#1
I searchbar'd and didn't really find exactly what I'm looking for, so here goes...

I have a Peavey Ultra+ 120, and it's time for a retubing. I had JJs in it (the high-gain set from Eurotubes), and it was way too over-the-top on the gain. I put some old GE 5751s in the preamp and it sounded much better. The JJ 6l6s are still in it, and I like their sound, but based on some research, SED Winged Cs appear to be worth a shot.

My question is: What tonal or quality differences am I likely to notice if I do go with SEDs as opposed to JJs, and is the difference worth the higher price for SEDs?

I think my mind is made up to at least try the SEDs, but I would just like to know what to expect.

EDIT: Also, if anyone has any experience with different NOS 6l6s that are comparable in price and quality to SEDs or better, any info to that end is appreciated. Thanks in advance for any help. Please let me know if more information is needed.
Last edited by BCKRedBaron at Jan 13, 2012,
#2
I don't have the exact experience you are looking for but I'll give you my two cents.

I put some SED =C= power tubes in my Splawn about a year ago and I must say they are nice tubes. Are they worth the extra cost? I don't know. I would say they are very similar to the JJs. I had British Mullards in before and I know that Mullards are similar to JJs as far as their smooth somewhat darker tone. Therefore, I probably would not worry about power tubes right now. I mean if you have extra cash and/or you gig with this amp and you want to go ahead an be proactive then knock yourself out.

Otherwise, there may be some other things to tame the gain. The 5751 is actually pretty close in gain output as a 12AX7. Maybe 90%. I'd try a NOS 12AT7 (75% of the gain) or a 12AU7 (50% of the gain of a 12AX7).

I can't remember if these amps can be manually biased or not but maybe it is biased too hot?

Also, there are quite a few mods that can be done to these amps so maybe it is just a matter of swapping out some resistors. Maybe Cathbard will see this and offer his 3 cents.

Ultimately, power tubes do not have nearly the affect on your tone as some of these other things I've mentioned. Also look into Ruby SRTs and Mullards.
Last edited by 311ZOSOVHJH at Jan 13, 2012,
#3
SED make the best modern tubes money can buy. However the gap between JJ and SED when it comes to 6L6's isn't as big as with other tubes. (Even smaller with 6V6's)

As for NOS, the best thing I ever did for my Abbey was to stick in a couple of old British Brimar 6L6's into it. I was lucky enough to score them very cheaply off Ebay. I think the main reason for that was that they were labelled United Electron (who were a rebranding outfit back in the day) and I don't think the hoi poloi knew what they were looking at so they didn't bid.

As for taming the gain. JAN Phillips 5751's will help a bit and they are quite cheap for what you are getting. They aren't much lower in gain than a 12AX7 but they may be just what you need to take the edge off without going too drastic.
'Twer i you I'd grab a few different valves including some 12AT7's and even 12AY7's and try them out one at a time in different positions - be methodical. You can often score NOS valves of those rather cheap on Ebay because they aren't in high demand. I managed to score a GE 12AY7 the other day to go into a Fender for $10 and it's a little pearler.
But whatever, sort out the power amp first before you move onto the preamp.
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Cathbard Amplification
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Last edited by Cathbard at Jan 13, 2012,
#4
Quote by Cathbard

As for taming the gain. JAN Phillips 5751's will help a bit and they are quite cheap for what you are getting.

I just wanted to help clarify this. I believe he said he just put in GE 5751s throughout the preamp. And when you say 'quite cheap for what you are getting' I want people to know that that is a good thing not a bad thing. They are well made good sounding tubes that are not super expensive.
#5
Quote by 311ZOSOVHJH
I just wanted to help clarify this. I believe he said he just put in GE 5751s throughout the preamp. And when you say 'quite cheap for what you are getting' I want people to know that that is a good thing not a bad thing. They are well made good sounding tubes that are not super expensive.

Correct.
GE are pretty good too but a Philips will kick its arse.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#6
Thanks for the replies gentlemen!

I found those 4 GE 5751s on ebay for a decent price. I tried one in V1 first, and that really helped the gain, compared to the 12ax7s. I tried another one in the PI, and eventually ended up putting all four in. Before, i was getting plenty of saturation on the Ultra channel at 1 or 1.5 on the dial. It was definitely metal territory. Now, at the same setting, it's maybe classic hard rock territory.

311, I'm about 99% sure that the Ultra is "fixed" bias, and knowing Peavey, they biased it pretty cold. In the future, I'd definitely like to try the bias adjustment mod. Is it just replacing the resistor with a trim pot? I'll probably have a tech do it b/c I'm totally inexperienced in that area.

As far as the 6l6s go, the main thing is they need to be changed one way or another. I bought them in '07, so I think they've outlived their life expectancy!

Thanks also for the suggestions on preamp tubes. I'll definitely keep my eyes open for a Philips 5751 and some Ts, Ys, and Us. Any suggestions as to what NOS brands were the best?

One last thing, while I have your attention: since we're on the subject of SED, how do their EL34s compare to, say, a JJ E34L? I have New Sensor Mullards in my Quick Rod, and E34Ls in my Stiletto.
#7
Correct, the Ultra is non-adjustable fixed bias.

The EL34L is the newer version of the EL34. It can handle higher plate voltages and when run in an amp designed for EL34GC's it results in more headroom. They also have more bottom end and just sound "bigger". One would use EL34's over EL34L's when one planned to use power tube breakup.
I think SED make an EL34L as well but i could be mistaken.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Jan 14, 2012,
#8
Ok. I was just wondering b/c my QR's about due a retube too, and I want to try to find something better than the Valve Art tubes Splawn sent me.

As far as the Ultra, how would one go about modding it to be manually adjustable bias?
#9
You'd have to replace R99 with a pot. Say, 100K linear.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band