Kit amp recommendations??

[JSP]

have any of you guys built kit amps for altecs?

if so, P/P or SET? What are your recommendations?

[bfish]

Consider that Altec amps were all PP, not a single SET in the line (that I know of).

Here it comes...

[RonSSS]

What do you mean by "kit"?
Are there kits on the market?

Unless you spend quite a lot of money, SET will be very low power. It takes transmitting type tubes to get more than about 10 watts. Unless you parallel output tubes.
10 watts will drive Altec quite nicely however. But the low end will suffer at high levels.

PP amps on the other hand can do 30+ watts pretty easy. 30 watts will rock and roll pretty well.

Also, PP amps can be done with Pentodes, Beam Power tubes as well as DHT triodes. And PP amps can have no global feedback, or a ton of it. All these things affect the sound.

There are a lot of vintage PP tube amps out there that sound great and fit the bill well. My favorite is the Heathkit W5M. Although they have gotten quite spendy of late.

The amp in my Avatar is PP 300B, about 35 watts, transformer coupled and sound great to my ears. They weren't exactly a kit though......

Ron

[ZilchLab]

I'm becoming a broken record:

Biamp and acquire control.

Use wimpy tubes on the HF

Run ballsy SS on the LF

Push the CD Comp button for HF extension, or add on a custom passive compensation filter like 30923. Vary R-2 to optimize.

Dial in the time alignment with built-in woofer delay, as appropriate.

Less than $150 to try it on the cheap, Behringer CX3400....

<font color="#FFFFFF" size="1">[ January 23, 2008 04:20 PM: Message edited by: ZilchLab ]</font>

[bfish]

I've had little exposure to kit amps since the '70s, so I Googled a bit to see what was out there now. Kinda surprised at the variety of kits available. Here's one example that seemed to be middle-of-the-road;

http://www.tubedepot.com/diy-k4040.html

Specwise, it looks to be a decent amp with enough power for most home Altec apps.

If you have the requisite skills to build a kit though, you should be aware that you can likely rebuild a vintage model for a whole lot less $.

Take the above $2K 90Wx2 kit as an example. A pair of Altec 1569s will run you around $600 on eBay. Another $3-400 for new caps and tubes. Is the tradeoff for a pair of green monoblocks vs a shiny chrome stereo amp worth $1K to you or not?

That's just an attempt at a helpful reply to your question though. If you were to ask my opinion of how to get the most from your Altecs for the least money...what Zilch said works for me.

[Seadweller]

I've been researching amps for my 604 system for the last 2 months, and it's an eye opener....There's SET, parallel SET, Push/Pull and OTL technologies, along with a dizzying array of tube options....

There are some pretty slick kits out there from companies such as Welborne, Bottlehead, Antique Electronic Supply, Transcendent, Audio Note, etc...I've read of folks getting excellent results from all of them...

Based on my research, the finest reproduction comes from an SET with 45 tubes...Problem is, they're around 2/wpc...

Next is an SET with the 2A3 tube at around 4/wpc, then the 300B tube, at around 8/wpc...The 300B tube is said to have the most "magical" midrange of the bunch, but suffers at the frequency extremes...The 2A3 betters the 2A3 at the extremes, and the 45 trumps them both...Careful speaker matching is mandatory with the 45 of course, and likely with the 2A3 as well...The 8/wpc from a 300B may be enough for most listening...

The overwhelming majority has recommended an SET amp, but I'm concerned that I won't have enough power...On the other hand, 8/wpc of tube power evidently doesn't compare to 8/wpc of solid state power; or so they say...

I guess the next step would be a push/pull configuration using EL34 tubes...This is said to give you better performance at the frequency extremes, at the expense of some of the SET "midrange magic"...

If you need more power yet want to retain the "SET magic," OTL technology purportedly comes the closest to SET in a high powered amp, but it's expensive technology, and requires a huge number of tubes...Transcendent makes OTL kits, and Atma-Sphere makes some of the best commercially available amps on the planet I'm told...

Anyway, I'm getting very tempted to try an SET amp with my system...Everything I've read about the "SET magic" in the midrange is consistent, and I'm addicted to detail...Supposedly, SET's have detail in spades! I'd love to try the 45 tube, but 2/wpc won't cut it for my purposes...

Good luck!!

[bfish]

I can't help but wonder why none of the SET users from the old days considered them magic? They abandoned them like cross-eyed 3-legged dogs when something better came along. Has some genetic change given our generation better ability to percieve and appreciate magic? Something in the water maybe?

Not until the '80s, when some creative folks with magic to sell came along, did the SETs come out of the closet and reach their current indescribably fine cult status. Selling magic has to be the easist job in the world, at least as long as sufficient numbers believe in it. You never have to explain why it's magic...because it's magic.

##############

Added;
I wonder how some of the current SET mfrs would respond if an intelligent owner brought his SET back during the warranty period, claiming the magic didn't work, and never really did...?

###############

Added in the night when the fire died out;
"What do you mean sir, no magic?"

"Nothing happens. I mean...it just sits there and ...amplifies..."

"Why that's unusual, have some coffee and kruellers, while I let the Magician check it out. Make youself comfortable."

(The amp is removed to the apothecary's lair. While staring in his coffee, the customer can overhear the ensuing conversation);

"Says the magic's out. Hope it isn't another evil spell...better take a look."

"Sure. Just let the old magicoscope warm up. I'll start a pot of potion while we wait." (tinkling of glass, muffled burp).

"OK, let's take a look. Hand me those magic interconnects if you please."

"Hmmm, the magic levels are a bit low, and...Oww! That's hot!"

(muffled indestinguishable expletives)

"OK, I put in a new magic capacitor, and just to be sure, a whole new set of matched magic tubes. Did you say the guy was waiting?"

"Yeah. He looked bummed. I thought he was gonna ask for his bread back.."

(Silence)

"Here. Good as new. Magic as all get-out. Where you eatin' lunch?"

"Merlin's. Thursday special. Eye of newt grinders. Think I'd better demo the amp for the guy first...where's that Heart album with "Magic Man" on it?"

"Right where you left it, over on the Sorcerer's Stone. I'm gonna start hiding all the junk you lay around. Play "Magic Carpet Ride" too." (snicker)

"OK, here I go...turn on the alpha waves."

##################

Added later;
Now, The Human Instrument,

that there's real magic.

Added way later;
then removed. Enough's enough.

<font color="#FFFFFF" size="1">[ January 30, 2008 05:46 AM: Message edited by: bfish ]</font>

[Seadweller]

bfish, you bring up some interesting points....I owned my one and only tube amplifer back in the early 80's, a Dynaco ST-35 I believe, that powered my Altec 19's for a short period of time....It was noisy, hummed, and sounded dreadful....Granted, it was 100 years old when I got it, but regardless, it wasn't a good first experience....

I'm not sure what this "SET magic" is, but I intend to find out....Many have said that Altec designed their drivers around the higher output impedance of tube amplification, so perhaps tube equipment does have a place with some systems....Perhaps modern circuit topology and components has benefited the technology....

Anyway, while I question speaker wires made from moon rocks, Shitake stones, and $5,000/pr interconnects, I'm going to stick my neck out and give tube amplification a try, and despite my fears of not having enough power, I may just go the SET route as a start....

I'm not walking into this with rose colored glasses, so it'll take real, demonstrable magic to convince me!

[Richard C.]

Bfish - A great post to start my day with! Thank you! But, you've taken the "Magic" out of SET for me

Yeah, I often think that "IF" people were completely logical, there would be millions of salesmen out of work. I know, life would then be boring and society would collapse. I'm just glad I didn't spend a couple of thousand on an amp and then wake up to the realization that it just sits there and ...amplifies...Buyers remorse???

I do know that for many people, the saying "the first watt is the most important" holds true. With speakers in the mid to high 90's (SPL/Watt), this can be more than they will ever listen to.

Richard C.

[bfish]

Anytime Richard!

Yep, that first watt's pretty doggone loud. And it would often be enough... unless you care about little things like...oh I don't know...15dB transients...little stuff like that.