Heavy Metal Amplifier

[Ray P]

Ray, where did you get that U channel - Ive never seen any that wide before.

https://www.ebay.co.uk/itm/192874068699 ... 2749.l2649

[iansr]

Lots more metalwork again today, the chassis is coming together nicely.

Drilled and tapped another 20 or so holes today - that's around 40 all in and not a single failure (hope you're reading Phil) - the tap guide I bought was pricey but worth every penny. Some more pictures tomorrow.

I’ve previously used the manually turned drill press method. It’s great for accuracy, but a bit of a faff, so perhaps I should try a tap guide. You seem to like yours Ray, which one is it?

[Ray P]

I’ve previously used the manually turned drill press method. It’s great for accuracy, but a bit of a faff, so perhaps I should try a tap guide. You seem to like yours Ray, which one is it?

https://www.amazon.co.uk/Big-Gator-Tool ... C96&sr=8-5

[Ray P]

Back onto my SissySIT build today, installed the speaker terminals, input sockets and a switched shunt attenuator.

Rechecked all the bias and offset and had a listen using the Mission speakers I dug out for Steve. Not the ideal arrangement, my mobile phone didn't have enough gain so I ended up using my Noir HPA as a preamp, and the Missions haven't been used for a while, so the music was a bit compromised. After 30-40mins the SissySIT was just starting to warm up (literally) and the speakers were starting to relax a bit so the sound was improving and there were clues to this being a really good amplifier.

The build is all but finished now, all that's left to do are front and rear panels for the chassis.

[Ray P]

I hooked the SissySIT up to my Lowthers, source was my ValveDAC DSD decoder, straight into the SissySIT, and I played a variety of tracks at DSD256 via HQPlayer.

There was a little edginess at the top end to start but that was definitely reducing as the SissySIT warmed up and got into it's stride. Detail and separation are excellent and the bass seems to have more 'oomph' about it than I have experienced with any other amp driving the Lowthers - reminded me a bit of my 300B SE-OTL amps but after they had been on a diet of steroids! I have a tiny bit of buzz/hum if I put my ears close to the drive units but I didn't pay much attention to the cabling when i set it up so may be easy to resolve - I'll check it out later - it didn't stop me from smiling as I tried different tracks. With a few more hours clocked up this is going to be an excellent amplifier, it's really very good straight off the building blocks.

Maybe it'll motivate me to finally complete the 6C33C SE-OTL so I can compare.

[iansr]

Looks the business Ray.

[Ray P]

Cheers ian. I'm just workng on drawings for front/rear panels to finish it off.

[jack]

I like your sense of priorities: Amp first, room later...

[Ray P]

I like your sense of priorities: Amp first, room later...

Yeah, I used to worry about things like that but as my time remaining diminishes so does my interest in domesticity - I'll get around to finishing it one day and in the meantime do the things I enjoy.

[Paul Barker]

I like your sense of priorities: Amp first, room later...

Yeah, I used to worry about things like that but as my time remaining diminishes so does my interest in domesticity - I'll get around to finishing it one day and in the meantime do the things I enjoy.

Me too.

[jack]

I like your sense of priorities: Amp first, room later...

Yeah, I used to worry about things like that but as my time remaining diminishes so does my interest in domesticity - I'll get around to finishing it one day and in the meantime do the things I enjoy.

Me too.

Completely understand. Using reducto ad absurdum, I never do anything other than what I want as time remaining is always diminishing...

Lots to do this morning, but decided to look at some bees I moved to an area of apple orchards late last night and went for a walk round with SWMBO & the dog.

Now back to annoyed clients and a server whose SSL certificate expired yesterday and didn't auto-renew...

Photo doesn't do the place justice - the blossom is just getting fully out (there's about 200,000 apple trees here), there's a mist in the valley, it's cool and bright, Lovely. And I'm the only beekeeper...

PXL_20220421_070314066.jpg (254.07 KiB) Viewed 3392 times

[Nick]

Had a look at the circuit for that amp. Was taken by the ACS723 current sensors, trying to resist the thought of using them to auto bias output valves

[jack]

Had a look at the circuit for that amp. Was taken by the ACS723 current sensors, trying to resist the thought of using them to auto bias output valves

The AD8212 & ADuM5402 are interesting too - see CN0218 - https://www.analog.com/en/design-center ... d-overview

TBH, the ADuM5402 is the most interesting one for me - the ACS723 series are great but ISTR that they're really for BIG currents...

[Ray P]

Had a look at the circuit for that amp. Was taken by the ACS723 current sensors, trying to resist the thought of using them to auto bias output valves

Is resistance not futile...