Today we have a lot of tube amps output Transfourmer that are only 0-4-8 taps an no 16ohm taps, i have moved the ground from the 0 to the 4ohm tap . Then put the Speakers on the 0-8 ohm taps.There is a more open fuller sound,gives great sound on the Magnepans an Martinlogan i have, Is this a more push pull output?Have others done this,any info
Thanks for your time
Thanks for your time
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![800px-Kt88_power_tubes_in_traynor_yba200_amplifier[1] (2).jpg](/community/data/attachments/213/213596-9bde092e08cdf913ea1c879fa944a687.jpg?hash=m94JLgjN-R)
Depending on the schematic this will reduce the amount of global negative feedback.
Can't think of any other effect..
Can't think of any other effect..
I, too, think that you have simply reduced the negative feedback and that is why is sounds different.
This reduces the amplifier's damping factor and possibly increases the susceptibility to the amp oscillating.
The other effect is that ground is now referenced as a virtual ground between the two speaker terminals, which has no audible effect at all.
That is not quite right, the 4 ohm tap is not the middle between 0 and 8 ohm.
It would be the middle tap between 0 and 16 ohm.
Calculate the voltages if you dont believe me 🙂
Ground is somewhere between the two speaker lines, but not half-way between.
Reducing the NFB will probably reduce the risk of oscillation, but may give a more lumpy frequency response and more distortion.
Reducing the NFB will probably reduce the risk of oscillation, but may give a more lumpy frequency response and more distortion.
more
[Reducing the NFB will probably reduce the risk of oscillation,]
I have even ran the Amp with out any Ground an did not get any oscillation,
i get the less feedback well give more output,but the sound is great but the panels can eat power an Keep on trucking, I think that ARC output tube setup is Geart,why more dont do this can anyone Say??I dont buy the front end ARC thay love more an more parts,not my bag like the output setup,I have a pr of Dya MK3 setup as the ARC70.Just the output tubes.The Amps are full pentoid not UL.
Thanks for all an more input an info
[Reducing the NFB will probably reduce the risk of oscillation,]
I have even ran the Amp with out any Ground an did not get any oscillation,
i get the less feedback well give more output,but the sound is great but the panels can eat power an Keep on trucking, I think that ARC output tube setup is Geart,why more dont do this can anyone Say??I dont buy the front end ARC thay love more an more parts,not my bag like the output setup,I have a pr of Dya MK3 setup as the ARC70.Just the output tubes.The Amps are full pentoid not UL.
Thanks for all an more input an info
Attachments
![ARST-70schematic[1].jpg](/community/data/attachments/214/214170-36cc831ad32ef574cca94b831b2e9308.jpg?hash=NsyDGtMu9X)
Yes you are right The amp is a Jolida502a that i have ran with out ground,an now have the 4ohm tap grounded, i was not clear ,The MK3s are set up as the ARC 70 .
thank you
thank you
Do you know if the Lumley M120 power amps have a grounded 4 ohm tap. It seems Audio Research have .... Just that I am struggling to wire my rel sub not knowing the facts...
Just look inside. Is there any connection to the 4 ohm tap other than the output transformer wire?
There is a control tag on the secondary of the output transformer separate to the 4ohm tag. That is where the Black negative wire goes back to the speaker ground connection from. I've just had the output transformers rewound at Surrey Amps on my Lumley M120's ... See my diagram that I put together so I could rebuild ' as the transformers were rebuilt with the original tagging. If you can understand it.... It seems 4-ohm tap is not grounded. I wish Lumley had schematics for this amp. Would have made my life a lot easier.
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It's safe to say that, if the 4 ohm tap were actually grounded, there would be a warning label to that effect
on the chassis near the speaker terminals, to discourage improper wiring.
on the chassis near the speaker terminals, to discourage improper wiring.
yes and that Ground could be connected to the heater.. Making a connection to the filter in the REL sub impossible ?
Anything connected to the outputs (0, 8, 16) that is grounded will upset the operation of the amplifier.
Possibly it could be connected to the 4 ohm (ground) and the 16 ohm (hot).
Possibly it could be connected to the 4 ohm (ground) and the 16 ohm (hot).
