• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Amplifiers Which Test Well, Under $1,000 USD

maty

Major Contributor
Joined
Dec 12, 2017
Messages
3,846
Likes
2,322
Location
Tarragona (Spain)
You know, every day the mains are more and more noisy. Cheap chinese SMPS chargers (or not).... and now cheap dimmers with cheap LED lights.
 
Joined
Feb 22, 2019
Messages
16
Likes
4
You know, every day the mains are more and more noisy. Cheap chinese SMPS chargers (or not).... and now cheap dimmers with cheap LED lights.
My 230Vac-main-out to my hifi is isolated from the rest in our house.. i.e. seperat ground ect.... :)
 

maty

Major Contributor
Joined
Dec 12, 2017
Messages
3,846
Likes
2,322
Location
Tarragona (Spain)
Ron Texas, the problem are the cheap SMPS like telephone chargers and others and many other cheap electronic hard that is imported from Asia and that do not meet the strict EU standards in this respect.

Others machines that inject DC at mains is the other problem.

KNielsen, you know! But, remember, electrical grid outside your house is also dirtier every day.

- End off topic -
 
OP
Ron Texas

Ron Texas

Major Contributor
Joined
Jun 10, 2018
Messages
2,984
Likes
3,140
Location
Miskatonic University
Thread Starter #105
Ron Texas, the problem are the cheap SMPS like telephone chargers and others and many other cheap electronic hard that is imported from Asia and that do not meet the strict EU standards in this respect.

Others machines that inject DC at mains is the other problem.

KNielsen, you know! But, remember, electrical grid outside your house is also dirtier every day.

- End off topic -
I guess we are all doomed.
 
Joined
Feb 22, 2019
Messages
16
Likes
4
Ron Texas, the problem are the cheap SMPS like telephone chargers and others and many other cheap electronic hard that is imported from Asia and that do not meet the strict EU standards in this respect.

Others machines that inject DC at mains is the other problem.

KNielsen, you know!
Yes. That's why I paid my electrician to find a solution, so I didn't have to listen to my refrigerator :).. it's a new build house, but just in case! ;)

Regards
 
Joined
Feb 10, 2019
Messages
13
Likes
6
I suppose, that probably any ICEpower amp that has not had the OEM fiddle too much with it to get a "house sound" will be good. However, it will not compare to the nc400, nor will it compare to the other NC derivatives that are lower in cost to the OEM and lower in distortion than the ICEpower series but higher in distortion than the NC400 (per data sheets). Yet the lowely 125asx2 is still heads and shoulders above most amplifiers. However, with a lot of the ICEpower amps, they often make an input buffer stage to deal with tube amps etc., since the default input impendence is something like 7k ohms at its lowest. I would assume that you should be able to trust the manufacturer data sheets since they are not meant for end users but engineers at other companies. So that relatively inexpensive 125 asx2 module that is on parts express, should give you .0018% THD+N at 1w 1khz (SINAD 95db?), however at say 7khz SINAD will be around 77db. Which is not terrible for an amp, but in theory is more than acceptable for what should be a $300 kit. OR much more.... http://www.ghentaudio.com/amp/ga-s250p.html



Also, for sake of comparison, a ncc122mp will have .0015% @ 1w (97db SINAD?), unfortunately, you cannot build that amp for 300 dollars, but certainly under 1k. The more affordable UCD series should have similar or better performance the ICEpower amplifiers, but people seem to prefer the Hypex UCD series amplifiers.
 
Last edited:

maty

Major Contributor
Joined
Dec 12, 2017
Messages
3,846
Likes
2,322
Location
Tarragona (Spain)
More off topic, sorry.

Yes. That's why I paid my electrician to find a solution, so I didn't have to listen to my refrigerator:).. it's a new build house, but just in case! ;)

Regards
Refrigeratorrrrrrrrrrrrrrr

I suffer from a terrible electrical mains in my house. After research I managed to drastically reduce the interference, noise and DC, but I still noticed the sound improvement after 8 pm on weeknight. And the weekend too.

Last Friday I changed the old refrigerator and it improved the sound! I suppose the engine had to inject DC. And not little. It could have been chance, for the weekend, so I had to wait until Monday. Verified, the amplifier heats up less (EI transformer side) and sounds better. In the main system, the same.
 
Last edited:
Joined
Feb 22, 2019
Messages
16
Likes
4
Last edited:
Joined
Feb 22, 2019
Messages
16
Likes
4
There has only been one problem with the low noisefloor that my mooded amp produce... Now I can hear the rest of my system.. next mod is my already modded preamplifier, the Acurus L10, it has to do better!!... And the another step backwards in the system as I progress ;)

It's not easy...
 
Last edited:
Joined
Nov 14, 2018
Messages
26
Likes
29
More off topic, sorry.



Refrigeratorrrrrrrrrrrrrrr

I suffer from a terrible electrical mains in my house. After research I managed to drastically reduce the interference, noise and DC, but I still noticed the sound improvement after 8 pm on weeknight. And the weekend too.

Last Friday I changed the old refrigerator and it improved the sound! I suppose the engine had to inject DC. And not little. It could have been chance, for the weekend, so I had to wait until Monday. Verified, the amplifier heats up less (EI transformer side) and sounds better. In the main system, the same.
Off topic (sorry)

It's a great business opportunity for someone like @tomchr or @March Audio:

ap refrigerator.png


disclaimer: @maty , please don't take it as i don't believe you - you just gave me the idea!
 

maty

Major Contributor
Joined
Dec 12, 2017
Messages
3,846
Likes
2,322
Location
Tarragona (Spain)
:D

My current problem is that I have finally managed to minimize all types of noise and interference present in my disastrous home electrical mains (house and street). And the atmospheric RF / EMI interference too.

The sound is so good now that I do not have a real justification for building or buying an amplifier to my second system!!!
For those who I had budgeted, years ago, € 2000. Spending a lot less I have got a much better sound in my two systems.

Yesterday I had an adrenaline rush again (not only dopamine), with a quite noisy concert and guitars with a lot of distortion. Since few months ago the frequency of such rushes has increased a lot, and with recordings that did not excite me before!

Bob Seger And The Silver Bullet Band - Nine Tonight (1981), Vinyl x2, Capitol Records, Europe
https://www.diyaudio.com/forums/music/6958-playing-listening-post5712488.html
 

tomchr

Senior Member
Technical Expert
Manufacturer
Joined
Nov 5, 2018
Messages
443
Likes
1,358
Location
Calgary, Canada
KNielssen, you can not be less than Nelson Pass :)I have seen the RF/EMI inlet filter just now! Btw, thick aluminum walls.
The main hum injection point I see is the incredibly long ribbon cable to the volume control that goes right by the power supply section.
Judge for yourself: https://www.stereophile.com/content/pass-labs-hpa-1-headphone-amplifier-measurements

My Modulus-86 can be built for about $400 if you are able to machine your own chassis. Even the Modulus-186 should squeeze in under $1k under the same conditions. I do recognize that OP is probably not expecting a DIY project, but I thought I'd throw my name in the hat. There. Back on topic. :)

Tom
 

maty

Major Contributor
Joined
Dec 12, 2017
Messages
3,846
Likes
2,322
Location
Tarragona (Spain)
Allow me the new off topic.

Ten days have passed since the change of refrigerator and the sound is better than ever. I just heard for the second time this night an album that I had never before excited. I was sick of the bad sound in my house for a few years. A lot of DC in my home grid!

I already know that it is a subjective comment, without measurements but it is my impression and I feel the need to tell it.

Meat Loaf - Bat Out Of Hell (1977), Vinyl, CBS 1980, Half-Speed Master, US

https://www.discogs.com/Meat-Loaf-Bat-Out-Of-Hell/release/3081447



DR Peak RMS Duration Track
--------------------------------------------------------------------------------
DR12 -0.09 dB -15.93 dB 9:50 01-Bat Out Of Hell
DR13 -1.83 dB -17.90 dB 5:06 02-You Took The Words Right Out Of My Mouth (Hot Summer Night)
DR13 -1.96 dB -19.28 dB 4:40 03-Heaven Can Wait
DR13 -0.06 dB -15.46 dB 4:18 04-All Revved Up With No Place To Go
DR14 -0.73 dB -17.39 dB 5:24 05-Two Out Of Three Ain't Bad
DR13 -0.06 dB -15.77 dB 8:28 06-Paradise By The Dashboard Light
DR13 -1.49 dB -20.12 dB 8:44 07-For Crying Out Loud
--------------------------------------------------------------------------------

Number of tracks: 7
Official DR value: DR13
 

jsrtheta

Senior Member
Joined
May 20, 2018
Messages
354
Likes
330
I have an old Acurus A250 gathering dust. It was $995 in 1994 or so when I bought it.

Here's someone who measured his: https://insta-stalker.com/post/BtrlP4QBEyP/

It says "modded" but still...

"My rebuild/moded Acurus A250, measurements: Pic1: Full load just before clipping, 2 x 320watts @ 1KHz, THD+N 0.013% with a 6.6ohm load (average load of an 8ohm speaker). 1 channel driven: 349watt. Voltage drop at PSU is only 3V between one channel load or both channels driven, so the transformer is doing it's job pretty good. Maximum THD+N measured were 0.076% @ 10KHz. Also look at the harmonic distortion after 1KHz and up, looks pretty good! Under normal operation the noise floor were close to the limit of our scope.. that's under THD+N 0.01%!! "

View attachment 22291

"Pic2: Noise floor; 50Hz hum from the transformer is now completely eliminated with the new starground. Also the 100Hz from the HexFred-bridges is at a level where it really can't be any better then this... we wouldn't be able to hear it anyway."

View attachment 22293

"Pic3: A 10KHz square wave: Yellow is the target curve, Green is the amplifiers output. To come closer to target I could go lower on C13/14, but they are 220pf now, it's minimal how much this would change selecting a smaller value, as the transistors has an internal C itself, open/close time... anyway! - this test was also OK."

View attachment 22292

---

I'd rate mine perfectly adequate. Somebody else's picture:

View attachment 22294
I think that at that time, William Snyder, former design manager at Krell, was involved with Mondial, the company that was responsible for Acurus and Aragon. So, modded or whatever, it was a good 'un to start.
 
Joined
Feb 22, 2019
Messages
16
Likes
4
A/B test so far..
Acurus250Modified vs unmodified 1,5mm2 power cable.jpg

A 40db noise reduction!

I provide a link to the person who does the measurements for me..
Kaj Mogensen :here it also shows a diagram of my starground

We were (mostly him ) testing the influence of power cables in the link... My standard A250 Vs the new DIY A250. The new starground does pull some new tricks..- And we can't measure differences between power cords on the modded one, but the old A250(!!!!) is very sensitive to what power cord we use.

Regards
 
Last edited:

Snarfie

Addicted to Fun and Learning
Forum Donor
Joined
Apr 30, 2018
Messages
532
Likes
283
Location
Netherlands
NAD C370 as far as i know one of the few amplifiers using a Impedance Sensing Circuit at the time. It raises the power shortly in to 8 ohms from 120 to 210, 340 in to 4 ohms an 450 in to 2 ohms.
Thought this technology is quite elegant rasing IHF dynamic power whitout getting to hot. IMO it can almost handel everything from funk, soul, Jazz to clasic music.
It is brutal for bad recordings. Used you can buy this amp here in Holland for less than 200,- euro ha ha because the wife wants to have something small like a soundbar or someting bluethoot, wifi. Next exit are the speakers that were feeding the C370 incredible.
https://www.stereophile.com/integratedamps/633/index.html
 
Last edited:
Top Bottom