Ok I had a listern to your prob,,, If it has a spring rev tank pull it out, completly disconnect it. The tank will likely be fine but the circuitry running it may have gone futt. See if that helps,, Phil.

Nice ,,similar in concept to the Mesa VTwin pedal.
BTW I think the schematic has a bobo next to *R40 and R42* looks like a dead short to me   as drawn that shorts out the secondary winding of the power transformer. Just thought I'd mention it.
Cheers, Phil.

Hi billyjoe,
              As *JMF* has already noted it's hard to work out as many things might be happening altogether.

My thoughts on this;
ANY Tube amp with that many preamp triodes is bound to hum, some worse than others. From the pics I can't tell if the preamp heaters are DC or AC powered?

If they are AC heaters then with so much gain you *WILL have Substantial HUMMMMMMMMMMMMM*

I recently worked on a Laney 30 watt unit and it's 2nd channel Hum was so bad the owner wanted to sell it for similar reasons you mention here.

The gain on the laney was insane so I just turned it all down to an exceptable level and Now it gets played at all his gigs. 8|

So I can understand the chaps reluctance to fix it knowing that without some modification it will always hum.
Other comment is the yellow wire crossing the top of the 3rd Electro from left is Cut rather badly I'd get that fixed.

You could ask a good teck to pull one of the triodes out of circuit and rewire it to a more civilised circuit,, you will still have more gain than you will ever use,,, well if you know valve amps you know it can be done.

I get looks of confusion when I try to explain to the young players that Brian May used the *Normal* Ch on his Vox amps,,, not the *Bright Ch* as most would assume.
Now if you follow the signal in a Vox Amp the Normal Ch passes through one Triode (half an AX7) and then after passing through a Volume control goes Directly to the PI and power Amp.

With a good guitar and a simple treble booster you can have masses of distortion,,,,,,,and very little hum even though it's still using AC heaters.
Anyone who builds an all Valve Amp using more than 3 triode stages
(1 1/2 AX7's) does not understand valve teck.
So even if you get the potential ground issue fixed it may still hum quite a bit.
Sorry I can't be of more help. Phil.

Hi again Zappa,
               Just a thought on the Pod.
I have an old Quadraverb which I could never come to grips with.
Short story is, Once I hung a *Cab Sim After it* it did bring it to life and became far more convincing.
Cab Sim *Before it*  did nothing much but *After it*,,, Wow big improvement.

The reason I mention it is because I wonder if a Cabsim may have a similar benifit *After* the Pod. :tu:

I used the Cab Sim Circuit from the JTM 30/60 Marshall.
Google *Ed Rembold Cabsim* if you want to find the circuit,
or I can post mine if you get stuck.
Cheers Phil.

Darn pic did not post,, trying again.

Hi Zappa,
        Not sure I fully understand exactly what you are trying to do but I'll share my thoughts which may help you come to grips with what can be excedingly complex.

The pic attached is what I take to my local mucic club when I don't take my Valve reamp setup. The Amp is just an old Laney *Keyboard Amp*
The white front unit on top is the *PhAbbtone* (Left) Then into a 3 knob Drive circuit partly based on a *Nobels SS1* Headphone amp from the 70's and I liked what it did so I tweaked the paremeters to suit a *Live rig*.

Then the signal goes to a 30 year old HiFi Graphic EQ (All 3 preamps are bypass if needed) then onto the Laney which has a very simple Bass Treble and gain on each of it's 3 channels.
So All done by Cheap simple and effective Equipment.

One word about *Efx loops in Amps*  I never got that joke, I just can't see the use of such needless complexity. I've never been able to find a use for them?
Unless it is a *paralelled EFX with a blend knob* attached then all rather pointless dodads.
As you obviously wish to use the pod thing then you've got most of what is needed anyway, just plug straight into the front of any SS Amp and go.

My thoughts on signal path setups.

My Rig; Tone box > Dist > Graphic > clean SSAmp
As you have the Pod then mix an match until you find what works best.
Try inserting the Pod after a Graphic before Clean poweramp.

My thoughts on the Amplifier in general.
I like most just wanted *Everything + more + more* All in one neat pakage.
It took me 20 years to fully grasp that it's a very limiting approach.
By keeping everthing seperate you can mix and match and when an amp goes fut you have not lost *Everything All at once.* If my laney breaks down I just use another cheap SSAmp.
I have a Killer SS Stand alone spring reverb and because It's in a seperate unit I can take that reverb unit to any Amp I wish.

As to getting a signal from a preamp unit into a poweramp just use a 100k pot from the last stage. A simple opamp buffer and a 100k pot will work here. If you have trouble with getting enough signal swing then easy to introduce some gain in the buffer.

The Marshall tone stack you are thinking of is likely to be uninspiring.
If you assume a marshall sound from it's use you will be quite disapointed.
Just having a marshall tone stack is like having a racing car with no engine.
(going nowhere fast)

Marshall amps (old) the tone controls actualy don't do much at all once you crank them up high as the power tubes and output transformer just produce one basic honky wall of tone/sound and you either work with it or sell it as they don't do much else.
This won't happen with the circuit you wish to use as it's only one small part of a very big picture.
You will need a Cab sim type circuit or similar to get that wall of sound to happen.
My SS1 does a decent job for those sounds.
Interesting to note that when I use a Real Tube Amp After my preamp I have no need to use the SS1,
I just use the PhAbbtone to tweak the tone.
SS1 is only needed when running into SS Amps.

Oh yes Stereo only works on recordings.  Live situation *forget it* there are enough problems to overcome already.

Hi
Don't forget to check the 2 diodes on the PSU,, if one goes fut it will still work but with much greater hum.  ,,, At least I think that's what happens. 
Phil.

I'm with *Enzo* :tu:
Yeah well if it still works just rebuild the input section,,, but with a lot of surface mount and double side boards you still have a long way to go.
Hope your  eyes  are good.
Phil.

The white stuff is likely just the factory goob used to support large components like Electro Caps. (in the old days they used Real Brackets).
Judging by what you have said and looking at the fried components at what looks like the input socket, Then it's all bad news.

If *Mains* Voltage has been induced into that circuit then probably a lot more than 2 resistors are fried, unless you are gods best friend I'd say most chips will also be fried.
The poweramp may still work but that would be the best you can hope for.
Now it's just *Spare parts*
Phil.

These problems are always a pain to track down.
Anything from a *Cold Solder* joint,,, but my guess is (A) a gain pot has gone OC
or (B) a PSU Cap on the way out.
Hope you get it all sorted out,, Phil.

Check continuity on the *Primary winding* first be fore worrying about the Secondary ones.
A high or fluctuating reading means the primary side is likely blown.
Some mains Transfomers have *one shot internal thremo fuse links* which renders tranny unuseable once they trip.
Don't forget the AC cord as well,, all the way from wall plug to internal connections.
I doubt a schematic would be of much help with this sort of problem.
Sorry I can't be of more help. Phil.

Hi Zappacat.
            A stereo amp is effectively the same as a two mono Amps.
A stereo amp that recieves two mono signals is just a two ch Amp but the signal is still *mono*
It is only when efx like chorus or trick dely (ie,ping pong) are engaged that you can here stereo.

Remember all these fancy *Stereo* efx do little for live gigs, they are far more suited for studio work.
My advice is get a great *Mono* Guitar Amp sound *First* ,,,an worry about all the fancy stuff when your famous.
My 2 cents worth.  Phil.

Quote from: awdman on October 10, 2009, 09:06:57 AM
Phatt,
Do you have any schematics of a Chip pre-amp going to power tubes, and is there a way to bypass the output transformer? It seems that the Transformers are why Tube amps cost so much to build.

Hi awdman,

Re bypassing OTr's,,, yeah like you wish!
Yes give me $10 million for the R&D an I'll get back to you in about 10 years
Some People claim to be able to bypass the OT or at least emmulate it but even with the best minds and tecks workin overtime trying to do such things, well let's just say from a hobby perspective a Valve output section (using an OT) might work out quite a lot cheaper. (If you catch my drift?)

I have no doubt that some things come close but most will want an arm an a leg for their efforts. A bit of effort using simple equipment (both valve and SS) can be setup to give you most of what you will ever need.
To save repeating it all,,
My setup is found on this page: http://www.ssguitar.com/index.php?topic=1017.msg8118;topicseen#new

The preamp is the Passive input tone box found here; http://www.ssguitar.com/index.php?topic=1136.0

Yes I've messed with electronic circuits for over 20 years,, played guitar on an off for close on 40 years, built heaps of pedals, Amps (both Tube and SS) and all sorts of other audio stuff.

I have arrived at a very simple way to understand the vastly complex,,
EQ> dist/gain> EQ> dist/gain> EQ> speaker.
Get the right EQ happening in the right places in the signal chain of events and even with very basic equipment you may be quite suprised at how good it can sound.
Even with an all SS affiar just EQ before a reasonable dist pedal and again after it will reap great rewards.

Behind the viel of all the amazing mojo Tone heaven teckno gear you guys drool over lies a really simple concept that I believe all guitar players should know.

""Great tone is arrived at via the culmination of one tonal response curve which is then imposed onto the next element with a different response shape,,, add them all together in the right combination and *Magic stuff* will happen.""

The simplicity of it all is *LOST* because there are just so many places in any given circuit that can alter the tone that you can quite literally go on forever making small or large changes to the resulting sound. Without a solid understanding of *Which part to tweak?* You are just guessing.
If they made every internal paremeter adjustable then your front panel would have 100 knobs on the front, Not very user friendly ay?

You have to do a lot of reading between the lines when it comes to tone tricks as each tone guru has his own idea of which internal bit to tweak ,,, more often than not it won't be what you want.
You need to work out what is going to give you enough of a tone change to be of *True Value*

The Pickup is an obvious but mostly over rated major tone tweak;
The aftermaket Pup industry is rampent with wild claims,, Yet the simple truth is that you would get more value from better amplification. If you think that better pups will magically transform your tone you need help,,, it is an *Electric* guitar for gods sakes,, so the AMPlification is the *Active Tone Altering Factor*.
(yes the right pups can help but it's only a marginal improvement)

You want tweed sound,, then a dip at 1kHz will help
You want british tone,,, then all mid boost  (from 100Hz up to 3kHz)
You want big Fender clean then,, Boost at 100Hz with a big dip at around 400Hz and then boost all the treble from there up. 

*Obviously* That's a simplified rule of thumb but it might help you get your head around what you are trying to achieve. Each Amp will have it's own natural tonal Q factor which will of course make it sound better or worse.

I've learnt enough to say hey don't get caught up in every new gizmo as a lot of it is just sales hype. Sure you can add a lot of teck stuff to my simple explanation of tone but most guitar players start to get lost in tecknical mumbo jumbo and in the end just rely on *Name Dropping* because it sounds so kool to say;
I've got a triple recto with a matched quad of cryogenicly stabilised 6550's in my rig.
Which of course means nothing to those that know better,, it's just a trick way to sell more tubes ,,AT Inflated prices.

My advice to your original Q; Build yourself a very simple tube amp (a champ if you want). If I've done a good job of explaining all this then it should be obvious now that all the rest can be done with relitively cheap external workarounds.
Have fun, Phil.

Quote from: Brymus on October 09, 2009, 02:50:41 PM
How is your project coming ?
I missed this thread somehow,but I had the exact same idea.
Re-amping a Firefly type amp with a lm3886.
I recently heard a Firefly that used ECC99 for the output tube and it was SO much better sounding than the 12AU7 version the guy built it out of.
But the ECC99 is a new tube and there isnt much on the web about it.
I would love to see a schemaitc of a 10 watt PP amp using 4 ECC99 tubes(sorry off topic)
Also I like the idea of the NEO spkr.
I want to build a light weight amp using toriodal trannies and a NEO spkr,aluminum chassis,
And Pine cab shouldnt weigh much like that.

Brymus,
           I have no doubt that the firefly would work as you describe but 10 watts from a quad of small signal triodes (ECC99) I very much doubt?
From my understanding  these are still ONLY a small triode.
I've already stated in my last post why the firefly may not be the ticket some dream of but hey,,,I've been wrong many times before.
In my experience even a small Single ended Pentode like a Fender champ would Eat a triode PP amp for crunch.
Phil.

Quote from: Zappacat on October 10, 2009, 12:13:29 PM
Hey Phatt, can you elaborate a little on what "semi-passive" tone stack means in your diagram?  Thanks!

Sorry for any confusion ,,,It's the very same one I've posted here under schematics and Layouts.. *The PhAbbTone box*.

I only used the phrase *semi passive input* simply because only the input is passive the output is of course *Active*. Since posting my tone circuit I've realised that by calling it *Passive tone * some may see it as bending the truth

That little gem of a circuit just saves a whole lot of stuffing around with the needless complexity of a whole front end preamp.  Heck who wants the cost and work of wasting a whole triode stage when this simple trick does the same job.
Cheers, Phil.