Power Amp advice needed, for my JBLs 4312 power thirsty...

[Michelag]

Hi,
just finished my tube phono preamp after the well know scheme of Diego Nardi (Kos't, on sound practices), powered it up using my marantz 2235b as a power amp, and the speakers scream "let me fly, gimme power"...

So now, I was told about interesting projects by the Papa, but I can't find my North Star yet...
Well, what i need is preferably one chassis, big power (more or equal than 100W), class AB (yes, with the wattage involved I don't want to turn my living room in an oven)

Any hints?
Or should I go again back to tubes ?

Thank you!
Mike

 

[AudioSan]

I quess you were thinking of the AB100: AB100 Class AB Power Amplifier

Another option could be the Honey Badger: diyAB Amp The "Honey Badger" build thread

 

[Michelag]

uhm, both seems nice...
have to look if pcbs are to be found somewhere

 

[2 picoDumbs]

According to this site JBL 4312 Monitor Loudspeaker System Manual | HiFi Engine

They are 91dB, 8 Ohms

That is actually a very easy load.

Your diy time and money would be best rewarded with a 25W Class A design.

Unless you are in the habit of having parties that require police attendance for noise pollution. I promise, you don't need huge voltage swing.

EDIT: What it sounds like you need is voltage gain, not power

 

[2 picoDumbs]

Do you know what the max output of your preamp is?

 

[Zen Mod]

buy bigger JBLs, use smaller amp(s)

 

[Michelag]

Do you know what the max output of your preamp is?

a little over 60V RMS, 2k5 Ohm output impedance

 

[Michelag]

According to this site JBL 4312 Monitor Loudspeaker System Manual | HiFi Engine

They are 91dB, 8 Ohms

That is actually a very easy load.

Your diy time and money would be best rewarded with a 25W Class A design.

Unless you are in the habit of having parties that require police attendance for noise pollution. I promise, you don't need huge voltage swing.

EDIT: What it sounds like you need is voltage gain, not power

I'm telling you, my marantz 35wpc is not enough for these speaker.
I don't make police parties, i want to hear separation in the woods at the end of first movement Mozart's 40th symphony. I want to hear clearness, flutes whistling up with their harmonics, strings not like a blobb but with soundstage and finesse.

and don't tell me wrong speakers for Mozart!


thank you however for your suggestion, I appreciate.

 

[2 picoDumbs]

Ok.
Classical music is a little different

 

[2 picoDumbs]

In that case maybe 10W Class A, transistioning into AB all the way to 100W

 

[2 picoDumbs]

a little over 60V RMS, 2k5 Ohm output impedance

That seems way higher than normal, but if true all you need is a high powered F4.
F4 with 45V rails

 

[wdecho]

My understanding is that the Honey Badger can be biased to stay in class A longer with enough A/B power when needed. Not sure if 10 watts though.

 

[Michelag]

In that case maybe 10W Class A, transistioning into AB all the way to 100W

I don't have any experiences with solid state, so if you please could just say a model name... and i'll do the dirty job

 

[Michelag]

That seems way higher than normal, but if true all you need is a high powered F4.
F4 with 45V rails

what about the f5turbo?

 

[2 picoDumbs]

Yes you could do F5 turbo.

I think a high powered F4 would be nicer assuming the phono preamp outputs 60V rms as you said earlier.

You would need to run it without the input jfets though, unless you're ok doing it on a proto board or making a pcb, in which case a modified circuit could be provided (ie if you needed the jfets at input)

Maybe the best solution would be to use a high quality audio transformer to convert the signal from single ended to balanced then no circuit modifications would be needed, you could make a balanced version of the F4.

Or balanced BA3 without the signal transformers at input

The easiest will be high powered F4 without input jfets

 

[Michelag]

well... really not fond on making pcbs... nor very confident of modding a schematic... with doubled rails voltage should I change all the componetns' values in there or just look for better dissipation?

 

[2 picoDumbs]

F4 without input Jfets then.

 

[2 picoDumbs]

Is this the schematic of the phono preamp.

http://www.enjoythemusic.com/magazine/sound_practices/16/mono_preamplifier/schematic.pdf

 

[Zen Mod]

buy S/H Treshold from Papa's era and that's it

better that way than going DIY just to have an amp, perfect recipe for struggle

your Marantz is a piece of Drek, comparing to any of FW format amps, not just in Verity but also power

man replaced his Audiophool Series Marantz 100W/ch amp with my Babelfish M25, for driving his Dynaudio Contour (first 1.3 then 1.8) and never looked back

go figure

 

[2 picoDumbs]

Yeah.

25W is generally more power than anyone ever needs.