Fortes and tube amps .... but which ones ?

[laurenc319]

hi all,

I have a pair of Forte I's and a EICO hf-81 tube amp ( push-pull 6bq5s, 14 watts a channel) and am looking to "upgrade" at a resonable price ( $2000 to 2500 for an amp). BTW I love the sound of the EICOs as compared to my Soundcraftsmam A400 ss power amp.

Ok,... where do I go from here. Higher power push-pull tube power amps or the SET route with 3 to 8 watts per channel. The higher power tubes amps have a intuitive advantage, but I've been reading a lot about SETs and they sound very interesting.

see here: http://web.mit.edu/cheever/www/cheever_thesis.pdf

Comments appreciated from any who are using the Fortes and various tube amp combinations.

Thanks,

Larry

[Daddy Dee]

Hope you can find a forum member near you to audition an amp or two. I dearly love SET and am perfectly happy with 3.5 WPC. However, SET is not everyone's cup of tea.

In your price range you could get a Juicy Music BlueBerry or Peach preamp and a nice poweramp. If you don't do vinyl, the Peach would be excellent and some savings over the BB.

[Cal Blacksmith]

It is a personal thing. I like the sound of a push pull amp with a little more power with my Forte 1s but that is me. Try to listen to as many amps as possible. Great gear can be had well within your price range if bought used, lots of new gear there also.

It is a personal thing and what you listen to has a lot to do with what you like, I listen to 70s rock, blues, electronica (thanks for the definition Nick!) some orchestra and jazz. I like it loud and clear.

To each their own.

[Colin]

upgrade? add a sub, you are missing the low bass...

[Thoriated_Tiger]

Driving mine with a 60wpc pushpull 6550-based Audio Research D-70 II. It wasn't for power, it was for the cleanliness, control, authority and sheer *whack*. Cleanest thing I've ever heared. Like if they were made for each other.

Colin, you find the Forte bass lacking? That's the first thing that grabbed me by the ya-ya, once I got past how *clean* the mids are..

Bass-shy they aren't ;o)

[Colin]

Fortes are excellent loudspeakers for the money. They produce great sound. At a low 32Hz to 20kHz, within a normal ±3dB, which means that some frequencies are TWICE as loud as others, I think the Fortes with tube amplifiers probably need some additional depth and slam in the low and mid-bass regions. My super-sensitive walnut-oiled Cornwall 1s, with their B2 crossovers did, and my AK-2 crossover Khorns do. Unless the amplifier output transformers are huge, normally tube amplifiers dont have the iron to push around the low impedance dips of the woofer. Measured together, the frequency response of a loudspeaker with a tube amplifier often more closely resembles the loudspeaker impedance curve than the amplifiers flat line response.

Then I would investigate refurbishing. When was the last time that little baby was coughed, hiccupped, cleaned and changed? Unlike solid-state equipment, which quits as suddenly as a candidate, tube amplifiers wear out slowly. Their sound degrades without you knowing it. Check out NOSvalves here on the Klipsch forum. He has a web site.

After that I would investigate your room some acoustic paneling can make a big improvement.

After that, look intowell, you know, it never ends.

[anarchist]

I am using KG4's and have swapped in and out with an Eico HF-81 and a Consonance with 40WPC. The Consonance is a $1600 integrated. The difference - a bit more bass and loudness. Worth the difference? Dunno. In a very large room, most likely. In a 12X15 or similar room, the Eico gives you plenty of volume and is very, very good with presentation, soundstage, and separation of instruments. Don't just drop the money. Audition in your room and see if you really need to upgrade.

I am long past "needing" to upgrade but "wanting" is an entirely different matter and I will of course add more equipment regardless.

[Mick Bell]

I just purchased a new tube amp (integrated) for use with my Belle Klipsch. Check out the JoLida 707A --- 40 watts, 60 peak. JoLida designed this amp to give nearly the sound of SET but to put out 40 watts. You can get a Level One modified 707A delivered for about $1,400. Check the JoLida site (Jolida.com) for the phone #. Michael Allen -- the owner -- will be glad to discuss the design goals of the amp.

Mick

[3dzapper]

"Fortes are excellent loudspeakers for the money. They produce great sound. At a low 32Hz to 20kHz, within a normal ±3dB, which means that some frequencies are TWICE as loud as others,"

Twice as loud is 10Db. One Db is the absolute minimum sonic difference audible. 3Db is the point where a change in volume is noticable and appearant. 3Db IS the point where the power requirement doubles ie: 1watt @104Db; 2watts@107Db; 4@107;8@110; 10@114 where the sound is twice as loud.

If a speaker can truly produce 32 to 20KHz +/-3 Db, that's dern good IMO. That doesn't mean in itself good sound though. It could be +/-3Db of mud.

Rick

[Deang]

Colin, you say strange and interesting things.

Before giving any useful advice, I would like to know more about the rest of your system. Why did you decide it was the amp you wanted to upgrade? Just curious.

[sfogg]

Rick,

"One Db is the absolute minimum sonic difference audible. 3Db is the point where a change in volume is noticable and appearant."

Minimum SPL difference if it is over the full range is closer to 1/3dB then 1dB. If the SPL difference is in a narrower band then the level needs to be higher for it to be audible.

A person probably won't hear it as a difference in volume level though, it will sound like a difference in clarity or imaging or something like that. But it is perceivable and identifiable and have been demonstrated in double blind ABX tests.

I've never ABX tested myself below 1dB level differences but at 1dB I've consistantly scored 25 out of 25 on ABX tests.

Shawn

[3dzapper]

"JND in Sound Intensity

A useful general reference is that the just noticeable difference in sound intensity for the human ear is about 1 decibel.

JND = 1 decibel

In fact, the use of the factor of 10 in the definition of the decibel is to create a unit which is about the least detectable change in sound intensity.

That having been established, it can be noted that there are some variations. The jnd is about 1 dB for soft sounds around 30-40 dB at low and midrange freqencies. It may drop to 1/3 to 1/2 a decibel for loud sounds.

Caution must be used in applying the "one decibel" criterion. It presumes that you are increasing the same sound by one decibel. If you were adding a sound outside the critical band of frequency from this sound, you would be exciting fresh nerve endings, and the one decibel rule can't be presumed to apply. This causes some concern about the perceptual encoding schemes used with modern digital recording which might eliminate some significant audible content by the use of a "one decibel" criterion for dropping content."

Source: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/db.html#c4

This is the most concise defination I found in a Google search. The original research was done "by ear". Not all ears are equal however, the definition is applicable and standardized. The original research was rather crude using single tones which is what a speaker frequency response plot to a sweep is. So we are both correct.

Either way, 3Db is not twice as loud.

Rick

[sfogg]

Rick,

"The original research was rather crude using single tones which is what a speaker frequency response plot to a sweep is. "

Single tones would be harder to tell a 1dB level difference on. That was why I mentioned full range level difference. On pink noise for example 1dB difference is easy to hear.

There are quite a few places on the net that list 1dB as being the threshold of audibility.

But if you read the various AES papers from those that scientifically test things like this (Floyd Toole among others) the minimum level for audibility is given as being lower then 1dB, usually around 1/3dB. A proper double blind listening test matches the two things under test to 1/10 of a dB to get rid of SPL differences in being a factor between the comparison. Toole in there speaker testing rig matches levels to I think 1/30 of a dB or something extremely small like that.

"Either way, 3Db is not twice as loud."

Agreed.

Shawn

[Colin]

dBs are a logarithmic thing. They are scaled to a minimal 1dB difference which most people can distinguish. 3dBs is said to be a bit louder, although some people notice it more than others. With one frequency up3dB and another down 3dB, the difference is quite noticeable depending on the frequency. Obviously, hills and valleys in the hyper-critical range of 1 to 4kHz are immediately noticeable. Studies show that peoples hearing is more accurate and far ranching than previously supposed; which is why you see equipment with responses below 20Hz and above 20kHz. Studies show that we perceive tactile sensations beyond the mere ear canal response. In the hyper-critical range, people can find a 6dB difference between two frequencies as twice as loud. That is what I was thinking of when I dashed off that remark. My bad. In general though, a 10dB difference is usually said to be twice as loud.

By the way, a 3dB boost requires twice the power, while 10dBs more require about ten times more power.

[3dzapper]

Colin, I think you are picking nits with your critisism of the Forte's 32-20K+/-3Db response here. The Forte is a $1500/pair(new?) speaker. Looking at a recent issue of Stereopile Magazine, the Martin Design Coltrane's 32-20K response is +/- a little better than 4Db( between 32 and 12K +/-3Db) The Coltrane is a fine speaker as well it should be at $50K for a pair.

That makes the Forte a spectacular speaker at it's price point!!!!!

A similiarly priced speaker($1500/pr), the Spendor S5e is rated a best buy by Stereopile. It's 32-20KHz response? +/-5.5Db with a - 3Dv point of 40Hz and a large + 5Db peak centered at 70Hz and an 5Db drop centered at 175Hz. That is a net change of 10Db 70Hz will be twice as loud as 175Hz! Between 200 and 20KHz it is +/- slightly under 3Db.

That makes the Forte a spectacular speaker at it's price point!!!!!

I rest my case.

Again Shawn, The fact that further research has shown that an individual can discern 1/3Db change in volume, does not change the definition of a bel (doubling in loudness) or a decibel (1/10 of a bel). Might it be better if speaker measurments were specified in SONES which have a specific pressure per square centimeter definition? But then, that would be like specifying our cars power in dynes. I'd rather Dyne at home. Give me good ole HORSEPOWER!!!!

Rick

[Colin]

Agreed, no arguemnet there - the Forte and other Heriatge speakers are spectacular speakers at their price!!!!!

[laurenc319]

hi all,

Thank you for your replies. The room I listen in is 24 x 14 x 8 with hardwood floors. A little on the bright side but not overly so in that there are drapes, rugs, and not that many windows.

The little EICO opened my ears to the sound of tubes, although only 14 watts per channel it can fill the room with more adequate listening levels. The highs and mids are glorious and the bass if not pushed too loudly is accurate and not mushy.The sound stage is very deep and life like. The bass is much tighter with the 200 watt/channel ss amp but the mids and highs are not as mellow or pleasing to the ear... just a bit harsh in comparison.

The first thing that falls apart at loud levels with the EICO is the bass of course, not enough horswpower to move the big bass cones.

I listen to all kinds of music from Pink Floyd, to John Coltrane, to Mahler with a little touch of bluegrass and blues. Day time I like it loud and night time I like it soft. In addition to crisp fast transient highs and mids I like the kick of solid, room rocking bass ocassionaly. So the dilemma fo me ... a SET fot the realism an highs/mids or a push pull for more thumping bass. Can a 7 or 8 watt SET move enough air fo good bass definition ?

The new Jolida ? 701 40 watt/channel sounds intriguing ... maybe it can combine both. It is claimed to have the sound of a SET in a pp 40 watt amp. The mods by Underwood make it more enticing.

Thanks,

Larry

[Colin]

so use the Soundcraftsman to power a Parts Express passive 15" sub kit (no amp)= bass plus!

[sputnik]

Hello Larry,

I also have Fortes that I'm very happy with and I'm experimenting with older orphaned and neglected SS amps. I am amazed at the range differences each individual component or combination makes. That masters thesis is a great reference - thanks for the link.

Tubewise, have you or anyone here looked at the Antique Sound Labs amplifiers? I don't get to the big city much but I got to listen to a 50 wpc integrated Antique Sound Labs amp in Denver recently. With no warm up and feeding a pair of older JBL speakers it sounded pretty good in a bad room (it did have upgraded tubes). It's Chinese but seemed very well built - the connecting posts were nicer than most I've seen in my limited experience. Also, it is as pretty and shiny as the Jolida. No phono stage. The one they were selling as a demo was going for one kilobuck - I think the list is $1,700. Any experience out there with one of these?

[Duke Spinner]

well ...why dontcha bi-amp ????

SS for the lows, tubes, say, over 120 hz .....