Rectifier Tubes - Advice needed

masongary44 · Post by **masongary44** » Fri Feb 28, 2003 4:52 pm

I own an Orange AD15/10 with non stock tubes (well the EL84's are a matched pair of mullards). I know little about amp electronics, and would like to know, what the rectifier tube actually does, and how it affects the sound of the amp.

The pre-amp tubes are still stock, and i would appreciate any suggestions for alternative tubes that give a little more overdrive.

Don't get me wrong, I love the amp as it is, but I have read many reports of people turning good amps into great amps by mixing and matching different tubes from those originally supplied.

Live and kickin'

VintageJon · Post by **VintageJon** » Mon Mar 03, 2003 5:55 am

The rectifier "converts the large AC voltages from your power transformer into large DC voltages which your tubes use.
This action is known as RECTIFICATION!

Some say the rectifier doesn't have any effect on your tone which in the strict sense of "tone" is true. BUT it does have an effect on your sound. The amount of DC voltage produced varies with different rectifiers and different makers within a type of rectifier. This has an effect on the power your amp produces. They also have a characteristic known as "sag" which is really a propert of the whole rectifier circuit. This has an effect on the headroom your sound has.
Both of these are primarly due to the internal resistance of the rectifier and is more noticable with tube rectifiers than solid state diode rectifier schemes. This is due to the fact that all solid state diodes have a forward voltage drop of between 0.5 and 0.7 volts and you probably can't hear the differance. Forward voltage drops across
different rectifier tube types may vary by as much as 40 or 50V and this is 10% or greater of the final supply voltage. You can hear that.
I've tried to explain this as non-tech as I can. I've been dealing with these things for nearly 40 years so it's hard to not go technical when asked a question.

Hope this answers your question,
Jon

tone_temple · Post by **tone_temple** » Thu Mar 06, 2003 5:27 am

check out my post titled "ad 15/12 mods". i mentioned changing one of the 12ax7's with a 12at7 (jan nos philips). i was blown away with the amount of distortion after this simple mod. i replaced the one furthest from the output tubes. even when the volume is low, i can get a good distortion. i can now also set it up where i'd just adjust my volume and i would get a nice "bachman-turner" overdrive. i'm still not done experimenting. i'm gonna try and move the 12at7 to the other slot and see what happens.

tone_temple pilot

masongary44 · Post by **masongary44** » Fri Mar 07, 2003 5:33 pm

I have done a little more research, and found that despite having a nice pair of mullard valves in the power secion i hav sovtec 12AX7WA's which on independant testing are seen to be low gain, low quality, 3.50 a shot, suitable for cheap repair tubes.

I have ordered some Ruby sepcials from www.watfordvalves.comm which are rated as high gain, and much better tonally.

Is the effect you have seen replacing the 12ax7 with a 12AT7, down to pre-amp valve possition , or just down to the fact it is there...In other words, does the possition of the valve make a big difference to its tonal and drive contribution.

Live and kickin'

Post by **bclaire** » Sat Mar 08, 2003 4:51 pm

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
i would get a nice "bachman-turner" overdrive. i'm still not done experimenting.

<hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana, Arial, Helvetica" size=2 id=quote>

If you've seen these guys recently (for me, I'm talking about 12 years ago....) they're more like "Bachman Turner Overweight."

tone_temple · Post by **tone_temple** » Mon Mar 10, 2003 10:10 am

ha-ha-ha! yes, they are a quite a bit on the heavy side. now seriously, going back to masongary44's question -- i haven't moved the 12at7 to the other position yet. i've only tried it on the connector farthest away from the output tubes (v1 or v2? does anyone there know?). anyway, i'll let you know as soon as i have the time to open the amp again. i just picked up a gz34 mullard online and will be receiving it next week. when i get it, i'll move the 12at7 at the same time.

regards,
tone_temple

snip, snip...
"....If you've seen these guys recently (for me, I'm talking about 12 years ago....) they're more like "Bachman Turner Overweight."

R2D2 · Post by **R2D2** » Tue Jun 17, 2003 2:11 pm

I've only recently bought an AD15 12" and I am well pleased with it. However, I couldn't resist the temptation to experiment and so I've replaced all the tubes with Harma's from watford Valves. I've left the stock rectifier where it is though. I re-valved my Laney LC15 and was amazed at (to my ears anyway) the improvement in tone.

With my AD15 the new valves have (as I'd hoped)increased the gain available, and they've sort of "smoothed" the overdriven tone, but reduced some of the sponginess and my guitar "feels" more dynamic and strangely easier to play fast(ish) licks. The clean/crunch tone has changed a tad, but the most obvious difference is when I use my BOSS GT5 to give me overdrive. It sounds great now. With the old valves it had an awful high end buzz about it and I was about to go on a quest for a better overdrive device. Not now.

There's no right or wrong as I see it, but I am pleased with the change the new valves have made. If in doubt, and if you can afford it, experiment. If the worst come to the worst you could always put the old valves back... assuming they're not shot.

so long and thanks for all the fish...

<img src=icon_smile_big.gif border=0 align=middle><img src=icon_smile_big.gif border=0 align=middle>

Rectifier Tubes - Advice needed

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