symphonic Line RG4 III vs RG4 IV?

I haven't heard the latest Mk IV amps but when I got the Mk III version (That I still have), I was told by a long-time Symphonic Line dealer that the midrange on the Mk II version was better than on the Mk III 'cuz the Toshiba output transistors in Mk II were better than the Sanken transistors in the Mk III.
Looks like something similar has happened bwtn Mk III & Mk IV.
Seems like one gets the extension at the cost of richness. There is a person here who claims that he can modify my RG4 Mk III to have even better sound. Maybe I will take him up on his offer. The modified sound might approach the Mk IV sound???

dear Gregm,

I saw the RG4 IV, but not sound or music from it.
from your comparsion, maybe I will prefer the MKIII sound. A local dealer told me, SL is changing its sound due to change of designer? is this true? thanks

Tim

Hi Tim--
I wouldn't be surprised if the designing engineer changed, it happens quite often apparently!
I WOULD be surprised however, if the sound were drastically changed by the engineer as the equipment voicing is done by the owner (Mr Gemein) as far as I know. (BTW, allegedly one of the better known, past engineers was Mr Lindemann of exotic cd/sacd player fame)

Bombay: It would be interesting to know what the mod entails? Last time a guy I know tried to mod old rg4's, he never got the transistor biasing right & stable for some strange reason -- & promptly blew the output stages (but SL sent him new circuits, so it all turned out OK). Cheers

Bombay,

i did own Rg1 MKII which used Toshiba output transistors in Mk II and also owned a RG1 III which use the Sanken transistors in the Mk III. I feel MKIII has slightly better bass and sound stage is better but did not notice the midrange? However, they always sound the flavor of symphonic Line.

Gregm,

I can share w/ you what this person told me over the phone re. modifying the RG4 Mk 3.

He told me that most of the work would go into the power supply mod. Swap out the present rectifier diodes for Fairchild HEXFRED diodes. These rectifier were "soft recovery" (that's what I remember, I think!). Replace the power supply electrolytic caps w/ computer grade Panasonic caps. He felt that the present p.s. caps had done their time w/ several on/off cycles. Then, he was going to change all the signal path caps w/ Blackgate caps, which he felt were the best. He said that he was not going to touch the power amp electronics as that was biased the way the designer intended. Neither was he going to touch the internal cabling.

So, w/ all these mods he felt that the amp would be more transparent, music would flow more easily & bass response would improve. However, he told me that this was a double-edged sword in that once I heard the "truth", it was possible that I "could not handle the truth!".

Tell me what your opinion is.