Model T tone questions

[CLD]

Finally got my new-to-me 1974 Model T back from the shop after a thorough refurbishment.  Would appreciate some insight from experienced Model T owners about the sound.

1. If I turn the gain knob ("brite" or "normal," depending on which input jack I use) past 2, I get distortion.  Is it supposed to have this hair-trigger sensitivity?  On my Ampeg SVT and Aguilar amps I can turn the gain up to 10 or 11 o'clock and still have a clean sound.  Yes, I know the Model T was originally intended as a guitar amp but based on my Sorado and other, earlier Sunn tube heads I didn't think there would be such a limit on a clean bass sound.

2. The "presence" knob doesn't seem to do much more than add a little distortion and sustain.  On my Studio Bass, the "presence" knob adds more low end.  Is this how it's supposed to be?

Thanks!

[loudthud]

Where are you running the Master? On 10? Back it down to 3 to 4.

[CLD]

I'm running the master volume between 3 and 4 already.

[Isaac]

Yes, it is. Sunn used linear taper potentiometers rather than audio taper, so most of the effect is in the first bit of rotation. Why they made that choice, I cannot say, but they did, and that is the result. What you describe is normal operation.

[CLD]

Thanks, that's good to know!

[Mr.Golden]

Okay, I have a similar problem but that answer does not satisfy. Yes I get a lot of distortion off of 2 or 3 regardless of the master setting with both bass and guitar. And it's not good distortion because it's just really muddy. However, I also own a Sonic2 (200S) and this thing not only sounds way cleaner at 6 or 7 but actually has a girthy low end response. A real thump to it. I a/b-ed both heads through a 2-15 and then again through a 4-12.

Sonic 2
-loud transient peaks
-lots of low end
-stays clean until 6/7

Model T
-squashed sound, no peaks
-minimal low end, the pot works for the first quarter and makes no audible difference after that
-distorts at 2/3 regardless. the "cleanest" sound I can get is all tone pots to 0 and treble to 10 and the sonic is still far nicer sounding

What really perplexes me is that the Sonic2 is way louder despite using half the tubes. This amp has been looked over and over and I need some expert opinions. My tech is good but has never worked on an original model t so has nothing to compare it to. Everything on the schematic seems to fit right in. We even put in a new transformer and all it did was add harmonics to the crappy distortion. Why so much gain? Why would twice the amount of tubes put out less low end and volume overall? I'm stumped.

I hear of the model t being a really good clean amp but I beg to differ if this is normal operation. Can anyone shed some light?

[loudthud]

Mr. Golden, Does your tech have an oscilloscope? Did he measure the power output of the Model T? Is it putting out over 150W? (looking for yes to each question)

Comparisons based on volume control settings are meaningless. If the Model T won't go way louder than a 200S, there is something wrong with the Model T.

Here's something for your "tech" to check if he has a DVM and knows how to dischagre the B+. There are four 47 or 50 ohm 5W wire wound resistors and four 1K 5W wire wound resistors right at the power tube sockets. These need to be checked with an ohm meter, bad or old tubes will cause these resistors to go bad (open).

[Mr.Golden]

Okay, okay. I know it's easy to assume that my "tech" is a retard but come on, really. For real, he ain't a hack, he is a good tech. All that you ask was done and came up okay electronically. But just because the measurements come up fine doesn't mean something else isn't going on.  The tubes are new, the caps were replaced. There are a few odds and ends that could be replaced but still measure up to spec. Thing is, this amp was messed with electronically by the previous owner and it took a serious ride through many states and provinces in a box without sufficient padding. One theory so far is that it's just one wire that isn't supposed to be where it currently is. But who knows. Does anyone have some detailed pics of model t guts (1st generation) to post so we can see if there is ANYTHING different. Can anyone tell me at what setting do you expect the model t to stay clean at it's loudest? And what about the lack of response from the bass pot? It also measures okay electronically but no change after the first quarter turn.

[Mr.Golden]

This amp will be for sale if I can't get it to sound, well,  better. I have invested a lot of money at this point and could really use some feedback. Anyone? At all? What's the deal?

Anyone? Please? Hello?..........

(sounds of crickets and owls hooting in the night followed by a trash can falling on a screaming cat)

[Mr.Golden]

 

[loudthud]

What city are you in? Your profile says City of Champions. Boston? Philly?

[Mr.Golden]

Edmonton, Dude!

Wayne Gretzky!!!!! 

[biltmore]

Maybe giving your tech the schematic for the Model T might help? Sucks that you're having problems with it. It definitely sounds like something funky is going on.

[Mr.Golden]

We have a schematic too. It's like every last component has to be changed out to find out what's wrong. All on the clock too. Does anyone from the is site live in Alberta, Canada? If so, do you own a 1st generation model t? Would love to compare. You might get a tune up out of it? (not guarenteed but I would step up to bat for you)

My tech owns more miscellaneous parts for almost all tube amps than any tech I have ever seen. He has been stock piling them for years now. He also has an enormous selection of tubes ranging in all types and qualities.

I should say too, I am pretty sure I own the only vintage sunn model t in these parts. I would like to be proven wrong but mine didn't come from here and not a lot of people, techs included, know or have worked on Sunn gear around here.