Low watt tube amps/pros/cons


300B's, 845's and others. What are some of the benifits of these tubes as well as the limitations. I see someone posted that he has a 15 watt tube amp and wants to get 30hz bass. It is highly unlikely that his amp will deliver as low as 30hz, even if he did find a speaker that went to that level, would the bass have any authority? Also by saying I want to find a speaker that goes to 30hz hows the mids anf highs. IOW I'd never buy any speaker based on the fact that it goes to 25hz, its a package deal.
Back to the main idea here. Can anyone give a list of +'s and the ='s of the low watt tube amps. For myself its not something I'm interested in as all my listenings are classical, and I want the orchestras to sound full rich, dynamic, that is the low and high end extended. I heard a 300B amp, the Cayin, and was incredible with light jazz, blues, but for classical orchestral it fell flat and lifeless. The speakers were the Silverline Sonatas.
bartokfan
I see someone posted that he has a 15 watt tube amp and wants to get 30hz bass. It is highly unlikely that his amp will deliver as low as 30hz, even if he did find a speaker that went to that level, would the bass have any authority? Also by saying I want to find a speaker that goes to 30hz hows the mids anf highs. IOW I'd never buy any speaker based on the fact that it goes to 25hz, its a package deal.
Bartokfan (Threads | Answers)
Since you're commenting and criticizing my request, I ask you to reread my post. I never said I owned a 15wpc amp. I said I was interested in speakers that could be powered by an amp with as little as 15wpc primarily because most of the integrated tube amps have relatively low power (less than 60wpc). If such an animal doesn't exist, then so be it. There is nothing chiseled in stone.

Bass is important to me. Therefore speakers that go down to 30hz are a factor. Clearly the midrange performance and sound of the highs is important, too.

BTW, here is an efficient speaker that goes lower than 30hz. I'm not suggesting that this is the one for me, but the tone of your statement suggests such a speaker doesn't exist. Here's proof that one does. There are others, I'm sure.
Bartok,
You are certainly the single most consistent poster here in regards to content, knowledge, and style. I'm constantly amazed.
You auditioned a setup that is not even close to ideal for orchestral music. Even if the speakers have an impedance that is easy to drive, 93 dB speakers still require more than a few watts to get them going. I wouldn't dismiss low power amps based on a single audtion. Paired with the right speakers those amps will sound incredible with more than jazz and blues.

The pluses are just what you heard, incredible sound. The minus is they must be paired with the right speakers, if you can call that a minus since matching components is a must with any set up.

For myself its not something I'm interested in as all my listenings are classical, and I want the orchestras to sound full rich, dynamic, that is the low and high end extended.

These things are easily obtained with low power amps. One solution is to use a powered woofer for the lowest octaves. Avantgarde and other highly regarded speakers go this route. Take a look at my system. It delivers all you asked for and more.
Tvad Apologies if I misread your post. That aside lets get back to the limitations of low powered tube amps. Sure I've not heard the 845, so I cannot judge. I did hear the 300B and it was flat on complex orchestra. I've heard several KT88 amps and were also very flat in the fq's. Anyone heard a KT88 tube that was dynamic in the bass and highs?
Bartok, I told you, and as I look at your other posts, others have also told you, that the 300B has nothing to do with what you heard. If you drove a BMW with a flat tire would blame the car for poor handling? You can't pair a low power amp and a low efficiency speaker and get good results.

Why do you post these questions and then completely ignore informed responses?
"Anyone heard a KT88 tube that was dynamic in the bass and highs?"

Sure, mine are...If they were not, I would change tubes.

Dave
08-27-06: Sogood51
"Anyone heard a KT88 tube that was dynamic in the bass and highs?"
Yes. I owned a KT88 tube amp that was exceptionally dynamic in the lows and the highs. I suspect the KT88 tubes had something to do with its sound.
Then hows the KT90's compare with the K88's? Or no noticable differences? I mentioned the low performance of the KT88 with classical and the slaesman said that is the character of the KT88 tube, rools off at bottom and top.
I heard the new Audio Research KT88, VS110 and it didn't offer great highs nor deep bottom. Not from a amp that size with 8 KT88's.
"I heard the new Audio Research KT88....."

The reason you didn't hear 'great highs nor deep bottom end' was most probably because the units don't have tone controls which you can set to their maximum levels as you have told us is you preferred way of listening to your JOR's.

ROTFLMAO!
Barfan,

Once again you have proven yourself.......

Enjoy,

TIC
These 300B & 845 SETs act as tone controls, & most are deficient in the bass & topend.
Out of curiosity, I clicked on the link Tvad provided above.

The link took me to a speaker with an internal volume of roughly 3 cubic feet (my estimation), and a claimed efficiency of 94 dB/1 watt/1 meter with bass extension (-3 dB) to 26 Hz.

According to the loudspeaker modelling programs I have, and based on my recent experience building prototype speakers of comparable efficiency in similar sized boxes, I'm skeptical of the manufacturer's claims. Placed up against the wall and close to a corner, maybe. But not standing out in the room away from walls.

Duke
Duke,

Can you recommend any freeware loudspeaker modeling programs? I have a pair of Hemp Acoustics FR8.0DIY drives currently installing is a cabinet that was not really designed for them.

I know the manufacturer recommends an 85 liter vented box whch places the center of the driver at about ear height. He also recommends side venting with a 4" port that is 3" long.

Any suggestions for a program that will do a simple bass reflex cabinet?

Thanks,

TIC
Hi Reubent,

Here's a pretty good freeware program. The vent length calculations aren't totally reliable. Box stuffing isn't accounted for, nor is enclosure wall losses, but this will get you in the ballpark:

http://www.ggimages.com/spsim/

In practice, expect that a vent slightly shorter than recommended will give the proper tuning frequency. It takes a pretty sophisticated program to properly account for the fluid flow dynamics at the ends of the vent (even if you use a flared port).

Enjoy!

Duke
Thanks Duke!

TIC
These 300B & 845 SETs act as tone controls, & most are deficient in the bass & topend.

Attributing this to the tube is simply wrong. It comes from misinformed individuals who don't understand electronics especially the interaction of amps and speakers.

Amps that use these tubes are often paired with incompatible speakers and the combination can be deficient in the bass & top end. They are sometimes used in amps of poor design or that have poor output transformers. However, the tubes are capable of amplifying from near DC to way beyond what is audible. Used in a well designed amplifier they are not the limiting factor.
I agree with Herman "it's all in the application", both for speakers and amps. Particularly in the output transformers. I use a Viva Solista, which is a 2 man lift. Only 22 watts, but it seems to have the grip to drive Wilson Grand Slams. Alright that is an exageration, but it certainly has greater grip than my 50watt Lavardin IT. In terms of speakers and tubes, it seems to me that impedence is more important than sensitivity. A flat impedence not dipping below 6ohms seems more important than 95db sensitivity. Perhaps others will disagree.
Finally, I think there are differences between tubes, given an equally competent application. I can't speak for all tubes and it is not a new observation, 300B's have the mid range magic, 845's greater control at the frequency extremes, i prefer 845's.
I use KR KT88s in my 18 watt per SET. Delivers the goods top to bottom with my speakers. Herman and David12, I hope, have put you on the right track....
I just posted a thread in the amp section about 845's. I won't go into here but what I have found , from research , is that the 845 seems to combine the plus's of the 300b tube with those of the KT 88 tube !
Does this sound correct ?
This topic should be in the amp section, but seems no one minds.
I've not heard the 845 "set" amp. My limited experience with the 300B , Cayin with Silverline Sonata, was that it was great with light jazz, but even with these high sensitive speakers the bass and highs were not spectatular. With classical it fell so falt that it was unlistenable. Zero dynamics. I've heard several 88 amps , plus had KT88's in the JOR and the results were not near the KT90's dynamics. The bass and treble was much superior in the KT90's vs the "fluffy" KT88's. I wrote to the seller from which I demoed the KT88 amp, and he said, "that fluffiness is the character of the KT88 tube". As much as i loved the mids of the 300B on jazz (although the Sonatas "barked" on certain fq's with vocal's) it was extremely limited for classical.
So I just can't see myself having the wonderful 845, 805, 300 tube amp and always in search for the ideal speaker. i've found my ideal speaker and am lucky that I've found a tube amp that delivers classical. Which is the JOR KT90. If the Jadis did not deliver classical with dynamics,, nor any other tube amp, then I'd go ss amps with my ideal speaker. Speaker comes first, amp comes second.
I could not deal with a tube amp that has limitations. It absoluetly must be VERSATILE.
>>It absoluetly must be VERSATILE<<

Which inevitably includes compromises.
I could not deal with a tube amp that has limitations. It absoluetly must be VERSATILE.
Bartokfan (Threads | Answers)
Since you listen primarily, if exclusively to classical music, and since you have no other speakers that you enjoy other than those with SEAS drivers, your comment about versatility is a conundrum.
BF,

I'm curious. Why did you start this thread?

In your original post you state "Back to the main idea here. Can anyone give a list of +'s and the ='s of the low watt tube amps. For myself its not something I'm interested in as all my listenings are classical, and I want the orchestras to sound full rich, dynamic, that is the low and high end extended."

So, you state "For myself its not something I'm interested in", yet you consume the time and effort required to post the question.

So, what's up? Are you a troll or are you just bored? Enquiring minds need to know.......

Enjoy,

TIC

So, what's up? Are you a troll or are you just bored?

Reubent (System | Threads | Answers)
I agree. The thread is bullshit. Plainly speaking.
I don't know about you guys's but BF's mere existence as well as the state of his knowledge makes me feel good about myself, both personally and as an expert in things audio. Be thankful for small things! :-)
I just purchased a Cary Rocket 88 and enjoy it tremendously. I use it almost exclusively in Triode, I find the Ultralinear a little dry for my taste. This system has a very black background with very good bass, and a very low noise floor, for a tube amp. It is more powerful than some but at 20 watts in Triode lower than most. With 95db efficient speakers it produces excellent dynamics from very low to more than moderate volume levels for a 18 x 24 room.

I find the KT88s sound very lively a lot like the EL34s but not rounded off in the upper frequencies. I am very impressed with the build quality of such a low end price point for Cary.

Compared to SS this amp does not have the “punch” in the very low end, and my preference is single driver speakers with this amp. I have a pair of triangles that are more than efficient enough but in my listening environment with this amp the bass seems just a bit bloomy or loose, where as the Abbys seem more controlled. I prefer the Triangles with the Tripath amp that I have, as the bass just seems to regain the punch.
unfortunatley its a forum of grown men putting way too much time into electronic dreams... Oh well gotta find a new hobby.!
Ok I see my error. No amp can be all things. That there are tradeoffs with any design. I have my eye on a pr of 845 amps and hopefully one day will own the pr and will report back.
Whacky spot for this thread! As for the question posed concerning KT88 amps I can report that amongst my amps is a KT88 tube integrated with what I consider to be a remarkably authoritative low end that is on par with the best SS amps I've spent any time with. In fact, I was under the impression that KT88 amps were pretty much the class leaders for low end dynamics amongst tube units. N'est-ce pas?
Beemerrider, Not everything is equal. You cannot make such a broad assumption.

I think one of the reasons that folks like KT88's is that they serve up a warmer frequency response than other pentodes and are a better match for a lot of components which have been designed with emphasis on detail and resolutionion the forefront. They err, if at all, on the warm side of neutral.

I have an amp designed around the KT90 that I use with KT88's that sounds better and and has better lower bass than a KT88 designed amp I use. I also have a pair of mono's designed for KT90's that sound better than either of the former amps w/KT88's (or KT90's) using 6550's. Using the KT90's in any of these gives even better bass response than any of these other tubes, I just don't care for the mid-range and highs of the KT90's in those amps.

What I have found in my amps is that the KT88's give a warmer upper bass, not as tight, but very pleasant and a bit more air and warmth again in the upper mid-range/highs, where as the KT90s have very strong tight bass, cool mids, and I think up tilted highs, and the 6550's are more neutral than either and can produce some very clear highs with no exageration and no bass bloom either.

Anyway, thats just my amps, my ears etc. YMMV. FWIW.
Newbee, thanks for sharing what you have learned about the sonic characteristics of power tubes. My experience is limited to EL34s, EL84s, and KT88s. Is it common for 6550s to be interchangeable with KT88s, or is it always going to be amp-specific? Thanks.
Usually an amp which can take a KT88 can take a 6550 - however its always best to check with the manufacturer. This might not apply to substituting KT88's into a curcuit designed for a KT90 however (as I recently descovered the hard way!)