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RS1003 in SE triode-UL monoblocks

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davorin

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Joined 2005
Curves for triode connection RS1003 and SRS551 tubes (2 pictures with 2x10 steps; V:20mA/div.; H:100V/div; Ug1:2V/step).
Curve tracer have only 10 steps, and I must test tube at first Ug1=0-20V, and second Ug1=20-40V (negative voltage:D).
 

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V

vtr

Member
Joined 2010
only to repeat to

davorin said:
Lights (dark red) from center inside tube is NORMAL for RS1003 tube! No problem with screen voltage over 500V! I must use grid stopers with ferite-pearl for G1 and G2 to prevent oscilations in HF (VHF, UHF, etc.) region, because tube have very high Gm!
Now, I am testing RS1003 in experimental PP amp with Ua=900V and UG2=450V, and have no problem (Pout>200W!).
Click to expand...

to understand correct. i have seen the grid wire of the g2 grid glowing not the heater or anode, and i hae heard this from several people. the test was done in triode mode, in pentode mode with some difference between g2 and anode everything was fine
 
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davorin

Member
Joined 2005
vtr said:
to understand correct. i have seen the grid wire of the g2 grid glowing not the heater or anode, and i hae heard this from several people. the test was done in triode mode, in pentode mode with some difference between g2 and anode everything was fine
Click to expand...

My amps works ~500-600 hours in triode mode, and have no problems with this glowing!
Voltage over screen grid stoper 470 Ohms is ~1,5V (no signal), curent is ~3,2mA, and with UG2-Uk=405V, and disipation of screen is ~1,3W.
With signal (full power; P=14W) voltage over 470V is ~8V, current is ~10mA, and disipation is PG2<5W. Maximum disipation for G2 is 9W (from data sheet), and I think that tube working properly.
At UL-connection voltake over 470 Ohms is ~8V, curent is 17mA (maximum power), and with voltage UG2-Uk=405V, maximum sreen disipation is under 7W.
Next week I'll replace screen grid resistor 470 Ohms with 1 kOhma to see diferences.
 
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davorin

Member
Joined 2005
Before 6-7 monts, I build 2 adapters for RS1003 coket to octal base (wired like EL34 tube), and put 2 RS1003 in "Dynacord" A1000 (output amplifier with 4 tubes EL34 and 1 tube ECC81; Pout=160W; Ua=820V Ug2=430V) for substitute 4 EL34 tubes. With only small modification (and adjust) in bias cercuits, tubes works perfect (original "Dynacord" transformer with 4kOhma primary impedance) with over 200W of output power (limit was smal size of original output transformer iron core!).
Maybee You can try with 1 kOhm screen grid stopers, and than check Ig2 curent (I can't try before next mount, before I am not at home), or try with 470 ohms with more curent control?
I don't know, maybee is more version of RS1003 tubes (I have SIEMENS, TELEFUNKEN and AEG, but there is no differece between them inside)?
I also try SRS551 (WEB-RFT), and results are the same as RS1003 tubes.
 
D

davorin

Member
Joined 2005
Quote:
Originally Posted by Zoran View Post
great +++
Is this the answer for question above ?

Quote:
Does anyone take comparision on sound quality this tube with usual one, eg KT120, KT90, KT88, 813, 811A... ?

davorin said:
Sonds very good, more like some other bigger transmitting tubes with direct heating, not like 2-3 paralell connecteed EL34, KT88 or GU50 tubes.
In triode connection sunds like 811A or 812A, but with less distorsion. UL-connection provide much more power, and can drive less sensitive speakers. Less detail than triode connect, but with BIGG sound for rock, metal and simphonical music.
Click to expand...
After 200 working hours, sound is better, loud, clear, strong with deep solid bass, precision middle, and very detai treble.
New SRS551(RFT/RWN) tubes are little stronger than RS1003(SIEMENS).
 
D

davorin

Member
Joined 2005
tcqanh said:
davorin,

my plan RS1003 here : V B+ 500V, fixed bias in triode strapped.

is it safe for G2 (G2 resistor 1K) at max power ?

driver will be D3a/ 7788 or 6e5 with plate choke . what do you think about this ?
Click to expand...
Yes, 1kOhm is good value for screen stoper and curent limiter resistor.
With Ua=500V, and Iag2 120-130mA You can expect ~15-16W output power, and output transformer must bee very, very big!
D3a is my favorite tube (maybee bether for phono pre-amp:D), but 6E5S is also very good choise.
Very good tubes for drive are 6P15S (and very cheep!:)), 12HG7, 12GN7, 6CL6, and many others video output pentodes/tetrodes.
You do not need choke, because RS1003 is very easy to drive, with maksimum ~24-25Vpp swing at grid.
 
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T

tcqanh

Member
Joined 2011
davorin said:
Yes, 1kOhm is good value for screen stoper and curent limiter resistor.
With Ua=500V, and Iag2 120-130mA You can expect ~15-16W output power, and output transformer must bee very, very big!
Click to expand...

my OPT use Fe Silic 115x50mm with airgap 0.4mm, I hope it can run 110mA and get over 15W P-out.

D3a is my favorite tube (maybee bether for phono pre-amp:D), but 6E5S is also very good choise.
Click to expand...

I did D3A for my pre phono. this tube is not bad :)


You do not need choke, because RS1003 is very easy to drive, with maksimum ~24-25Vpp swing at grid.
Click to expand...

Could you show me how much gain of RS1003 with Va 500V, Ik 110mA ?

12Au7 input and 6p14p driver seems suitable...
 
D

davorin

Member
Joined 2005
tcqanh said:
my OPT use Fe Silic 115x50mm with airgap 0.4mm, I hope it can run 110mA and get over 15W P-out.
Click to expand...
You transformer 115x50 (~3,8x5cm=19cm2 BRUTTO;~15-16cm2 NETTO) is good for 15W/25HZ, but with air-gap 0,4mm You have not enough primary inductance. You need transformer with 24-25cm2 (EI120-120x60-4x6cm or EI150-150x50-5x5cm) with air-gap 0,4-0,5mm and primary inductance not less than 12H.
 
D

davorin

Member
Joined 2005
tcqanh said:
Could you show me how much gain of RS1003 with Va 500V, Ik 110mA ?

12Au7 input and 6p14p driver seems suitable...
Click to expand...

Gain of RS1003 at Uag2=500V and Iag2=115-125mA is ~21x, and You need drive tube with ~15x real gain/NO-ShadeFB, or ~22x-30x with 4,5-6dB ShadeFB.
You can do it with only one tube (EL83/803 or 6P15S are ideal for that job with gain ~25x, and low internal resistance), because 2 tubes have much more distortions than one!
6P14P/EL84/6BQ5 (triode connected) is NOT best choice with internal resistance ~5kOhms and low gain!
Total input capacitance for RS1003 (Cout of drive tube, Cin of output tube and Cmiler=Cg1g2+Cg1a x21 of output tube) is totl ~160pF and give Rc~25kOhms at 40kHz(-3dB).
With 150kOhms grid resistance (Rg1 of output tube) in paralel (total ~18kOhma) You need drive tube with internal resistance less than 1,8kOhms.(18/10 kOhms)
EL83 with internal resistance ~1kOhm in triode connection is good choice, but many other tubes are also good.
12Au7/ECC82 is not to much linear, and You can use many other more linear tubes like 6CG7, 6FQ7, 12BH7, 6N6P, 6N1P, 6DJ8/ECC88 or more others tubes with NOVAL sockets.
 
T

tcqanh

Member
Joined 2011
davorin said:
You transformer 115x50 (~3,8x5cm=19cm2 BRUTTO;~15-16cm2 NETTO) is good for 15W/25HZ, but with air-gap 0,4mm You have not enough primary inductance. You need transformer with 24-25cm2 (EI120-120x60-4x6cm or EI150-150x50-5x5cm) with air-gap 0,4-0,5mm and primary inductance not less than 12H.
Click to expand...

3.8cmX5cm is true for my OPT. Henry meter shows nearly 20H at level scale 100Hz, because my Fe silic is quite good (grey Fe-silic lamination). I don't know how exactly my Henry meter is, but I believe Henry meter become more precicse only at 20Hz scale.
 
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T

tcqanh

Member
Joined 2011
davorin said:
Gain of RS1003 at Uag2=500V and Iag2=115-125mA is ~21x, and You need drive tube with ~15x real gain/NO-ShadeFB, or ~22x-30x with 4,5-6dB ShadeFB.
You can do it with only one tube (EL83/803 or 6P15S are ideal for that job with gain ~25x, and low internal resistance), because 2 tubes have much more distortions than one!
6P14P/EL84/6BQ5 (triode connected) is NOT best choice with internal resistance ~5kOhms and low gain!
Total input capacitance for RS1003 (Cout of drive tube, Cin of output tube and Cmiler=Cg1g2+Cg1a x21 of output tube) is totl ~160pF and give Rc~25kOhms at 40kHz(-3dB).
With 150kOhms grid resistance (Rg1 of output tube) in paralel (total ~18kOhma) You need drive tube with internal resistance less than 1,8kOhms.(18/10 kOhms)
EL83 with internal resistance ~1kOhm in triode connection is good choice, but many other tubes are also good.
12Au7/ECC82 is not to much linear, and You can use many other more linear tubes like 6CG7, 6FQ7, 12BH7, 6N6P, 6N1P, 6DJ8/ECC88 or more others tubes with NOVAL sockets.
Click to expand...

your information is really helpful. agree with this. tube driver has lower internal resistance better.

I did use some low resistance tube, like E801F with Ri about 1K in triode connection, 6FD7 unit 2 with Ri approximate 800 ohms. I have also ED800 (Ri 200 ohms) but this tube is running at high current.

EL83 I have no, but I can try to find them.

what do you think about tube 6C19P ?

paralleled 6922 or 5687 or 6h30 for noval base/ 6BX7 or 6BL7 for octal base... will be hopefully to get very low Zout for driver stage :)
 
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