Same loudness with 6v6 or el34's?

[jcr1234]

I have asked this question before, but I just dont understand the answers. I have been told that the Express will not be much quieter with 6v6's as opposed to el34's. I dont understand this, doesnt a 6v6 put out about half the power of the el34?

I understand that a 50 watt Marshall is almost as loud as a 100 watt, the main difference being the amount of (semi) clean headroom rather than db's.

What concerns me is that this amp will be built to be enjoyed in my home, I dont gig.

I can enjoy an 18 watt Marshall, or a tweed deluxe, but a 50 watt Marshall, no way.

Will I be disappointed with the Express 6v6 clone? Ie, will it have to be too loud to get to the sweet spot to enjoy in a home?

[ampgeek]

It has more to do with the fact that "loudness" (e.g., sound pressure) is quantified on a log scale and electrical power is linear.

So....it takes about 1/10th the electrical power to get ~1/2 the "loudness". A 10 watt amp will be about half as "loud" as a 100 watt amp.

My understanding is that an Express won't satisfy the "easy" home listening desire. However, I also understand that a well done variable voltage regulator (VVR) might get you close.

Cheers,
Dave O.

[sst4270]

simple answer...

"In general" a doubling of power will get you a 3 db increase in loudness and vice-versa.

So with EL34's you're getting about 35W out of the Express.
With 6V6's you're getting about 20W.

So it's less than a doubling/halving of power and hence less than a 3 db increase/descrease loudness or SPL.

So expect less than 3 decibel difference when going from EL34's to 6V6's in terms of the overall loudness of the amp.

With 6V6's the Express is plenty loud enough to gig with but also tame enough to be played at home (albiet) not at bedroom levels.
If you want bedroom levels you're gonna want to use a power brake.
There's plenty of threads on here regarding how to build the one that Ken helped design and sold by Dr. Z.

Hope this helps.

Steve

[sst4270]

Also to reiterate what Ampgeek said...

I'd also recommend (you mentioned having it built) getting your amp built with one of Dana's VVR circuits so you can vary the power of the amp.

See here: http://www.hallamplification.com/main.html?src=%2F#2,2

Steve

[mcrracer]

Regarding the VVR in an Express, which would best preserve the character of the amp? Scaling the whole amp, The PI and PA or just the PA?

[dartanion]

Regarding the VVR in an Express, which would best preserve the character of the amp? Scaling the whole amp, The PI and PA or just the PA?

I prefer scaling the whole amp, but others may contend differently. I like this solution as it keeps the whole circuit running proportionally. I also change the low limit on the VVR to keep the amp operating at a minimum voltage that retains the best tone to my ears.

I can hear and feel the difference in the Express circuit when using EL34s vs. 6V6s, so to me it's more a tonal choice than changing output power. I prefer 34s, but I have a couple sets of 6V6s that for some reason sound just as good and just another flavor of Wreck goodness. I'm also not using the ubiquitous speakers of choice either, but why not be a Maverick! Tone has no boundaries!

[Richie]

i built this for a guy that wanted 6v6s and VVR.. This one uses cap cans, a few changes made here and there, but thats about it..

[dartanion]

She's a beaut Richie!

What's her name?

[funkmeblue]

what cans did you go with if you don't mind me asking

[Richie]

What's her name?

I don't name them, i let the owner do that.
I used dual 50, and a 40-20-20-20

changed the 220k to a 150k in the bias feed. And useing a single 270k bleeder.
Got the dc blockers on the V1 tube. Dana has some pics of one of his VVR build on here somewhere. Pretty much used hes layout,using the VVR and cap cans. Very quiet amp too.. Till you hit a chord.

[ampgeek]

Very nice! Exactly what I am in the process of acquiring parts to build. Just got the VVR from Dana. Exceptional looking little package by the way.

Quick question: what is the material underneath the VVR board? I know about the insulator on the mosfet but can't quite make out the other "pad".

Another quick one: What size DC blockers did you use on V1? They look smaller than the generally recommended 0.1 uf. Are those OD PS series? Ok..ok...more than one quick question there!!

Search the Trainwreck Discussion board for "Express with variable voltage regulator" to find the thread that introduces this plan.

Thanks for sharing your work!

Cheers,
Dave O.

[Richie]

they are .1uf, just less voltage size. really don't need a 600v cap there..

the pad, is just fish type paper. similar to the fender board stuff, just a bit thinner. Kind of about the size they put on the side of the chassis, beside the indicator light in the fenders.
you could use about anything along those lines. Just something i had on hand. I just like having something under it.

you can get the PVC or PS series in lower rated voltage.
http://www.westfloridacomponents.com/mm ... allory.pdf