after a 5min on my calc. this is what i came up with:
calculated with +/-21V. dont know if that is correct.
bias of 0.5A will give 21W dissipation pr ch. i dont know if that chassis can handle more then that.
and 0.5A bias, gives 0.5W classA at 4ohm🙂
calculated with +/-21V. dont know if that is correct.
bias of 0.5A will give 21W dissipation pr ch. i dont know if that chassis can handle more then that.
and 0.5A bias, gives 0.5W classA at 4ohm🙂
Well the amp just came, im using at a home as we dont have our campervan yet. and im extremely surprised, im only running 2.5amps power suupply into this thing at the moment and altho a slightly distorted at high levels it sounds amazing and i feel as good as the F5 that i built properly.
Thanks for all your help
what happens if you put a 2.5 amp powersuply to a lead acid battery ? i presume u need some kind of protection so the battery dosent reverse power blow up the PSU. was thinking of using it as a charger for now.
gonna order some batterys today...
permaneder; ill check the voltage drop soon cheers for that info
JGuilherme; midrange sounds great at the moment but i know the bass wont be punchy with this awfull PSU lol
Audiosan; it is a cheap amp that is scraped.... what do you mean with the word scraped sorry. cheers
Ok will check the voltages and get back, got to play live music tonight with a band good good fun 🙂
Thanks for all your help
what happens if you put a 2.5 amp powersuply to a lead acid battery ? i presume u need some kind of protection so the battery dosent reverse power blow up the PSU. was thinking of using it as a charger for now.
gonna order some batterys today...
permaneder; ill check the voltage drop soon cheers for that info
JGuilherme; midrange sounds great at the moment but i know the bass wont be punchy with this awfull PSU lol
Audiosan; it is a cheap amp that is scraped.... what do you mean with the word scraped sorry. cheers
Ok will check the voltages and get back, got to play live music tonight with a band good good fun 🙂
permaneder: The power supply is a pulsed two-rail type. Correctly dimensioned, it should measure at least +-20V. It converts the 12V battery voltage to 2 x 21V.
thats right confirmed 🙂
do i need to measure both resistors for bias, also in the orignal circuit
Hiraga 20W Amp
the resistors are 0.33ohm and mine are 0.47ohm, does this mean everything will be confusing.
ok so i have about
0.14v on each resistor - 0.47ohm = 0.29787amps lol thats rather low!
also i noticed the heatsinks are warm and the bar over the transistors it hotish, so im going to replace the sill pads with mica and thermal paste. done this before and it worked wonders. then ill add some more heatsinkage and try to bias up a little.
thats right confirmed 🙂
do i need to measure both resistors for bias, also in the orignal circuit
Hiraga 20W Amp
the resistors are 0.33ohm and mine are 0.47ohm, does this mean everything will be confusing.
ok so i have about
0.14v on each resistor - 0.47ohm = 0.29787amps lol thats rather low!
also i noticed the heatsinks are warm and the bar over the transistors it hotish, so im going to replace the sill pads with mica and thermal paste. done this before and it worked wonders. then ill add some more heatsinkage and try to bias up a little.
Rixsta, your link shows the 30W version, higher supply voltage, higher bias.
Yours is the elder 20W version and the .47 Ohm collector resistors are OK. The voltage drop across the two resistors should be similar and indicates the bias current.
Yours is the elder 20W version and the .47 Ohm collector resistors are OK. The voltage drop across the two resistors should be similar and indicates the bias current.
This kit is still on sale but states replacement output's. What do you think?
Value Designator Qty Remark
1R/3W R11,R14 2 3W *resistor
10 R16 1 DALE RN60D 1% resistor
243 R10 1 DALE RN60D 1% resistor
476 R2,R3 2 DALE RN60D 1% resistor
1K R1 1 DALE RN60D 1% resistor
2.21K R6,R7,R8,R9 4 DALE RN60D 1% resistor
45.3K R15 1 DALE RN60D 1% resistor
2SA872 Q5 1 Hitachi BJT
2SC1775 Q1 1 Hitachi BJT
2SD756 Q2 1 Hitachi BJT
2SB716 Q4 1 Hitachi BJT
2SJ74BL Q7 1 Toshiba JFET
2SK170BL Q3 1 Toshiba JFET
47uF/25V C1,C2 2 Nichcon Muse KZ E-Cap
100R Rp1 1 Bourns Multi-turn
2SD1063 Q6 1 Sanyo Power BJT
2SB827 Q8 1 Sanyo Power BJT
NI. R5
NI. R4
Last edited:
Jean Hiraga used the lowest hfe 'O' Toshiba 2sd844/2sb754 output transistors with 15 Mhz Ft and 250 pF Cob. For him this association with the 2sb716/2sd756 gave the best result. The new combination may not meet requirements. The circuit was designed for 13v max. It may work with higher voltage but new optmization, voltages and bias current could be required. Circuit may not be stable in HF. Spectrum analyzer and distorsion meter shoud be involved. It may work but in a different way compared to the original.
I started building my "Monster".
I got the trannies from MCM.
Today I started measuring the 2sc1775. BUT: hfe is between 33 and 304. It should be 400 to 800. Tomorrow I will measure the 2sa872.
What now? Where can I get 2sc1775 that fit? Should I go for BC550/560 (hfe>370) instead??? Or the sanyo trannies mentioned earlier (2SA1016/2SC2362
Dirk
I got the trannies from MCM.
Today I started measuring the 2sc1775. BUT: hfe is between 33 and 304. It should be 400 to 800. Tomorrow I will measure the 2sa872.
What now? Where can I get 2sc1775 that fit? Should I go for BC550/560 (hfe>370) instead??? Or the sanyo trannies mentioned earlier (2SA1016/2SC2362
Dirk
Who is MCM?
Might be that I have a couple of 2SC1775 over. I'll have a look when I'm back home and will keep you informed.
Hi Dirk,
In my parts, 2SC1775A E grade have Hfe above 550 and 2SA872A E around 450. Try to find 2SA1775A with D grade maybe can match with 2SA872A
Best regards,
Josh
In my parts, 2SC1775A E grade have Hfe above 550 and 2SA872A E around 450. Try to find 2SA1775A with D grade maybe can match with 2SA872A
Best regards,
Josh
My final results...
I used this to measure:
NEWEST Transistor SMD Tester Detector *NPN PNP MOSFET /diode /resistor capacitor | eBay
Results 2SC1775:
Most: 40-300, 4 pieces >450 (all: 24)
Results 2SA872:
Range: 230-250, (all: 25)
Results 2SB716:
Range: 330-350, (all: 25)
Results 2SD756:
Range: 310-420, most near 350, (all: 25)
Results 2SB754:
Range: 180-370, a lot around 280, (all: 19)
Results 2SD844:
Range: 24-81, some around 60, (all: 25)
Well, I feel I should get these:
(20pcs) 2SD844 Original Pulled Toshiba Silicon NPN Power Transistor D844 (20pcs) | eBay
but the seller does not tell me the hfe group.
Anyone who has a lot of 2SD844???
My wishlist:
21 x 2sc1775
25 x 2sa872
6 x 2sb756
25 x 2sd844
This thread said, 2sc2362/2sa1016 and 2sc3423/2sa1360 are perfect replacements for the cascade. If so, where could I source them?
I'm quite sure, bc550/bc560 would maybe be ok.
But: 2SD844 wit hfe < 200 seems worthless...
Please comment / help, part offerings...
Dirk
I used this to measure:
NEWEST Transistor SMD Tester Detector *NPN PNP MOSFET /diode /resistor capacitor | eBay
Results 2SC1775:
Most: 40-300, 4 pieces >450 (all: 24)
Results 2SA872:
Range: 230-250, (all: 25)
Results 2SB716:
Range: 330-350, (all: 25)
Results 2SD756:
Range: 310-420, most near 350, (all: 25)
Results 2SB754:
Range: 180-370, a lot around 280, (all: 19)
Results 2SD844:
Range: 24-81, some around 60, (all: 25)
Well, I feel I should get these:
(20pcs) 2SD844 Original Pulled Toshiba Silicon NPN Power Transistor D844 (20pcs) | eBay
but the seller does not tell me the hfe group.
Anyone who has a lot of 2SD844???
My wishlist:
21 x 2sc1775
25 x 2sa872
6 x 2sb756
25 x 2sd844
This thread said, 2sc2362/2sa1016 and 2sc3423/2sa1360 are perfect replacements for the cascade. If so, where could I source them?
I'm quite sure, bc550/bc560 would maybe be ok.
But: 2SD844 wit hfe < 200 seems worthless...
Please comment / help, part offerings...
Dirk
Hello
I have at least 40PC 2SA872A E 100% orig. I have to measure them, usually they are between 400-450
All do these bunch I didn't measure them.
I would be interested on trade 2SA872 to 2SC1775 if someone interested
Please ask Dan who built the Hiraga Supper Class A, he also built the Le Monstre and to him some Sanken power transistor sounded better than the Toshiba..
Greetings Gabor
I have at least 40PC 2SA872A E 100% orig. I have to measure them, usually they are between 400-450
All do these bunch I didn't measure them.
I would be interested on trade 2SA872 to 2SC1775 if someone interested
Please ask Dan who built the Hiraga Supper Class A, he also built the Le Monstre and to him some Sanken power transistor sounded better than the Toshiba..
Greetings Gabor
I am amazed to see that no one pointed out the missing base to emitter resistors on the output devices. They are necessary to eliminate cross-conduction in output devices.
Lineup, How could you miss that buddy?
Lineup, How could you miss that buddy?
That is the best.
Well done Workhorse.
I have tried with other placement of that resistor. One from each base to output.
And I have tried another alternative.
But a single resistor Base to Base gives lowest distortion.
I suggest one 100 Ohm resistor from base to base.
Well done Workhorse.
I have tried with other placement of that resistor. One from each base to output.
And I have tried another alternative.
But a single resistor Base to Base gives lowest distortion.
I suggest one 100 Ohm resistor from base to base.