Analyzing 1981 original TS-808

On the TS-9 MOD advanced, I reached the 1982 original TS-9 sound by modifying reissue TS-9. Further more, for getting closer to original TS-808 sound, I collected older original JRC4558Ds.
4 digits number on JRC4558D means like following.
1xxx = made in 1981
0xxx = made in 1980
9xxx = made in 1979
7xxx = made in 1977
Older JRC4558D has purer sound. However, I compared the sound with 1981 TS-808, the sound is still different. 1981 original TS-808 is sweeter and dryer.

The first 1 of Serial number 131522 means that was made in 1981.

The original TS-808 has aged, sweet and dry sound and has longer sustain. The schematic must be the same as others but there are some differences.

1982 original TS-9 1981 original TS-808 Description
OP amp Original 4 digit JRC4558D TI RC4558P Malaysia TI RC4558P made in Malaysia
JFET 2SK30A O rank 2SK44 2SK44maybe made by Sanyo
Clipping diodes Toshiba 1s1588 Look like 1s1588, blue line diodes
16V 10μF Electrolytic capacitor Tall Nichicon capacitor Tall Nichicon capacitor(blue) maybe for audio

Replacing OP amp with RC4558P

I expected the aged dry sound caused by the OP amp. So I got some old TI RC4558P on the auction and install them onto TS-9. In fact, the sound was getting closer to TS808. The sound got rich high and middle. There are two types of TI RC 4558P. One is made in Malaysia and another is made in Japan. Japanese RC4558P has two types of manufacture code, AET and AEB. All are rich sound but purer and tighter with the order of AEB, AET and Malaysia. AEB is the purest. When I turn down the volume, the sound has rich harmonics like the sound on Ray Vaughan's performance with all of TI RC4558P. Japanese AEB is very rare item but Malaysian RC4558P is the best for TS-808 I think. Malaysian RC4558P is not too fat mid and sweet sound. There are slight difference.

Replacing FET 2SK30A with 2SK44

After installing RC 4558P I got aged and dry sound but I became to mind FET's really electronic sound. By replacing 2SK30A with 2SK44, the sound became natural and the tone color became almost the same as original TS-808.

Clipping diodes

Comparing with the TS-808, the starting point of distortion is higher and the sustain is shorter. So, I thought the clipping diodes are different. Then I collected various diodes with blue line and measured the character of positive voltage down. I also measured the diodes of original TS-808 and the blue line diodes on the Maxon's 1981 GE-601. Measuring the input voltage and current. actual voltage is Vin =V-I*1000 because the current meter has 1K ohm resistor inside. The diode of TS-808 is lower current than 1S1588 around 0.4-0.5V input. This might cause the earlier break up and long sustain. The diode in the same era Maxon GE-601 is almost the same character as TS-808's. When I install the diodes into reissue TS-9, it got the early break up and long sustain sound! I am not sure the part number of TS-808 diodes but the 1S2076 is the nearest.

TS-808 '81
1s2076 1s2076A '82
1s1587 1s1555 1s2075K
V I uA I uA I uA I uA I uA I uA I uA I uA
0 0 0 0 0 0 0 0 0
0.1 0 0 0 0 0 0 0 0
0.2 0.1 0.1 0.4 0.3 0.4 0 0.2 0.3
0.3 1.6 1.2 2.3 3.1 2.4 3 1.6 3.1
0.4 10.6 9.2 11.4 14.3 13.7 13.3 13.1 17.1
0.5 42.1 38.3 48.9 49.2 53.3 49.1 49.6 59
0.6 101 96.1 100.5 110.1 98.5 113 113.9 115
0.7 165 165.4 178.5 177.6 201 177 177 186
0.8 257 256.4 256 263 285 266 265 262
0.9 339 338.8 349 368 349 349 361 367
1 420 421 458 439 468 436 452 435
1.1 521 517 571 543 575 567 536 547
1.2 614 614
1.3 711


OP amp Replace with TI RC4558P
FET Replace with 2SK44
Clipping diodes Replace with 1S2076 or blue line diodes on Maxon pedal before 1981
Output resistor Combination of 100 ohm and 10K ohm

OP amp need to be replaced with TI RC4558P. It depends on each favorite that which RC4558P you select, Malaysian, Japanese AET or Japanese AEB. Japanese AEB is the brightest, powerful and has the most TI RC4558P character.And also the rarest item that is difficult to obtain. 2SK44 FET makes the aged sound pure and clear. Clipping diodes need to be replaced with the Hitachi 1S2076 or the blue line diodes in the vintage Maxon effector. 1981 Maxon effectors use several types of diodes, some are white line and some are black line but only the blue line diodes can be used for TS-808 emulation. Also original TS-808s have several combinations of OP amp and FET, some are JRC4558D and some are 2SK30A. Most favorite combination is Malaysian TI RC4558P and 2SK44. I think it's the closest to Ray Vaughan sound. Finally my reissue TS-9 mod reached the original TS-808 vibes and I will use it as a buffer to be always On after the TS-9 connected series. like Stevie Ray Vaughan.