New ReleaSSSes

[LeftyStrat]

I had always thought that #001 was the silver chassis in the combo, and that #004 was the black chassis in the green suede head

Bill, AFAIK this is correct.

Cheers,

Max

Max, do you know the approximate dates these amps were built?

[Max]

the approximate dates these amps were built?

Taking into account all I know about these amps I would think that #001 was probably built around 1977/78 and #004 somewhere between 1979 and the early eighties. But of course it's possible - or perhaps even probable - that Alexander Dumble implemented some mods at some later points in time.

Cheers,

Max

[talbany]

Since the genie is partially out of the bottle - SSS #4. No guarantee of accuracy. Some questions may be answered by comparing both.

Well now since I worked with Bill on this schematic I have a right to say that we never intended it to be posted and now I see it's made the rounds and ended up posted here really pisses me off!!..You can't trust anyone!!.. I think I'll take a break from this place for a while..Later!!

Tony

[David Root]

Well, now that #001, which I also thought was #004, is out, I can confirm that the hi filter resistors that Bill showed in his schematic are at least partly not right, because I am building it.

I also have used 10K, 20K, 40K, 56K and 82K, and they are too low values, especially the lower ones. Massive volume cut and bass loss. Based on that I would also agree with Bill that the values in the #002 sketch, from 39K to 390K, seem to make more sense. I'll be changing my current values to higher ones.

I think the LNFB from V2A to V1B and from V1B to V1A should both originate from the plate, rather than from the grid, on V2A, and out of nowhere, from V1B.

Haven't done the lo filter caps yet, and there is something odd going on there with that 10n in the middle on #002. 20 to 1000pF seems more like it to me, I'll find out soon enough now that I received my polystyrene caps in the mail.

Bill, or Max, can you advise what the tubes are in #001? I am building mine without reverb or tremelo as I cannibalized an existing smaller chassis. I have 12AX7 in V1, V2, and the PI, and I used a 12BZ7 in the driver slot because it can handle more current and the cathode can handle minus 180V, just in case. I believe HAD would have used 12AX7 in all slots but I don't know that.

I am currently changing the PT out to something that will go closer to a Twin PT as I have had some problems with the amp, and the higher plate voltage I was using has indirectly caused some of these problems. I also have too much gain, I think because I dropped the reverb circuit out, and I also wonder if the 100R GNFB tail is right with the 4K7 feedback resistor? Should it maybe be 390 or so?

No problems with the bias supply I came up with though. I used a 20mA 120VAC source, a BR34 bridge rectifier and a 47uF 250V cap on the raw driver cathode bias and another 47uF 100V on the driver grid bias. I inserted a 56K resistor ahead of the standard HAD 10K bias pot/22K tail and get minus 175 to 180V raw bias. With 310V on the driver plates I get minus 44.3V on the cathodes and minus 45.8V on the driver grids. I do use the 150K driver grid resistors as shown in Bill's schematic, and also changed the 100K 2W cathode resistors to 51K. Works fine.

[passfan]

So, oddly enough, stolen info making the rounds and being stolen again has ruffled a few feathers ???
I thought the "spirit" of the board was above all that. My mistake...

So here is my contribution to this "project for all"
A simple interpretation of the LFNB

P.S.
Forgive me B.
I think I'm going to be sick.

[stratcat62]

Looks like a 250K mid pot and 500K bass pot, which differs from both SSS schematics recently posted here. FWIW, those who posted said that errors were possible. They could also be changes made by Nick.

[LeftyStrat]

So, oddly enough, stolen info making the rounds and being stolen again has ruffled a few feathers ???
I thought the "spirit" of the board was above all that. My mistake...

Thanks for the contribution.

You know when Omar started this board, we had very little information. There was a frustrating time when the few that had seen the guts of a TW would throw out a hint now and then.

Now we have a catalog of the designs of two great amp gurus. This board has become something of great historical value.

How many commercial amps out there started from schematics on this board, where so many freely contributed to the making of?

If some don't want to give back, fine.

However, if any members here feel they have benefited from all the schematics posted, perhaps you'd like to give something back to the community that created such benefit for you. I would ask if you have information about the SSS, or pictures, please share.

It's interesting to note, since my sharing of #002, and the subsequent contributions by others giving info, making schematics, running spice simulations, etc, we've actually got what looks to be a working filter implementation, which is more than can be said for the schematic developed in secret.

There is power in numbers, and as is said in the Open Source movement, "given enough eyeballs, all bugs are shallow."

Let's document this design and put one more great tool in the hands of guitarists everywhere.

[passfan]

I've played Nicks filter setup and it is very musical. There is a pic on here somewhere of it.

[10thTx]

Can someone comment on the CF section between the LTPI and the power amp?

Which of these three is correct? Two of them come straight from schematics .


I am curious that the reported #102 has something that looks somewhat like an LTPI (kind of). And that something is between the traditional LTPI and the 12BH7 tube.

The reported #104 looks closer to a traditional CF with the exception of the coupling caps between the LTPI and the CF.

Can someone explain what is going on with each of those topologies?


with respect, 10thtx

[LeftyStrat]

I've played Nicks filter setup and it is very musical. There is a pic on here somewhere of it.

You know, I've played quite a few inductor-based tone controls over the years, and have always found them to be useful and musical. Must be some mojo in inductors.

Ampegs used a multi tapped inductor for the mid control. And even the inductor-based Craig Anderton "Passive Tone Control" sounds really good when you use something other than the original Radio Shack part.

[LeftyStrat]

Can someone comment on the CF section between the LTPI and the power amp?

Which of these three is correct? Two of them come straight from schematics .

#3 in your diagram seems to best agree with the hand drawing. It seems both 2 and 3 look valid.

#2 seems to be closest to the SVT post pi cf. #3 just seems like a different way to accomplish the same thing.

Note sure why HAD would change so much between subsequent versions.

[LeftyStrat]

For reference, here is the Heathkit w6m schematic, which also uses a post-pi cf. This looks closer to #3, except with individual bias.

[oldmacman]

2 makes the most sense. You want the greatest possible negative voltage on the cathodes of the drivers in order to give the output the greatest possible headroom in the negative direction.

I did this with IRF820 MOSFETs in my OD Reverb -- you guys might want to consider that if you don't have room for an extra tube.

[David Root]

I've built #2 and it works fine. So should #3.

#1 is not right as Gary already pointed out, because the 100Ks should not be connected directly to ground and are not needed anyway as the 220Ks are already doing the job correctly.

When I first started looking at direct coupled CF drivers the Heathkit W6A was the first schematic I found that was what I needed. Essentially same as the W6M.

Topologies, 10thtx's question. I have seen direct coupled PI to driver, then cap coupled driver to power tubes and vice versa. I think you want the direct coupling from the driver to the power tubes, ie you want the vice versa....Hmm, maybe I should rephrase that. Anyway, that gives you the current draw capability to the power tube grids. The other way does away with blocking distortion out of the PI though.

[Structo]

Anybody ever heard of a surgistor?

Is that like a thermistor?

This Heathkit W6 shows one on the primary of the PT.