Weber 6S100

[stratcat62]

I happened by this amp today and it looks pretty sweet. I was wondering what people have heard about it or what kind of amp it looks like to them.
https://taweber.powweb.com/store/kits_60a.htm#6s100

[oldhousescott]

Looks to be based on the Sunn 100S (non-reverb)

Weber's schematic

Sunn 100S schematic

Differences here and there:
-- Sunn used ultralinear output transformer
-- Sunn used 6AN8 pentode/triode tube, Weber uses EF86 and 12AU7
-- PS dropping resistor values
-- Weber adds pull-boost and presence pot

Looks pretty cool and should be plenty loud.

[briane]

I built a sunn100s clone a while back, 6an8 and all.

There is at least one major mistake on the sunn schematic (sparks required!), but it really does not affect the circuit performance.

I would describe the amp as a wild hound dog from hell. Tons of gain, very crunchy, little clean sound, way too loud, and a very poor bass amp. It worked OK for guitar if your really into heavy metal, and not much else. Then again I am more of a clean, bluesy amp type of guy, so I am sure this will really suite the needs of some, just not me.

brian

[stratcat62]

Thanks a lot guys. That's interesting that the Sunn clone you made had heavy metal type gain. Weber claims that they're model is super clean. It must be the EF86 in there.

[LOUDthud]

Sunn amps were never known for their high gain. But, without the ultra linear connection and a switch to kill the feedback, the 6S100 should have more than a Sunn. I'm wondering if it really does 100 watts using one pair of KT88's and Weber's Marshall transformer set.

[Funkalicousgroove]

You can still get the Dynaco OT's if you want the UL. Heyboer and Mercury both make them.

[Tubetwang]

These guys stock it...http://www.triodeelectronics.com/dytr.html

[briane]

yep, thats what I used....The 470 model in ultralinear....the dynaco clone, from triode.

Its now in an ods 101 HRM, and rocks the house! I'm starting to really like that OT in a dumble clone. thats the 4.3k/ 35-70 watter (not in ultralinear on the ods 101). Its got some real low end, without losing the top end. But its a new amp, so its still in the voicing stage. Last night I did a shootout of the 4 dumble clones I have, and it won hands down!

I've always suspected my definition of clean was a bit more strict than others.

I have not poured over the weber schematic, but if its representative of the sunn 100s, then clean tone will be hard to come by. I assume weber is running the ef86 in pentode mode? If so, then it should be very similar to the 6an8. If its in triode mode, then yes there would be more clean range. Even just switching the pentode over to ef86 would be a vast improvement over the 6an8 in my mind. Noneless, this amp still has a lot of gain stages before it hits the PI.

Also I have built a few amps using the 6an8 tube. I eventually came to the conclusion that it is not the same as an ef86, but rather more shrill and harsh sounding. I eventually recycled all my 6an8 builds.

Plus, correct me if I am wrong, but wasnt the MAN (mr HAD) known for using the dynaco's?

[Tubetwang]

yup.

[Funkalicousgroove]

I love dynaco OT's, they are friggin spectacular!!

[dBe]

Truly: with the UL taps for jazz amps and without for everything else. The A-470 is in a class by itself for mid power amps. The frequency response is like a ruler: 20__________________________________________20K.

I'd rather work with lots of available bandwidth and trim it than wish I had it.

David Hafler was a very savvy dude.

Dave

[LeftyStrat]

I have an original A470 (4.3k, UL taps) and a clone from triode. I've been meaning to do a shootout between them, just to see what the difference might be.

I had originally planned to use them for a stereo, but lately I have been eyeing them for a couple of different amps. Maybe a 2xEL34 and a 4xEL84.

I've never built a guitar amp using UL feedback, but it seems to work for the Route 66, so I may give it a try.

[David Root]

Looking at the A431S OT with a pair of 6550s. What plate/screen voltages was this OT designed for?

At 12 lbs this matches the behemoth PT I have in mind (One Electron BFT-1B...you only get one guess as to what BFT stands for) weighs 15 lbs. 385-0-385 AND 260-0-260 (for choke fed screen supply!) 277VA total.

[LeftyStrat]

Looking at the A431S OT with a pair of 6550s. What plate/screen voltages was this OT designed for?

At 12 lbs this matches the behemoth PT I have in mind (One Electron BFT-1B...you only get one guess as to what BFT stands for) weighs 15 lbs. 385-0-385 AND 260-0-260 (for choke fed screen supply!) 277VA total.

The A431 was used in the Sunn 200s bass amp. I have one of the originals made for with "Sunn 3-60T" stamped on it. That was about 480 on the plates. The power section in the 200s is pretty much the same as a Dynaco Mk 3.

Here's an eBay auction from triode for a A431/P782 pair used in the Dynaco Mk 3, along with the specs:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... MOBOX:CUST

That OT would go nice with your BFT, with either 6550 or KT88.

[David Root]

I'm also looking at 6146B instead of 6550, because it seems to fit the Vp and Vs I can get out of my BFT-1Bs (Vp~480, Vs~235, to a choke fed filter). Plus I can get NOS for $30 each. Try that with a 6550!

However, when I run the graphical analysis on the plate curve interpolating Vs=235, with Vp=480 I get Zaa=3400, not 4300, so the A431S OT is not optimal. OTOH I don't really need 98W output either,

If I drop the Vs to 210V, then the optimal Zaa is 4300. Po max is 73W, which is OK.

What's the best way to drop 25V out of Vs? Resistor with a bypass cap to reduce impedance?