Higher gain build

[Gaz]

I'm hoping the lower voltages and lower filtering
will balance out and give it a good sound.

Hi Darin,
the Bogner Extacy (whatever version you find), in my opinion, is the way to go with the PT and OT you have. Xtc's reamp sounds good with lower voltages (Soldano not so much).

Why is that, Robert? The preamps are not radically different.

[roberto]

They seem really similar if you look the two preamps "on web".

But if you take a closer look at them, taking into account how they work, and working a bit on them, you'll see that one hundred volts changes alot the working points of the preamp, so the balance of the entire preamp.

I don't like how classic soldano preamps sound when supplied below SLO voltages. I even prefer to raise that voltages a bit. In my opinion this is part of the reason why Mike decided to supply the first two tubes in parallel from the PI+2CFs node through a pair of 15k resistors.

With lower voltages, we are talking even lower than standard Marshall, I'd go for preamps that have been designed for those voltages, or at least that sound good with lower voltages. Bogner has both features.

Of course this is just my opinion.

[Gaz]

Thanks, Robert. I have to admit I was playing a little dumb because I wanted the full explanation Thanks again, your opinion on high gain stuff is always appreciated.

[dcribbs1412]

They seem really similar if you look the two preamps "on web".

But if you take a closer look at them, taking into account how they work, and working a bit on them, you'll see that one hundred volts changes alot the working points of the preamp, so the balance of the entire preamp.

I don't like how classic soldano preamps sound when supplied below SLO voltages. I even prefer to raise that voltages a bit. In my opinion this is part of the reason why Mike decided to supply the first two tubes in parallel from the PI+2CFs node through a pair of 15k resistors.

With lower voltages, we are talking even lower than standard Marshall, I'd go for preamps that have been designed for those voltages, or at least that sound good with lower voltages. Bogner has both features.

Of course this is just my opinion.

I found this quote which seems to agree with roberto

One of the things that contributes to the sound are the relatively low plate voltages on the preamp tubes. In most modern high gain amps (the SLO, for example) the plate voltages are in the 360-390V range. In the Ecstasy, however, the plate voltages are more in the 260-300 range. The power tubes still have pretty high plate voltages (~500V), it's just the preamp that's lower. By lowering the plate voltage, you are essentially squashing the tube response curves together in such a way that a smaller signal will cause distortion compared to the amplitude of a signal that will distort in a tube at a higher plate voltage. What you end up with is a fairly compressed signal with different distortion characteristics than most other amps. Obviously, this isn't the only contributing factor to the amp's sound, but it's one big one I've noticed.

I have seen how voltages change the tone.... voltages matter
So its back to the drawing board
I found this schem to go by not sure of the accuracy.
Will give it a try

Darin

[Smokebreak]

FWIW I built a 2x6V6 Avenger out of old AO-50 organ iron and could not believe how awesomely sinister crunchy it is. IIRC I dropped the filtering quite a bit, used a resistor in place of choke, and ran lower voltages(430?) than SLO types. Other than that, straight from the Avenger schem. It is unbelievably loud too. I think lowering V and filtering helped it not sound so sterile like some super high gain amps but that's a guess. Sorry, I'm no help with fx loops.Sounds incredible as a simple amp , though.

Hi smokebreak, I have an old push pull 6v6 pa amp that I want to rebuild into an avenger. What circuit changes did you have to make to allow it to run with 6v6's?

Hey Mike, I only had to make a few changes. My filtering is 47uf/22/22/22/22, which is obviously very low for SLO. I didnt use any caps in series, I just bumped the reservoir 47uf up to 500V. BTW I'm not necessarily advocating my filtering, I just had space issues, and there was no way I was gonna get two 560uf/400V, 220u/400v in there, plus the guys at sloclone suggested these values for 2x6V6.
I also subbed a 100ohm 10w resistor for the choke, which is pretty low as well. I didn't know anything about chokes then, and I would use one if I built another. I used a strict star grounding where every section's ground point is fed back to the cap feeding it, then a line from there to my single star ground point at the chassis by the PT. Lots of wires! So that's the only changes I made. I never even tweaked it. I didn't even need to change the bias circuit to get my range.
I got inside the amp yesterday and my plates are only 400V! I believe Roberto is correct these voltages will not yield classic SLO tones, but then again I've never played a real SLO, so I'm not sure how different mine sounds. I do think that this setup can work depending on playing style though. I'm not doing super technical articulate Dream Theatre stuff, more Matt Pike style riffage, and this works great for that. Hell I'm a jazz/country player mostly, just chasing the sounds of my metal youth, so take this with a grain of salt. I'll record some clips hopefully this afternoon and post. Oh I find the "low" channel pretty unusable. I've heard folks like it for "bluesy" stuff but it ain't happening over here.

[Smokebreak]

Ok I had my own little medium-high gain shootout here with my Express clone(50K slope,470p bright on,PPIMV), cascaded Plexi/Chupa(no diodes, w/ cathode master, no treble cap, no treble bleed), and low B+ Avenger/SLO 2x6V6(400V plates).

All gain/tone controls set at noon, except the plexi(both gains around 2/3 oclock). All masters set to neighbor-annoying levels. Recording quality is soso as I used my trusty Agile LP, V30 through $10 mic.

Might as well make it fun and see who can guess which is which. http://snd.sc/152YeB1

BTW I just heard a clip of the Bogner and it sounds killer! Now I'm contemplating making some changes

[dcribbs1412]

Ok I'll bite
All seem pretty similar...but last clip is a little darker, Chupa/Plexi?
1st part seems like the 6V6 avenger, which leaves the Express as middle.

Darin

[Reeltarded]

Spress chupa venger

[Smokebreak]

Express is the first, then Plexi, then Avenger. The Avenger is darker bc of the lower voltages I figure. I was really surprised how similar the recordings sound. In the room they all feel and sound a lot different. Express still my fave, in the room at least. Thanks for playin!

[dcribbs1412]

A unfinished test layout using a schem I found.
Not sure about accuracy of values, or my interpretation of it.

Wondering about the use of tag strips on V2 and V3 as grounds.
Is this asking for noise?
Comments or suggestions are greatly appreciated
Thanks
Darin

[Lindz]

Hey Roberto

not to hijack the thread but I am in the middle of an SLO inspired 50 watt build and I am using Marshall style iron that I already had (690v ct Classic tone PT w/matching OT and choke) - I think the Soldanos are something like 720v.

I had not put much thought into the voltages and your comments in this thread kind of made my heart sink since I have so much work into this thing already. In your experience will this voltage be enough to get me in the ballpark tone wise using the stock Soldano values in the preamp (since I already finished up the board)?

If I come in a little low for SLO style tone, could I not adjust some dropping resistors slightly for the preamp to bump it up a bit if necessary? I tend to think most of the Soldano vibe is the preamp (is it not?) so that might get me more on track.

I appreciate any input -

[roberto]

You should have something around 460-470Vdc B+.
Usa a 4k7 for the PI and everything should fit.

Take a look at my threads on sloclone (I'm the zintolo moderator over there), two of my amps have exatly the same voltage.

For a 50 Watt Slolike I'd:
- lower supply filtering from 220u to 110u on plates and screens;
- lower the NFB (raise the value of the NFB resistor);
- raise the mids on the clean/crunch channel;
- lower the extreme lows on the OD channel (via coupling caps);
- lower the PI's coupling caps from 47n to 22n;
- add a bit of depth on the PA.