6L6 rocket

[Normster]

You're welcome. If you look at Vox AC30 and Matchless Chieftan/Clubman schematics, you'll get an idea of how many different cap values are used in this circuit. .1uF seems to be too much for EL84s even though that's what the AC30 used. The Clubman used .1uF feeding the PI grids, but .047uF to the power tubes. The Chieftan used .022uF all around. Nice to know there are so many "legitimate" values, eh?

BTW, this is an EL34 amp (and obviously fixed bias w/SS rectifier).

[RJ Guitars]

... RJ-
Do you have any idea as to the ideal cab dimesions for 2X10?
I want to build a combo, but I would lke to size the cab such as not to lose any lows and mids

Markus V

Markus, I have an unresearched and unproven idea for a 2x10 combo cabinet that I am willing to share. I apologize for the drawing quality, the lines are so thin that they don't show well on a computer screen although they print out fine.

Zippy likes his 2x10 Super amp, it is slightly taller and narrower.

With what I know now, I might be inclined to make it 12 inches deep rather than 10, but that is just more guess work on my part.

Actually, I think Normster and the Brown Note guys have much more experience in cabinet design than I do. Maybe they have some ideas on a 2x10 cabinet?

rj

[Markusv]

RJ

Many thanks-
The picture does not print out legibly though

Could you just provide the dimensions?
Just list them please

Regards
Markus V

[RJ Guitars]

RJ

Many thanks-
The picture does not print out legibly though

Could you just provide the dimensions?
Just list them please

Regards
Markus V

Easy enough...

21.5 Wide x 16.5 Tall x 10 inches deep. As I said, this is an untried design.

I'll work on a better copy for the post. Until then, you can get a good print if you do a save image, then bring it up in a photo viewer.

rj

[Markusv]

RJ

Thanks very much!

Somewhat similar to a 2x10 combo cab on 18 watt forum
(1958 MiniBluesbreaker (2x10) PowerPoint Presentation)I'm not sure if they would mind me posting the plans here so I will refrain. Please do a search there
Of course, the chassis is not the same rear-mounted affair. so the controls will be in front and I will have to make sure the tubes allow enough space for the speakers...

Will work on it and report back

Markus V

[RJ Guitars]

Here is something that Zippy found... http://www.alessandro-products.com/work ... /boxer.htm

Looks a lot like my cabinet... only his has "proprietary" construction techniques that make it 50% lighter. I am thinking foam core with wood (or plastic) laminate?

I wonder if this amp has $12 each pots, teflon coated silver strand wire in it, and of course the careful handmade one at a time construction technique?

At any rate, there you have the same basic geometry as the cabinet I proposed. I am all for the low profile and light weight and I think a pair of tens can really put out the goods. I have had no problem getting the low end out of the cabinet I currently use which is the same size as my proposed combo cabinet.

rj

[Markusv]

Here is something that Zippy found... http://www.alessandro-products.com/work ... /boxer.htm

Looks a lot like my cabinet... only his has "proprietary" construction techniques that make it 50% lighter. I am thinking foam core with wood (or plastic) laminate?

I wonder if this amp has $12 each pots, teflon coated silver strand wire in it, and of course the careful handmade one at a time construction technique?

At any rate, there you have the same basic geometry as the cabinet I proposed. I am all for the low profile and light weight and I think a pair of tens can really put out the goods. I have had no problem getting the low end out of the cabinet I currently use which is the same size as my proposed combo cabinet.

rj

Thanks, RJ (and Zippy)

That cab from the looks of it has no more than 22-23 Inches width for the baffle board, and probably about 16-17 inches height. (Minus the 2 or so inches the chassis would take up at the top if mounted as a hanging chassis fender style)
So it is more or less the Golden ratio provided that the depth is around 9 inches
(9x14.5x23)
Provided pleasing dimensions at least. Before I get taken to task on the validity of Golden ratio, I realize that these are guitar cabs, the internal volume for the speaker is important, and then also the fact that is probably going to be open-backed, so this is more of an observation than an assertion.
What I have found though is that a while ago I built a pine cab (open back) of the same dimensions and it sounds glorious with any speaker I use in it. Currently it has a ceramic Tone Tubby.

About Allesandro
You`ve got to give him credit for beautiful construction, and the hardwood products seem top notch.
I believe you can order an amp with a solid silver chassis if that turns your crank, and of course the copper in the wires is all grain oriented, so of course the electrons flow very much faster.
They litterally go "Wheeeee!" all the way to the speaker. But you have to listen closely.
Still, I am jealous, and I wish it was my amp company.

Back to speaker choice
I believe that if I think in terms of the typical speaker choices used in a Bassman I will be in the right ballpark. I had a look at the webers you suggested and I think there are a few winners there
That said, I will slap together a test cabinet for some 10's I have here, give it a listen and then finally make up my mind

Thanks again

Regards,
Markus V

[ER]

Hi Markus-

I would try something just a little bigger, golden ratios are nice but you can't cheat physics.

A quarter wave length of 80 hz (low E) is ~42.375", so 26" wide X 8" sides X 16.5" tall plus a little for the chassis puts you square in brownface vibroverb (2x10") territory (8" sides are 16.186 divided by 2 to give the quarter wavelength baffle width of 42.3").

The thing with golden ratio is that the divisions added together equal the next ratio; 43.375/1.618=26.189, 26.189/1.618=16.186, 16.186/1.618=10.004, So even the 10" speaker fits the ratio for a nice 80Hz fundamental.

I'm working on a tweed 6L6 bandmaster right now that will use a trainwreck layout just in case I want to change it over after hearing it (looking for a blues amp that will keep up with a drummer and also get the tone of the first Montrose album when needed).

-ER

[Markusv]

ER

Thanks

What you say makes sense. Physics deal with wavelength and ratio's are just that- Ratio's
Once I built a combo for a Traynor Clone and the cabinet was waaay oversized
Looked ridiculous but sounded incredible, no matter what 12" speaker I put in it. The bass and mids were incredibly full but not overpowering and balanced the highs nicely as I voiced the amp quite bright.

It's too late though
My cab has been built and the dimensions are as follows:

Inside dimensions:
23 1/2" wide
16 " high
9" deep

So it is pretty much in the ballpark. I hope I am not disappointed, but we willl see
The cab came out well. I chose quarter sawn pine and Imbuia trim for the edges and the faceplate surround.
The corners are half blind dovetails and the 1st oil finish layer (of 3) is curing as we speak

Markus V