audio-talk

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

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 ) .

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

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/

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

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

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.

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

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....

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

???

Static induction transistors

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........

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.

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.

What are those amps the Bert Doppenberg supplies - any idea of the device & topology ? ( BD-design )

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.

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.