Orange 86 Build Thread - no PCBs for sale

[guavatone]

Jensen 115K and 110K  should do a good job for input but their output ratios are a bit low. The 115K will give you another 3 dB of gain if the standard 7:1 is used on the output.  With other transformers you’ll have to follow their suggestions on a different Zobel or termination. 

Maybe call Jensen and ask about 7:1  tube output transformer. For a parallel E88cc.

I’ll try to ask David Garen what’s going on. Last time we talked he seemed to half joke of weather I knew anyone interested in learning the transformer winding craft.

Then there’s always sowter, but may be a wait as well especially with those August European summer breaks.

The small beyer’s Probably  can’t take too hot a signal but they show up on auctions and come in 1:7 1:10 and 1:15.  They are said to have nickel cores and Burnbue likes em here:

https://groupdiy.com/index.php?topic=29830.0

Data Sheet:

http://www.technicalaudio.com/pdf/Beyer_Dynamic/Beyer_Dynamic_input_transformers_1976_oct_cat.pdf

 

[alexc]

I did note that the 6J32P had a bit of variation in the bias in the same circuit ...  and it was a little different from the ef86 data curves too ...

My own bias is a little 'colder' than typical - I like to have a little more headroom for my hotter guitar pickups (with the DI).

I haven't measured or experienced any excessive hum or hiss, however - all of the Orange86 pcbs I built up have been super quiet for output noise with all 5 of  6J32P that I have.

I am curious about the ef86 and subs, so looking for a couple of likely ones  now 

Also doing a another sub of the au7 type output tube  ..  the 5963  ... it's a nice tube imho.

 

[deuc224]

Well the cinemags are on their way, might just bite the bullet and order another stereo set now even though its a lot to pony up at once.    Charles, what exactly does the squish  function do?  Im contemplating just adding it since its just a 500k log pot, but real estate is running low on my 2RU front panel so im not sure if I should just leave it out or do it?

 

[guavatone]

I don’t use the squish bc I’m a bit of a minimalist engineer for tracking. Some engineers really like it. It can give 1-3 dB of compression.  Maybe shoot Holger a PM, he seems to be pretty fond of it. He may also mention it on his build posts.

 

[Marc Duchesne]

Finally got to finish line with this REDD47 using Orange86 boards,  input transformer backward is a NOGO, . Cinemags xformers, NOS telefunken and Siemens tubes. This pre is just amazingly sounding, silent with this presence we all desire in vocal mids. Thanks for the great help Guavatone, you're tha man. 

-Marc.

 

[guavatone]

Congrats Marc. It looks good. I’m curious of any variations you did.

My advice to all is to do away with the fine gain trim and use a 100-120R  in place of R5 or a variable stepped resistor faith values 39, 60, 80, 100, 120, 150, 250, 500, 1k,  2k and 3k5.  Give or take 5% of values. This makes low gain settings very low THD and can make settings with greater THD. This is what I believe one major manufacturer is doing.  The low resistor setting will give about 2 dB more gain but at the price of .05% More THD.

 

[alexc]

..  Miller cap  mod ..

Interesting, I have to try that    

I find the freq response to be pretty flat, generally speaking .. certainly no lack of really crisp 'air', when set for quite low thd ... and with some hi-fi signal input ...

(like a gibson sg with passive ceramic pups  ..  emg hz)

I'm already  into the 'diy season'  ..  things are thawing out a month early!  ...  usually snowing about now. 

Also, a month or so into my testing Orange86 with Trimax 30K:600 ....  very happy ... definately lower thd than my previous edcor wsm 15K:600 (which is a very good performer for the price). These outsized broadcast units are top notch, and impart a very classy finish to this classic topology.

I'm just ordering a  'plate load inductor' for V2  ... I have an 8K6/5W resistor in there at present.  - that's my exciting mod-to-investigate 

No need to do so, gain is fine and noise performance is exceptional - I just like to check these things out!

 

[guavatone]

Another mod that’a Making this sing is an Ixys 10m45s on V2. it’s a nice mod for tube rolling v2 because you can dial in current.  It’s a $2 chip but worth it.

I also gave V1’s screen Supply it’s own branch from B+ taking a 33K resistor to a 22u cap to a 100K resistor to an 80V Zener (2 39V Zener) on g2). This combo is giving incredibly low THD.  and almost all 2nd harmonic.  More importantly is that I feel it makes the amp fast and emotive.

 

[alexc]

I'd like to do a version with the led bias and ixys active plate load for V1 for sure 

It really is a fine lead-in to a nice tube back end ..  hifi style.  el84 or 6V6 and more.

I get the feeling, orange86++ with el84s could be grand.

 

[guavatone]

Can’t do led on V1 if you want NFB.

On V2, 2 red led’s brought me close but I felt it was overkill.

Will I Studer did an ef86>e80cc >el84 - Model 52 8 watt.
https://elektrotanya.com/studer_model_52_sch.pdf/download.html
- on V1, it’s interesting that he boosts high end and drops the screen voltage a bit from the standard data sheet values.  EMI only copied the data sheet on their V1 circuit. The only interesting thing in it is V2’s local feedback and using a paralleled valve.

I was thinking about doing a hybrid V76 with 2 ef86’s into the V2 stage off the redd.

 

[alexc]

Ahh yes - you're right of course!  Not possible to do a led on V1 with nfb into the cath.

I can try what you describe - a pair on the V2 cathode circuit

That,  and a large plate load choke for 15mA or so -  and as high an inductance I can find/afford. I think Hammond have one with something like 70H ... which is prolly at the minimum end of interesting ...  also an eby hk one that is more like 120H or so.

..

I use my simple built Orange86  feeding  an old  'ax7+el84' pp integrated amp which I refurb'd with variable nfb ... it's superb to play my guitars thru ...  I like the bax on the integrated amp and so I can some quality sound from my bass-heavy guitars to airy top enders too. Hard to describe the richness of the tones and the propensity to harmonic singing on my hollow bodies.  :-X

Power is just right for me ..  like typical listening levels at around 5Wrms  stereo into 8 ohm speakers  - THD+N is around the 0.2% mark (1KHz sine testing), and the el84 have a bass kick that belies their modest size.

I have a project going to 'better' this modest 60s japan 'Encel' amp (like a Fisher of that time) .. if I can. It has a bunch of stuff I don't use ...  I like a simple, balanced input power amp kind of thing .. more suited to studio gear.

I seem to have difficulty making good eq units ...  always too noisy or this or that.  So my project is to include an effective bax and/or tilt eq circuit. 

...

I have to re-look at the v76 type .. I know it's an interesting type .

Cheers

 

[vmanj]

Greetings to all.

Please tell me, for what purposes are C16 and D8 used, and what can change if I remove them from the circuit?

 

[guavatone]

Greetings to all.

Please tell me, for what purposes are C16 and D8 used, and what can change if I remove them from the circuit?

C16 is needed and serves 2 purposes. 1. Bypass Zener noise and 2. It’s a classic capacitor multiplier. So really you could get away with a 100nF cap. D8 should help minimize crosstalk between channels. Not really needed.

 

[vmanj]

It is clear, thanks!

Now, instead of zener's and transistor, I use the Oa2 controls (on the image).
I would like to redesign the power supply unit by combining part of my old scheme and the part of Orange 86 (instead of Oa2).

Please see, this option can work correctly, or you need to change something (maybe a 10K resistor or something else)?

 

[guavatone]

I don’t like the 470K across the bridge, although though the original appears to have it.  See how it goes. The 510R before the 0a2  May need to be 1K like the original. The 220K can probably be between 220K tom 470K.  The only trouble you may run into is V2’s filter caps.

 

[Marc Duchesne]

"Congrats Marc. It looks good. I’m curious of any variations you did."

Hi, not many variations actually other than using great red dot telefunken EF86 and Siemens ECC88, Edcor transformer with 6VAC tap (plenty of current). The internal layout as suggested into the doc's with power cabling in one side (power supply side) and audio in the other. All XLR shielded cables for audio paths. Edcor transformer in mounted on the outside of the case. I used the squich pot, still need to install a bypass switch as suggested. VU meters on the transformer out with 3.9kohms resistor was fine. It was a very long built but it's totally worth it. I will upload more photo's of the inside.

 

[vmanj]

In the original circuit, the filters use 1K resistors.
But at me with such values of resistors - Oa2 are not "ignited".
My transformer has 275V and 50 mA, probably it lacks its power and the voltage sags.
Therefore, it was necessary to reduce the value of these resistors to 510 Ohm, that would all work.

I added capacitors (in the image), so will it be correct?

 

[guavatone]

In the original circuit, the filters use 1K resistors.
But at me with such values of resistors - Oa2 are not "ignited".
My transformer has 275V and 50 mA, probably it lacks its power and the voltage sags.
Therefore, it was necessary to reduce the value of these resistors to 510 Ohm, that would all work.

I added capacitors (in the image), so will it be correct?

At first glance last night I thought it may be a concern of low current supply. You’ll need a separate circuit for each PS with VR tubes since they are only 30 mA.  Once again, remove the bypass caps on V2 the 10-22uF and the 100nF and alsomremove the 470K bleeder resistors until you get it to strike. 

Are you using solid state or 0a2’s?

Also make sure the PS has a load with the preamp tubes all hooked up. Or at least V2

I found this thread on further googling.  Appears the 100nF will be good and possibly preferred.  But they won’t like more capacitance than that which is why I say remove V2 bypass el cap.

http://www.diyaudio.com/forums/tubes-valves/281605-vr-tube-rf-issues.html

You may want to post over there. They have some serious wizzards over there. But please report back and keep us updated.  I went with a solid state supply so we would enjoy many hours of recording and the cons of tube VR outweigh the nostalgia.

If you want sag, which IMHO  doesn’t really play out in preamps, put a 100k pot in series with the 10K resistor  to Zeners and adjust to taste.  This will starve the current supplying the zeners.

 

[vmanj]

Thanks for the link.

I use a VR tube in the PSU according to the scheme I mentioned above.
Now I have two separate transformers - one for heating and phantom power, and the other for B +.
(Later I want to order a new transformer with all the windings I need).

Everything basically works fine, but I have to enter one more switch for the voltage B +.
In order not to leave the VR tube without load, I have to apply voltage to them with a delay, until the remaining tubes in the circuit warm up and do not "load" Oa2.

I want to remove the separate B + switch and for this reason I want to remake my PSU to solid state.

I hope this helps me.

 

[guavatone]

Merlin has a cool no frills delay on his page here:

http://www.valvewizard.co.uk/OtherStuff.html

For some reason. I totally misunderstood what you needed. But it seems you are up and running .