vintageHIWATTconvention.com

i have a 78' 2 input DR504 that is stock except i replaced all teh electrolytic capacitors and installed teh M Huss bias mod.
i have seen teh "Spitty" Mod on that website but i don't have the feeling mine has that problem, especialy when i hear the "before" clip of teh normal channel on M Huss website.
this clip sounds like an old fuzz that is not working that well or pushed over the top with gain (makes compression, what's called the blocking distortion from what i understood) and my amp with normal channel and master volume pot turned to max don't seem to have that spitty / blocking distortion sound although it has much gain already on teh normal channel (i pu the presence and treble on 3) .
the bright channel really bears its name as it is really bright with an SG and 68' T-tops or with an SG with actual p90's, even with the presence pot and treble turned nearly all teh way down !
this bright channel really has tons of gain , more than the normal channel.

so i was wondering if all these late 70's 2 input DR504 (and maybe DR103 as well) amps need that spitty mod or if some already sound right from teh start.

the M Huss "before" normal channel clip has a type of tone that is so noticeable that i don't think i could miss it on my amp (i use it with an old early 70's hiwatt 4122 cab with original Fane speakers).

electricsky wrote: so i was wondering if all these late 70's 2 input DR504 (and maybe DR103 as well) amps need that spitty mod or if some already sound right from teh start.

Not enough evidence to say one way or the other. If yours sounds right, I wouldn't mess with it. As you said, you'll know "fizzy" when you hear it.

Dave

it seems to get the right amount of gain with the SG / T-Tops volume on 8 or 9 and with teh amp bright channel treble and presence on 3 .
it sounds really good, i don't understand why i don't get that spitty noise, i thought they all needed that mod !
i won't complain though ! LOL
great amp , i'm sure it could sound like on " who are you " or some led Zep riffs as on the royal albert hall even if it's not the same amp they used !
i wonder what is the difference in tone and gain with my 78' 2 inputs DR504 !
i already have more gain that i would need for that type of music , so when i think they released another model later with even more gain, i really wonder what the guys were doing with so much gain !
i could let my SG or les paul and go have a coffee, it would still be playing alone with so much gain !

i'm not sure this amp would sound good with a strat or tele, at least maybe not the bright channel ...!
i wonder if Gillmour used his hiwatt amps for studio recordings of the most well known pink floyd from the early to mid 70's ?

I have a 1979 DR103 (2-input) Canadian Import with the high-gain mod that the importer typically applied, and it does NOT have the spitty/splatty fuzz sound either. It overdrives very nicely with a ton of preamp gain at low volumes. For an overdriven sound, I like it the way it is and have not un-done the mod (sound being such a personal taste). Notwithstanding, it will also play very nice and clean at considerable volume, perfect for use with effects, so no desire to make any changes at this point.

Cheers,
The REAL Joe

I have only seen this problem in stock (unmodded) 2-input amps.

Like Dave said, you'd know it if you heard it! I would never dream of modding a vintage Hiwatt unless it *really* needed it.

--mark

My 1980 (Canadian modded) DR504 was really "spitty" with blocking distortion... but I never tried it with only the gain mod removed. I just went ahead and reworked V2 to the early '70s configuration. Plays like a vintage Hylight now, except with perhaps a tad more gain due to the shared cathode and different component values at V1.

I have a 78 2 holer that had the Canadian mod. It was a tad spitty, so I decided to do mHuss's mod to fix the blocking distortion, while it sounded better I still wasn't quite satisfied. So I copied mikhailwatt's mod, and converted my V2 to the early 70's config. My amp now plays amazing, the tone is more powerful with more definition. I jumper the two channels and the amp is amazing, very dynamic and touch sensitive. I love it.