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[kfowler8]

OK gents. The wife and kids are out of town for a week so I've got some serious time to screw around. Taking what I learned from the power amp comparison, I wanted to see how different tubes compare to each other.

I had a theory before I got started on this that the difference between tubes would be much more subtle than the difference between power amps. The last test I compared a solid state Crown, Marshall EL34, Mesa 6L6, Picovalve 6L6, and Peavey Classic EL84. I thought the Marshall sounded the best out of the ones tested. My theory though is that the tone is much more driven by the amp itself vs. what tube was used.

So, for this test I used my Picovalve which can handle any tube. I even have an adapter for EL84s. So I'm playing my PRS into the MP-1, into the Picovalve, into an Iso cab with a Scumback M75, and mic'd with an SM57. So the only difference you're hearing is the change in tubes.

Note, the tubes are changed after each drum fill. Both the lead and the rhythm are played with each tube.

The test order is:

- Marshall JCM 900 SL-X power section w\ EL34 from the first recording
- Picovalve EL34
- Picovalve KT66
- Picovalve 6L6
- Picovalve EL84

https://soundcloud.com/kfowler8/power-amp-test-2

So what do you think?

[El Chiguete]

Sorry but since you played different parts in this test I can't compare the same as the other test, on the other one there where some pinch harmonics that REALLY stand up in the mix with the EL34s but this time on some of the recordings you dont hit them... could you play the same each time or recorda a base track and reamp each time to have a real comparison more like before?

[kfowler8]

Sorry but since you played different parts in this test I can't compare the same as the other test, on the other one there where some pinch harmonics that REALLY stand up in the mix with the EL34s but this time on some of the recordings you dont hit them... could you play the same each time or recorda a base track and reamp each time to have a real comparison more like before?

I'll see if I can run a loop or something.

My conclusion after doing this is the tone is much more dependent on the amp than the tube. It's what I suspected. I think the lack of punch in the Pico make come in with the lack of power. It's 5 watts vs. 50 watts in the Marshall. The Marshall was pretty well cranked when I recorded it.

I can certainly hear a difference between the tubes but it's much more subtle. Interesting thing to me is the EL34 is my least favorite in the Pico. I typically run the KT66 in it. So you can definitely tell that the right tube complements the amp.

Big thing I as trying to get out of this was for power amp shopping. I was hoping that this would tell me what tube and I wanted and therefor what power amp I needed. However it looks like it's going to be just trying out different power amps for the right fit.

[rnolan]

Had a listen, the Marshall sound is alive and full of energy (as you say 50 w compared to 5 w).
In this it's so hard to compare apples with apples, in the end, it's just "does it sound good/what do I want".  There are a bunch of variables, amp, tube, guit, player the list goes on as they all make part of the sound. I agree, the KT66 in the pico are probably the go, each sound had it's merits but all round I'd also pick that combination.  But you can't really compare that with the first Marshall (easily) as it was by far the best in many ways but the most "ragged"  and a large part of that was probably 50w cranked (well you probably weren't doing the full 50 ?).
With MP1/2 I go for clean transparent power amp. I used a B200s for years and loved it (it just wasn't there, except I had lots of grunt).  I currently use a Carvin TS100 all tube amp. it claims to be a good amp for studio monitors (very clean/transparent), anyway works a treat, love it, a bit heavy though (as are all tube amps), my version is running the 6L6s' (I may try some 6CA7/EL34s in it next tube change (it takes both, switchable), as you say tubes here will make a subtle difference, and compare apples with apples). I don't expect a huge difference though as all my tones are coming from my fingers/guit/MP2.  It's a little more finicky with the MP1/2 input tubes, there seems to be more variations at this point of the circuit (but again, if you've selected decent tubes, the differences are (mostly) subtle). And I should add subjective.
Cheers R

[kfowler8]

well you probably weren't doing the full 50 ?

Pretty close. Running it at 7 of 10. The ISO cab lets me do that. Pretty neat box.

[El Chiguete]

All those power tubes normally have different current values and voltages that you run them (they will sound different if the voltage that you send to the internal components of the tube is lower or higher) and also depending on what you actually want to do in your design you can change that too... so by just changing tubes maybe for one tube you will run the tube at a good efficient values but for another no. So I agree too that the complete amp design is more important.