Good morning!
Sure, it works perfectly with 6N1P tube, or small changes to 6N3P, is prohibited in this floor 6N2P tube, the tube is very good but the amplification factor (mu), is too large for this floor and do not.
You can use successfully 6N8S tube, very stable and noise free.
Galvanic coupling directly to the final tubes GU50 grids makes the low frequency response to be excellent.
However, the main problem is the great achievement of the OT.
Schematic no.3, GU50 is in pentode mode, but I posted only for comparison, or maybe someone wants such amplificator.Sound qality is very good in both cases, but the schematic 3, and the SPL speakers are small, so not too expensive.
If you wish, I posted (future) and all details to (manufacture DIY)achieve a quality OT.
No secret, just skill and attention.
*************************************************************************
Thank @<Wavebourn> for appreciation and attention, for I am honored!!!
Sure, it works perfectly with 6N1P tube, or small changes to 6N3P, is prohibited in this floor 6N2P tube, the tube is very good but the amplification factor (mu), is too large for this floor and do not.
You can use successfully 6N8S tube, very stable and noise free.
Galvanic coupling directly to the final tubes GU50 grids makes the low frequency response to be excellent.
However, the main problem is the great achievement of the OT.
Schematic no.3, GU50 is in pentode mode, but I posted only for comparison, or maybe someone wants such amplificator.Sound qality is very good in both cases, but the schematic 3, and the SPL speakers are small, so not too expensive.
If you wish, I posted (future) and all details to (manufacture DIY)achieve a quality OT.
No secret, just skill and attention.
*************************************************************************
Thank @<Wavebourn> for appreciation and attention, for I am honored!!!
Last edited:
6N1P does not seem to be a direct replacement for ECC85 though....
If 6N3P to be used, what would you change?
But the good ones, the MELZ metal base, are rather expensive nowadays.......
What do you man by "galvanic coupling"?
Since the OPT are responsible for a great part of the good (or bad) sounding of a tube amp, I have decided not to save on this part, planning to go for Lundahl amorphous core OPT.
.
Lazaroiu: I like your GU50 PP schematics! I hope you will publish the details for making the output transformers!
François: Lazaroiu's schematic uses a special transformer with windings for cathode feedback, I don't know if Lundahl makes such transformers... There are some very good such toroidal transformers made by Menno van der Veen: Specialist Range Output Transformers
François: Lazaroiu's schematic uses a special transformer with windings for cathode feedback, I don't know if Lundahl makes such transformers... There are some very good such toroidal transformers made by Menno van der Veen: Specialist Range Output Transformers
With pleasure, have in the schematic drawing data for OT GU50 PP (triode mode), Raa = 3700ohmi (4000ohmi)
There are two variants: with core E + I-section of 18 cm * 2 and another on the core C-core section of 8-10cm * 2.
The coil design is the location but also their connection phase.
For a PP pentode will be recalculated for Raa = 5000ohmi.
I hope the drawing is understood.
If there are questions, answer with pleasure.
The transformer is made practical and works in multiple copies, project schematics and the OT is personal.
Excuse my English!
Last edited:
Isn't Raa=4k quite high for a unity transformer?
Unity transformers usually have Raa/4 of a normal transformer since each tube use both the push and pull side of the transformer.
Jan.
Raa = 4000ohmi, is seen and calculated as an OT like normal and then will distribute a 1/4 anode and katod tasks for the two final floor tubes.
Be sure OT is running PERFECT!
But everyone thinks it sees fit, so I was thinking and it seems that everything is OK!
I'm not sure I understand you, but:
In a normal push-pull stage each output tube sees 50% of the windings that is Raa/4 (in class B). In a unity stage each tube sees 100% of the windings (anode + cathode windings) that is Raa. If you want the tubes to see the same reflected load in a unity stage as in a normal push-pull stage the unity-OPT should be Raa/4 (where Raa is the anode to anode load in a normal pp stage).
Jan.
Can we not understand, but I did a test simulation result for LTC and have equivalent Raa 3700ohmi results of pictures, but the schematic is made and practical.
Of course I made a proposal, but you can improve all.Proposal another configuration transformer, with some drawings and can get along better.
LTC simulation images below to Raa = 3700 ohm (equivalent), everyone on this forum can verify this.
Thanks for your attention!
Last edited:
rectify and apologize:
it is: Fourier analysis,not Forier.
Bode diagram ... and if it is useful ...
Last edited:
Please escuse me, i dind't understood you're question. Do you want a scheme in format ".asc", for a simulation in LTC? or do you want something else?
Last edited:
Exactly as I said. But is not important as I am almost ready with the LTSpice drawing. I can share that one instead. What is the primary inductance of your OPT?
I will post the scheme in format ASC, without considering it perfect. It depends on the models of the components from LTC librarys. If you think there is something to change, please feel free to share. (of course in format ASC)
Hey,
Have corrected a few errors and used Koren and Bench´s models that are reliable.
You will have to work with the working points as it´s not up to your specs.
The concertina must have higher Ua to work properly, it now is in the ballpark of 50V.
I am not fully aware of how the SRPPs with 27k on top works? Also they seem to run on very low current, 1,5mA.
The GU50 ran on ca 40mA but should maybe run ca 100mA/tube, A knows.
The transformer inductances where much off. Use 2.5H for the primaries and .08H for the secondary to get 4k/8. Gives you a low 40H primary but that´s good enough for initial sims. If you go for 5.55H, secondary should be 0.18H. 5.55/0.048 is ca 15k/8. But maybe strange things happen when you go with cathode windings?
Also some Spice-commandos should be adjusted.
Have corrected a few errors and used Koren and Bench´s models that are reliable.
You will have to work with the working points as it´s not up to your specs.
The concertina must have higher Ua to work properly, it now is in the ballpark of 50V.
I am not fully aware of how the SRPPs with 27k on top works? Also they seem to run on very low current, 1,5mA.
The GU50 ran on ca 40mA but should maybe run ca 100mA/tube, A knows.
The transformer inductances where much off. Use 2.5H for the primaries and .08H for the secondary to get 4k/8. Gives you a low 40H primary but that´s good enough for initial sims. If you go for 5.55H, secondary should be 0.18H. 5.55/0.048 is ca 15k/8. But maybe strange things happen when you go with cathode windings?
Also some Spice-commandos should be adjusted.
Last edited:
Vincent,
Thanks for the link.
Now, I must say, and maybe it's a novice reaction, that to purchase "special" transformers for a project that I don't know if it will please me or meet my expectations worries me a little bit.........
But maybe I should not?
Here is my version of GU-50 PP triode:
Single ended driver stage and cathode windings to keep the output impedance low (enough) without the means of gNFB.
Should be finished during the summer..
Wow that should take care of the drive problem! I am eager to see your measurements when it is done!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.