[Niteshade]

Ok- This is a BIG topic because I made it into a blanket statement. There are many different kinds of tube amp designs. We all know that. However, I want to know the stereotypes that people have in place about tube amplifiers in general. I need to know the good and the bad. This is a Lab discussion because we'll most likely break the topic into various kinds of tube and solid state designs. Which ones you like and don't like, etc...

Let me start off with the Pro's:

1) Simple, elegant circuits are possible
2) As a result of #1, tube amps can be very,very easy to repair

Some Con's: (difficult for me!)

1) Can have a low damping factor
2) Require good ventilation

Just a note: The cons are not necessarily cons because there are situations where either issue doesn't matter.  I have been working on methods to reduce heat output without sacraficing sound. Ditto for the damping factor. Oftentimes corrective circuits have a way of coloring sound and I like to avoid that.

Have fun!

[JoshK]

Cons....you forgot expensive (relative to SS) and heavy, both primarily from good iron. There is also the fact that tubes die off quicker than SS devices typically.  Not as many manufacturers making new devices, ones that are making good ones are expensive typically.  Requires high voltage, when can be a safety concern, especially to the builder.


Pros...linearity leads to simplicity of circuit which means less stuff in the signal path and less chance for things to go wrong (arguable to decent generalization).

ventilation isn't only a problems for tubes.  Real class A SS amps, not the marketeers class A requires massive heatsinks and lots of ventilation too.  Class A/B SS amps often still require big heatsinks and lots of ventilation.

[Niteshade]

Are you certain about the expensive part? How much would a SS amp have to cost to reach the quality of a good, zero feedback push-pull or single ended tube amplifier? This isn't something I've looked into in great detail but I have heard they cost **allot**.  I think as you reach the high-end part of the market, the cost evens out in regards to performance and possibly wattage too. There's some BIG tube amps being made. I don't know what they sound like though.

[JoshK]

Good quality output transformers, especially higher powered ones are quite expensive.  If you in into cheap chinese iron (not all bad mind you) then made it can be done more competitively. 

Edcor makes inexpensive iron up to 100w. Hammond makes some decent iron.  James, Electraprint, O'netics (Level I maybe II), Silk and some of Lundahl & Magnequest are all in the medium price range.  Tamura, Hashimoto, Lundahl amorphous, Magnequest's higher lines, O'netics (level II/III) are alll getting quite pricey.

[Hunter]

New here 

Cons....you forgot expensive (relative to SS)...

Way over priced in my opinion, seems to be a victim of a niche market. I picked up a couple of 60's era Dukane mono blocks at a $100 bargin, can't see spending more then 1K or even 500 on a decent tube amp. Mind you I'm no audio aficionado or anything, just like the warmer sound but don't think it should break the bank.

[richidoo]

Tube treble usually more natural/beautiful sounding than SS at similar price.
SS bass usually more exhilarating than tubes at similar price.
Nice midrange warmth from budget tube amps.
The quality of some brands of new tubes is hit or miss, even batch to batch of same tube.
Tube amps often have PS noise grunge where ss of similar price are often more quiet.
Can't leave the tubes running all the time, warm up time is inconvenient.
Offset voltage from tube preamps until warmed up.
Even well designed reliable tube circuits still need frequent maintenance because tubes degrade.
SS amps are basically maintenance free.
I hate tube amps.    /  I love tube amps.  

Welcome Hunter!!!! Glad to have you at AC!!

If someone doesn't like vintage tube warmth, then tube amps with low distortion and high power are VERY expensive. With SS amps, spending $20k is an unnecessary dream fantasy, but a tube nut has to plan a decade ahead because that's just what 200 clean watts really costs.

[miklorsmith]

Nice post Rich.

If one can get away with under 10 watts there's a whole universe of killer amps out there that won't break the bank.  Of course if bank breaking is desired we can accommodate that too.     Within this group is found some midrange properties which I haven't heard replicated by anything else. 

Being most familiar with this sector I can say "that warm tube sound" does not generally apply to current offerings.  300Bs are probably most likely to fall in this descriptor but even those seem to be tending away from purely lush and romantic.

[Hunter]

Thanks for the welcome Rich!

Well, I don't mind the distortion nor do I really notice it I guess and I do have plenty of low end thanks to the rather "Boom Box" feel of some JBL night club speakers that I put new drivers in. Ive seen some 300B's that just seem way to expensive as well, but mind you, Ive "only" just seen them.. Two ears and a brain in the middle- a very unique combination for sight and sound 

Pix of my amp mod and media server to be posted soon.

[hmen]

FWIW, there are a zillion "high-end" SS amps out there that claim in their advertising that they have a tube-like sound. Has anyone ever seen an add for a tube amp that claims to sound like SS?

[Bigfish]

FWIW, there are a zillion "high-end" SS amps out there that claim in their advertising that they have a tube-like sound. Has anyone ever seen an add for a tube amp that claims to sound like SS?

 

Very good!!  Also true!

Ken

[konut]

FWIW, there are a zillion "high-end" SS amps out there that claim in their advertising that they have a tube-like sound. Has anyone ever seen an add for a tube amp that claims to sound like SS?

Conrad Johnson amps are one of the few tube amps that have have distortion and S/N specs that equal SS in transparency though most of the audible spectrum. Big $$

http://www.conradjohnson.com/It_just_sounds_right/news4.html

Audio Research also comes to mind.

[Niteshade]

Seems that most of the cons are centered around price. What would you say is a good price for a decent solid state amp? From what I have seen, good SS amps can easily run into a couple thousand dollars.

[rklein]

Good post.  I have used SS gear forever and just recently bought an Empire 598 TT which I plan to build a tube based system around.

Here is what I have decided to put in this new system.

Dynaco ST-120 Comes in a kit form with links below.

http://www.tubes4hifi.com/bob.htm  (Scroll to down to see ST-120)

I also have replaced my SAS 10A pre with a Mapletree Ultra 4A SE (has a phono stage whereas the SAS 10A did not) 

http://hollowstate.netfirms.com/ (Scroll down to see the Ultra 4A SE)

I am the first to say that my experience in tube amps is next to none.  However, I have welcomed the challenge of finding a speaker that will synergize with the above components. 

rklein

[Niteshade]

Tube Amplifier Parts:

There's a multitude of parts that are over priced. Edcor is a great example of a high performance transformer manufacturer. Xicon makes excellent resistors and capacitors. The list goes on.

Asian iron seems to be good as well. I never used it but have used Edcor and Hammond.

[Bigfish]

Seems that most of the cons are centered around price. What would you say is a good price for a decent solid state amp? From what I have seen, good SS amps can easily run into a couple thousand dollars.

You might be misreading the responses.  While I think it is true that watt for watt out-put power tube amps tend to be more expensive than SS amps I don't believe people who love this hobby see that as a show stopper.  I personally have pondered the question of tube amps versus SS many times and thus far have elected to stay with SS.  Some facts I have considered:

1.  Tube Amps tend to put off a significant amount of heat.  You will find the same is true for a Class A SS Amp but most "reasonably priced"  ss amps are class AB.

2.  Tube life effect sound performance.  You will have to periodically replace all of the tubes which represent a higher maintenance expense vs. SS.

3.  You will have to adjust the bias of a tube amp and check the bias to make certain it is properly adjusted.

4.  If you require an amp(s) with more than 100Watts/channel then price of a tube versus SS amp really gets magnified.  However, high quality, highly reverred SS amps are not inexpensive.


Advice I have been given by many on this Circle, "take your time, experiment with loaner equipment in your system and base your decision on what sounds best to you."

Ken

PS.  If you are looking for high quality, performance oriented equipment, priced fairly and is back by a 20 year warranty I recommend you take a serious look at Odyssey Audio.

[Niteshade]

I see where you're coming from regarding heat and maintenance issues. I do agree that amps over 60 watts are expensive. The thing with tube amps is this: Many believe you get better performance per watt and this makes up for the lack of brute force. I never liked solid state amps because they are built like throw-away devices- even the good ones. When a SS amp blows a power transistor, something that I call a cascade failure can occur. It's a domino effect: A power transistor goes, takes out it's push-pull mate(s), takes out the driver stage which in turn takes out the pre-drivers and so on. In a nutshell, cascade (domino) failures are a huge mess! Can this happen with tube amps? To a degree- but it's easier to design fail safes for tube technology and limit the damage easily. Most of the time, even without fail safes, the damage area is limited.

Class A to me is a pure waste. Class AB is extremely efficient and is able to sound as good as class A. When tubes are transistors are biased for efficiency correctly, there is very little heat output. Lower heat also means longer component life. Tubes can be made to auto bias as well. Prima Luna has a neat bias system and there are other methods as well. 

If I were to compress all this- it would be to say that there are measures to correct the negative attributes you listed. Price is a tough one- but I am a firm believer that when shopping smartly, you can get what you pay for and then some.

NOTE: I don't pretend to be a SS amp guru. Please correct me where I need correcting.

[kbuzz3]

I love tube amps. I hate biasing tube amps. 

[Syrah]

I love tube amps.  Another overlooked point is that tube amps perform very well in a capacitant load.  For years I followed conventional wisdom and didn't even think of tube amps to drive my Martin Logans.  Huge mistake.  I happened to have some Dodd 120W monoblocks for a second system, tried them on the panels - never looked back, better in every single way.  The flip side, is that they did not sound good on the large heavy Martin Logan woofer.  Bryston took that prize.  Horses for courses.

Now I'm biamping GR OB7s with two sets of Dodd 120s.  Sweet, but turn that AC up.

[Niteshade]

I don't think anybody has mentioned the sound of a tube amplifier, including myself. A better way to put it would be to say, "How did the amp you listened to sound?" It's been my experience that tube amps can be made to sound any way someone wants it to sound. For example, I have an Allen tube stereo amp which sounds very clear and clean yet doesn't sound warm nor clinical. It's more like a high-end solid state amp to me. The Fisher 500C has that traditional tube sound- warm, not clinical, smooth, plenty of bass and slightly rolled off treble. The internal designs of the stereo Allen and 500C are considerably different. Then comes the AMC 2030 tube amplifier. This is a hybrid that uses FET's to drive the EL34 power tubes. The highs are extremely rolled off, has plenty of bass and the mids are mildly warm. It has a distant sound stage too. It reminds me of some older solid state amps I've heard.

Some favorite economically priced solid state gear I have used:
1) Denon 3805 Receiver
2) Crown DC-300
3) QSC USA-850 
4) VERY old Realistic receiver with capacitor coupled outputs. Can't remember the model. Sounds A++
5) Large green Altec solid state mono blocks that have transformer coupled outputs. Model- Can't remember.
6) Ashly FET 500

What I have never listened to:

1) OTL Amplifiers
2) Circlotron Amplifiers
3) Parafeed Amplifiers
4) #45 Tube Amplifiers

The circlotron holds my interest the most. Anybody ever listen to one?

[cujobob]

Peter Mcalister (of Mcalister Audio) told me he believes self-biasing tube amplifiers sound worse than those with fixed bias.  However, biasing tube amps can be a bit of a pain for those who don't like to worry about maintenance, that, along with replacing tubes and warmup..

My feelings on tube vs. SS are as follows:  Few good tube amps for less than a grand (most are SETs with less than 10 watts) and more decent solid state offerings which also offer more power.  From $1,000-2,000 there's a few more high-quality options, but not many offer the wattage most need for their setups.  There are a LOT of poorly designed tube products and reviews are pretty much useless because people come to expect tube amplifiers that sound inaccurate but 'lush' and appealing for other reasons.

Finding a tube amp with > 50 watts, good bass, mids and highs...for under $1500 is nearly impossible.