Well, it seems that the gainclone indeed is simple to build, however i'm havin som minor problems (ofcourse )
.
The amp is Brians basic kit with a transformer 24x24V @300VA (unrectified).
When i was going to measure the DC-ofset (between the speakerterminals on each shannel, right?) i got a low value on the right one, about 2.0 at the lowest setting. On the left however, i didn't even get a value.... No indication whatsoever. The 3 groundcables is connected at one point in the chassi but not to the outlet in the wall, so to speak. No grounded output in the building.
When i turned it on, with my CD-walkman connected, a rythmic zapping eminated from the left speaker. A hightening in intencity occured when i raised the volume. It is not a hum but more like a Sci-fi Zapping sound, Tzing!. (sorry for the bad explanation).
Any ideas how to get rid of it?
Best regards!
P.S.
The chip is connected to an Aluminum heatzink 7x7cm and from 3 to 10mm thick depending if you measure at the point och connection or higher up where there are ridges for heat dissipation.
The chip is running quite hot it seems
.The amp is Brians basic kit with a transformer 24x24V @300VA (unrectified).
When i was going to measure the DC-ofset (between the speakerterminals on each shannel, right?) i got a low value on the right one, about 2.0 at the lowest setting. On the left however, i didn't even get a value.... No indication whatsoever. The 3 groundcables is connected at one point in the chassi but not to the outlet in the wall, so to speak. No grounded output in the building.
When i turned it on, with my CD-walkman connected, a rythmic zapping eminated from the left speaker. A hightening in intencity occured when i raised the volume. It is not a hum but more like a Sci-fi Zapping sound, Tzing!. (sorry for the bad explanation).
Any ideas how to get rid of it?
Best regards!
P.S.
The chip is connected to an Aluminum heatzink 7x7cm and from 3 to 10mm thick depending if you measure at the point och connection or higher up where there are ridges for heat dissipation.
The chip is running quite hot it seems
Accually, It just vanished. I connected the amp to my regular system and now there's not a sound, no humming, nothing. It's deadquiet.
To bad the music also is just that
Even if it's a steal for about 200$ depending on chassi and so on there's no "life" in the music so to say.... Good sound but nothing that makes you feel the music.
Perhaps it's because my speakers has a recommendation of 100W to be at their best but anyway...
To bad the music also is just that
Even if it's a steal for about 200$ depending on chassi and so on there's no "life" in the music so to say.... Good sound but nothing that makes you feel the music.
Perhaps it's because my speakers has a recommendation of 100W to be at their best but anyway...
My speakers are DIY bookshelfspeakers with Vifa PL18WO09-08, 6.5" and Vifa DX25TG05-04, 1"
Their sensitivity is in the lower 80's.
The source consists of aPioneer DV-656 hooked up to a Xindak DAC3
Cables are also fron Xindak, AC-02 and SC-01
Its the isolated version and when i started it up I accually burned my finder on the heatsink after only a few minutes. I switced it of and started it up again after an hour or so and now there not hot at all.....the wierdest things keep happening
DC-offset.
Right: 27,8mV
left: 0,16mV
An externally hosted image should be here but it was not working when we last tested it.
Sorry for the swedish but the signal runs from RCA-in to selector to volume to chip.
Signal ground from RCA-in to volume to chip.
Starground has the 3 wires noted in the instructions.
Anyway, it works fine
Linjeväljare = Input selector (in the picture)
Good it turned out good for you.
PS: kmj, you have the same trouble as I have: Insulated, isolated, only one word in swedish for that. The same problem with feeling and emotion which also has only one word in swedish.
PS: Don't forget to have "svettpasta" as I call it (sweat paste), heat compound between the LM3875 and the heatsink. The heat transportation will increase.
If you don't have any you can get a click from me.
Good it turned out good for you.
PS: kmj, you have the same trouble as I have: Insulated, isolated, only one word in swedish for that. The same problem with feeling and emotion which also has only one word in swedish.
PS: Don't forget to have "svettpasta" as I call it (sweat paste), heat compound between the LM3875 and the heatsink. The heat transportation will increase.
If you don't have any you can get a click from me.
KMJ,
what is your pot value?
do you use the zobel network (2R7ohm + 0.1uF cap)?
I have my amp transform a lot after 150 hours of burning...
My experience with zobel on my amp: do not change any sound but make the amp less hot...
I also just change the pot from 100K log to 10K log... the lower register (bass region) is improved, treble become sweeter, mid become more calm but detailed is improved... (NOTE: my cd player output is 1.2volt RMS, which is quite save to use the 10K pot)
Then, you can also check the High-Capacitance tweak as per-Carlosfm suggestion..., which I do not apply yet currently...
Regards,
---
David
what is your pot value?
do you use the zobel network (2R7ohm + 0.1uF cap)?
I have my amp transform a lot after 150 hours of burning...
My experience with zobel on my amp: do not change any sound but make the amp less hot...
I also just change the pot from 100K log to 10K log... the lower register (bass region) is improved, treble become sweeter, mid become more calm but detailed is improved... (NOTE: my cd player output is 1.2volt RMS, which is quite save to use the 10K pot)
Then, you can also check the High-Capacitance tweak as per-Carlosfm suggestion..., which I do not apply yet currently...
Regards,
---
David
Potvalue is 20K liniere (Alps RK18) and Zobel is in use.
Exept for the speakers this is the fist thing i have build and since it was quite cheep the tweakingpotential is quite high
However, perhaps i chould let it burn in before i start to get into trubble again
The only anoying thing is that the GC doesn't have the slightest hum when my Integrated amp buzzes like a beehive (non DIY), that amp however has a wonderful sound, large and rich. At sertains cd's it sounds as if the singer is standing in a lagre cathedral.
Anyway. The commersial amp (Xindak A100) didn't cost more than 280$ and it's tempting to ripp its insides out and put something more fun in, Hyper or somthing similar
Edit:
PA.
Saw your post just now.
Thanks, Svettpasta in use (have a computerstore 50m away)
As you probably have noticed, i often påst here and at hififorum. Thats because i seem to have a problem with that place....problem opening the page.
Exept for the speakers this is the fist thing i have build and since it was quite cheep the tweakingpotential is quite high
However, perhaps i chould let it burn in before i start to get into trubble again
The only anoying thing is that the GC doesn't have the slightest hum when my Integrated amp buzzes like a beehive (non DIY), that amp however has a wonderful sound, large and rich. At sertains cd's it sounds as if the singer is standing in a lagre cathedral.
Anyway. The commersial amp (Xindak A100) didn't cost more than 280$ and it's tempting to ripp its insides out and put something more fun in, Hyper or somthing similar
An externally hosted image should be here but it was not working when we last tested it.
Edit:
PA.
Saw your post just now.
Thanks, Svettpasta in use
(have a computerstore 50m away)As you probably have noticed, i often påst here and at hififorum. Thats because i seem to have a problem with that place....problem opening the page.
GC's tend to really suck the first 10-20 hours. i remember how increadible dissapointed i was when i first got mine working.
now, after putting on the snubber, cat5 cables and diode bypassing caps the amp sound superb. original i think this amp sound like the music is filtred through a big bowl of oatmeal. (havregrøt)
lacks life and deffinition. it makes sound, but very unmotivating as such. i use speakers not very different from you. seas trebles and sammi mid\bass.
trust me. with a litle love and care, it'l sound so much better!
-marius
now, after putting on the snubber, cat5 cables and diode bypassing caps the amp sound superb. original i think this amp sound like the music is filtred through a big bowl of oatmeal. (havregrøt)
lacks life and deffinition. it makes sound, but very unmotivating as such. i use speakers not very different from you. seas trebles and sammi mid\bass.
trust me. with a litle love and care, it'l sound so much better!
-marius
So, if I understood your internal wireing is CAT5? I'v had CAT5 internal wires in my unregulated version. Now with regulated PSU
I have used some wires from computer cable. Haven't actually compared with CAT5 and can't decide which is better because the wireing wasn't the only thing I have changed.
What are your impressions with CAT5?
Tomislav.
"Sweat paste" is good but don't mess with it. Use "lagom" which is pretty little.kmj said:PA.
Saw your post just now.
Thanks, Svettpasta in use
As you probably have noticed, i often påst here and at hififorum. Thats because i seem to have a problem with that place....problem opening the page.
About www.hififorum.nu, works good with Explorer 5.1 or higher Macintosh and works fine with Mozilla, Firefox, Opera, Explorer etc on XP. Which browser and OS do you use?
demogorgon said:
What I have found is that the GC was difficult to drive until the chip had been warmed up for a few hours -- my guess is that it has to do with the thermal protection circuitry. It's almost as if has to find a comfortable thermal position.
and nota bene I am a skeptic when it comes to the necessity of having to burn in and other hocus pocus. I like stuff to work "out of the box".
shusha said:
Hi! actually i'm using standard speaker cables as internal wiering in the power department, better current handeling
i'm using cat5 as speakercables and on the voulume controll.
i like it better than standard tinn coated copper cables we have at school at teh very least. allthough i uppgraded almost everything at the same time, i cant really claim i know exactly what helps where. i didn't get much time to listen befgore it all was done.
jackinnj said:
your guess is as good as mine, but the fact is my ears haven't let me down before, there was a very distingt difference in the sound before and after burning inn. (i used a 10ohm fixed resistor in a to220 pack and a heatsink, full volume. a few hours with speakers at first too.)
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