Premier Rock Forum

penningtron wrote: Wed Jun 14, 2023 8:10 am Yeah.. I realize it's a bit irrational to like (and to build?) brand new combo amps but Hot Damn.

Wait what? why? Combo amps are great, especially 1x12s. Even better if they can run an additional ext cab!

Garth wrote: Wed Jun 14, 2023 8:20 am

penningtron wrote: Wed Jun 14, 2023 8:10 am Yeah.. I realize it's a bit irrational to like (and to build?) brand new combo amps but Hot Damn.

Wait what? why? Combo amps are great, especially 1x12s. Even better if they can run an additional ext cab!

By basically every objective measure it makes more sense going head + cab. The only sorta exception is Champ-like amps, as they aren't really any harder to schlep around and less likely to be paired up with a variety of speaker cabs.

A 1x12 combo probably won't bang up your knees going up stairs at least!

In this case the amp is for a friend here (NYC) where minimizing gear transport to show is key. A lot of places have a backline guitar cab, but not all. A combo is great because it will easily fit in any cab/car service.

Also, FWIW it measured 37 lbs on my bathroom scales, and below is what a few in production 4xEL84 heads weigh. Its not heavy.

Orange TH30 - 34.28 lb
Orange AD30HTC - 36.4 lb
Vox AC30 - 41.48 lb
Dr Z Maz 38 - 35 lb
Dr Z Wreck - 38 lb

Dr Tony Balls wrote: Wed Jun 14, 2023 10:06 am In this case the amp is for a friend here (NYC) where minimizing gear transport to show is key. A lot of places have a backline guitar cab, but not all. A combo is great because it will easily fit in any cab/car service.

Also, FWIW it measured 37 lbs on my bathroom scales, and below is what a few in production 4xEL84 heads weigh. Its not heavy.

Orange TH30 - 34.28 lb
Orange AD30HTC - 36.4 lb
Vox AC30 - 41.48 lb
Dr Z Maz 38 - 35 lb
Dr Z Wreck - 38 lb

Owner of the amp could put in a Celestion Neo Creamback and drop ~6 lbs from the overall weight too!

Point one, please put NSFW tags on amp porn.

Point 2, the AC30 weighs about 96 pounds more than you indicate here.

Frankie99 wrote: Wed Jun 14, 2023 2:40 pm Point 2, the AC30 weighs about 96 pounds more than you indicate here.

Sorry was comparing it to the current production AC30 head!

Dr Tony Balls wrote: Tue Jun 13, 2023 3:23 pm Balls VIP-30 combo. The circuit is kinda like an AC30, but the normal and brilliant channels merge *before* the Vox top boost, kinda like a jumpered plexi (oh and no tremolo channel, either). Normal and brilliant volume controls to blend the two signals, full tone stack, and a *proper* master volume to allow adjustment for all use cases. 1x12 with a Celestion Vintage 30. Rock 'n roll dream machine.

That is lovely.

I've been playing my Balls Hiwatt 50 clone a lot lately. Sounds great. Taking it on tour end of June/early July.

bassdriver wrote: Mon May 22, 2023 3:59 am the power transformer is from Don Audio "Mila" transformer 75$ with a 48V secondary for the phantom power

https://www.don-audio.com/Toroidal-Tran ... -63vct-48V

This is something i'm not getting. That tap shows a single 48V tap, but that's AC. Once rectified it'll be nowhere near 48V DC for phantom power. How did you wind up doing that?

All that said, i'm well versed in pulling a bias supply off the HT secondary of a power transformer. Could probably just do that for the 48V.

Are there generally issues with putting a power supply in the same enclosure as the preamp? My world is guitar signals which are much more noise tolerant than microphone.

Dr Tony Balls wrote: Sat Jun 17, 2023 12:24 pm

bassdriver wrote: Mon May 22, 2023 3:59 am the power transformer is from Don Audio "Mila" transformer 75$ with a 48V secondary for the phantom power

https://www.don-audio.com/Toroidal-Tran ... -63vct-48V

This is something i'm not getting. That tap shows a single 48V tap, but that's AC. Once rectified it'll be nowhere near 48V DC for phantom power. How did you wind up doing that?

All that said, i'm well versed in pulling a bias supply off the HT secondary of a power transformer. Could probably just do that for the 48V.

Are there generally issues with putting a power supply in the same enclosure as the preamp? My world is guitar signals which are much more noise tolerant than microphone.

Yeah don't get that either - dropping a ton to ground?

my world is piezo signals , because of the high high impedance input you would have to keep gain very low with a quality differential amplifier or op-amps, and still likely you would want to shield the preamp on it's own with that proximity.

Dr Tony Balls wrote: Sat Jun 17, 2023 12:24 pm

bassdriver wrote: Mon May 22, 2023 3:59 am the power transformer is from Don Audio "Mila" transformer 75$ with a 48V secondary for the phantom power

https://www.don-audio.com/Toroidal-Tran ... -63vct-48V

This is something i'm not getting. That tap shows a single 48V tap, but that's AC. Once rectified it'll be nowhere near 48V DC for phantom power. How did you wind up doing that?

All that said, i'm well versed in pulling a bias supply off the HT secondary of a power transformer. Could probably just do that for the 48V.

Are there generally issues with putting a power supply in the same enclosure as the preamp? My world is guitar signals which are much more noise tolerant than microphone.

not sure if those PTs are custom made or if they just took a toroidal that gets you in the ballpark of what you need. I used a TL783 to regulate it down to 48V and that works fine.
I'm sure you could use any PT with 2 secondaries one being around 35VAC. or, as you said, pull it off the HT secondary. as I said before, I'm a tinkerer and by no means an expert.

I opened the one I built years ago, and I actually used AC for the filaments.

of course you could make an external power supply if you're going to make a table top unit. maybe with two power outs, in case anyone would like to run a pair of preamps?
the Universal Audio Solo 610 has an internal power supply for example, so I guess it is doable without being too noisy.

my 48V regulator looks something like this, PS 1-4 being the rectifier: