What have you done with your T-amps?

CamshireGordon,

Thankyou for your detailed and helpful reply. It seems this little amplifier may not be particularly daunted by the awkward ESL load. I might give it a try with my ESL-57s.

Regards,
Tim.

 

Trying it for oneself is the only way! If you do, perhaps you would post your findings here?
I hope my ramblings are not taking this thread too much off-topic: for me it is not so much "What have you done .. .. " more "What will I do with my T-amps". I do (did?) have great designs for upgrading and re-housing!

Having read so many positive things about the SI T-amps, I felt I had to try it and at the price, it is not too much to lay-out even if it were not to meet with expectations! On first hearing it is, IMO quite a revelation and even better after the 100 hours burn-in.
I currently have solid state, (Quad 33/303) which I was about to have serviced or replaced, when HiFi World "went digital" with the June issue. It, along with the Forums, whetted my appetite. I am a valve man basically so I have been interested to read that Class D, when fed with a simple valve pre-amp, has so many of the sound qualities I so much like with valve amplification.

My decision then? Will there be enough of those qualities to get me to switch permanently to Class D? Or will I find Class D sound no more than revelatory gloss that will quickly tarnish in a couple of months? Or maybe I will follow my natural instinct to go with valve Class AB / B? Still, at the price some of this DIY Class T is selling, maybe I will invest in both, and then alternate between systems!
My indecision solved!
CambshireGordon

 

CamshireGordon,

Quote....''If you do, perhaps you would post your findings here? ''

Of course! If it is of interest I will also let you know how it compares with my highly modified JLH - a pure class A (transistor) amplifier which has a particularly 'valve-like' sound.

Tim.

 

I have one of the Audio Digit prebuilt modules on order. The SI T-amps are built down to a price and mine lasted a week in my system before I eBayed it. Rather than 'modifying' the amp I'd rather get something with good components to start with, hopefully the Audio Digit is that amp.

 

You echo my sentiments entirely. Audio Digit is more appealing to me because it does not use SMD's and hopefully it does set out with better quality components. But if not, it should be a lot easier to upgrade. Part of the challenge with upgrading the little SI seems to have been keeping it minature! For me that is not an issue - if quality components mean a tea-chest, then a tea-chest it will be! (Does anyone know what a tea-chest is? I am showing my age!)

Maybe a new thread is needed on the Audio Digit kit? Perhaps you will post your first impressions there?
CambshireGordon

 

I've had a 'version of this for quite a while' the power supply is key without question

 

What sort of psu do you recommend WM?
I have been playing about with a 41HZ Audio Amp3 which uses the TA2021b chip.
I've tried a 12v 7AH battery and also a regulated supply using LM338.
I have a couple of ALW Super regs spare although I don't think the current of these are high enough

Cheers

 

Leo
Well, you gunna laugh, a 300va torriodal, 24K of smoothing, custom diode bridge, some dc blocking caps.and some custom quantum regs which can handle 2.5 amps. I would consider that a minimum.
If you want to go bib and braces, then 4 times 10K BHC's 63V caps, full N/c supply bridge and 2 quantum regs or those Audiocon Invisis regs (One as a pre reg), some quality wire, M-caps as filtering,
Sink the main caps inside 10mm ally box and fill with clear silcone, hard wire the rails together, short wire lengths, and encase the lot with decent sheilding inside the box you've chosen for amp.
Also look at the board layout, most people tend to stick to the tripath method, careful thinking & application will pay good rewards. Wm

This sort of idea should suffice, but remember too much is not enough

 

Cheers mate
The psu costs more than the bloody amp
So do you think these type of amps are the way to go? I don't mind spending some time and effort on it just as long as the results are worth it, theres been plenty of people rave about these amps.
I don't need high watts, just the best sound quality I can afford.

Other amps I have are a diy Avondale NCC200,cap-6,modified Naim pre, Highly modified diy WAD Kit88 valve amp with custom Sowter output transformers, diy Gainclone based on Pedja Rogics design, I'm also half way building a SE classA mosfet amp.
I enjoy building these things but I'm not sure which way to go now if you know what I mean

Thanks again,
Leo

 

leo,

Yesterday I compared a t-amp (with M'cap film/foil input cap and Noble volume pot) with an extensively modified class A 'SE' JLH (using bipolar output transistors). The t-amp has superior tonal accuracy, clearly more focus and detail. The JLH was more relaxed. Both sound smooth, the JLH slightly more so though a little hazy in comparison with the t-amp. My piano tuner who also had a listen agreed that the two amps were very different. This was very much a case of personal preference.

Tim.

 

Thank you Tim!
I basically started building the SE classA mosfet amp because I didn't know what else to try out
My Amp3 is currently powered by a single 12v 7Ah battery and two parallel 10,000uf Siemans sikoral caps, the two decoupling caps on the pcb are 680uf BG NX (temporary until 330uf Rubycon ZA arrive) the input caps are the supplied 2.2uf ceramic bypassed with 0.47uf BG NX-HiQ I'll remove both later and replace when I can find something better, the volume is controlled by a Panasonic for audio pot, I have a spare Attenuator I may try next.
The sound is not bad at all but not as good as I'd like

So what sort of coupling caps do you guys like?
I have a spare couple of 2.2uf LCR mkp and M-cap (standard in white case) which I may try in the Amp3.
It also seems that alot of people prefer the sound of the T-amps when used with an active pre

 

Leo,
It may cost more than the amp, but for around £5-600 you can build an amp that really does take on £6-8K units and some of the most hardened Valve boys are now starting to wonder!!!
Last week I heard a 2021 derived amp, take on a Border patrol Bp 20 on some OBX R2s
The amp cost about £300 to make, using the same set up it was a real ear opener.
Especially in the Tonal & bass depts !!!!
Thats all I'm going to say.
Tim is right, they are very different prsentations.
You get the tripath to sound very sweet & more relaxed, however that involves some serious multi psu's & quality regulation. Wm

 

Well thats good enough for me WM! I always take peoples opinions seriously and if you say that these amps have potential then I'll get some serious modding done
My current best amp is the valve amp but only after the stone each Sowters and other various mods.
I'd be very happy if this little class-T amp could be as good or even be better, the money saved on new valves etc would be a bonus
I'm just deciding what coupling caps to use instead of these nasty ceramics, maybe 4.7uf BG N's or Polypropylenes

 

Just got my T-amp and even with batteries it doesn't sound too bad!
So a question about psus- I have a 1200mA 12 volt regulated psu at home I was planning to use - but which way round is the polarity?
And would I be better off buying a 13.8v 3A psu such as the XM20W from maplins or even the 5A version? (XM22Y). And in this case what tip do you need?
Cheers, Liam.

 

I'd be careful with a voltage that high .....12v seems fine with a decent psu. it's centre pin positive. A three amp psu should do it as long as attention has been paid to its design.

leo ....

I'm not fond of BG's ....I've used silmics in there place before.

I've just decouples the input with some axial foil 2uf2[polyprops?]..that I had knocking about and replaced the nasty chip res...taking the signal into the board via one of the three small holes near the led. The other channel going in one of the other two holes [I can't tell you which at the moment as my wife is listening to a film!]

Another good mod is the removal of the standard 300uf cap between the four inductors. I built a strip board and placed three 100uf silmics , 10uf oscon and a 1uf wima to bypass them, in parrallel with short leads to the board. This has increased the bass and just made things less edgy.

 

Thanks Zanash,

Remember though I use the Amp3, its pcb is different to the T-amp.
There is two 330uf and 100nf SMD caps on the pcb thats for decoupling the VDD supplies of the chip, its these I've replaced with a pair of parallel 680uf BG NX's, the non foil end goes to the others foil end, they sound better like this if used in pairs on the same supply line.
I now use 1uf Multicap RTX polystyrenes for the input coupling
A modified SMPS with 10k Sikorel caps with a snubber on the output.
The pot I use is a Panasonic for Audio.
I've just had to replace the Tripath chip because it went down but the sound is becoming very good indeed I'm not always a fan of BG caps but they simply cannot be beaten in some places IMHO I've already tried Elna Starget,Cerafine and Silmics,Panasonic FC, even a pair of 470uf Sanyo Oscon SG's
All have been burnt in.
What else is there worth trying

Cheers,
Leo

 

Certainly the inductors could be upgraded .....even wind your own !

As I don't use mine as an intergated I've no vol pots to worry about....look at the wiring and make certain its the best. But as yours is the amp3, and mine is the sonic impact its difficult to really suggest anything.

 

The inductors that come with the kit have to be wound by hand on ferrite rings (10uH each)
Some people seem to like Aircores but I'm not sure if thats the best solution in this application, Maybe somebody could comment
The signal and output wiring is some multistrand silver plated copper in a ptfe sleeve I had spare.
It would be nice to try an active pre-amp, I'll have a search to see if theres anything thats diy worth building, any idea's most welcome

 

Leo

The transcendant sound grounded grid would be worth a look.

 

Thank you Penance!

I'll check it out