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Looking for SET amp for my Altec speakers

107.77.215.38

Posted on October 14, 2020 at 07:14:18
Posts: 109
Location: texas
Joined: April 17, 2006
Hi,

OK you guys, need your experience & knowledge.

I am looking for a good match SET amplifier for my speakers. they are Altec Valencia components in new custom cabinets and new cross overs. The specs on the Valencia 846B say efficiency 97.0 dB SPL.

Can I get good volume with only 2watts? Looking at Decware Zen?? or other??

also need a matching pre amp phono input - what is a proper match? Can I get by with a cheap pre amp? or is that a mistake?

Recommendations?


thanks for your input

 

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I was not happy with my 846Bs or Model 19s with low power a.mps, posted on October 14, 2020 at 10:43:24
viridian
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YMMV, but I needed push-pull power for those. Klipsch Cornwall's, Klipschorns and JBL Apollo seemed to work better with SE, for me. But we all have a different sense of what we need on ultimate loudness and dynamics.

You can always sell the Decware on if it does not work for you.

 

RE: I was not happy with my 846Bs or Model 19s with low power a.mps, posted on October 14, 2020 at 13:20:04
Posts: 109
Location: texas
Joined: April 17, 2006
what brand and power did you try with the 846Bs and Model 19?

my room is not large, don't need to rock the walls.

but I do hope for great mid range vocals, instrumentals from the horns and solid bass from the 15" 416s.

how many watts do I need??

 

RE: Looking for SET amp for my Altec speakers, posted on October 14, 2020 at 13:20:16
Tre'
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2 watts, 97db is 100db
with two amplifiers and two speakers that would be 103db

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Can I get good volume with only 2watts?, posted on October 14, 2020 at 13:27:41
Ivan303
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Maybe.

Maybe 4 watts?

Just built a Bottlehead S.E.X. amp (2 watts at 8 Ohms)for all of $550 and it sounds way better than it should. OK, 106 dB horns, but still...

It can be bridged for mono (you would then need to build two) and produce 4 watts.

4 watts for 97 dB speakers is about the same as 120 watts for 82dB speakers and that's done all the time.







 

Bottlehead Paramour, Musical Paradise and Audio Electronic 300B.nt, posted on October 14, 2020 at 15:50:14
viridian
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Nt

 

IMHO, simple discussions of wattage do not account for impedance and phase angle. nt, posted on October 14, 2020 at 15:53:19
viridian
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Nt

 

Wattage table, posted on October 14, 2020 at 16:32:06
RayP
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Paul Joppa (of Bottlehead fame) has posted about this topic. Look at this link and go down to the third comment. To get to 102 dB, the table shows you would need 4 to 8 watts.

For a speaker system like yours that would not have been inexpensive, you might audition 2A3 or 300B amps and see what you think. There are of course many other output tubes that will deliver power outputs in the 4 - 8 watt range.

ray

 

RE: Wattage table, posted on October 15, 2020 at 07:22:30
lokie
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Excellent info at Bottlehead and coincides with my observations with my own diy Altec variants and various tube amps.

My thought is that absolute minimum is 2A3 PP. I never tried the big tubes but I imagine SET 211, 845's and GM70's based amps would be pretty fabulous. I settled on KT77's PP (particularly the Gold Lion Re-Issues) which put out around 25W's in my amps. They seem to be a good fit for my size of room, 15" woofers and the type of music I listen to the most.

Having said that, I had a lot of fun with SET 45 amps, but they are limiting. Having two pair of amps is the way to go!

 

RE: Looking for SET amp for my Altec speakers, posted on October 15, 2020 at 07:45:51
Grinnell
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I use a Grommes PHI-26 int amp to run my Klipsch Quartets. it puts out 2/6 wpc depending on the setting. It gets plenty loud with the quartets (97.5db)

I also have a Decware Mini Torii 4 WPC and use them with 92db Ref 3A de Capos. Not concert loud but no problem driving the speakers and a very sweet sound

 

No simple answer, posted on October 15, 2020 at 08:00:11
Salectric
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There are plenty of folks who seem very pleased with their flea-power SE amps driving speakers with a wide variety of sensitivities, even down to the low 90 db range. Then there are others who say you need much more power than a 2A3 or 300B can provide with even very efficient horns.

If you are looking for some widespread agreement on the issue, you aren't going to find a satisfactory answer. There is just no substitute for trying a SE amp in your own system and reaching your own conclusions.

In my case, I concluded that I need the power and control of a good PP amp even though my speakers have a 99 db sensitivity. And I don't listen at loud volumes.

 

It's unlikely that you'll be happy....., posted on October 15, 2020 at 13:39:04
Rod M
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I ran my 45 amps with my Altec Model 19s, which are essentially, larger Valencias, and they just didn't cut it. My Dynaco was awfully close with wonderful mids, but still not able to really handle the bass. I ended up using my Atma-Sphere S30.

OTOH, my EdgarHorns using simple 1st order crossovers are about 105db efficiency sing with 2 watts.
-Rod

 

RE: Looking for SET amp for my Altec speakers, posted on October 15, 2020 at 17:10:01
belyin
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About 20 years ago I drove Altec Valencias with an Audio Note Otto integrated amp with phono. It uses paralleled EL84 pentodes in a single ended configuration and it advertised as good for 12 watts into 8 ohm load. I was happy with the set up, and the practicality of an integrated amp sounds like something you would like. I you are into headbanging, you might do better with a classic EL84 push pull integrated amp like a refurbished Scott 299 or the similar which should offer better control of the woofers.

 

2A3 driving a Pass F4!, posted on October 16, 2020 at 11:40:01
amandarae
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Radical, yes. But it will give you the 2a3 sound and drive but 25 watts of power. What more do you need? :)

I have both (2A3 and Pass F4). If interested, link below...

Abe

 

Good idea! DHT feeds Solid State output. , posted on October 18, 2020 at 01:31:25
andy evans
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I like this thinking. A DHT as driver tube gives quite a bit of the DHT sound, which can survive a non-DHT output stage. I'm using a similar idea - a DHT driving an IDHT output.

 

RE: Good idea! DHT feeds Solid State output. , posted on October 18, 2020 at 15:09:25
amandarae
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Hi Andy,
I am feeding the 2A3 with either a type 26 or a 01A preamp. Excellent sound and a vise like grip on the woofer.

Abe

 

RE: I was not happy with my 846Bs or Model 19s with low power a.mps, posted on October 19, 2020 at 09:58:26
triodesteve
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Using el84's (Shindo) on my 864b's. Could not be happier. Some folks use a Cortese which is about 10 watts of single ended power....maybe you could get by with a 300b amp?
I have used a 1626 amp which is less than a watt and it was a no go.
Have fun

 

RE: Looking for SET amp for my Altec speakers, posted on October 19, 2020 at 18:22:48
Stuben
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The strapped pentodes will do a decent job at 2 watts with the efficiency you're working with. The 2a3 approach will let more magic out using a comparably thought out design and build. I've implemented both with good results. If you've done neither to date, and have a budget, start with Deckert's offering. my 2 cents. The EL84's and their pentode brothers can sound fine for the money. Alos, a well designed and built SEP will surprise with a good system match.

Stuben

 

RE: Looking for SET amp for my Altec speakers / Follow up, posted on October 19, 2020 at 18:51:09
Posts: 109
Location: texas
Joined: April 17, 2006
Well...after review and discussion, I decided to go with the MP-301 MK3 (with upgrade tubes). Also ordered the P2 phono pre amp.

It will be interesting to compare the different amps (SS / Tube) when it is set up in my system.

Wish me luck.

 

I had one of those, fun amp, congrats. nt, posted on October 19, 2020 at 20:21:32
viridian
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Nt

 

With that sort of efficiency you'll want 30 watts at least., posted on October 21, 2020 at 09:54:37
Ralph
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My speakers are a similar efficiency and 30 watts works pretty well in most rooms as long as its clean power. There isn't a 30-watt SET that would do the job; SETs of that sort of power output tend to have poor bandwidth due to output transformer limitations.

One thing to keep in mind is that with SETs you really don't want to be driving them to full power if you want to really hear the best out of the amps! At higher power levels SETs make higher ordered harmonics which show up on the transients, causing them to sound 'dynamic'. But this is because the ear uses the higher ordered harmonics to sense sound pressure, so this is distortion masquerading as 'dynamics'. With a more efficient speaker this does not happen. But because of the ear's logarithmic character, to make the kind of power you'll need past 2 watts, 30 is a good place to start.

 

RE: With that sort of efficiency you'll want 30 watts at least., posted on October 21, 2020 at 19:35:21
Tre'
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My midrange and tweeter (padded to match the midrange) are 97db and crossed at 200Hz (bi-amped) and I use a SET 300b for the mid and tweeter. The 300b amps are setup for about 5.5 watts max and it's plenty for me.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: CD, Vinyl, Watts, and Requiems, posted on October 22, 2020 at 04:14:18
B. Scarpia
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When I first came upon the SET/Hi-Eff scene 20 years ago my music was on silver discs and was mainly classic jazz and folk rock. 2A3's, 300B's, 45's; every conceivable combination of JBL, Altec, Emilar in all sorts of cabinets. I built everything and loved it all.

Then a funny thing happened. I got back into vinyl which reminded me more of what the instruments and voices sounded like when I was playing in orchestras and house bands but I was missing the digital clarity that kept singers from sounding like Stan Freberg's mumbling in "Sh-Boom".

Concurrently, my Canary and Folky listening began to be replaced by the large orchestral and choral music I grew up with. (The further into my 70's I get the more I seem to appreciate the Requiem Mass) 1.8 UX-45 Watts into 97dB speakers @ 85-90 dB's even in my small room just weren't cutting it.

More or less on a whim, having come across the diyaudio thread on building 60 Watt KT-88 mono blocks based upon the Mullard 5-20, my Tube Wizard friend and I built them.

That was 5 years ago and I've been happily ever after listening to all the power, majesty, and inner detail of Mahler as well as the sweet delicacy of Billie Holiday.








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RE: With that sort of efficiency you'll want 30 watts at least., posted on October 22, 2020 at 09:15:25
Ralph
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At higher power levels SETs make higher ordered harmonics which show up on the transients, causing them to sound 'dynamic'. But this is because the ear uses the higher ordered harmonics to sense sound pressure, so this is distortion masquerading as 'dynamics'.

One thing about how the ear perceives the higher ordered harmonics- it also converts them to a tonality. This is heard as additional brightness and harshness and its why so many solid state amps are bright. The thing is, because the higher orders are also used to sense sound pressure, if they are present in sufficient quantity, the system will sound 'loud'. If they are not present, you won't be able to tell how loud the system is and it will sound more relaxed. IMO the higher ordered harmonics are the most insidious of all the colorations.

 

RE: With that sort of efficiency you'll want 30 watts at least., posted on October 22, 2020 at 12:38:14
Tre'
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Direct heated triodes do not produce much upper order harmonic distortion.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Not at low power, posted on October 22, 2020 at 12:42:35
Ralph
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At low power they can be very low distortion.

But at higher power levels the higher orders show up; that is why SETs sound so 'dynamic'. That occurs when the speaker used isn't efficient enough and the amp is being asked to make a bit more power.

 

RE: Not at low power, posted on October 22, 2020 at 15:14:34
Tre'
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My 300b SET at 3.5 watts has zero 4th order HD.

At 5.5 watts (full power as designed) the 4th is .028%


Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

you might find this interesting., posted on October 22, 2020 at 15:32:10
Tre'
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Chart by Harry Olson.


.
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Impedance matters a lot, posted on October 23, 2020 at 02:21:51
Frihed89
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NT.

 

Link is broken nt, posted on October 23, 2020 at 09:06:00
Ralph
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-

 

RE: Link is broken nt, posted on October 23, 2020 at 09:42:22
Tre'
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Measured by Harry F. Olson

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Yikes!, posted on October 23, 2020 at 12:11:39
Ralph
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Those charts really don't tell the story! On modern test equipment you would see a lot more information; the ear is very sensitive to the higher ordered harmonics as it uses them to sense sound pressure. That's pretty sensitive, because the ear has a range over 120dB.

Sorry, but the idea that any SET is lacking harmonic distortion above the 4th just isn't reality. I've linked a stereophile review below, which is more typical of what you actually see.

 

RE: Yikes!, posted on October 23, 2020 at 12:18:56
Tre'
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"Each Thöress also contains a pair of new-old stock Telefunken EL803S pentode tubes"

.
Have Fun and Enjoy the Music
"Still Working the Problem"

 

That really won't make any difference., posted on October 23, 2020 at 12:22:52
Ralph
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Any SET will have a similar distortion spectrum. It won't be identical (which is a reason why you hear differences between them since the ear converts distortion into tonality) but on paper it will be close enough for government work.

 

RE: That really won't make any difference., posted on October 23, 2020 at 14:38:37
Tre'
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You don't believe me, you don't believe Harry Olson (shame on you) and you probably won't believe this so that's leaves me with not much to say.

Now don't try this with a triode wired 6550 or similar or a triode wired power pentode and don't try this with a 6as7g, none of them are linear enough. You will end up with a lot of distortion.

Direct heated triodes are special.

.
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Its not that I don't believe Harry, posted on October 23, 2020 at 15:18:20
Ralph
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its just that his charts don't depict what's happening- he didn't have access to test equipment with greater resolution.

Your load line appears to be a simulation. Have you measured what the amp actually does?

I've seen simulations off enough that I've learned to be distrustful... I can give you a number of anecdotes but that's all they are.

 

RE: Its not that I don't believe Harry, posted on October 23, 2020 at 17:07:09
Tre'
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"its just that his charts don't depict what's happening- he didn't have access to test equipment with greater resolution."

He had the resolution to show the upper ordered harmonics on the pentode but not on the 2a3?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: With that sort of efficiency you'll want 30 watts at least., posted on October 23, 2020 at 19:03:37
RGA
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I am not so sure - I run Audio Note E speakers which are lower in sensitivity ratings, and they are ALL fine with 7 watts.

And since AN has sold massively well compared to most high-end audio brands to customers who used to own high power amps there seems to not be too much issue there.

Albeit they are generally designed for medium sized spaces, not the sort of space a large horn might occupy.

Im my space though, a recent 100 watt Class A ampifier offered no noticeable power adavantage (audibly) on any music over my 8 watts 2a3 parallel Single Ended amplifiers. And my speakers are not as sensitive as the OP's.

 

Yes. He didn't show the upper harmonics on the pentodes either, not by a long shot! nt, posted on October 26, 2020 at 11:58:28
Ralph
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-

 

He did up to the 14th. , posted on October 26, 2020 at 13:24:09
Tre'
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but the 2a3 didn't have anything passed the 4th.

That is my point.

BTW We don't need to see HD clear out to the 81st, a tiny bit of 7th and it's game over. 7th sounds really bad.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Any of the odd orders above the 5th are bad!, posted on October 26, 2020 at 14:06:43
Ralph
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And with any tube amp its almost impossible to put enough feedback in the circuit to really do what needs to be done. So the next best thing is no feedback at all IMO. But you wind up with higher output impedance.

However, Harry's gear didn't show anything above the 4th, but it was there nonetheless. Any modern test gear would show it.

 

RE: Its not that I don't believe Harry, posted on October 27, 2020 at 03:59:24
morricab
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I think the point is that these plots go down to "only" -80db and there is a lot going on below that level that could still be audible.

Ralph is right that there are still some higher order harmonics being generated by DHT SET, especially when the power goes up but they are balanced by the pattern of a relatively monotonic decay, which seems to be as important as the raw distortion harmonics themselves.

 

RE: Its not that I don't believe Harry, posted on October 27, 2020 at 09:01:54
Tre'
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The bottom line, DHTs sound cleaner that any other tube I have ever heard.

And I have heard a lot. I've been building for 40 years.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Sad but true...., posted on October 27, 2020 at 09:05:03
Ivan303
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The 'First Watt' may really be the 'First 100 Milliwatts'.

Even listening to my arguably 105dB (sorry, not 106dB) Edgarhorns, offending odd order distortion becomes evident with but a bit of cranking up on the volume knob, at least with 2 watt indirectly heated triodes.

Will soon be bi-amping each driver with its own 2 watts of SET magic. Should give me an additional 3dB of 'headroom'. :-)

And with active x-overs I can get rid of 3dB of the 6dB padding-down on the JBL 2441. Might help a bit as well.

Make that the 'First 10 Milliwatts' :-)



 

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