Amps for the rest of us?

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I second the chipamp.com and Peter Daniel boards. Keep the chassis construction simple (unlike what I did). If you are looking for a similar tube amp project (similar in that everything is on a PCB), check out George's SimpleSE: http://www.tubelab.com/SimpleSE.htm You'll find lots of support for it over here. If you do need comlete, step by step instructions, I'd go with Bottlehead.

pj
www.wildburroaudio.com
 
I haven't done one of these yet, but I have been in contact with the folks at S5electronics and they seem very helpful.

http://www.s5electronics.com/thome.html

Plus, there is plenty of info on the web about these kits and some modding/upgrading info. They come complete too; no searching for transformers, etc. The price can hardly be beat as well. With mono kits starting at $150 and stereo kits starting at under $200, they look like good kits for beginners.
Just my 2 cents worth...
Mike
 
I've built a couple of Gainclones with the 3875 and the 3886. I've also built the s5 electronics tube amp. The biggest problem is DC offset. And the same is true with the current amplifier that I'm using the Nu Force Icon. I used to listen to Sonic Impact T-amp that was better, but with efficient drivers its tough not to hear dc offset, especially since I am neafield. My Gainclones got better and better as I learned more about interference. I am friends with Brian Bell (chipamp.com) and he and I built a couple amps and he showed me a lot of tricks, but sitting nearfield I think that T-amps are the best. Otherwise I loved the sound of my tube amp at larger distances, although I don't think the amp has quite enough power and bass output. My kit was heavily modified as well. I need to pull it out again and listen.

Josh
 
As the noob I am I wonder what kind of amplifier it takes to support a pair of full range speakers. I’m planning to build a pair of Ron’s Austin II, A166 (or III from hifiZens drawings). Are there any affordable options? Are there any specific characteristics that I should pay attention to when it comes to support a pair of full range speakers? How much output effect do the Austin’s require, most tube amps seams to have very low output?

/Fredrik
 
Forsman said:
How much output effect do the Austin’s require, most tube amps seams to have very low output?

/Fredrik

"That motorcycle cannot be very fast, it only has a 750cc engine.
My Volvo V70 with a 3200cc petrol engine is clearly a better solution for speed, the engine is several times larger."

Efficient speakers (such as the Austin) with small tube amps (3 to 5 watts) are the motorcycle.

The V70 with a 750cc engine would be a mistake. But for the bike, it's a natural choice.

Rick
My avatar is a 3wpc tube amp resting on the hood (bonnet) of my STi
 
rkevans said:
"That motorcycle cannot be very fast, it only has a 750cc engine.
My Volvo V70 with a 3200cc petrol engine is clearly a better solution for speed, the engine is several times larger."

Thanks for the grate analogy, very vivid. I’d rather have the motorcycle :D

As far as I understand, in theory a driver in a horn can be up to a 100 times more efficient than the same driver mounted in a box. In the Austin A166 there is a Fostex 166 at 65 w. Then that figure is irrelevant.
Interesting that the horn is so efficient that I doesn’t need more than 3-5 w? Then there is a lot more DYI amp kits to choose between.

/Fredrik
 
frugal-phile™
Joined 2001
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Forsman said:
As the noob I am I wonder what kind of amplifier it takes to support a pair of full range speakers. I’m planning to build a pair of Ron’s Austin II, A166 (or III from hifiZens drawings). Are there any affordable options? Are there any specific characteristics that I should pay attention to when it comes to support a pair of full range speakers? How much output effect do the Austin’s require, most tube amps seams to have very low output?

You want an amplifier with a highish output impedance. Unless you want to play at levels that push the 166 (and your ears) to the limit, 2-10W is sufficient.

A relatively affordable amp would be something like the RH84, some of the bottleheads, used Decware Zen (SE tube amps tend to have higher output impedance). A bit more costly are things like SEWA, firstwatt F1, F2.

People use a lot of different amps with these, an amp with a lower output impedance can be tamed to some extent by using very thin speaker wire.

dave
 
planet10 said:
You want an amplifier with a highish output impedance.

[...]

People use a lot of different amps with these, an amp with a lower output impedance can be tamed to some extent by using very thin speaker wire.
Why is it that you want highish output impedance? I am surprised... I ran my 207e Mets with a tube amp (Onix SP3) and also some Icepower modules. The latter delivered much more "disciplined" bass. There was no correction circuit in that experiment.

Peter
 
Trying to learn about output impedance...
I looked on audiosector.com, but couldn't find what the output impedance of the LM3875 GC is. Can anyone fill me in?
I was running a pair of JBL L40's on the 3875, then I put a Marantz 2235B on the JBL's and the difference in the "punch" was quite noticeable. Could that be due to output impedance? What's the general idea or rule of thumb with output impedance?
Thanks.
Mike
 
CFT said:
Any news on upgrading the amps in your Pluto? (Curious to know as I've built a pair too)

Did you put together the MyRef_C? Any recommendation?
:)

I totally got sidetracked. Yes, I got started on the revC thing because of the chip amps in the Plutos. Now I am building a bunch of single driver speakers. Totally different world than the Plutos but fun no less. (The Plutos are awaiting their second revision with furniture grade tubes, double walled with sand, and a Corian base; parts of this have been done for a while, other parts... well I keep getting sidetracked...)

For value the revC is pretty incredible. But I have not compared with the other extreme of a minimalist point to point wired LM3886. That's on my list too (as are several other amps... :))

Peter
 
On the other end.......
Pro amps are not currently "in", but are very good for O.B. and big bass units.
They work well for the bottom end of a bi or tri amp system. I just ordered a second QSC RMX 1450. There's a rebate from QSC now.
These amps will run at 2 ohm. Bridged mono I think the 1450 does 1400w at 4ohm. I doubt I'll buy a regular 100-200w amplifier again. the low power amps, including tubes, are interesting. The pro amps now have very good specs, they are mass produced, and you know they behave very well with high power transients and difficult loads. Even with the more expensive T-amps, THD goes up a lot at modest power levels.
I like QSC RMX because they are not light weight (Every company have light weight amps for touring) and the specs are good for the price. There are cheaper amps, but QSC has a six year warranty and has a good support reputation.
 
Yeah, likewise Peter, I've found full range vintage drivers and SET/ T-amps interesting too soon after my Pluto 2.1 was complete...

I am exploring on amps for the other high eff. speakers I have these days (and possibly for the Pluto's), and currently I have GC, Charlize 2, and a vintage SE tube amp, but somewhere on the site I read that MyRef_C ranked better than GC and T-amps...and just wondered.....
 
planet10 said:
A relatively affordable amp would be something like the RH84, some of the bottleheads, used Decware Zen (SE tube amps tend to have higher output impedance). A bit more costly are things like SEWA, firstwatt F1, F2. [/B]

Thanks Dave.

I am looking at the RH84 or the Boozehaund to build. I don’t know which is better but the Boozehound has more instructions.

/Fredrik
 
planet10 said:


An externally hosted image should be here but it was not working when we last tested it.


Just ordered one of those. Even for just the chassis & power supply probably worthwhile. Doubt it will stay stock.

dave

I've had my eye on this amp as well to power a pair of subs. How do you intend to use it? Have you had a chance to listen to it? What mods do you plan to do to it?
 
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