Questions About KT66 VS KT88 tubes

[ELPisthebest]

I am a newbie to tube amps.... I'm building my first from Ceriatone. I havent made up my mind on which one yet though. I'm looking at a JTM45/100 "experianced" or a JTM45 bluesbreaker.

Both have KT66's in them. The 45/100 has 4, 45 has two.

I am wondering if I can buy the JTM 45 and put KT88's in instead of 66s to get the same amount of wattage as the bigger one (100w).

I know it fits in the same socket but I am worried about the difference in Bias voltage, screen voltage, and if the same circitry could handle the higher wattage...

I Kinda want the smaller JTM45 because it has a tube rectifier instead of solid state, but I also want a 100 watt head so?? Decisions decisions

Here are the two amps:
Ceriatone Amplification ---JTM45

Ceriatone Amplification ----JTM45/100

[Wakculloch]

A pair of KT88's will only put out 100W with an appropriate power supply. The one in the JTM45 can only give you 50 or so watts no matter what valves you put in.

[ELPisthebest]

so If I amp up the power supply, Can I get the full 100w?

[ELPisthebest]

like put in a 100w, power supply?

[Albert Kreuzer]

You need a 100W power supply, a 100W output transformer and a 100W rectifier (that's either 2 recto tubes or a SS rectifier).

[Gibsonman63]

I am sidestepping your question a bit, but...

100 Watts is only 3dB louder than 50 Watts and both can be plenty darn loud and neither will have a problem keeping up with drums. The older style Marshall circuits are not super high-gain amplifiers and will sound better cranked to most people, which is easier to do with less power.

Or if you really need 100 Watts, the tried and true JCM800 2203 is a nice choice.

[ELPisthebest]

Your not... info is much appreciated.
yeah... I kinda figured there would be a problem with the circuits, I'm not really sure if I need 100w, I run a peavy 2x8"+1x15" cabinet so I thought I might need the extra power to drive the Sub. And I'm not being snotty but how is 100w only 3db louder? And wouldn't that depend on which speakers you use?

And I'll probably stick with just using the KT66's seeing as there is to much to Mod from Albert.

[Gibsonman63]

This is an open exchange of ideas, so asking technical questions here shouldn't provoke any ill feelings.

Everytime you double the power, you pick up another 3dB and you are correct, the speakers will make a huge difference. Some are more efficient than others, and how your sound fits frequency-wise in the mix will also change your percieved volume. My gigging rig is only 35 Watts, it it cuts through just fine at a little less than half volume.

Is the 15 really a sub or are you running it full range in parallel to your other speakers?

[J M Fahey]

Rather than worry about the small differences in using one or the other tube , I would worry *a lot* about the speakers, seeing that you are using a *bass* cabinet instead of a guitar one.
What's wrong with, say, 2x12" Eminence, Celestion, Jensen or Weber; or some other typical, time tested guitar configuration?
As far as to which kit build, a 40 to 50W amp will provide you *much* more pleasure and usability than a 100W one.

[ELPisthebest]

This 3db measurement is in DB(VU) correct? The speakers determine the DB(SPL) levels...I think.

I am running the 2 8" in series then parrellel to the 15"... And I was going to put a crossover in the cabinet so it would be a full range but I ordered the wrong one (I ordered a low pass filter). I returned it.

Is it important to have the freq's within the response range of the speaker? I'll order a 500hz 2 way crossover if thats so.
The treble is quite muffled in my system. Right now im running it with a super cheap 60w Phonic powered mixer. haha i really really need this upgrade.

[ELPisthebest]

Yeah I decided on the KT66's so the tube parts over...

I got this peavy cab for free and I use it because it what i got. haha. It has a Blackwidow 15" and 2 JBL 8"s but the treble is very muffled and it lacks a lot in tone.

My next project after the tube amp is to upgrade the speakers... I'm thinking about putting all new Eminence speaks in there, probably the "Commonwealth" 15" or "Big Ben" 15". Not sure... And I'm having trouble finding 8" *guitar* speakers. Most are PA and would probably lack the shimmer thats needed.

Another reason I would enjoy the cab(if it had better speakers), is the amount of Classic Rock, Metal, and sloppy blues i play. I love that "Chunk" sound. and the 15" is perfect for that.