How do early Sound City 100 amps compare to Hiwatt?

[VintageCharlie]

Hi folks!

I'm wondering how the Sound City one hundred L105 amps (with 5 preamp tubes) compare tonally and schematically to the later Hiwatt DR103 custom amps? Do they sound similar or rather different and why?

Thanks a lot in advance!

Kind regards,

VintageCharlie

[shakti]

You sghould head over the the Vintage Hiwatt Restorations site and ask this question there as well, Karlis.

I can answer it fairly well though, as I have both a mint '73 DR103, as well as replica I built of a Custom 100 "The Who" aka CP103. Those amps are almost identical in circuit to a Sound City One Hundred.

I'd say those two amps are actually very different. Circuit-wise, the first stage and the tone stack are completely different. The phase inverter and power amp is just about identical though. However, the preamp differences yield quite different results. The DR103 is cleaner, smoother and warmer. The EQ also gives it a lot of versatility. It does break up quite a bit at the end, but not as much as the SC100/CP103. The CP103 at full tilt is crunchier and more distorted, but it's a very crystalline sort of crunch, very far from your typical compressed, fat Marshall sound. The real fun begins when you roll back the guitar volume. The CP103 then reveals the world's greatest clean tone! The EQ, with only bass and treble and no presence control, is quite limited in the range of sounds you can get. The controls are very active (and interactive!), but the EQ itself seems quite scooped in a blackface sort of way (yet not exactly...it still has some British kind of midrange), so it's hard to dial in anything resembling a smoother, fatter kind of tone. But as mentioned, this gives it a very distinct, crystalline crunchy tone at full breakup, and TREMENDOUS chimey, vibrant clean sounds with the guitar volume rolled off. It sounds a bit like the world's biggest AC30 at those settings, only better...

However, I should also mention that the loudness and somewhat hard breakup can be a little grating over time, and it doesn't match particularly well with bright guitars. It loves P90s. It's no great secret that Townshend's Live at Leeds tone is a bit of a benchmark for these amps, with good reason. I also think it needs to be matched with a Fane-loaded cab to reveal it's full potential. I can't for the life of me dial in a good tone with a Strat with this amp, it sounds like a scooped mess...makes me wonder how Jimi used his. May have something to do with the cab though...

In a few words:
DR103: versatility, full range character, clean, smooth, warm with gritty, grunty breakup. Cleans up well.
CP103: not as versatile, picky with guitars, extremely punchy, crunchy, crystal clear and with amazing clean-up.

The differences between the SC100 and various incarnations of Hiwatt CP103s are primarily that the SCs and early Hiwatts had a pair of 82k PI plate resistors, vs 91k and 82k in the later ones. The latter yields a little more compression and breakup, and smooths it out a little. I like both - listen to The Who at Woodstock for the former and Live at Leeds for the latter. Furthermore, there's a small difference in the pre-PI circuit with a 1M resistor in the earliest amps, then 470k and the 100k for 1970 and one. Also tends to brown out the amp a little more. Finally, there's a difference in how the B+ line was laid out, but I don't think that impacts the overall sound all that much. Oh, and the SC had a 6k8 voltage dropper between PI and the rest of the amp, vs 1k in the later amps.

[Xplorer]

so you want to build an early sound city too?
Since Roe told me that the cleans on axis album, little wing, castle made of sand .. Came from an SC MKI 100l i want to make it instead of building a second JTM45/100 .
But i can't find the right schematic and pictures, clips... ( any datas guys ? ^^ )
The site related to the sound citys shows a 105 , but i can't find this 100L MKI...
Thorleif, thanks a lot for these details, very cool. I'm even more convinced to build one now.
Also, guys, are we ok with the iskras ?
Cheers.

[Xplorer]

some Jimi pictures with soun city one hundred amps

http://www.soundcitysite.com/sc_webpage ... age_17.htm" onclick="window.open(this.href);return false;