Best psu for T-amps

t.

Member
2003-05-26 1:35 am
notts
Hi,

I'm currently running my Amp3 from a 12v 7aH battery, 2 x 10,000uf Sikoral caps and Carlos snubber

The sound is rather good for such a small unit but would I get better results using a transformer based regulated supply?
Any designs worth trying out?
 
Power supply question.

Ah, another cat person! (People who are owned and trained by cats.)
My little amp 3 is sounding fantastic! I am using a 1.25 amp supply I purchased cheap from All Electronics. I did some tweaking on it like a better pot for adjustment, better output and input caps. But that was about all. This is followed up by a 10,000uf @ 16v cap to buffer it. Couldn't ask for better but you could spend a great deal more for no or - benefit.
The only tweak to the amp, so far, is a pair of 2uf @ 200v Auricaps for input coupling.
Roger
 

t.

Member
2003-05-26 1:35 am
notts
Thank you Roger:cool:

Yes, I'm afraid I am another cat person:D

I may build a regulated supply using LM338 next just to see how it compares.
The Auricaps are not available in the UK although I would like to try them out, I'm currently using 0.47uf BG NX-HIQ bypassing the supplied 2.2uf smd caps which isn't exactly ideal

Leo
 
bypassing

Bypassing coupling caps creates multiple signal paths and destroys signal timing information. Not a good thing, screws up the imaging. It is much better to use only the BG in this case.
I think if you execute the LM338 circuit properly you will be well satisfied with the improvement. Use very low ESR caps on the output.
Roger
 

t.

Member
2003-05-26 1:35 am
notts
Cheers Roger
I tried 4.7uf BG N's no bypasses although I still want to try out the Auricaps.
Only polypropylenes I've spare are 2.2uf ICW's which are fairly large but should fit

I'll post the results of the regulated supply once built, it will be based on Carlos ciruit normally used for the GC's.
I've got a few other diy amps I'd like to compare the Amp3 against once its had some mods:)

Leo
 
I'll post the results of the regulated supply once built,

For my T-Amp, I have built a regulated supply using the LM338. a 160VA/12 volt tranny, MUR860 diodes. It is better than the plug-in supply but not as good as the SMPS.

Yes, I know people keep saying don't use them but my ears tell me different! ;)

PS. Leo, you and your cat will soon have a chance to see if I am right! :att'n:
 

t.

Member
2003-05-26 1:35 am
notts
Nuuk said:


For my T-Amp, I have built a regulated supply using the LM338. a 160VA/12 volt tranny, MUR860 diodes. It is better than the plug-in supply but not as good as the SMPS.

Yes, I know people keep saying don't use them but my ears tell me different! ;)

PS. Leo, you and your cat will soon have a chance to see if I am right! :att'n:

Well I always trust your judgement uncle Nick:)
Me and Bender (the cat) look forward to trying out your supply;)

So whats your honest opinion on these class-T amps? do you think they have potential?
I've still got some tweaking to try yet before I have a final verdict
 
So whats your honest opinion on these class-T amps? do you think they have potential?

Mine has only been here a couple of days so perhaps it's not fair to say anything other than at present, I prefer the GC. BUT I know the T-Amp needs some more hours under its belt and that it also needs a few mods to improve things like bass response.

Do I think that it has potential? Yes I would say so and look forward to getting in there with the soldering iron! That's what I'm doing here - reading up on all the mods! ;)
 

t.

Member
2003-05-26 1:35 am
notts
Nuuk said:


Mine has only been here a couple of days so perhaps it's not fair to say anything other than at present, I prefer the GC. BUT I know the T-Amp needs some more hours under its belt and that it also needs a few mods to improve things like bass response.

Do I think that it has potential? Yes I would say so and look forward to getting in there with the soldering iron! That's what I'm doing here - reading up on all the mods! ;)

I agree Nick, my Amp3 currently is not as good as my best GC but to be fair just about everything for this little amp is standard although to be honest sounds very good for what it is.
Once I try the SMPS, 2.2uf polypropylene coupling caps, 330uf Rubycon ZA decoupling caps on the board etc I'll compare again.

BTW I'm not sure which I prefer between the 12v 7aH battery or the LM338:)
 
Hey Nuuk,

How goes? I have a couple of t-amps on the way. I was just thinking about what to use for PSU on it, i have a couple of options. I have a switch mode power supply at work from an old firewall do you think it might be worth a try using that? If not maplin do a regulated 13.8 V rated at 5 amps, they are very heavy and seem like might fir the bill. Only £20. Do you think i should try the SMPS first?

Also one thing i have been meaning to ask is about my buffered preamp, the thing is that now usinf my Carlos subberised lm3886 chipamps, what a mouthfull. The thing is that for example listening to movies I have to have the volume pot at about 3/4 volume, is this right with a 10k pot or sould i change the gain of the actual chipamps? Sorry of topic.

Be very interested in what you do to your t-amps, let us know how you get on.

Phil
 
BTW I'm not sure which I prefer between the 12v 7aH battery or the LM338

I'll be trying an SLA battery as soon as it is charged Leo!

The thing is that for example listening to movies I have to have the volume pot at about 3/4 volume, is this right with a 10k pot

If it's loud enough for you Phil then it's OK. The idea is that the gain of the system should allow you to use as much of the pot/attenuator range as possible, giving you greater control. Of course, some like to have max volume with the volume control advanced only a little as that gives them the impression that they have a (more) powerful system!

If you can't go loud enough with the pot at full volume, then is the time to increase the gain.

Be very interested in what you do to your t-amps, let us know how you get on.

I'm very much playing follow-my-leader with the T-Amp! ;)
 

t.

Member
2003-05-26 1:35 am
notts
Well lets hope some more post their results:D

Regarding the battery I started using a pair of 10,000uf Siemans sikoral which seemed good enough, I tried the snubber on the end of the caps but to be honest I feel it does not suit this set-up too well, the sound certainly changed but something was not right, strange because it worked great with the GC's :confused: try it Nick and let us know what you think.

Reading other posts it seems the input stage is the biggest flaw with the SI T-amps, removing the inductor and replacing the low value ceramic coupling cap with around 2.2uf polypropylene is supposed to make a huge difference.
Also alot seem to say an active pre improves the T-amps alot, most seem to use tube pre's

BTW did the cheque arrive ok NUUK?
 
Input caps and SLA power

t. said:
Well lets hope some more post their results:D

Regarding the battery I started using a pair of 10,000uf Siemans sikoral which seemed good enough, I tried the snubber on the end of the caps but to be honest I feel it does not suit this set-up too well, the sound certainly changed but something was not right, strange because it worked great with the GC's :confused: try it Nick and let us know what you think.

Reading other posts it seems the input stage is the biggest flaw with the SI T-amps, removing the inductor and replacing the low value ceramic coupling cap with around 2.2uf polypropylene is supposed to make a huge difference.
Also alot seem to say an active pre improves the T-amps alot, most seem to use tube pre's

BTW did the cheque arrive ok NUUK?

Try looking in this thread.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=59058