1K1.
So the output of the amp almost helps to drive itself.
Thats my understanding but i am only a college student so it might be a load of #### .
Regards
Craig
Quad 606 cloning
hello aarsoe,
I cloned a 405-2 and it sounds very good, however in my spare time I would like to build the 606 as well.
could you please send me/post a couple of photos of your Quad 606 amplifier board's component and solder side.
sorry, I know that this thread is not about cloning...
thank you in advance,
zsolt
hello aarsoe,
I cloned a 405-2 and it sounds very good, however in my spare time I would like to build the 606 as well.
could you please send me/post a couple of photos of your Quad 606 amplifier board's component and solder side.
sorry, I know that this thread is not about cloning...
thank you in advance,
zsolt
Could someone tell me what a "(47uF) PP cap" is, please?
I have a 606 and am very very curious.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Post #17
Until now I had modified my OLD 606 (> 15 years?) for three times.
For the first time, I replaced each 6800uF power filter capacitor with new 4700uF x 2.
I then rewired the connections among PCB, PSU, and the sockets.
The grounds are wired by using the single-core 2.6mm OFC cables.
The binding posts have also been replaced.
After playing I immediately noticed that the base is getting tighter and deeper (just a little).
For the second time, I replaced all the small capacitor to silver mica cap and PP cap.
The bridge rectifier was changed to Motorola 25A. In this time, the SPEED of the sound is dramatically improved!
Finally, I change the 47uF electrolytic cap (C7) to 47uF PP cap.
Wow, the sound is so clear. A lot of details¡K
Now I have been thinking about separating PSU for the two channels,
or, add regulated PSU for the driver-units / OP-amp.
I also thinking about replace the power transistors from GE17556 to MJ15003, and, replace the old 0.1R emit resistors.
Don¡¦t know whether these help...
I have a 606 and am very very curious.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Post #17
Until now I had modified my OLD 606 (> 15 years?) for three times.
For the first time, I replaced each 6800uF power filter capacitor with new 4700uF x 2.
I then rewired the connections among PCB, PSU, and the sockets.
The grounds are wired by using the single-core 2.6mm OFC cables.
The binding posts have also been replaced.
After playing I immediately noticed that the base is getting tighter and deeper (just a little).
For the second time, I replaced all the small capacitor to silver mica cap and PP cap.
The bridge rectifier was changed to Motorola 25A. In this time, the SPEED of the sound is dramatically improved!
Finally, I change the 47uF electrolytic cap (C7) to 47uF PP cap.
Wow, the sound is so clear. A lot of details¡K
Now I have been thinking about separating PSU for the two channels,
or, add regulated PSU for the driver-units / OP-amp.
I also thinking about replace the power transistors from GE17556 to MJ15003, and, replace the old 0.1R emit resistors.
Don¡¦t know whether these help...
PP stands for PolyPropylene, it is a dielectric material used in capacitors.
If you would like to upgrade your amplifier I would suggest to send it to these guys: http://quadrevisionspot.blogspot.com/
They could do all the mentioned stuff for you, probably better than you could do it.
If you would like to upgrade your amplifier I would suggest to send it to these guys: http://quadrevisionspot.blogspot.com/
They could do all the mentioned stuff for you, probably better than you could do it.
FWIW, I once used a BG N type cap (47uF, 50V) in that position in my 306. The results were pretty good (better dynamics and transient attack). AFAIR the original cap had a 63V rating.
I had even better results with a complete DADA upgrade (look here for details), some of which you easily achieve with bypassing the Zener diodes with 100nF film caps and changing the op amp for a better type (OPA604, OPA134). I also soldered a 100nF ceramic cap across each op amp's Ve+ and Ve- pins, which took away any residual harshness; for some reason this simple enhancement was not included in the upgrade kit.
I have also tried the OPA627 in this position and did not like it. I would advise this only if your speakers need extra punch and clarity, with the B200s it was way OTT.
The DADA upgrade includes a change of input sensitivity and makes the amp work much better with 'standard' pre amplifiers.
I am not connected in any way with the seller.
Best,
Oliver
Edit: ATM I'm using the Dada supplied OPA604, is it worth swapping for an OPA134?
I had even better results with a complete DADA upgrade (look here for details), some of which you easily achieve with bypassing the Zener diodes with 100nF film caps and changing the op amp for a better type (OPA604, OPA134). I also soldered a 100nF ceramic cap across each op amp's Ve+ and Ve- pins, which took away any residual harshness; for some reason this simple enhancement was not included in the upgrade kit.
I have also tried the OPA627 in this position and did not like it. I would advise this only if your speakers need extra punch and clarity, with the B200s it was way OTT.
The DADA upgrade includes a change of input sensitivity and makes the amp work much better with 'standard' pre amplifiers.
I am not connected in any way with the seller.
Best,
Oliver
Edit: ATM I'm using the Dada supplied OPA604, is it worth swapping for an OPA134?
I noticed for C7 in both the 606, and 707 and 909 that 47uF cap is rated 63V.
Can one safely use a 50V rated cap for C7? Looking at the circuit diagram is appears there's only approx. 27V across it?
http://quad405.com/606schematic.pdf
Cheers,
- John
Can one safely use a 50V rated cap for C7? Looking at the circuit diagram is appears there's only approx. 27V across it?
http://quad405.com/606schematic.pdf
Cheers,
- John
Output voltage is ~80Vpp at full output, so it varies between +40Vp and -40Vp.
If the output voltage is 40Vp and the negative rail is -50V, then the voltage on the cap is 45V.
In case of Quad 606, 707 or 909 changing the opamp for a better one is useless as it is only to have 0V DC on the output, nothing more, it is not in the path of the signal as in the Quad 405.
A 100nF across the zenners can be put but I don't think that it changes anything.
Probably a speedy opamp like OPA604 or OPA627 can even cause oscillation if the layout does not take care for the speed.
For the bootstrap capacitor C7 use 47-100uF rated for 63 or 100V (to be on the safe side)
A 100nF across the zenners can be put but I don't think that it changes anything.
Probably a speedy opamp like OPA604 or OPA627 can even cause oscillation if the layout does not take care for the speed.
For the bootstrap capacitor C7 use 47-100uF rated for 63 or 100V (to be on the safe side)
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