| goodas |
Hi,
I am a complete beginner but will shortly be building a valve amp kit. The problem is that I will need a phono stage to go with it.
I could of course buy one already made up, but I would like to try to build one myself.
I know this is the tube section but I though I would start with a simple op amp design, has anybody used one of these with a tube amp?
The problem is that although there are many schematics on the WEB I do not have the necessary skills to convert these into a circuit that can go onto a matrix board.
Any help would be appreciated. :nod:
Thanks. Simon. |
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| miguel2 |
Hi Francis,
Where is the phono stage in the svetlana site?
Regards from Coimbra. |
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| halojoy |
Figure 3 shows the EF86 in triode connection. When this is done, the resulting triode is among the lowest-distortion electronic amplifying devices ever made. Typical second-harmonic distortion with 10v RMS output is on the order of 0.05%. This result is achieved without any negative feedback, so this circuit is an excellent choice for high-end audio design. The voltage gain will be about 25 in this connection, making it suitable for line stages.
halo |
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| halojoy |
APR8 is a Riaa Phono EF86 amplifier
EF86 Riaa Phono Amp
halo - a TRUE EF86-fan ;) :) :cool: :cool: :) ;) |
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| halojoy |
From the PDF:
The Svetlana EF86 is a glass envelope miniature pentode intended for high-quality audio
preamplifier service. Close manufacturing specification tolerances and improved
processing provide improved reliability and superior sonic performance. The Svetlana EF86 is
manufactured in the Svetlana factory in Russia, and is designed to be a direct replacement for
any EF86 or 6267 type.
The Svetlana EF86 features:
• Low microphonics and low heater hum induction - suitable for input stages in high-gain
microphone preamps, phono preamps or as a gain stage in condenser microphones
• Electrostatic shield is built-in, covers entire inner structure - no external shield required
• Low distortion in pentode or triode connection
• Extended processing and aging for stability and reliability
• Comprehensive static and audio amplifier testing before and after aging
:cool: EF86 Svetlana PDF datasheet :cool:
/halo - loves EF86 :cloud9: :cloud9: |
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| Sch3mat1c |
| quote: | Originally posted by halojoy
Typical second-harmonic distortion with 10v RMS output is on the order of 0.05%. This result is achieved without any negative feedback, so this circuit is ... |
*Ahem*, connect the screen to a constant voltage supply (wrt. cathode), then I'll believe it has verty little NFB. ;)
Tim (if this sounds like an attack on the tube, I have no doubt it's linear, at least as much as 5876...er...whatever that RCA AF pentode is ... 5879? :D ) |
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| miguel2 |
That phono is exactly what I have been searching. I have the line stage with the EF86 in triode mode, like the schematic posted here by Halojoy. It is quite nice, and I compared it with one with 12AX7 and like the EF86 best, although I cannot compare the tubes but the designs.
I cannot clip the zenV4 with this pre, but it goes quite loud. I added a cathode follower to protect the triode stage from the Zen low input impedance, but things got worse, so back to the original.
I think I am gonna give this phono a try. Do you have an opinion about it Halo?
BTW I am using old Phillips tubes. |
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| Petman |
Oi Miguel! Tudo bem aí em cima? ';)'
Ok, the photo is photo nr. 1 from the svetlana site, a very high gain stage for phono, cond. mics, etc. The one halo showed is the line amp version.
Haven't tryed it, as i have very little valve stuff built, but will do it ASAP, if time permits.
All the best,
Francisco |
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| halojoy |
| quote: | Originally posted by miguel2
That phono is exactly what I have been searching. I have the line stage with the EF86 in triode mode, like the schematic posted here by Halojoy. It is quite nice, and I compared it with one with 12AX7 and like the EF86 best, although I cannot compare the tubes but the designs.
I think I am gonna give this phono a try. Do you have an opinion about it Halo?
BTW I am using old Phillips tubes. |
I cannot have any opinion of this Phono circuit.
I have only teoretical knowledge of TUBE circuits.
Have not yet built any Tube Amp.
But would really like to try!
------------------------------
I only know that, if I would build a TubePhono Amp
I would use EF86. It is very low noise.
I would probably use EF86 in LINE amp also, in TRIODE mode.
EF86 is a Penthod, but can be used as a Triode
if you don't need so much gain.
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There are at least 10 different EF86 Phono Riaa
on the WEB.
I searched with Google using this words:
EF86 phono
or
EF86 riaa
I would suggest you download the schematics you can find
on the webb. Copy and show a diagram here.
Then you can get opinions of the other guys here,
that knows more about tubes than us.
(you know which I mean: dhaen, Joel ... and more ...)
---------------------------------------------
Problem use to be that everyone have Their personal
favourites. And they want you to build JUST as they have.
My advice: LISTEN, and make YOUR OWN choice!
If you let others choose, you will have to change every minute,
and make 10 choices at the same time ... :eek:
halo - makes his own choices, but gives good advices an ear :goodbad: |
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| hagtech |
Goodas,
Here's another tweaked out phono stage you can build:
Cornet
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| Rob M |
| quote: | Originally posted by goodas
I am a complete beginner but will shortly be building a valve amp kit. The problem is that I will need a phono stage to go with it.
I know this is the tube section but I though I would start with a simple op amp design, has anybody used one of these with a tube amp?
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I'm also a complete beginner, and I'm in the middle of building an opamp phono stage using Rod Elliott's Phono Stage and Preamp Power Supply PCBs. Elliott sells the PCBs cheap, and so far at least I haven't run into any problems. Of course, that's if you haven't been tempted by any of the tube stages that have been suggested already. ;) |
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| mcelaj |
refering to the above mentioned svetlana schematic(s). is the riaa circuit included in variation 1?
EF86 Preamp Variation 1
thanks and regards |
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| Mike C |
Simon,
First, a suggestion about your immediate short term need for a reasonable phono stage.
Look out for a 'midfi' amp from the 1980's; NAD, Armstrong, Sansui, etc. I see you are in the UK (not far from me!) so I suggest trying a car boot sale; £10 should get you something OK. Or try Ebay. In the 80's, phono was the primary input so the inbuilt phono stages were pretty good, even in otherwise modest amps.
Taking the output from the 'tape out' socket gives you a reasonable phono stage. A fairly simple DIY phono stage of the type you are considering is unlikely to prove any better than this.
This strategy will enable you to concentrate on the DIY amp without needing to compromise it to fund the phono stage.
Learning to lay out a PCB and use solid state devices may be of little long term benefit if you end up using valves and hard wiring.
Later, I'm sure you'll want to build a decent valve phono stage.
Be aware - this is by far the hardest thing to design and build! I'm in the middle of my own project at present, and I know enough to see the problems ... not sure if I have the answers though! :)
I'd suggest you get more experience before trying a DIY phono stage, and also do plenty of research.
Review designs such as K&K, Nardi's Psi42, the True Realism; most of these have writeups describing how the unit was 'engineered' to solve the problems inherent in a phono stage.
Then perhaps choose one of the many schematics or a good kit and build this? |
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