Taming 36watter....1/2 Power Switch or Mass Unit?

[I360UP]

The subject line pretty much explains it all. 18 watts is great, but when you want or need that extra ummppff which way would be best to kick it in high gear.

Bob

[markh]

1) Halving the output power does not really reduce the volume much at all.
2) There's a certain magic in four bottles that always sounds a bit different than two.

Therefore, I recommend an attenuator. (I like my Hotplate, but every attenuator has its own vociferous proponents. )

--mark h

[Plexi]

1) Halving the output power does not really reduce the volume much at all.
2) There's a certain magic in four bottles that always sounds a bit different than two.

Mark... very well said.. Half power switches really don't seem to make much of a change in amps. Then to dial in the bias for each set or all being used has a give and take no matter what you use.
I like the VVR over any of the load boxes or attenuators..

I think the MV on the 36, will get you as close to the half power switch does..if the amp was full out in 18 mode. And yes the 36 and 18 do sound different even if the same circuit is used in an 18 or 36 amp.. maybe the transformers or as you say..just something about how they sound between the 2.. its just different.

Richie

[blaren]

wellll...while I cant argue with you guys in a technical arena, and while I've never tried the vvr...which, of course I'm sure IS the best way and I wish I could try/get/make/install or whatever one....oh..AND...I think Plexi can probably blow the guitar playing doors of me..well maybe kinda in a way...BUT....oops...I mean AND...I do KNOW that half or double power is only a 4dB difference,..oh and while I pretty much HATE any attenuator (havent tried the UA) even though a lot of people love them and get useable tones with them....after all that, I have to disagree that there isnt much "difference". The difference isnt so much a volume one, it's just the difference in how much easier it is to overdrive it in half power. To me, the half power switch (when working properly) is such a cheap and easy(?) thing to install I dont see why not. It makes the amp WAY more versatile. Granted the master vol does work VERY well in 36W mode, it works very well in 18W mode too. For REAL small rooms, to ME, there's nothing better than to have the 36er in half power just screaming. I dunno, I dont play witha lot of finess and I aint that great of a player but I've been playing live in bars since I was 12 (30 years almost) and I still play almost every weekend. I dont have a variable voltage regulator and I dont usse my attenuator unless I HAVE to ...like first set in a 50w sized room, just to ease the crowd into things. Sure feels good to turn that thing off.
The way it was described is pretty much exactly how I use my 36...I use it as an 18watter and only use it in 36W mode if/when things get out of hand and I need a bit more oomph...no not oomph...plenty of that in 18...a bit more POW. You think 18 and 36 watts are close volumewise...a 36 and a 50 should be even closer....but....it's a bit different. Just like (to me) the 18 and 36 are not interchangeable, neither are the 36 and 50. I play 3 different sizes of rooms...tiny (18w)...med (18-36)...huge/outdoor (50 or 100).
I CAN get away with it in 36w for the tiny rooms but, while the master is great, I still prefer to crank the powersection if I can.
Just my weekend warrior uneducated 2 cents
Now you can take MY word for it, OR you can take Plexi's word for it. He designed the circuits, tweaked them, plays the hell out of a guitar.....
So who you gonna believe? lmao...
I still say, get the half power switch (it's free) and if you dont like it, dont use it..use the atenuator.

[I360UP]

Hey Richie;
Is blaren really mad or just off his meds. Sometimes he make a whole lot of sense and sometimes I don't know WTF hes talking about. It must get lonely up there in the Great White North.

Bob

Btw Is there a schem of the 36 floating around with the 1/2 power switch.
TIA

[Igbit]

Not to hijack the thread, just a quick casual question: has anyone done a half-power switch for an 18-watt?

Karl

[Chubsman]

Blaren you savage.... Tell me this...

I have not plugged in the 1/2 power switch yet... it's there... everything is there... But.. I am nervous... Is yours workng well in 18?

Does it break up earlier? Cause if I listen to myself... I'll be wirering it in tomorow...

[LeeMo]

Karl,

has anyone done a half-power switch for an 18-watt?

I think that the way it works in the 36 watter is by turning off two of the output tubes. It won't work in the 18watt because it only has two output tubes.

LeeMo

[markhan]

Can you run a 36W as an 18W by removing 2 of the output tubes?

[LeeMo]

I couldn't tell you. But, I do have a schem that I saved from somewhere.

LeeMo

[markhan]

I think I found my answer on another thread. It looks to me like you could pull 2 tubes if you gave each pair a separate bias circuit.

[blaren]

Hey Richie;
Is blaren really mad or just off his meds. Sometimes he make a whole lot of sense and sometimes I don't know WTF hes talking about. It must get lonely up there in the Great White North.

Bob

Btw Is there a schem of the 36 floating around with the 1/2 power switch.
TIA

MOOOAAAAAHHHAAAHAAA lmao
I hope you mean "crazy" mad and not "angry" mad...cause it's the first and if you meant the second then you're making me mad lmfao.
I thought I make perfect sense all the time...dont I? lol

Anyway...here's one...so today I was crankin my 50 and 36 and...when I went from the 50 to the 36, the 36 seemed to have WAY WAY too much bottom end. Going from the 36 to the 50, I found myself jacking the bass a bit to fatten it up a bit but after a few minutes I rolled the bass back down to about 4 where it usually is.
I think I DO have to run the 36 with the bass on 0. I think I finally have to admit that I could use less bass in the 36. Richie, you mentioned somewhere that you had a remedy for those who found it a bit thick in the bottom end. Will going to the 150ohm cathode resistor pair and/or going back to those 470Ks from the 330s? Or something different?
Oh AND...is everyone who's running the 1K5W instead of the 100ohm resistors using a choke or the resistor on the cancap ?
I aint mad...........I'm mad!

[NitroLiq]

Oh AND...is everyone who's running the 1K5W instead of the 100ohm resistors using a choke or the resistor on the cancap

If folks are building off the new layout, it would be the resistor across the capcan. Some people had problems in the past using chokes, but they do work...resistor option is cheaper and works just as well.

[timquigg]

I'm thinking of building a lite 36watt using 2 hammond 125e output transformers. I have access to them, so figure I'll just use them. Is it possible to wire up a half power switch if I'm using 2 output transformers?

[Breogan]

I'm thinking of building a lite 36watt using 2 hammond 125e output transformers. I have access to them, so figure I'll just use them. Is it possible to wire up a half power switch if I'm using 2 output transformers?

I am interested in this one too...

The "Tube Amp Book" states that part of the overdriven tone comes from actually pushin the OT to its limit. This this can't be achieved with a 36W OT and a half-power switch.

[markh]

If you build two complete parallel 18w output stages (including two OTs), and connect each to a separate speaker, you could shut one of the two off to do the half power thing, and still be pushing the remaining OT.

I (theoretically) like the approach for this reason, even though it is a bit technically complicated and messy to implement. Using half the speakers will also decrease the total volume a bit.

--mark h

[seancostello]

Hi (this is my first post, or my "don't get kicked out of the forum" post under the new rules):

What are the tradeoffs of transformer saturation vs. bass response when running a 36 watt TMB with only one pair of output tubes? Does transformer saturation truly add useful coloration? Will the bottom end be "tighter" with a 36 watt OT using a single pair of output tubes?

Also, how much of a factor is the power supply? Does the 36 watt have a more robust power supply than the 18 watt, and will pulling a pair of tubes from the 36 watt really give you a sound closer to the 18 watt?

Thanks,

Sean Costello

[seancostello]

Hi (this is my first post, or my "don't get kicked out of the forum" post under the new rules):

What are the tradeoffs of transformer saturation vs. bass response when running a 36 watt TMB with only one pair of output tubes? Does transformer saturation truly add useful coloration? Will the bottom end be "tighter" with a 36 watt OT using a single pair of output tubes?

Also, how much of a factor is the power supply? Does the 36 watt have a more robust power supply than the 18 watt, and will pulling a pair of tubes from the 36 watt really give you a sound closer to the 18 watt?

Thanks,

Sean Costello

[zevoz]

I have a Weber 6M36TMB. I am working on a pentode/triode switch which is the way the Marshall 25/50 amps achieved half power. I figure between the master volume, the half power switch and the pentode/triode switch I won't need an attenuator. Theorectically, with the two switches engaged you would have around 9 watts. The triode mode gives you a little softer sound and the distortion comes a little sooner and easier.