amplification?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
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
 
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.
 
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.
 
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?
 
xstephanx said:
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.
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.

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
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
 
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.
 
lndm said:
. . . However I would not compare valves and gainclones. I think their strengths lie in different areas.
Fair enough. I happen to like my gainclone, but never really have been a big fan of tubes (at least not the ones that fit my budget). Go figure!

Anyway, some people think gainclones have a "more laid back, tubey sound" than most SS amps. :rolleyes: Just though I would pass it on. . .
 
I feel that gainclones are a terrrific stating point, I have now built 6 or so, they are however very tuneable once you start to play.

I don't think a std clone is really comparable in sound to a tube amp, however I can say that an LM1875 based clone. running on 12V smps power and with lowered gain and plenty of capacitor reserves does indeed sound a lot like a nice tube amp. The power output is pretty similar too.

The downside is that building an amp like this requires a lot more attention to detail to avoid oscillation, but it is still cheap.

The gainclones to my ears sound very different on lower volatage supplies regardless of the chip used, but only the LM1875 approaches the valve sound.

Surprisingly with about 4700 uf caps the 12v smps clones produce amazing tight bass without sacrificing highs.

The really neat thing is that you can easily build bi-amped and triamped systems with modules optimised for the frequency range you are working with.

A while back I tried using a 5v smps supply clone with small caps for tweeters, it produced micro detailed highs like you wouln't believe, it also made a good headphone amp, the output was probably only a watt and half, but for a tweeter this is fine.

Overall I'd say have a play, theres a good chance you'll move onto something else eventually but a good DIY amp of any type is likely to find a home someehere in your house when replaced, such as part of you computer set etc. I say start cheap, learn and have some fun.

Oh and if you want to use a transformer supply, you can get very nice results with cheap regular transformers, for example Dick Smith Electronics in OZ sells a 2 amp transformer
( M 1991 ) which is just $10.00 and powers an LM1875 clone very nicely, heck one for each channel is only $20.00! LOts of cheap Oz clones have been built with this!
 
50 watts is PLENTY for a pair of fe166e, and its even plenty for a pair of energy c-1(my other speakers).

i think, that i WILL build the lm388(?) amps, now i just need to find a place to source transformers from in canada.

also since im building the dual monos, i will need a preamp no? this i do not have unfortunately. but when it comes to pramps all i need is a volume knob!

SO i have a couple more questions for you guys, does anyone of you happen to know of any tutorials/build diaries for a chip amp? also anyone know of places to get transformers in canada?

and thirdly thanks to all who helped, yesterday i was lost, today i know what direction im going in, thanks a bunch.
 
also once again SORRY FOR THE DOUBLE POST!

but i will be (probably) ordering from audiosector, but which kit should i order? also it doesnt look liek they come with power supplies like they do at chipamp.com. maybe im jsut reading stuff wrong.

also can someone reccomend the range of sizes for toroidal and non toroidal transformers? this will help me find one.

for heatsinks do you NEED to use a special machined one? or will a 1/4" thick pannel of 6061(i think) aluminium be fine?
 
I've used nothing but Haflers for many years and have sampled the sound of several different models, plus made comparisons to those with the Musical Concepts circuit cards. My favorite for lower power and price is the Hafler 9180 or the DH-120.

They both put out 65 watts per channel and use the same circuit. The 9180 is a little newer and a bit pricier but it has a few polyprop film caps in certain places that the DH-120 uses mylar -- hence a slight improvement in the upper mids. And, there are guys who mod their DH-120s with these film caps and are pleased with the results.

These amps hold their value so if you don't like one, just sell it for about what you paid for it.

My $0.02 ;)
 
Go do some reading in the chipamp forum, all of your answers about gainclones are in there. Also try the decibel dungeon site for lots of gainclone info.

The lm3886 has plenty of clean, solid power (it's loud enough for me with my very inefficient Dayton BR-1 kit speakers).

Just about any old heatsink will be just fine.
 
The audiosector LM3875 Dual Mono Classic Kit
http://www.audiosector.com/lm3875.shtml should get you started quite well. It comes with two rectifier boards and two amps (so yes, the power supply is included here). The documentation Peter has on his site should answer most of your basic assembly questions. (there is even a section on soldering, since you said you didn't have much experience.)

Also, you can easily use a 2 gang pot as a "passive preamp" (though this technically isn't a preamp since it doesn't amplify anything!). There are even instructions on how to do this in the documentation.

Finally, I'll second the 160VA transformer as being sufficient, though I have used +/-21V secondaries with good success. Higher voltages are often a little moody with harder to drive loads, so keep that in mind when picking rail voltages. Anywhere between 18 and 25V for the transformer secondaries should suit you well, though.
 
Considering your speakers are going to be very efficient there is little point in going for high power and thus large transformers, so stick to the smaller ones, less cost, less size and lower noise!

Let me put it this way, my current system runs Double Bass boxed 4 inch drivers (very similar to fostex 103s) with LM1875 based amp running on smps and low gain. It puts out probably 5 watts per channel and the drivers are 93db efficient, probably higher in the boxes though.

Bottom line, this system produces ear splitting sound levels in my 18 by 12 room, but with very high clarity, the fostex 166s etc should be even more efficient, so forget about the max power output it fairly irelevant in your situation even allowing for transients etc. The difference in power requirments between a low efficiency bookshelf speaker at say 84db and yours are like a mouse to an elephant. You'd need all the watts you could muster for the 84db ones.

I would say that most of the time you'd be using 1/10watt or less.

You could even run the 3886s on lower voltage, cheaper again and it will sound sweeter in the highs. From experience the main changes in sound will be dirived from the power supply set-up, including the size of the bypass caps.

Two options for really serious consideration SMPS or Battery power, both in my opinion take the clone to a whole new level, but start with the cheap transformer first.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.