Speaker sensitivity, SPL at 1Watt and at
1Metre, dB. 
Amp power max for one channel giving 102dB
SPL. ( 105dB SPL, both channels used ) 
PushPull Tube type recommended 
Single Ended Tube type recommended, Multigrids used as tetrodes/pentodes. 
87dB 
32 Watts 
2 x 6550, KT88, KT90. 2 x EL34, 6L6, KT66, 807. 4 x EL84, 6V6. 
1 x 13E1, 4 x EL34, 6L6, KT66, 807, 300B parallel 3 x 6550, KT88, KT90 parallel. 
90dB 
16 Watts 
2 x 6550, KT88, KT90, 300B. 2 x EL34, 6L6, KT66, 2 x EL84, 6V6 4 x 2A3 
1 x 13E1, 1 x 845, 211. 2 x EL34, 6L6, KT66, 807, 300B parallel 2 x 6550, KT88, KT90 parallel. 4 x EL84, 6V6 parallel. 
93dB 
8 Watts 
2 x 300B, 2A3. 2 x EL34, 6L6, KT66, 2 x EL84, 6V6, 6BM8, 6GW8 
1 x 845, 211, 300B. 2 x 2A3 parallel 1 x 6550, KT88, KT90, EL34, KT66, 6L6, 807. 3 x EL84, 6V6 parallel 
96dB 
4 Watts 
2 x 2A3, 45. 2 x EL84, 6V6, 6BM8, 6GW8 
1 x 2A3, 6550, KT88, KT90, EL34, KT66, 6L6, 807, EL84, 6V6. 
99dB 
2 Watts 
2 x 2A3, 45. 2 x EL84, 6V6, 6BM8, 6GW8 
1 x 2A3, 45. 1 x EL34, KT66, 6L6, 807, EL84, 6V6, 6BM8, 6GW8. 
102dB 
1 Watt  2 x 2A3, 45. 2 x EL84, 6V6, 6BM8, 6GW8 
1 x 45. 1 x EL84, 6V6, 6BM8, 6GW8. 
1 
Output
transformer
number,

OP1 
2 
Push Pull or Single Ended ?  PP 
3 
Weight in Kg  7.4 
4 
Overall size, length x width x height, mm  176 x 132 x 138 
5 
Turn ratio, TR, Pri to Sec  23.7 : 1 
6 
Impedance
ratio, Pri to Sec, ohms 
562 : 1 
7 
Primary load x secondary nominal centre
load value, ohms. 
2,845 x 5.0 
8 
Primary turns, NP, and wire size, Cu dia, mm  1,496 x 0.45 
9 
Primary layers x turns per layer  11 at 136t 
10 
Primary section number, all in series, 
11 
11 
Secondary
turns, NS 
63 
12  Secondary layers x turns per layer x wire size, Cu dia, mm  12 x 63 x 1.0 
13 
Number of parallel Secondary sections x Secondary turns per section  12 x 63 
14 
Grain oriented steel core with max µ > 4,500, description  double Ccores 
15 
Afe,
Tongue
x
Stack,
or
total
strip
build up x strip width, T x S, mm x mm 
52 x 52 
16 
Window
size,
L
x
H,
mm
x
mm 
76 x 28 
17 
Iron path Magnetic Length, ML, mm  296 
18 
Insulation,
Nomex
or
other,
P
to
S,
mm 
0.22 
19 
Average turn length, TL, mm  300 
20 
Primary winding resistance, RwP, ohms  50 
21 
Secondary winding resistance, PwS, ohms 
0.036 
22 
Total winding resistance RwP + RwS at
primary, ohms 
70 
23 
Total winding losses, % 
2.5 
24 
Maximum allowable current density in any winding at idle, Amps dc per sq.mm  2 
25 
Maximum continuous allowable dc or ac
current, primary wire, Amps 
0.48 
26 
Maximum design value for dc current, primary wire, for SE operation, Amps  NA 
27 
Load values for tests, primary anode load x
secondary load, ohms. 
2,845 x 5.0 
28 
Nominal Anode Source resistance ( between
highest and lowest Ra possible ) for tests, ohms 
2,845 
29 
Maximum primary inductance, PP operation, Lpmax, no air gap, µ > 4,500, Henrys, H  128 
30 
Minimum Primary inductance, PP operation, Lpmin, approximate, no air gap, µ = 1,000 at low Vo, Henrys, H  28.4 
31 
Effective permeability, µe, with air gap for SE operation, Bdc = 0.75Tesla  NA 
32 
Air gap calculated for reducing maximum
iron µ to above wanted µe, mm, ( confirmed by
experiment in amp ) 
NA 
33 
Non magnetic material thickness used to gap
cores on both breaks in magnetic loops, mm 
NA 
34  Primary inductance, Lp, for SE operation, for µe, Henrys, H  NA 
35  Leakage Inductance, at primary input, LL, mH  0.24 
36  Shunt
capacitance,
at
each
anode
primary
input/s,
pF 
3,000 
37  Maximum audio power at anodes for THD <
2%, at 1kHz, at rated RL loaded, Watts 
135.0 
38  Maximum
anode
signal
voltage
across
primary
at
THD < 2%, Vrms 
620 
39  Maximum class AB1 power, PP operation, at rated RL, Watts  135 
40  Maximum class A1 power at rated RL, Watts 
30 
41  Frequency of core saturation at max audio power signal across primary at Bac + Bdc = 1.5 Tesla, Hz  22.3 
42  Low frequency cut off at 0.1 x max Vo,
source resistance = 1/2 anode RL, Hz 
8 
43  High frequency cut off with Secondary loaded. Primary source resistance = primary RL, kHz  75 
44  Tubes
usable, type numbers 
6 x KT88 
45  Tube configuration, Ultralinear, UL, Cathode Feedback, CFB, Pentode, P, Beam Tetrode BT, Triode, T.  UL, CFB 
46  Maximum
Idle
dc
anode
and
screen
dissipation
power setting for each tube, Pda,
Watts 
25 
47  Maximum total tube idle dissipation power Pda, Watts  150 
48  Anode to cathode dc supply voltage ( excluding possible cathode biasing voltage ), Ea, Vdc  500 
49  Total
Idle
condition
anode
and
screen
supply
dc current for all output tubes, Idc,
mAdc 
300 
50  Anode plus screen Idc per tube, mAdc 
50 
51 
Actual anode plus screen dissipation in
each output tube ,Watts 
25 
52 
Maximum Idc needed for maximum output power
for stated load, approximate, mAdc 
500 
53 
PP tolerated loads with the tubes above, Primary load : Secondary load, ohms  1,686 : 3.0 2,248 : 4.0 2,800 : 5.0 3,372 : 6.0 4,496 : 8.0 
54 
SE tolerated loads with the tubes above, Primary load : Secondary load, ohms  NA 
1 
Output
transformer
number,

OP1 
2 
Push
Pull or Single Ended ? 
SE 
3 
Weight in Kg  7.4 
4 
Overall size, length x width x height, mm  176 x 132 x 138 
5 
Turn ratio, TR, Pri to Sec  11.85 : 1 
6 
Impedance
ratio, Pri to Sec, ohms 
140.5 : 1 
7 
Primary load x secondary nominal centre
load value, ohms. 
711 x 5.0 
8 
Primary turns, NP, and wire size, Cu dia, mm  1,496 x 0.45 
9 
Primary layers x turns per layer  11 at 136t 
10 
Primary section number, all in series, 
11 
11 
Secondary turns, NS  126 
12  Secondary layers x turns per layer x wire size, Cu dia, mm  12 x 63 x 1.0 
13 
Number of parallel Secondary sections x Secondary turns per section  6 x 126 
14 
Grain oriented steel core with max µ > 4,500, description  double Ccores 
15 
Afe,
Tongue
x
Stack,
or
total
strip
build up x strip width, T x S, mm x mm 
52 x 52 
16 
Window
size,
L
x
H,
mm
x
mm 
76 x 28 
17 
Iron path Magnetic Length, ML, mm  296 
18 
Insulation,
Nomex
or
other,
P
to
S,
mm 
0.22 
19 
Average turn length, TL, mm  300 
20 
Primary winding resistance, RwP, ohms  50 
21 
Secondary winding resistance for NS, RwS,
ohms 
0.144 
22 
Total winding resistance RwP + RwS
appearing at primary input, ohms 
70 
23 
Total winding losses, % 
9.0 
24 
Maximum allowable current density in any winding at idle, Amps dc per sq.mm  2 
25 
Maximum continuous allowable dc or ac
current, primary wire, at 2Amps/sq.mm Cu, 
0.324 
26 
Maximum design value for dc current,
primary wire, for SE operation, Amps 
0.324 
27 
Load values for tests, primary anode load x
secondary load, ohms. 
711 x 5.0 
28 
Nominal Anode Source resistance ( between
highest and lowest Ra possible ) for tests, ohms 
711 
29 
Maximum primary inductance, PP operation,
Lpmax, no air gap, µ > 4,500, Henrys, H 
NA 
30 
Minimum Primary inductance, PP operation, Lpmin, approximate, no air gap, µ = 1,000 at low Vo, Henrys, H  NA 
31 
Effective permeability, µe, with air
gap for SE operation, Bdc = 0.75Tesla 
278 
32 
Air gap calculated for reducing maximum
iron µ to above wanted µe, mm, ( confirm by
experiment in amp! ) 
1.0 
33 
Non magnetic material thickness used to gap
cores on both breaks in magnetic loops, mm 
0.5 
34  Primary inductance, Lp, for SE operation, for µe, Henrys, H  7.9 
35  Leakage Inductance, at primary input, LL, mH  0.3 
36  Shunt
capacitance, at each primary input/s,
pF 
5,000 
37  Maximum audio power at anodes for THD <
2%, at 1kHz, at anode rated RL loaded, Watts 
36.0 
38  Maximum
anode
signal
voltage
across
primary
at
THD < 2%, 
160 
39  Maximum class AB1 power, PP operation, at
rated RL, Watts 
NA 
40  Maximum class A1 power at rated RL, Watts 
36 
41  Frequency of core saturation at max audio power signal across primary at Bac + Bdc = 1.5 Tesla, Hz  14.4 
42  Low frequency cut off at 0.1 x max Vo, source resistance = 1/2 anode RL, Hz  7 
43  High frequency cut off with Secondary loaded. Primary source resistance = primary RL, kHz  75 
44  Tubes
usable, type numbers 
4 x KT88,6550 
45  Tube configuration, Ultralinear, UL, Cathode Feedback, CFB, Pentode, P, Beam Tetrode BT, Triode, T.  SEUL, SECFB 
46  Maximum
Idle
dc
anode
and
screen
dissipation
power setting for each tube, Pda,
Watts 
25 
47  Maximum total tube idle dissipation power
Pda, Watts 
150 
48  Anode to cathode dc supply voltage ( excluding possible cathode biasing voltage ), Ea, Vdc  295 
49  Total
Idle
condition
anode
and
screen
supply
dc current for all output tubes, Idc,
mAdc 
350 
50  Anode plus screen Idc per tube, mAdc 
86 
51 
Actual anode plus screen dissipation in
each output tube ,Watts 
27 
52 
Maximum anode Idc needed for maximum output
power for stated load, approximate, mAdc 
330 
53 
PP tolerated loads with the tubes above,
Primary load : Secondary load, ohms 
NA 
54 
SE tolerated loads with the tubes above,
Primary load : Secondary load, ohms 
423 : 3.0 564 : 4.0 711 : 5.0 846 : 6.0 1,128 : 8.0 