Looking for amplifier (tube or solid state) recommendation to drive a pair of Altec 511B horns / driver GPA 902 8ohm.
These horns will be used with Acoustic Elegance 15 inch Dipole open baffle with an Altec 9440A power amplifier.
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Looking for amplifier (tube or solid state) recommendation to drive a pair of Altec 511B horns / driver GPA 902 8ohm.
These horns will be used with Acoustic Elegance 15 inch Dipole open baffle with an Altec 9440A power amplifier.
I'm using a First Watt J2 to drive my 511s with Radian 475PB drivers. It's full Class-A 25W/ch:
SoundStageXtreme.com | UltraAudio.com | First Watt J2 Stereo Amplifier
FIRST WATT J2
If cost is a big issue, I've read that the First Watt F5 also does a good job.
If cost is a really big issue, a friend is using a 1W/ch headphone amp to drive his 511s:
Amazon.com: FiiO E9K High Output Desktop Headphone Amplifier and Dock for E17 (Not E7 Compatible): Electronics
At reasonable listening levels, it does a very good job. His drivers (BMS4550) are 16 ohms, so that may be an issue if yours are 8 ohms.
Sensitivity will be the big issue. BMS 4550 has nearly 10db higher sensitivity than a 902.Quote:
At reasonable listening levels, it does a very good job. His drivers (BMS4550) are 16 ohms, so that may be an issue if yours are 8 ohms.
Assuming ~500hz XO, 1 watt is probably gonna have a hard time cutting the dynamic mustard.
I'm running Altec 416As on the bottom and 811s/802s on top. Right now I'm powering the whole things with a 15W OTL (glorious), but the long term plan is to build two 300B OTL monoblocks to run the 811s and leave the 15W to power the bottom through an active preamp. Here's a pic of both:
Tubes and Circuits by Bruce Rozenblit
The scuttlebutt from people way more experienced than me is that the 300B OTLs are the best 1.5W in audio, barre none. The kits are in process and I figure they'll be around $500/ch. Plus $300/ch for the tubes they're not cheap, but compared to what other high end audio costs...it's a bargain if you have some soldering skills and can follow directions.
The 15W SOB for $749 +tubes is like stealing.
If you are into DIY:
Bottlehead - they have a 2A3 SET kit for $750, or a dirt cheap starter kit.
Triode, USA has several Dynaco clone kits
Shannon Parks over at DIYTUBE - has a few kits as well - for the more experienced builder.
Appears to be a high power pre-amp, so concept wise would tend to agree.Quote:
Originally Posted by alancohen
GM
No, 16 ohm LF and 8 ohm HF or vice versa is not going to be an issue, you just need to adjust the cross over calculations to reflect what impedance you have. I have several "Altec" friends with that kind of combo and I heard their system and cannot detect any problems. Every single one of them, using DHT SET amps.Quote:
Originally Posted by fpitas
Abe
I think he's bi-amping; if so, there's no crossover between the amp and driver. I was afraid the headphone amp wouldn't drive the 8 ohms properly, but bowtie427ss pointed out that 1W probably wasn't going to get the job done with a 902.
Quote:
Originally Posted by amandarae
Precisely.Quote:
I was afraid the headphone amp wouldn't drive the 8 ohms properly, but bowtie427ss pointed out that 1W probably wasn't going to get the job done with a 902.
The 4550 is so sensitive, that if you swap it into an existing Altec speaker system like a Valencia or model 19 additional padding is needed to properly balance the system. The stock network and pad cannot attenuate the 4550 enough.
So, while an active system using the 4550 HF on 1 solid state watt might well be sufficient, a 902 in the same system is probably going to be starved for power. A 1.5w SET with it's more forgiving even order harmonics might still be able to get the job done with the 902 however. Listening preferences of course would be a big factor as well.
I've tried the low power diet, if i only listened later at night i could probably live with it. However, lack of power always became the culprit in listening fatigue during extended sessions. When i find a color i like, i can live with the coloration of valves(tubes). But, fatigue caused by over-driven amplifiers is just not a compromise i can live with at the end of the day. Sign me up as a solid state class A space heater fanboy.
Ditto, though there's a certain synergy when a compression horn is driven with a ~matching output impedance, so want this as part of the system design.Quote:
Originally Posted by bowtie427ss
GM
Me too ! One watt has never been enough power for me, ever... I enjoy higher SPL's while listening to music.Quote:
Originally Posted by bowtie427ss
I read an article by the designer of my OTL. I quote: "A good rule to follow is that amplifier output impedance must be at least ten times lower than speaker impedance for good control of cone motion. This is called damping factor. Amplifier output impedance must be less than one ohm for best performance."Quote:
Originally Posted by GM
Here's the full article. I'm trying to understand as much as I can. Amplifier Output Impedance
I try to reproduce the SPLs that I would be experiencing if I was listening live.Quote:
Originally Posted by Altec Best
For example, my son and I were watching (listening to) the PBS broadcast of the 25th Anniversary Concert for Les Miz. It was taped in a large arena with full orchestra and maybe 200 choral members on top of the cast. (BTW, if you haven't seen it I highly recommend you do.) I can only imagine what it must have sounded like being there.
We were sitting on the couch about 9.5' away from the Heathkits and I adjusted the volume knob to achieve a sound level of what I believe it would have sounded like sitting in the middle of the venue. With 3W/channel available form my cathode follower I got the knob to about 5 where the sound began filling our heads more than sufficiently. It was loud. I don't know how many watts I was actually pushing, but it couldn't have been much more than 1ish.
So I agree, I might be a little powered starved with a 1W amp. But 3Ws is more than enough.
Go Altec!
And BTW, we listened for almost 4 hours in one sitting and not a bit of listening fatigue. If I had the time I could have started it again.
There should be a crossover somewhere. In this case, a line level type. As for the 902 using 1W at 104dB, wonder why that is not enough especially using a line level XO which makes the full 1W is directly behind the driver.Quote:
Originally Posted by fpitas
Is it wrong for me to think that it is not the power from the amp if 1W is an issue, to get the SPL you want, it is the sensitivity of the driver?Quote:
Originally Posted by Altec Best
So to say that 1W is not enough is not entirely accurate. Are we forgetting that the probable goal of having a high sensitivity low power set up is to minimize the distortion that is directly proportional to the amount of power output of any amplifier, tube or SS? To me, if you want high SPL at low power, then change the driver. Maybe I am wrong.
Just curious.
My comment was based on the specific system mentioned using the BMS 4550 and 1 watt solid state headphone amplifier(typically designed to driver higher impedance loads) and assumed a ~500hz XO. I think it's also safe to assume that said headphone amp driving an 8 ohm load will have little headroom to offer, i would expect it to clip easily on dynamic sources.Quote:
wonder why that is not enough especially using a line level XO which makes the full 1W is directly behind the driver.
For my own personal preferences, the 110db sensitive BMS driver might develop satisfying dynamics for me on that particular 1 watt amp. The 902 surely will not.
Agreed, IMO&E, micro-watts need mega-speakers.Quote:
Is it wrong for me to think that it is not the power from the amp if 1W is an issue, to get the SPL you want, it is the sensitivity of the driver?
If money and space were both no object for me, i'm pretty sure i could get along on a couple good watts for most of my listening. The clincher is that my speaker system would need to be all horn loaded and large format(read massive) to achieve the necessary sensitivity particularly at low frequencies.
Well I prefer the sound of my Altec drivers and a lot of the time I don't just sit there still for hours. I'll crank up the tunes and work around the house.So I will need to hear it all through the house.. :wink2:Quote:
Originally Posted by amandarae
Yes, understood. It is cheaper to increase the power of the amp than increase the sensitivity of the drivers.Quote:
Originally Posted by bowtie427ss
Yes,in that case, a 1W amp will never satisfy the need especially if you have a humongous dwelling. That's why I still have a back up SS amp. When I do something inside the house, or around it, and wants great background music where loudness is the importance, I use the SS amp instead of DHT's as it is way cheaper in the long run. :)Quote:
Originally Posted by Altec Best
My now-departed uncle used to talk about how, back in the late '50s, he would show off how efficient his 820 was by hooking it up to a cheapo transistor radio. When I asked him how it sounded, he said "like a *big* cheapo transistor radio". :)
I had the 820s hooked up to a MC2100 (105 w/ch), which I had plugged into a Kill-A-Watt meter. According to the Kill-A-Watt meter, the MC2100 draws about 40 watts at idle, and about 40 watts at 'loud'. So it barely knew the Altecs were hooked up.
Maybe I should plug my 511s into my Stax (class A) electrostatic headphone amp/preamp? :)
And why it's not normally a good plan to drive a woofer with a low DF amp, but like most things, it depends. Anyway, this subject is no trivial pursuit, requiring a fairly good understanding of both the electrical and mechanical physics of audio system design that goes well beyond a simple marketing white paper.Quote:
Originally Posted by alancohen
Compression horns OTOH are normally very highly damped electrically and acoustically in their usable pass-band, hence its response fairly closely responds to how the driver performs in a plane wave tube [PWT], so if driven with a high output impedance, it adds a 'smiley face' EQ to it, flattening it both electrically and acoustically over a much wider BW while remaining damped enough that it's still over-damped from a transient attack [impulse response] POV, so in some cases it may need to be higher than a matching impedance to achieve a 0.5 Qt 'critically damped' [transient 'perfect'] response.
To accomplish the same thing with a cone/dome driver requires a < ~ 0.25 effective Qt, combined with a 0.5 Qt OB, sealed, or aperiodic alignment, so can be done with some of Altec's and others drivers and why they are sometimes marketed as horn drivers.
GM
Hi everyone,
I have some extensive experience in this topic of low powered amps on Altecs, and would like to contribute up here.
The best sounding amp for an Altec speaker system in high fidelity home use will be a good one Watt amplifier.
It will be tube, two stages, and direct coupled. It will have about a two (or three) hundred Watt power supply, and it will be a "gated" one ( or two or three ) Watt audio amp.
It exists, and has since 1989. They are about $15,000 for a pair of mono amps. I know two people who run them at home on GPA 604s. Most all of you have never really had a good opportunity to hear them, but I have in numerous systems and rooms, hence my posting. I am posting this, just to set the record straight.
I suppose I better disclose, the fellow who builds these is a very close friend of mine, and has been for maybe twenty five years. I have NO financial interest in this, and am just introducing you to what I believe to be the best there is for Altec speakers, "IMHO". When you get a good chance to hear it, with good source material, only then can you easily understand.
Here we are :
Welcome to Serious Stereo. The ultimate SET amplifier, passive attenuator, High Effienciency Speakers, Vacuum tube amplifier, tube amplifier, single-ended amplifier, triode amplifier
Read the reviews, have fun.
Jeff
EDIT, On August 29, 2012, there was a forest fire in Montana, that has caused huge disruptions in this company's operation. ( GOOGLE : Pine Creek Fire, MT ). If anyone wants to contact this small artisan manufacturer, let me know and I will provide new phone numbers, etc.
Some amplifiers that I at the moment investigate is the Parasound Halo A23 , class A up to 2,5 Watt, and balanced input, but solid state, 1000USD. Other class A amps come to my mind.
The Decware brand as the Mini Torii about 3W 4ohm seams interesting.
Any recommendtaions and comments appreciated.
I noticed that Reno Hi-Fi has a used First Watt F3 for sale this month:
First Watt Products
FIRST WATT F3
Sorry guys, but my son took it apon himself to take my 15 years dead Crown 150 wpc DC300A with him over Christmas and just reported that it is breathing again. Just have to send in my Stax SRA-12S pre-amp, send in my 416-8A woofers for recone, and get a matched pair of pascalite diaphrams to get the A7-500s back in shape, and I will be back to rocking 120db music. Nothing beats POWER. You can keep your 1 watt, I also listen to my stereo outside, in -30 below temperatures when no one is around to call the police. :)
Never apologize for knowing and stating what YOU like.Quote:
Originally Posted by VolvoHeretic
That said, leaving a DC300 to lay in state for 15 years might be a tad sacrilegious. :D
I wouldn't be happy with only one watt either; like you, sometimes I listen loud. In my friend's situation he's on a budget, and a $109 amplifier that sounds pretty good at moderate levels is a keeper.
Quote:
Originally Posted by VolvoHeretic
Note, recommedation for the power amplifier I am looking for will only be used with the Altec 511B horn(s) not for the woofer(s).Quote:
Originally Posted by fpitas
How much power is needed and how much, may be too much ?
One thing would always concern me with a low power amp (especially 1W) is. Driving the amp into clipping,which would be very easy to do with a low power amplifier.
Hmm, the AE woofer is only around 90 dB eff., so even if no baffle step compensation [BSC] is required, shelving a 511/902 down this far means there's very little dynamic headroom left, so just to match typical cone/dome 'monkey coffin' SPL peaks will require at least 12 W and depending on what low distortion peaks the woofer is capable of may require up to the 902's rated power handling.
If BSC is required, then you might need 2-4x more power and hope the 902 can take the fast transients without bouncing off the phase plug.
Bottom line is that in either of these cases it's best to use a high XO point with at least a 2nd order slope to protect the driver.
GM
I'd think 10W minimum, maybe 50W maximum, although you won't find many class A amps bigger than 50W unless you're willing to pay a lot. And from my experiments, I think class A is the way to go with a horn.
Quote:
Originally Posted by MerlinVSM
The Crossover frequency will be about 1000hz 96db/octave.
Wow! You can use 500 Hz then if you wanted to.
GM