I bought these IT to Thomas Mayer gapped for 10mA SE connected Alt Q 4.5:1.
I guess if I connect Alt Q 4.5:1 the max. Primary DC current is 10mA, but what about if I use other connections? or doesn't matter because all connection are max. gapped for 10mA?
I guess if I connect Alt Q 4.5:1 the max. Primary DC current is 10mA, but what about if I use other connections? or doesn't matter because all connection are max. gapped for 10mA?
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Max DC with the two 2.25 windings in series should be 9mA, or 18mA when connected in parallel.
10mA is max when the four "1" sections are connected in series.
10mA is max when the four "1" sections are connected in series.
I don't understand very well, are you saying Alt Q 4.5:1 can handle 18mA? Attached LL1660 datasheet, thanks.
The datasheet shows, that LL1660/18mA at ALT Q connection the primary at 16mA has 100H inductance (at 0.9T induction).
The source impedance (tube Ri) will be less or equal 3k for undertaken freq. response.
The 100H at 20H represents 12 566 Ohm impedance, so -max- 3k source is OK for this impedance.
If you use 18mA primary static current, the primary inductance will be decreasing a little and the lower -3dB (low THD) limit is increasing.
The guaranteed 57V RMS output (80.6V peek) even "enough" for regular 300B, so this IT (with some restrictions) suitable for two stage amplifier too.
The source impedance (tube Ri) will be less or equal 3k for undertaken freq. response.
The 100H at 20H represents 12 566 Ohm impedance, so -max- 3k source is OK for this impedance.
If you use 18mA primary static current, the primary inductance will be decreasing a little and the lower -3dB (low THD) limit is increasing.
The guaranteed 57V RMS output (80.6V peek) even "enough" for regular 300B, so this IT (with some restrictions) suitable for two stage amplifier too.
18mA vs. 10mA.
Usually the difference is the air gap. The 10mA version (lower air gap) gives higher inductance, than 100H.
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801a has almost twice Ri, than 3k, so no.
Some years ago my friend tried to built 801 preamp with -horribly priced- Noguchi 24k:600 OPT... the LF result was 30Hz -3dB.
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Trioded 4P1L has enough low Ri for this IT.
Usually the difference is the air gap. The 10mA version (lower air gap) gives higher inductance, than 100H.
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801a has almost twice Ri, than 3k, so no.
Some years ago my friend tried to built 801 preamp with -horribly priced- Noguchi 24k:600 OPT... the LF result was 30Hz -3dB.
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Trioded 4P1L has enough low Ri for this IT.
Thanks Bela, I guess Alt S 4:4,5 130H source impedance 14K, right?
I also made mistakes also buying...
I also made mistakes also buying...
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130H at 20Hz has about 13k load impedance ... so I never use more than 3-4k source for it.
I'm not sure, that 4P1L g2-g3 as anode has enough low impedance for this load.
I'm not sure, that 4P1L g2-g3 as anode has enough low impedance for this load.
So what connection Alt Q 4,5:1 for Lundhal LL1660 and what schematic to use with 4P1L as lineamp?
Thanks Bela, C2 & R3 are to simulate the load, right?
The LL1660 needs zobel for secundary?
Do you know the output impedance?
The LL1660 needs zobel for secundary?
Do you know the output impedance?
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Without compensation (series/parallel zobel/snubber) each LL1660 has enough large bump at few ten kHz.
The output impedance depends of ratio of OPT and tube's output impedance.
The output impedance depends of ratio of OPT and tube's output impedance.
I have the same 'for Thomas Mayer 10mA', and it could be seen as a "LL1660 look-alike" transformer and so I was also puzzling:
Does the 10mA designation imply it is an adaptation of the standard 18mA version . . .??
All that Henry and Herz is bad for my Herz (heart).
I still have it on my shelf.
Does the 10mA designation imply it is an adaptation of the standard 18mA version . . .??
All that Henry and Herz is bad for my Herz (heart).
I still have it on my shelf.
Ditto. I met Per Lundahl but like always I was so stupid not to ask.
Nevertheless - I expect Alt S (all in series original primaries ) and Alt V (parallel 'primaries' in an inverted method = original secondary treated as input) to be the 'only' alternatives;
All in series, max 10mA? (yes of course. . .) So altS is already stated as correct specifically with 10mA - - because the type alteady says 10mA. [and that would give 130 Henry, BW 25-40k]...
In my bench top I did not get convincing results yet. - in what I tested there is ringing so I stopped investigating.
In setting up - There must be more, like an expected damping from a certain tube output impedance. ??
Or --> is the type correct??
I checked the Alt B. mentioned in the screenshot with the feedback from Lundahl. Now that gives a clue. LL1660S with Faraday shield might be the TM version; because that can be used in an Alt A. and Alt B. (The standard LL1660 has other alternatives, M, N, Q, ST, V. . ).
Test: are there two extra secondary pins 13/18 that should not have a connection, and tested with a capacitance meter (ging maybe 100pF)?.
I tried to find my transformers, could not find them in my Big Stash. 🤢
Nevertheless - I expect Alt S (all in series original primaries ) and Alt V (parallel 'primaries' in an inverted method = original secondary treated as input) to be the 'only' alternatives;
All in series, max 10mA? (yes of course. . .) So altS is already stated as correct specifically with 10mA - - because the type alteady says 10mA. [and that would give 130 Henry, BW 25-40k]...
In my bench top I did not get convincing results yet. - in what I tested there is ringing so I stopped investigating.
In setting up - There must be more, like an expected damping from a certain tube output impedance. ??
Or --> is the type correct??
I checked the Alt B. mentioned in the screenshot with the feedback from Lundahl. Now that gives a clue. LL1660S with Faraday shield might be the TM version; because that can be used in an Alt A. and Alt B. (The standard LL1660 has other alternatives, M, N, Q, ST, V. . ).
Test: are there two extra secondary pins 13/18 that should not have a connection, and tested with a capacitance meter (ging maybe 100pF)?.
I tried to find my transformers, could not find them in my Big Stash. 🤢