S.E. amps and voltages

[rzenc]

Hi forum,
A good friend asked me to build to his son a small amp - he used Fender Champ as an example - and I went on to check fender schematics for many variations on the subject. despite the fact that design changed from simple volume control to a bass, treble and volume, I was wondering about voltage relationships and how deep it is into class A.
5C1 feeds 6V6 plates @ 320V, G2 @ 280V, kathode @ 16V;
5E1 feeds 6V6 plates and G2 @ 305V, kathode @ 19V;
AA764 feeds 6V6 plates and G2 @ 350V, kathode @ 19V.
Preamps are:
5C1: 280V;
5E1: 260V;
AA764: 330V.

It's my first time with S.E. designs and I would like to hear opinios from you guys. I know there are a lot of folks here who have gone down this route many times. So here are my questions:

How do you like voltage variations? why? how does it color the sound? higher = cleaner? lower = browner?
How about dinamic response regarding voltages variations??? Is VVR a nice way to go here?

Many thanks in Advance!
Best Regards

Rzenc

[tomcatarnold]

In general, you are correct..  Higher B+, more headroom.. lower, browner tone.  It's not just the volts though, the size of the output iron/OT will have as much to do with volume potential and overall tone as how many volts you put on the PT plates.  Also, you're not really comparing apples to apples when comparing the tweed era champ power sections with the BF/SF one's.  The tone stack in the BF/SF circuits kill mucho gain, so to get a similar volume to those tweed era amps, the vDC on the power tube plate had to be a little higher.

Personally, I would rethink building a BF/SF champ circuit.  I've played many a BF/SF era Champ with the tone stacks and unmodded there's just no magic there.  Every one was very dry and sterile sounding.  The tweed era circuits are way more interesting tonally.    Using the usual champ transformer set, the tweed Princeton/5F2 preamp circuit (w/tone control) and a MV after the V1B plate, with maybe switchable NFB..  You'll have an amp that will do all a BF/SF Champ will tonally.. plus have all the cool tweed tones available to dial in.

[rzenc]

Well, maybe I wasn't clear enough... I'm interested in tone...not volume...I'm interested to know how much the change of voltages interfere with how the amp plays. If diving into Deep A, that is, almost no change from quiescence to full roar will impact the amp performance.. will it gimme more compression? Hotter sounds? Will it be a waste of time?...I don't know, it's new territory to me. Unfortunately, I don't have time - read money - to do all experiments I would like to do in order to get some conclusions on my own. And I trust folks here. There are many names that comes to mind when thinking about innovative approaches, with no disrespect to others, just to name a few, Geezer, LC, tubenit, Iso, butter...they do some amazing jobs that I feel glad they share with us all...
PRR, Merlin, FYL, HotBluePlates are very knowledge about this subject and they share what they know...and I'm glad they do so..
There is no offense intented here, please, don't take it that way, but telling me that i'm comparing apples to oranges without telling me why I'm doing so isn't fair.

I've played many a BF/SF era Champ with the tone stacks and unmodded there's just no magic there.  Every one was very dry and sterile sounding.  The tweed era circuits are way more interesting tonally.

Thru the years I saw many guys here building champ amps and then they modded it to taste, but overall the raw design is the same. I'm interested to know what mods you did to make it sing magic. Tone is subjective, we all know it, but there are agreements on what is a nice tone and what isn't.
I'm really opened to ideas and suggestions are you are welcome to share yours with us..

Best Regards
Rzenc

[tubeswell]

I second the emotion about tweed champ/princeton circuits. I did a 5F2A circuit a while back and loved it. That 5F2A tone/vol control set is really effective.

You can generally run the B+ on an SE 6V6 anywhere between 300 and 400V and the amount of OT iron will make a big contribution to overall tone.

FWIW I've just done a parallel SE with an EF86 (with Merlin's pentode/triode morph control) in V1 and a 5F2A tone stack and driver stage. The EF86 morph control allows nice cleans as well as excessive pre-amp gain which easily has enough to drive a 6L6 grid into clipping. The output stage has switchable cathode resistors for running a variety of octal 6V6/6L6 pin-out type tubes, and the rectifier socket allows easy adjustment of B+ with a given range.

[rzenc]

I've just done a parallel SE with an EF86 (with Merlin's pentode/triode morph control) in V1 and a 5F2A tone stack and driver stage. The EF86 morph control allows nice cleans as well as excessive pre-amp gain which easily has enough to drive a 6L6 grid into clipping. The output stage has switchable cathode resistors for running a variety of octal 6V6/6L6 pin-out type tubes, and the rectifier socket allows easy adjustment of B+ with a given range.

Any schem out there?

[tubeswell]

I've just done a parallel SE with an EF86 (with Merlin's pentode/triode morph control) in V1 and a 5F2A tone stack and driver stage. The EF86 morph control allows nice cleans as well as excessive pre-amp gain which easily has enough to drive a 6L6 grid into clipping. The output stage has switchable cathode resistors for running a variety of octal 6V6/6L6 pin-out type tubes, and the rectifier socket allows easy adjustment of B+ with a given range.

Any schem out there?

Here's the schematic as I have built the amp - but I've disconnected the trem for now until I can get it properly trouble-shot

http://www.el34world.com/Forum/index.php?action=dlattach;topic=10746.0;attach=21549

[PRR]

> 320V 305V 350V
> 280V 260V 330V

This is all +/-10%. Maybe not even different at all.... maybe the power in Fullerton changed over the years.

Cabinet shape and color will have a larger effect.

Speaker has a BIG effect.

Are you going to custom-wind transformers? If not, then there's basically about one OT and one PT sold for all Champs. (A few boutique winders, but not for a friend's son.... the kid has to learn the basics then find his own opinions.)

Build the AA, because the tone stack gives him more to fiddle with. Try the dropping resistors from the older versions, let the preamp strain.

[rzenc]

Are you going to custom-wind transformers

Yes,  P.T., O.T., chokes.
I'm thinking about SS rectos.
Also, I see some folks moddin power supplies and feeding power tube plate after chokes in order to reduce power supply noises. Some folks goes on and add another choke to feed G2. Is it worth the additional cost?

Many Thanks in advance for the help guys!
Best Regards

Rzenc