How much does the rectifier stage effect the character of an amplifier. So far, on nearly every SS/Tube decision that's come down, I've gone with tubes. Now, I'm looking at two 300b push-pull integrated amps, the main difference between the two is that one puts out 18W/ch and uses tube rectifiers while the other puts out 25W/ch and uses SS rectification. The SS unit has a much greater bandwidth and just specs out better in general. I'm leaning toward the SS rectifier as long as the amp will still have that tube magic. Your opinions will be appreciated.
Tube rectifiers take a few seconds to come up to voltage so tend to offer a "soft start" to tube gear. They also run at a bit lower voltage than a solid state rectifier.
For example, I have a Dynaco ST-70 I rebuilt and have a plug-in solid state module I can use in place of the 5AR4.. The most immediately noticeable factor when I change rectifiers is I have to rebias the amp. The solid state rectifier gives 10% or 15% higher voltage.
That said I don't notice any difference in sonics between the two. I do run the unit with the 5AR4 simply because it is at the original design voltage and I happen to like the look of tubes.
The Dynaco is in my second system, but I have a Image 65i (with 6550 outputs) as my main amp. It was designed with solid state rectification and the amp sounds great.
I know many are in the "everything makes a difference" camp, but I don't attribute any big sonic differences to the type of rectifier used. The important thing is that rectifier being used was a consideration in the design of the amp from the beginning.
Agree precisely with Tvad. I prefer having tubes in both places but there are products using both of these technologies that I love.
In the end it's about how that product delivers the music in your system. If ask to rate "the best" power amps my list would include VTL 750, Lamm ML 2.1 and Classe Omega mono's. All very different and all world class.
Thanks for your thoughts and advice guys. Based on the response I got from my "New Audio Frontiers thread" I didn't even try to get specific. I appreciate it.
Basically in a class a or b amp you are listening to the power supply modualited by an input signal. in other words the powersupply is the floor and its supposed to be flat and level. IMO filtering makes more differnce. RALPH.....RALPH!!!
If your looking for punch and impact in the bass,solid state rectifiers may do.But if you like all the excellent highs,mid range and good bass that you could listen to all day,it usually takes tube rectification. Tube rectifiers give you all the pluses that most tube amplifier people look for.Tube rectification is my preferred way to go.
Also if you are new to tube amps,you may get by with solid state on a 300B,although I thought they leaned toward tube rectification.Mostly when you spend a lot of time with triode amps,you may end up with a tube rectifier in the long run to get more of that tube magic.The tube ones just see to get it all better.
If you end up preferring tube rectification over SS, the next question might be: then how much of a difference do different rectifier tubes make?
I have a Cary SLA-70 I bought here on Audiogon a couple of weeks ago that uses 5AR4 rectifiers. I have been listening to it almost non-stop since I got it. It came with some Chinese 5AR4's, and I did a little poking around on the net looking for opinions on how much of a difference rectifier tubes could make in the overall sound of an amp. From what I gleaned, I thought it might be worth a tube-roll on the 5AR4's to hear for myself, so I now have a pair of Amperex-branded Mullard 5AR4's on the way, and will report back to you on what kind of differences I hear - at least with these particular tubes in this particular amp.
Tube rectification is nice if you can do it! Newer tube amps have bigger power supplies and so can easily damage a tube rectifier during warm-up. So a tube rectifier usually means that the capacitance in the power supply is limited to a small value that might have been considered adequate about 40 years ago, but likely not in a lot of modern designs, especially higher-powered amps.
Tube rectifiers are nice due to their inherent low noise while converting AC to DC. Silicon rectifiers have a commutation (switching) noise that can contribute to the background noise of the amplifier. Commutation noise can be substantially reduced by small networks bypassing the rectifier's junctions, but usually this is not 100% removal. But generally semiconductor rectifiers can survive the large current inrush that is common in a lot of high end amplifiers. That extra capacitance of bigger supplies translates almost directly to better sound, so you can see that there **can** be tradeoffs.
In an SET I think tube rectifiers would be nice- this is an application where they can work quite well.
In amps that have too much capacitance for a tube rectifier to survive, you can often get a lot of the 'tube rectifier sound' by using superior semiconductors. HEXFRED rectifiers are a good example- the ultra fast/ultra soft recovery characteristics of HEXFRED rectifiers approaches that of the tube rectifiers, although they do not have the variable voltage sag with current that is also part of that sound. You really don't want the voltage to sag as you draw more current from the power supply!
In a class A amplifier, the voltage sag issue is not a concern as the draw on the device is constant. In a class AB amp a good semiconductor can actually sound better!
My general preference from DIYing a few preamplifier and amplifier combinations has been to use a tube rectifier in the pre and ss in the amp. This has struck a nice balance between the warmth of tubes and the perceived speed and "snap" of ss.
Of course, the best alternative would be to have the opportunity for you to compare both in your system as there may be other attributes to each amplifier that would better suit your system.
Be careful trying out of those SS adapters. It will give a higher B+ voltage on the tubes,transformers,and caps/etc. These parts can be damaged.Those adapters don't have any voltage correction for different rectifier tube types.It can be risky.
Lewhite, not sure that battery power is a practical alternative for tube amps. My two amps need B+ voltages in excess of 400 volts. Not too many readily available batteries meet that need.
Alternatively, what's the point of have a lower voltage battery if you have to run it through a converter to step up the voltage? That is typically done with an AC conversion or switching process that defeats the whole point of the battery's pure DC output.
Hello everyone and thanks again for sharing your thoughts. I'm giving the SS rectified version a whirl. I have no doubt that on an even playing field, the tube alternative would be the way to go for me. The power ratings are a big issue here and I've been informed that the 25W/ch rating of the SS rectified amp belies its true power. If there had been an outcry of "traitor" from the tube community I might have waffled LOL, but what I'm taking from this thread is that, if it's done right, an SS rectifier won't necessarily be a bad thing.
The general scuttle-butt is a line-stage -preamp needs tube rectification to keep the magic; not an issue in a power amp. Just put a Weber WS-1 in my St-120. runs cooler.
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