3W amps - options: SS which sounds as good as DHT’s

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vinylnvalves
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#1 3W amps - options: SS which sounds as good as DHT’s

Post by vinylnvalves »

I have been using B&O ice amps on the top 2 channels of my active set up, well padded down for the JBL 2482 which needs milliwatts to drive it, and the Beyma TPL’s which don’t need my more power. I am feeling I need to change/ improve these amps which were stop gap amps. I have previously ran 6B4G amps on the horns, but the back ground noise is to intrusive. These amps are no slouch having individual heater power supplies, a Guy Sargent special. The B&O d class amps are quieter but still have some hum. Only my Ncore amps are quite, if I stick my head in the horn, which have a 128db S/N ratio. So I need something with a similar S/N ratio. I could use Ncore amps for all channels but I think 400 watts into the horns is excesssive. The million dollar question - can valve amps achieve these sort of S/N ratios, I don’t think so ( just opened the flood gates on comments correcting me) so was thinking solid state. I would rather not have an altar to amplification in my music room, even integrating the amps into the speakers if possible.

What ideas recommendations do you have, Mark once mentioned a chip amp which sounded better than a Pass 5 ihho. I have seen this which looked interesing too. The Wire LPUHP V2 http://www.diyaudio.com/wiki/The_Wire_- ... ained_Here
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#2 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by IslandPink »

I'm not saying it's ideal but the amp I built & liked a lot was using the TDA7297 chip boards you can get from China dirt-cheap - tried first here I think by Steve S. The midrange is better than my F4 amp, not sure against the F5, but it's got lots of midrange tone and the bass is nice & solid with the mods ( Salas ) that are recommended. HF is not quite up to a good valve amp. I may be able to do a check on noise in next day or two, feeding the 288/Yuichi - I can't remember how much hiss there was in that case, I used it typically with other speakers here and on holiday.
For valve amps some of the 'spud' amps using 6C45pi or 6E5P tubes might be quieter than a DHT and give you enough power ( OK, only 1.5 to 2W ) .
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#3 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by simon »

That's a lot of blue touch paper you've lit there :-D.

If I were looking at a chip amp I think I'd be inclined to go for one of tomchr's designs. They're not really cheap but have good specs and Tom's support looks to be excellent.

http://www.diyaudio.com/forums/chip-amp ... hread.html

https://www.neurochrome.com/product-cat ... -circuits/
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#4 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by Ant »

The f5 I have displaced my el34 amp. Put the el34 back in a few months later, then decided to dismantle it. It was no contest.
The f5 doesnt have a great deal of gain for its 25w, so it might actually be quite suitable for very efficient horns. The el34 amp had a load more gain than the f5 does.
Imo the f5 doesnt sound like a typical sand amp (if such a thing exists), doesnt sound like a valve amp either. I personally havent heard a good class d amp so i couldn't comment on the sound of that type of amp
I dont think the f5 has a particular 'tone' it just sounds right to me
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#5 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by jack »

simon wrote: Tue Jan 23, 2018 7:01 pm That's a lot of blue touch paper you've lit there :-D.

If I were looking at a chip amp I think I'd be inclined to go for one of tomchr's designs. They're not really cheap but have good specs and Tom's support looks to be excellent.

http://www.diyaudio.com/forums/chip-amp ... hread.html

https://www.neurochrome.com/product-cat ... -circuits/
Indeed - those are as close to a "straight piece of wire with gain" as you can get. The Doug Self "Blameless" series are pretty good too if you don't want a kit (though they are available as kits too) and prefer discrete instead of integrated amps.
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#6 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by Nick »

jack wrote: Wed Jan 24, 2018 12:04 pm Indeed - those are as close to a "straight piece of wire with gain" as you can get.
Though I would be interested to see what the numbers were for DIM30 with its 14v/us slew rate.

Not heard one though, so can't say
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vinylnvalves
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#7 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by vinylnvalves »

Some pcb’s can up on diyaudio for those “the wire” amps. Great I though, until I realised Ti made all the op-amps obsolete about 2 years ago. Not paying £20 for an obsolete one off eBay when I will need 32 of them for 4 channels. My mate Dave is a fan of Selfs amps, I will have to consulte with him. I am suprised no one has mentioned SIT amps yet....
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#8 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by ed »

vinylnvalves wrote: Wed Jan 24, 2018 12:45 pm I am suprised no one has mentioned SIT amps yet....

???
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vinylnvalves
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#9 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by vinylnvalves »

Static induction transistors
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#10 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by ed »

It's got to me....

how frustrating that I've been banging on about SITs for at least 5 years...attempting to get people interested...but alas, like the mosfets and jfets before them there were no takers.....and I got the ducking stool

there are numerous threads about them vinylvalves.....

I have some 2sk28s somewhere in the bitbox which I promoted at the time of L'Amp emergence, unfortunately I was strapped into SE as I couldn't get hold of any Js. I think you will find the threads/posts in the solid state section........
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#11 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by IslandPink »

OK an update on the TDA7297 for this, and it's a mixed bag.
I just ran this amp into the 288H + Yuichi horn (~109dB/w) with some nice vocal from CD ( Jackson C Frank ) .
Playing at a level that was a bit too loud for comfort at 3m , I can confirm the little amp is definitely quiet enough - only a little bit of hiss audible from 2ft or less when the CD was stopped.
Unfortunately the vocals sounded a bit hard & grainy , going back to the SE amp, it was a lot better, more or less what I was used to. So it appears the distortion is rising when used at sub-0.1W , the amp sounds fine driving speakers at 88-95dB/w, but not here.
I suspect you'll need an SE solution even if SS.
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vinylnvalves
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#12 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by vinylnvalves »

Thanks Mark. Almost to good to be true..

Need to try and find the spec sheet for these obsolete buffer chips to see if there’s a replacement. As the idea behind “the wire” amp intrigues me paralleling up 8 250mw op amps seems a neat idea. The new ice edge chips meant to be the dogs dangly bits, shame it’s only available in 1200w amps currently.
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#13 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by IslandPink »

What are those amps the Bert Doppenberg supplies - any idea of the device & topology ? ( BD-design )
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#14 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by vinylnvalves »

I have been thinking about this a little more... and I keep being drawn back to those “ the wire” power amps with the discontinued op amps. Does any one know what a good replacement for the LME49610 would be, if any. I probably don’t need the full 16watts so could get away with a buffer that has less than 250ma capability.

Also is there anybody with SMD soldering equipment, that I could populate the pcbs for me. I am willing to barter some cnc routing in exchange I can machine aluminium fascias, engraving too.
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#15 Re: 3W amps - options: SS which sounds as good as DHT’s

Post by vinylnvalves »

Looks like you can get lme49600’s from a company called element14 for about £5 each, will have to work out true cost though as importing them.
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