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Hi all. Completed my Spitfire over the last weekend. Had a hum problem that has been some what reduced. That's not my main concern tho'.
Not having any new tubes but lots of used , known, good tubes that I've been swapping, I get a nice clean sound until about 3 on both vol & master,Then very non-musical distortion from there. I did try the 5u4b rec. That dropped the voltage about 25 volts everywhere. Cleaned it up furthur on the volumes but still the annoying type distortion. With the gz34 rec the voltages are almost spot on. I bought the loaded board off ebay, everything is wired right according to all the layouts I've seen. Other than tubes is there anything I should look for? Any help is more than welcome and much appreciated.

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I think I'll build one of everything!

Can you tell if it's MV related or Volume control related? i.e try to isolate where down the line the problem is.

Sounds like V2 or V3 Try reversing V2 & V3 and see what happens. Note the control settings and see if there is any improvement to the sound.

What trannys are you using?

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

The trannies are from West so there should be no issues there. I did try some NOS 5751s' that I had. That moved the noise up a little furthur like the 5u4b did. As far as the volume or the master issue it doesn't seem to matter. I'll order in some new tubes and try those. What are you using in your amps? I have tried some JJs' ax7s' and was not overly impressed with them. Didn't seem to have the gain and kinda sterile sounding. I like old sylvania tubes when I find them. I'm 53 but I still love an aggressive sounding amp. Nothing buzzy/raspy.
Thanks for the help. Anybody else, any ideas?

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I think I'll build one of everything!

What happens when you reverse the tubes? Do the threshold of distortion change?

Try a differnt PI tube.

Is the speaker impedance is matched correctly?

I use Shuguang & Russian EL84Ms. They work pretty well together. The EL84s have some nice meat and the Shuguangs are crispy.

I will say, the stock amp starts to break up about half way. I have used 30W OT to avoid this for cleaner sound.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Finally got ahold of some new power tubes, made quite a difference! Seems the old power tubes I have are pretty much all used up .
Haven't tried any new pre-amp tubes but will try them next. Better start looking for speakers.

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I think I'll build one of everything!

So, did that cure the "non-musical distortion." Sure hope so!
What brand of power tubes did you use?

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

just stuck some sovteks in there for now. Will try another brand at a later date, not sure what tho'.

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I think I'll build one of everything!

Try some Russian Military ones. EL84M. See forum topic on tubes: http://www.trinityamps.com/phpbb/viewtopic.php?t=52

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

From what I understand, Matchless used EL84Ms in the Spitfire and still do in the Lightning.

The WoodCross Thunderbolt 9 Amps that I build are loosely based on the Spitfire Circuit. I use JJ EL84s for power, a JJ ECC83 in V1, and a Sovtek 12AX7 in V2. All tubes are exactly in the middle of the gain factor. Sometimes I use an old RCA 5751 in my personal T-bolt 9 stuck in V1. Instant Dr Z c@rmen ghi@.

CR ><>