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xstephanx 2nd June 2006 02:37 AM

amplification?
 
im going to build a pair of BIBs soon, with fe166e(id like to have the upper extension, and for what i listen to a bit of edge might even help!) and ive bbeen reading some about voltage vs current sources.(tube vs solid state?)

tubes are very pricey, the used stuff ive seen has been at around 500$, and the kits have been rather pricey too. Judging by my deign choice you should be able to tell that i wont need to much power.

Now i actually like the sound of solid state amps, and would have no problem going for one if i didnt hear that i would lose low end extension. Is this true? im not THAT concerned about frquency cutoff, if i get solid bass at 40hz thats great(which from what models ive seen i should) but then sme other models showed that it woudl have like weak bass with an f3 at 70 hz and stuff(with a solidstate)

then theres that whole series resistance thing, do i need any? i currently have 28 guage magnet wire, if i doubled that up for each terminal, woudl that be an OK sized guage? or should i jsut run 18guage copper inside and not bother.

the amps i was thinking of using with it were either the super t amp, or the audiosource amp one (100$ US at bhphoto!), i dont think the super t will have quite the kick i need though. I dont have time to build an amp, and have HORRIBLE soldering skills. if you can reccomend any other amps? (ive heard good things about adcom!), better yet if someone wants to sell me an amp, pitch me a price, but dont bother if tis more than 300$

so yeah ive got alot of questions. answer what you can, speculate if you want(just make it clear its speculation!).

TIA

lndm 2nd June 2006 03:11 AM

The fundamental resonance of a speaker typically involves a peak in the impedance around that frequency. Driving these from an amp that has a high output impedance (or low damping factor) tends to accentuate this resonance, filling out and sometimes peaking the response.

You mention voltage versus current amplification. Theoretically, a current source has an infinite impedance, I don't think this extreme will be found much in audio. Many valve amplifiers will have a high output impedance, but some don't. Many transistor amplifiers have a low output impedance but a series resistance can be added if desired (or you could collector load the output stage, or reduce feedback). Nelson pass' Zen amps might be one way of getting a somewhat higher output impedance whilst sticking with transistors. Personally, I like the valve approach.

At the end of the day, it comes down to what the speakers were designed with/for, and to your taste.

xstephanx 2nd June 2006 03:16 AM

oh how i wish it DID come down to that at the end of the day, btu at the end of the day, it all comes down to the best i can afford, and 300$ is my upper limit, and that would even be a stretch(id have to sell some stuff)

so could i put a potentiometer infront of the driver to see if i like any series resistance? and if so how much? then i coudl find what i want, measure the resistance across the pot and buy a good resistor.

theres still the prolem that is amps, so far the only ones ic an think of, apart from home theater receievers and such is the super t amp and the audiosource AMP one. gimme suggestions.

Godzilla 2nd June 2006 03:16 AM

I would choose the Super T without reservation. Just my opinion.

I had an adcom and i would imagine the amp one sounds similar... toriod solid state and all... grotie to the max dude.

xstephanx 2nd June 2006 03:21 AM

im concerned about listening levels, especially if i start adding series resistnace!(lowers sensitivity id assume?)

.125 watts probably wont be enough juice sitting almost 3m from the speakers.

xstephanx 2nd June 2006 03:40 AM

also sorry to double post but what about stuff like NAD, rotel, possibly even some older low level marantz stuff? what should i look for on ebay?

lndm 2nd June 2006 03:43 AM

If you choose to add series resistance, you might be lucky enough to enjoy the benefit of an ohm or less. Of course, you might try more, just for the benefit of knowing. :)

xstephanx 2nd June 2006 04:13 AM

OK so i understand the whole bass issue, and i can compensate for it a bit with some creative EQ. looking at the kit at www.chipamp.com i could probably afford one of the lm3886 or lm3875 kits,(80$ and 40$ repectively, i can DEINATELY afford that!) although id need to buy a toroidal and a case and heasinks(all would be somewhat hard to source)

it also never states how much power those litle guys put out anywhere. I would build dual mono, i just live the idea of TWO power supplies. id need a friend to help me with the soldering too, but that is not hard to find

also how big of a toroidal would that need?

lastly ive heard lots of good things about the sound, but it is SS and ive also heard lots of good things about the adcom sound, so who knows really. so would these sound on or close to the level of a super t?

dfdye 2nd June 2006 04:38 AM

Quote:

Originally posted by xstephanx
although id need to buy a toroidal and a case and heasinks(all would be somewhat hard to source)
Parts Express has a good selection of toroids, and you can usually find a pretty cheap case to fit the bill since the space used by the amps is so small. I don't know of a supplier in Canada, but I am sure some other people could point you in the right direction if you ask in the Electronics & Parts section of this forum. Seriously, these things are REALLY easy to find--don't let that scare you off.
Quote:

it also never states how much power those litle guys put out anywhere.
About 50W for the LM3886's. If that is too low, you can always bridge them. Also, Peter Daniel at http://www.audiosector.com/ sells kits that are essentially the same as the chipamp.com kits, but he is located in Canada. If you are worried about power, I would get the LM4780 kits and bridge them. If you need more power than that. . . . :D

There are options, but I am betting that this will be more than enough for you.

Quote:

I would build dual mono, i just live the idea of TWO power supplies. . . . also how big of a toroidal would that need?
I am running mine off of two 80VA toroids and it works just fine for me. I am, however, using larger caps than the gainclones, but there shouldn't be a problem. I got mine from ApexJr.com, and would highly recommend them. Steve is a great guy, but I am not sure if he will ship internationally. Drop him an e-mail and ask. (Also, Steve is a supporter of DIYAudio.com)

Specifically, I am using the Chia Yu Co 42VCT transformers for $12.50 each. Here's the URL: http://www.apexjr.com/miscellaneous.html#Toroids
Quote:

lastly ive heard lots of good things about the sound, but it is SS and ive also heard lots of good things about the adcom sound, so who knows really. so would these sound on or close to the level of a super t?
I would ask most of these questions in the chipamp forum to get a better range of opinions, but many people compare the gainclones very favorably to tube amps, but for MUCH less cash. With the small investment, I would recommend you build a set and see for yourself. I love my set, but my system is limited by my speakers, so

lndm 2nd June 2006 08:37 AM

Quote:

Originally posted by dfdye many people compare the gainclones very favorably to tube amps, but for MUCH less cash.
I would rate gainclones favourably, they perform well considering their value. I think they are an excellent DIY project. However I would not compare valves and gainclones. I think their strengths lie in different areas.


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