REDD 47 PCB
- Thread starter Gearsix
- Start date
Help Support GroupDIY Audio Forum:
ilfungo said:
http://www.twin-x.com/groupdiy/displayimage.php?album=322&pos=0
I'd do them p2p. Or atleast make the PCBs the same as the p2p layout. EMI's component, tube, and transformer placement was pretty well thought-out. They used anti-shock sockets on the EF86.
There were some 'Orange 86' pcbs in the black market recently.
They are excellent implementations of the redd47 circuit and are quite cost effective.
http://www.groupdiy.com/index.php?topic=50109.0
Cheers
They are excellent implementations of the redd47 circuit and are quite cost effective.
http://www.groupdiy.com/index.php?topic=50109.0
Cheers
buildafriend
Well-known member
Without having compared schematics personally, I heard from a reliable source that the orange 86 is basically a redd 47 with some additional options. I'll be starting a redd 47 soon. I have a friend who happens to have some boards laying around 
. I'm pretty sure his are drip boards.
. I'm pretty sure his are drip boards.Surely the closer you want to get to the original, the more dollars you must part with.
Originality is an exponential function of cost.
But, original magic aside, the circuit is pretty straight forward. Simple like.
So - good quality components and reasonable build quality will give a great result.
Drip pcbs are good quality. Charley's Orange 86 pcbs are good quality. PP builds give great results also.
It's all good.
Originality is an exponential function of cost.
But, original magic aside, the circuit is pretty straight forward. Simple like.
So - good quality components and reasonable build quality will give a great result.
Drip pcbs are good quality. Charley's Orange 86 pcbs are good quality. PP builds give great results also.
It's all good.
letterbeacon
Well-known member
I know you've pretty much decided on finding a PCB, but I can't recommend P2P enough -I've only built a couple of circuits using it and it really is much easier than you think.
pucho812
Well-known member
grow a pair and make it on a turret board. If you worried do a guitar amp kit first to get your feet wet. Doing turret versions are much easier and can easily by the board with all the turrets on it so you do not have to make that part of it. Now can anyone recommend a suitable output transformer or should I just wire the suggested cinemag input transformer backwards?
buildafriend
Well-known member
Hey pucho, if you dont mind my asking.
What output transformer are you referring to?
What output transformer are you referring to?
I've used lower ratio output transformers for my most recent implementations of the redd47 circuit.
I'm not going for any closeness to the original, just the circuit essentials of small signal pentode feeding paralleled triode parallel feeding output transformer. With feedback attenuator.
I like the utc a15 backwards as output 10K:500. Reasonably priced compared with some traffos out there.
There are some other similar models which can be used.
Even used it as 5K:500 for a higher output gain with a reasonably low plate resistance tube.
Very happy with the sound.
Other output traffos I've used with good results - Edcor 10K:600 XSM, Carnhill 9600:600 ungapped.
I prefer the lower ratios because the circuit doesn't have a huge amount of gain.
For mic input, I think the higher ratios are good, up to a point. Personally I think 1:5 is a good tradeoff between good input voltage gain without much possibility of input clipping. 1:7 and higher is a little to hot an input for me.
I like the utc ouncer o8 with shield backwards for the mic input - has a few taps so you can do some fancy impedance switching for some variety. Again, pretty reasonably priced.
I'm not going for any closeness to the original, just the circuit essentials of small signal pentode feeding paralleled triode parallel feeding output transformer. With feedback attenuator.
I like the utc a15 backwards as output 10K:500. Reasonably priced compared with some traffos out there.
There are some other similar models which can be used.
Even used it as 5K:500 for a higher output gain with a reasonably low plate resistance tube.
Very happy with the sound.
Other output traffos I've used with good results - Edcor 10K:600 XSM, Carnhill 9600:600 ungapped.
I prefer the lower ratios because the circuit doesn't have a huge amount of gain.
For mic input, I think the higher ratios are good, up to a point. Personally I think 1:5 is a good tradeoff between good input voltage gain without much possibility of input clipping. 1:7 and higher is a little to hot an input for me.
I like the utc ouncer o8 with shield backwards for the mic input - has a few taps so you can do some fancy impedance switching for some variety. Again, pretty reasonably priced.
No sorry - used OEP line inputs in an 1176 tho' - it worked very well for that.
If I didn't already have some Haufes to use in my current pair of Orange 86 builds as mic/line inputs, I'd use utc ouncers 08+shields for sure.
Something else I plan to do on these ones is to rework the plate and screen operating points and use some other pentode.
The russian 6J32P 'ef86' style I used till now have been quite variable in performance. I found maybe 1 out of 3 gave the operating points I expected. But the builds I've done with them have sounded good - just been low on the gain side with the standard plate/screen resistor values. And the operating points obtained didn't match the data sheets very well at all.
So, I conclude the 6J32P is not so similar to EF86. Even with curves published on net from a guy who measures them, still didn't match my circuit values too closely.
If I didn't already have some Haufes to use in my current pair of Orange 86 builds as mic/line inputs, I'd use utc ouncers 08+shields for sure.
Something else I plan to do on these ones is to rework the plate and screen operating points and use some other pentode.
The russian 6J32P 'ef86' style I used till now have been quite variable in performance. I found maybe 1 out of 3 gave the operating points I expected. But the builds I've done with them have sounded good - just been low on the gain side with the standard plate/screen resistor values. And the operating points obtained didn't match the data sheets very well at all.
So, I conclude the 6J32P is not so similar to EF86. Even with curves published on net from a guy who measures them, still didn't match my circuit values too closely.
I think I'd like to build a few of these point to point. Thanks for the tips!
How many of these do you think I could fit in a single rack case? Space saving is my concern.
How much gain does this circuit provide at maximum in it's stock form?
How many of these do you think I could fit in a single rack case? Space saving is my concern.
How much gain does this circuit provide at maximum in it's stock form?
