DATA.
Hi,
Are these the respective data for the OPTs you have?
primary impedance Raa
2491 ohms
secondary impedance Rls
4 ohms
turns ratio Np/Ns
24.957
-3dB frequency range
5 - 91,000 Hz
nominal power Pn (1)
13 watts
lowest full power frequency fpnom
20 Hz
total primary inductance Lp (2)
18 H
primary leakage inductance Lsp
5.5 mH
effectice primary capacitance Cip
1 nF
saturation primary DC-current Idc
204 mA
primary winding resistance Rip
40 ohms
secondary winding resistance Ris
0.1 ohms
tubes plate resistance rp
700 ohms (300B)
Insertion loss Iloss
0.175 dB
Q-factor 2nd order HF roll-off Q
0.487 (5)
HF roll-off specific frequency Fo
147,206 Hz (5)
And:
primary impedance Raa
3486 ohms
secondary impedance Rls
4 - 8 ohms
turns ratio Np/Ns
29,522
-3dB frequency range
4 - 90,000 Hz
nominal power Pn (1)
13 watts
lowest full power frequency fpnom
20 Hz
total primary inductance Lp (2)
28 H
primary leakage inductance Lsp
7 mH
effectice primary capacitance Cip
1.1 nF
saturation primary DC-current Idc
173 mA
primary winding resistance Rip
50 ohms
secondary winding resistance Ris
0.1 ohms
tubes plate resistance rp
700 ohms (300B)
Insertion loss Iloss
0.168 dB
Q-factor 2nd order HF roll-off Q
0.493 (5)
HF roll-off specific frequency Fo
142,500 Hz (5)
Cheers,
Hi,
Are these the respective data for the OPTs you have?
primary impedance Raa
2491 ohms
secondary impedance Rls
4 ohms
turns ratio Np/Ns
24.957
-3dB frequency range
5 - 91,000 Hz
nominal power Pn (1)
13 watts
lowest full power frequency fpnom
20 Hz
total primary inductance Lp (2)
18 H
primary leakage inductance Lsp
5.5 mH
effectice primary capacitance Cip
1 nF
saturation primary DC-current Idc
204 mA
primary winding resistance Rip
40 ohms
secondary winding resistance Ris
0.1 ohms
tubes plate resistance rp
700 ohms (300B)
Insertion loss Iloss
0.175 dB
Q-factor 2nd order HF roll-off Q
0.487 (5)
HF roll-off specific frequency Fo
147,206 Hz (5)
And:
primary impedance Raa
3486 ohms
secondary impedance Rls
4 - 8 ohms
turns ratio Np/Ns
29,522
-3dB frequency range
4 - 90,000 Hz
nominal power Pn (1)
13 watts
lowest full power frequency fpnom
20 Hz
total primary inductance Lp (2)
28 H
primary leakage inductance Lsp
7 mH
effectice primary capacitance Cip
1.1 nF
saturation primary DC-current Idc
173 mA
primary winding resistance Rip
50 ohms
secondary winding resistance Ris
0.1 ohms
tubes plate resistance rp
700 ohms (300B)
Insertion loss Iloss
0.168 dB
Q-factor 2nd order HF roll-off Q
0.493 (5)
HF roll-off specific frequency Fo
142,500 Hz (5)
Cheers,
indeed, those are the beasts
that weigh 5,4 kg each. Last year I had made an amp with them and i got some back-injuries from lifting them that costed me several weeks on the bed with very severe pains and I even don't want to know the financial costs of that amp including misses income and medical costs.
I use a normal untweaked sony scd 555 es cd-player (european model), so I suppose it has about 2 volts output.
I will try to ask the developer of the OPT (van der Veen) if he has a clue.
Jaap
that weigh 5,4 kg each. Last year I had made an amp with them and i got some back-injuries from lifting them that costed me several weeks on the bed with very severe pains and I even don't want to know the financial costs of that amp including misses income and medical costs.
I use a normal untweaked sony scd 555 es cd-player (european model), so I suppose it has about 2 volts output.
I will try to ask the developer of the OPT (van der Veen) if he has a clue.
Jaap
BEASTS.
Hi Jaap,
Sorry to hear about the back injuries...
It's been years since I talked to Menno.
In those days he had an "Inginieurs Bureau" and my former company assisted in a project he ran involving some EL 509s, can't quite remember what for though.
Anyway both xformers should be high quality thingies.
Cheers,
Hi Jaap,
Sorry to hear about the back injuries...
It's been years since I talked to Menno.
In those days he had an "Inginieurs Bureau" and my former company assisted in a project he ran involving some EL 509s, can't quite remember what for though.
Anyway both xformers should be high quality thingies.
Cheers,
perhaps I am a sinner
I have a 1K resistor between screen and plate
I thought the KT88 would still be in triode mode, but a little doubt is creeping into my mind
Could this resistor be connected with the reported problem ?
What is the best connection for a triode KT88 ? Plate directly on the screen or perhaps a smaller resistor in between (100R) ?
Jaap
I have a 1K resistor between screen and plate
I thought the KT88 would still be in triode mode, but a little doubt is creeping into my mind
Could this resistor be connected with the reported problem ?
What is the best connection for a triode KT88 ? Plate directly on the screen or perhaps a smaller resistor in between (100R) ?
Jaap
...KT88 triode connected...
As long as the screen exactly tracks the signal voltage variation of the anode the 88 is working in triode mode... This is not the only way of triode connecting a pentode or tetrode but it's the most common.
However some ways of connecting the screen and anode work better than others... Direct connection can cause oscillation so normally it's better to have a stopper resister (100R-1000R) between the two and since it's not a good idea to run the screen at higher voltage than the anode putting the resistor between anode and screen is preferred with B+ connected to the anode.
I prefer to set the screen about 30Volts negative from the anode dc wise but bypassed at ac. To me it sounds better and one day I will measure it and see if it measures better too....
hope that helps
James
As long as the screen exactly tracks the signal voltage variation of the anode the 88 is working in triode mode... This is not the only way of triode connecting a pentode or tetrode but it's the most common.
However some ways of connecting the screen and anode work better than others... Direct connection can cause oscillation so normally it's better to have a stopper resister (100R-1000R) between the two and since it's not a good idea to run the screen at higher voltage than the anode putting the resistor between anode and screen is preferred with B+ connected to the anode.
I prefer to set the screen about 30Volts negative from the anode dc wise but bypassed at ac. To me it sounds better and one day I will measure it and see if it measures better too....
hope that helps
James
in the mean time
I found a design with the 6c45 which is regarded as a better hifi-tube than the 12ax7:
http://www.diyforum.net/blasten/Scheman/SE KT88 REV0.pdf
There are also some designs of kt88se on:
www.diyparadiso.com
regards,
Jaap
I found a design with the 6c45 which is regarded as a better hifi-tube than the 12ax7:
http://www.diyforum.net/blasten/Scheman/SE KT88 REV0.pdf
There are also some designs of kt88se on:
www.diyparadiso.com
regards,
Jaap
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