[crewchief]

Ok a little background first, I have been playing guitar for a long time and as such I have owned quite a few tube amps. One of these amps happened to be a Mesa Dual Rectifier. Now on the back of Mesa amps you have a switch to go from tube rectifiers to SS based rectifiers. Now if you are into guitar then you will know that the only advantage to having tube rectifiers is power sag. Which some like, but most don't so most every modern tube amp uses SS rectifiers. Also to note why this is, it is the sheer fact the RECTIFIERS HAVE NO EFFECT ON THE SIGNAL CHAIN"S SOUND.

There I said it so again why are Head-Fi folks changing or "upgrading" thier rectifiers. Actually having amp sag in a audio amp is a bad thing. Believe me what I say as I made a name for myself as a local amp tech where guys were bringing me all there amps for bias adjustments, cap replacements and so on. If I had a Woo say I would replace the rectifier with this even though it might no look as "pretty" which it seems some are more concerned with looks rather than sound

. What you don't want in a audio amp is when your source puts out it sudden peaks for your power section to sag.

Again any amp tech worth his salt will tell you that the rectifier has zero effect on the signal chain. Now you can change drive tubes (your biggest effect) or your power tubes to change a amp's sound signature. So one last time, "Why are Head-Fiers worried about their damn rectifiers?"

 

[jamato8]

I don't have the energy right now but you are so wrong. Go post this over on the Tube Asylum on Audio Asylum and ask the question there.

One quick thing. The rectified AC is the DC the audio ac signal rides on. It is In the audio signal at this time and has a very big effect on the sound. Maybe I am misreading what you wrote but everything has an effect to a greater or lesser degree or it wouldn't be needed.

 

[dgbiker1]

I don't know a thing about guitar amps, but is the rectifier you're describing just part of the power supply as they usually are with other devices?
The actual rectifier bridge won't make a difference, but I'm sure some people lump the filter and rectifier together. The filtering portion of the circuit has the potential to have a pretty significant effect on the sound depending on the amount of ripple voltage it allows to pass through to DC.

 

[sunseeker888]

Indeed, rectification has a very substantial effect on SQ. Fact is, SS rectifiers in an amp are quick, clean and don't sag (if the unit was designed properly and is working correctly), while tubes allow for the 'sagging' you pointed out already.

If you think rectification doesn't affect signal quality, try cutting the power supply's capacitance in half, and see if that makes any difference. I just don't get what you are trying to prove.

 

[sunseeker888]

Actually, now that I think of it, rectifiers would have less importance in a headphones amp, since there is less demand on the PS than with speakers--but you do still need em.

 

[Uncle Erik]

Guitar amps seem to be a different beast than audio amps. You don't overdrive the tubes or saturate the transformers, either. Not that those things are "wrong," but they're not business as usual with audio. Same with linear RF tube amps; they're a different ball of wax.

While tube rectification might not be noticeable through an instrument speaker, a highly sensitive headphone transducer will reveal a difference. So will good speakers.

 

[Raylinds]

I have been playing guitar and have been into audiophile hi fi for 30 years and you could not be more wrong- rectifiers play a huge affect on both hi fi and guitar amplification. With all due respect, I suggest you do a lot more study on both guitar and hi fi amplification.

 

[crewchief]

Actually what you guys speak of in terms of changing an amp depending on rectification is because of the plate voltage. Tell me how many hours do you spend trying to get your bias dead on right? Now you are going to let that bias be subjected to tube rectification that will have the plate voltage walk on you. My point was not that though, my point was about the actual processing of the signal. That signal never passes through the rectifier tube. As far as a tube amp being more "organic" or as guitarist says has feel. That organic feel comes from your drive tubes. Now agian you have all of these "audiophilies" spending big bucks on power conditioners and power cords for their amp to get steady clean voltage. Yet you are going to subject this voltage to a tube rectifier that by no means is steady? Now go ahead and flame on because this goes against everything that you heard on the "net" which we know is the gospal truth right? Believe me I have done all of my studies on this subject and have been in plenty of arguments about this exact subject. Often times it happens to be with some person that got there little tube amp and 4 months under their belt and will argue till their blue in the face so that they can justify that NOS $80 tube they bought. BTW a lot of my "studing" has also been working with electronics in the areonautical field. How many of you have had formal training and not just what you read on some audio forum? I am also trying not to be mean or nasty I just would like to open some peoples eyes to this fact. As it seems the old saying rings very true in the audio world "If you can dazzle them with brillance, baffle them with B.S."

 

[nikongod]

Quote:

Originally Posted by crewchief /img/forum/go_quote.gif Now if you are into guitar then you will know that the only advantage to having tube rectifiers is power sag.

umm, there are also advantages with regards to "diode switching sounds" some REALLY good diodes (freds, and hexfred types) are QUITE quiet. there are also advantages on the part of a tube rectified supply that there is a heater-based delay before B+ hits the various tubes. this gives AMPLE time for any grid bias to come "down" to voltage, and for the heaters everywhere else to get warm.

regarding the idea of "power sag" its only going to happen if some part of the PSU is so vastly overloaded that it dosnt hold up. putting a rectifier rated for 150ma in an amp that draws 300 at peak is dumb and even designers of mid-fi stereo gear would not think of it.

Quote:

There I said it so again why are Head-Fi folks changing or "upgrading" thier rectifiers.

rectifiers DO have a sound. unless other means of filtration are pursued, a door slammer diode's noise is clearly heard everywhere int eh amp. a 60hz click. not even a hum, but a machine-gun of noise. even when using aggressive filtration, it is arguably better to have a quieter sound hitting the filter. surely you have seen improvements by putting a choke in the powersuply BEFORE an active HV regulator.
[qoute]Actually having amp sag in a audio amp is a bad thing.[/quote]
word, see above. you would have to be half dumb to put such underrated components in an amp. properly rated parts are not substantially more expensive once you have decided to take this rout.
Quote:

What you don't want in a audio amp is when your source puts out it sudden peaks for your power section to sag.

so, on this forum dedicated to headphones, we will now specifically discuss headphone amps.

lets say we have a cap coupled (OTL) headphone amp with the output stage running a conservative 75ma. the gain tube/driver tube is only drawing a couple ma. so we for all intents and purposes have 155ma (stereo) there are quite a few rectifiers that can handle this load and laugh.
Quote:

Again any amp tech worth his salt will tell you that the rectifier has zero effect on the signal chain.

zero is a pretty small number.
when applied to certain amps it has little effect, the thought of putting "standard" diodes in anything hi-fi makes me want to vomit.
Quote:

Now you can change drive tubes (your biggest effect) or your power tubes to change a amp's sound signature. So one last time, "Why are Head-Fiers worried about their damn rectifiers?"

because they make a difference.
Quote:

Originally Posted by crewchief /img/forum/go_quote.gif Actually what you guys speak of in terms of changing an amp depending on rectification is because of the plate voltage. Tell me how many hours do you spend trying to get your bias dead on right?

about 30 miniutes each time i swap tubes in the citation 2 (2X60W, big and ugly with nothing but pentodes in sight.) its not that hard. this is AC bias and DC bias.

I have only ever biased 1 headphone amp (a stax tube) and it took all of 20 minutes.

its actually biasing tghe SS gear that is the pain in the arsse. you adjust, then you wait for the transistor to settle. then you adjust some more....
Quote:

Now you are going to let that bias be subjected to tube rectification that will have the plate voltage walk on you.

the importance of bias is not as much ABSOLUTE value rather that the relative values are the same. watch what happens when a class a/b PP amp has one tube drawing mo0re dc and swinging more volts... weird does not even begin to describe, although its a sound "tone freaks" may like.

today the amps voltage is something, tomorrow something different. i expect the actual current through the tubes to vary accordingly, but both output tubes will flow exactly the same amount.
Quote:

That signal never passes through the rectifier tube.

eeeh, that is highly debatable. when you take the view that an amplifier is a device to modulate power coming from the wall to the speaker everything has an effect. the instantaneous load that ripples back through the power supply can meet a rectifier that is happy to deal with it (and not sag like a piece of crap) or one which is unhappy and inadequate. unhappy inadequacy is irrespective of whether the rectification is done with tubes or SS devices.
Quote:

Yet you are going to subject this voltage to a tube rectifier that by no means is steady?

nope, a tube rectifier supplying current within its means drops a few volts, but its constant.
Quote:

BTW a lot of my "studing" has also been working with electronics in the areonautical field.

im not sure if this constitutes straw-manning, or just changing the subject. by straw-manning i mean pointing out a fact that appears exceptional, but when you take a closer look has no bearing on the discussion. i will say straw-manning. a straw-man looks intimidating to a bird, but its really a harmless stick figure in last years overalls and jacket.

what value can be placed on a knowledge of aeronautical electronics when dealing with audio amplification? there are certainly virtues to be found with regards to safety, reliability, and repeatability but not much to say for any aspect of sound quality or even vacuum tubes for that mater.
Quote:

As it seems the old saying rings very true in the audio world "If you can dazzle them with brillance, baffle them with B.S."

agreed. your ******** is baffling.

 

[dgbiker1]

Quote:

Originally Posted by crewchief /img/forum/go_quote.gif Often times it happens to be with some person that got there little tube amp and 4 months under their belt and will argue till their blue in the face so that they can justify that NOS $80 tube they bought. BTW a lot of my "studing" has also been working with electronics in the areonautical field. How many of you have had formal training and not just what you read on some audio forum?

I've only had my little tube for ~1 month

I have plenty of formal electronic training. My BSc is in Biomedical Engineering, where the BE department was a part of the EE department, meaning my degree was very heavily EE biased. I'm just finishing up my thesis in the robotics field, and the power systems work I've had to do get my robot working gave me some good exposure to power circuits- getting an amplifier designed to work on 3-phase 240V to work on 1-phase 240V is far from trivial work

I'll admit my background isn't in tubes, but I'm assuming they function similarly to SS transistors based on the understanding I have of tubes.

Logically the driver stage has the largest effect. I certainly don't put much weight in the power conditioner/power cord marketing- it's definitely last 0.01% territory. I can understand how a conditioner would affect the signal (a miniscule difference in DC ripple), but I believe the effects to be minimal and likely inaudible. As for power cords, I think they're either adequate or not. As I stated before, I don't think an actual rectifier bridge "upgrade" will change a thing, but changing the filtering will. By reducing the ripple voltage, you're sending the driver stage more stable power.

Making the (possibly wrong) assumption that tubes and SS transistors operate on the same principles, the DC power coming from the rectifier/filter stage IS part of the signal path. The DC power term shows up in the transfer function of a driver stage transistor and is therefore part of the signal "path" (I bold this because that's all anyone with systems engineering background needs to read), so allowing more ripple in the DC voltage will have an effect on the output of your amplifier. Given a poor enough AC-DC stage, you could probably hear some 120Hz noise (2X mains freq. assuming F.W.R.) in your signal. Will upgrading an already decent rectifier/filter stage make a big difference? No way, not nearly as big as changing the driver stage, but there is a difference nonetheless.

Again, I'm making the assumption that tubes work on the same principles as transistors. I don't really have time to become a tube expert at this point in time, but I have some understanding of tubes and my assumption is based on a basic understanding of tube theory. This is just my 2 cents based on my background with the tube's SS counterpart.

 

[crewchief]

Bravo NikonGod now there is an agument I was looking for. Not just your wrong nananana.....LOL. See you pointed out the key component in the differance between headphone amps and well lets just say bigger amps. You are ultimately dealing with minute amps than the big brothers, so I see your point that pretty much all tube rectifiers would laugh at this. This is not so in the big brothers as this is a more real concern. Again I want to say good job as I am not being sarcastic I really mean it. That is why my post was provided in a question.

 

[Raylinds]

Quote:

Originally Posted by crewchief /img/forum/go_quote.gif Bravo NikonGod now there is an agument I was looking for. Not just your wrong nananana.....LOL. See you pointed out the key component in the differance between headphone amps and well lets just say bigger amps. You are ultimately dealing with minute amps than the big brothers, so I see your point that pretty much all tube rectifiers would laugh at this. This is not so in the big brothers as this is a more real concern. Again I want to say good job as I am not being sarcastic I really mean it. That is why my post was provided in a question.

Yeah, you're right- I shouldn't have just posted that you were wrong without trying to provide some useful information and have an informed discussion. That's just not helpful, please accept my apology.

I think the biggest difference in sound comes from replacing one tube type for another (for example GZ32 to a GZ34, etc.). Whether changin brands of rectifiers of the same type makes much of a difference is a matter of much debate. I think it is fairly negligible in guitar amps, but I have certainly noticed differences in the Woo Audio 5. I rolled the stock Sovteks for Tung-Sol NOS, to Mullard and can hear a noticible difference. YMMV.

Here are some links that discuss this issue:

Tubes Asylum

rectifiers

The Rectifier Tube

A guide to choose nos tubes for HiFi

HTH

 

[sunseeker888]

THis has turned into quite a nice discussion guys! I even learned something about tube biasing (It's been awhile since I had my Fisher 500 receiver)

I always felt that biasing a tube amp was a labor of love and should even be enjoyed! The maintenance is half the fun with tube stuff!

 

[jamato8]

It isn't just stating that someone is wrong and moving on that may not be the best method of discovery but also the frustration I feel with people who have not worked in the field and project what someone else may have told them. I started working with tubes and circuits, god too long ago, anyway over 40 years ago. A line conditioner doesn't deal with ripple but the AC signal that is going into the components. Tubes have the advantage of a soft recovery and normally no overshoot, which solid state can have and this adds artifacts to the DC that Will be in the audio, which is AC, path as the AC musical signal rides on the DC signal as it is amplified and is stripped from this by transformers or capacitors. I have built solid state rectification using different types, all kinds, and tubes using paralleled GZ34's, EZ90's, and on and on. My experience is from building use and experimentation and having a background going way back high school and then the Navy as a radioman where we worked with, at the time, all tube equipment.

Anyway my experience is from practical experience and not what someone has told me or just what I have read. There are no absolutes but I do like a good metal base GZ34 in the right application and have not found any solid state to equal them.

 

[derekbmn]

While searching for some 6ca4s ,I ran across this website and am curious more than anything if anyone has tried them .Weber Copper Cap Rectifiers