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Chip Amps Amplifiers based on integrated circuits

This is not just another gainclone
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Old 12th March 2003, 11:05 PM   #1181
Elkaid is offline Elkaid  Canada
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Thanks Peter

However my loudspeakers aren't very sensitive so I need more power than usual. Maybe 18-0-18 would be a bit tight (I own a pair of Energy Pro 3.5 which are 88dB)

Next project will probably be more sensitive loudspeakers. Maybe something looking like Jamo's Concert 8. (Seas Excel 6" + Seas Excel tweeter).
Maybe I think of replacing my tube preamp too... Looking at the PCB traces, I saw some components showing signs of overheating which leaves me perplex.Yeah, my ECL86 preamp described here

aaarrrrrrrrrgggghhhhh !!! Some much projects in my head. So little cash.... That drives me crazy !
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Old 12th March 2003, 11:24 PM   #1182
Peter Daniel is offline Peter Daniel  Canada
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Quote:
Originally posted by 2Bak


This one without any modifications.

This one is less prone to oscillations. The stripped version I'm using is more sensitive and chassiss has to be gtounded for best performance.

Elkaid,

When you added those extra caps did you notice any change in the rest of the spectrum, beside improved bass. I tried additional 10,000u and also one more 1000u at the bridge, but it actually degraded the sonics, taking away all the magical properties like imaging, 3-dimentionality, depth, ambience, detail and whatever else, they use to call the audiophile crap. It just didn't work for me, but I'm using BG and maybe those caps provide better bass extention and don't like any other company.
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Old 12th March 2003, 11:44 PM   #1183
Fred Dieckmann is offline Fred Dieckmann  United States
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Default I am so ashamed

I caved in to latest fad and built an LM1875 inverted amp. I have two bridges with BWY 29 fast diodes with snubber networks. A Plitron 225 VA toroid gives me two 27 Vdc outputs into 10,000 uF 100 V RIFA PHE169 naked filter caps. The caps and transformer are mounted on a polyethylene board external to the amp. The Rifas are damped at the mounted end with EAR damping material between the board and caps. These caps mount with one threaded stud that is attached to the caps aluminum body. A 0.1uF Wonder cap in series with 25 ohm resistor is mounted across each secondary winding of the transformer.

The +/- 27 volt suppy is regulated to +/- 20 volts by two LT1084 regulators with 47uF Black Gates at the regulators inputs and 100uF Black Gate at the regulators outputs. Two additional 100uF Black Gate caps are mounted next to each LM1875 for high frequency decoupling. The gain is 25 with a 10K input resistor and an additional 22K resistor to change the noise gain and insure stability with input cables removed. All resistors are 1%Corning RN60Ds. Output Zoble networks are 0.1uF Wonder caps and a 10ohm 1% resistors. Input jacks are Cardas and wiring is point to point silver plated solid core. Single point grounding is used except for a small ground plane for decoupling caps ground returns. Solder is lead free 4% silver. I PAID FOR MY LM1875s! I bought many of the parts surplus for ridiculously low prices. The Rifas were $ 5.00 each and fairly new. I bought all of them. I think the transformer was $20.00 The diodes were 69 cents each.This was really not that expensive and some of the parts Jocko swapped me for buying him pizza. Low Fi High Fi*

It sounds very good driving very modified Radio Shack speakers with 5" polyprop woofers with Linaeam tweeters. I don't think it will drive my MG IIIs though.... I win for most complicated design and tie with Peter Daniels for use of the most anal retentive parts! This a very analytical amp with the hardness that often goes with it. Great soundstage, micodynamics, and pitch definition. A suprisingly worthwhile project and a very musical amp. I am glad Scott Nixon lured me into it with his constant bugging me about how good these things sounded. I thought every one raving about these things was on dope. Low Fi High Fi*

Who Knew?

Can we change the name of the thread to: Not ANOTHER gainclone!

*low finance high fidelity
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Old 13th March 2003, 12:02 AM   #1184
Elkaid is offline Elkaid  Canada
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Peter :

My tests are done using the Carmina Burana CD distributed under the philips Digital Classic Label. This is a recording with a lot of subtilities and a wide dynamic range.

Test 1 : 1000uF standard capacitor + 1uF input cap

A little lack of bass which I think gives the impression that the choir is like 1 kilometer away. Sounds very, very good with other recordings.

Test 2 : 20000uF + 1000uF per rail, 1uF input cap
The bass came back and the scene seems closer. Haven't noticed any changes in the mid-high frequencies. The changes concerning bass response is pretty obvious concerning that recording. Less obvious with other music type.

It's hard to tell if the 3D image is improved or not because I don't really have very good references and/or experience. Using any of the previous setup, I can imagine that I surely can get more clarity and brightness

Moreover, my electrolytic caps are from digikey so no Black Gate or Jensen or any other high quality caps.
If I could afford to try Black Gate caps, maybe I could remove those extra 10000uF cans.
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Old 13th March 2003, 12:09 AM   #1185
grimberg is offline grimberg  United States
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Fred,

Could you tell me where I can buy RIFA PHE169 caps?

Thanks.
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Old 13th March 2003, 12:12 AM   #1186
Fred Dieckmann is offline Fred Dieckmann  United States
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Default Carmina Burana

I took my mother and stepfather to a performance of these piece with the Dallas Wind Symphony and Turtle Creek Choral in the Meyerson Hall in Dallas. They are still complaining about it. Jocko and I both love this piece and I have several recordings of it. My wife plays clarinet in the Wind Symphony. They did a bunch of recordings with Keith Johnson on Reference Recordings. That's her on the extreme left side.

http://www.dws.org/main.htm
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Old 13th March 2003, 12:23 AM   #1187
Fred Dieckmann is offline Fred Dieckmann  United States
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Default Rifa Caps

I think Grataku can. Get out your checkbook as they are very expensive new. I think the ones I got are over $50 new! I guess you don't want to hear about the $30 Vishay bulk foil resistors got for under a dollar each......
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Old 13th March 2003, 12:30 AM   #1188
grimberg is offline grimberg  United States
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Default Re: Rifa Caps

Quote:
Originally posted by Fred Dieckmann
I guess you don't want to hear about the $30 Vishay bulk foil resistors got for under a dollar each......
I would love to hear about it, especially if you left some behind...


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Old 13th March 2003, 12:46 AM   #1189
mlloyd1 is offline mlloyd1  United States
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Default Re: I am so ashamed

Dangnabbit Fred,
Now, I'm gonna' have to go and build this one of these things.

You traitor

What I want to know is do these chips count as "girly man" parts?

mlloyd1

Quote:
Originally posted by Fred Dieckmann
I caved in to latest fad and built an LM1875 inverted amp .... I thought every one raving about these things was on dope....
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Old 13th March 2003, 12:48 AM   #1190
Peter Daniel is offline Peter Daniel  Canada
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Default Re: Re: I am so ashamed

Quote:
Originally posted by mlloyd1


What I want to know is do these chips count as "girly man" parts?


It all depends how big is your power supply.
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