audio-talk

I’m currently in the planning stages for a guitar amplifier for my granddaughter.
She is getting to be a very good guitarist and has a couple of inexpensive electric guitars and an electro acoustic.

This amp project could very well take precedence over the other projects, in fact it probably will, and is based on the Fender Princeton model 5F2.
The amp itself is called the 2 Stroke and is a proven design by Dave Hunter, author of “The Guitar Amp Handbook” which I’ve read from cover to cover, twice over since I received it as a birthday present.

It’s a simple single-ended topology with a only a volume, tone and a three position “boost” switch that just varies the bias of the 12AX7 preamp tube to provide some degree of gain boost, rather than switching an extra preamp stage in and out, which would obviously give more gain flexibility, but we’re keeping things simple.

There’s no reverb or tremolo; it’s just a very simple amp that will provide 4W from a 6V6 or 10W from an EL34 or KT66.
It’ll give her the facility to practice, work on her tone and get a cranked up sound without deafening the street.

At the moment I’m weighing up whether to do it as a head with a separate 12” speaker cab or to do it as a combo unit with the same 12” speaker built in.

Should be interesting and different.

Separates will allow more flexibility to mate with different speaker etc.

Are you after the 'Grandad of the Year' T-shirt Steve?

Sounds like a nice little project and very laudable to offer encouragement in such a practical way - maybe the payback will be when she headlines at Glastonbury - and I hope she comes to recognise what a gift it is to be able to play a musical instrument.

I would keep it simple to build and operate as a one-box solution and I hope to see your trademark retro finishing...

Yes, the KISS philosophy is at the forefront of my thinking on this. As a result, I’ve done a bit more pondering and have gone even simpler, with the amp. It’ll now be based on the 1950s/60s Fender Champ 5F1 combo unit. The circuit uses an ECC83 preamp/driver stage, feeding a single 6V6. Rectifier is a 5Y3G. There is just a volume control, and apart from the ‘on’ indicator light, two jack inputs and a speaker output, that’s it.

All her tone adjustments can be done from the guitar tone control, and if push did come to shove, a 100pF ‘bright’ cap could be employed across the amp volume pot, just to give a bit of treble boost at the lower clean volumes.

A simple amp will help her to work on her picking technique and explore touch sensitivity, breakup and distortion. Effects pedals can come later.

Powder blue, or pink and chrome for the cab, with a silver/black Tygan speaker grille and tapered legs is the look I’m hoping to achieve.

Sounds great and is a project I'm interested in myself. Most amps are way over powered and as a result never get used in that wonderful sweet spot where the output stage starts overdriving. That's where the brown sound lives. I have it on my list to create a flea powered amp. I'd be very interested in how you get on. I'm not far away so would love to come and hear it when done.

Perhaps the next Owston could include a demonstration of the amp by your granddaughter?

RhythMick wrote: ↑Fri Jul 26, 2019 8:02 am Sounds great and is a project I'm interested in myself. Most amps are way over powered and as a result never get used in that wonderful sweet spot where the output stage starts overdriving. That's where the brown sound lives. I have it on my list to create a flea powered amp. I'd be very interested in how you get on. I'm not far away so would love to come and hear it when done.

Perhaps the next Owston could include a demonstration of the amp by your granddaughter?

Yep, the idea is to get the cranked up sound without having to be deafened in the process.
I don’t play, but I’m sure something can be arranged if you want to listen once it’s all done.

Just be aware that there is more than one "cranked up sound". What guitar does she play? Humbucker or single coil pickups?

Nick wrote: ↑Sat Jul 27, 2019 6:07 pm Just be aware that there is more than one "cranked up sound". What guitar does she play? Humbucker or single coil pickups?

Can’t recall the brand of guitar, but as far as I know it’s single coil pickups, which Fender Champs apparently love. From my guitar amp handbook, they do say that humbuckers can sound too dark with the 5F1 clone I’m building, and can cause the speaker to fart out, due to excessive bass, before you get anywhere near tube breakup. A change of input cap and a bright cap on the volume pot is supposed to be the cure for that problem. These mods can be made switchable so that both kinds of pickup can be accommodated, but I’m going to build it stock first and see what results she gets.

Admittedly I know absolute zero about electric guitars so it’s a case of get on with it and see what happens.

It is truly a golden time to play guitar, stupid cheap good stuff out there.

https://www.andertons.co.uk/brands/blac ... 275271b2d1

Steve....it might pay dividends to ask yourself why you are embarking on this path....

two ideas immediately come to mind:
are you doing this to satisfy your 'I must build anonther amp' itch, justified by the fact that you're helping your granddaughter out with an amplifier..

or

altrusistically trying to give her the best bit of kit that will help her now and long into the future, providing loads of alternative approaches to playing the guitar.

if it's the second then IMO you wont come anywhere near to that Blackstar for the money..they are simply awesome in their versatility...oh and did I say awesome for their VFM. Those Fenders are great for the retro brigade hankering for the nostalgia but they don't stand up very well when comparing with the new breed of modelling amps.

Thanks Nick/Ed,
That Blackstar looks awesome

@Ed
I can’t justify building something when that Blackstar exists, so I guess that’s that.

Bloody digital! Is nothing sacred?

Cressy Snr wrote: ↑Thu Aug 01, 2019 7:58 pm Thanks Nick/Ed,
That Blackstar looks awesome

@Ed
I can’t justify building something when that Blackstar exists, so I guess that’s that.

Bloody digital! Is nothing sacred?

Sure you can. You'd enjoy the design and build, and how much better to be able to give your granddaughter a hand built valve amp designed by her granddad.

Plus I'm sorry but I haven't heard any digital amp sound anything like as good as a proper valve amp. Call me old fashioned.

With the Blackface she'll sound like everyone else. With your amp she'll sound unique.

Back in my Danbury Transformers days, we used to get all sorts of correspondence including about guitar amp stuff, as Dave at Danbury was gradually adding guitar amp transformers (because people were asking him to make them as replacements or for new builds). There definitely is (or was) a fan group for the 5F1, including home made kit. One correspondent sent me the following schematic. Can't remember how he waxed lyrical about it but there was something about what the 6V6 does if memory serves.

Digital - schmigital! It's worth doing says I.
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Note how input jack #2 has a 1 Meg resistor (I think) to ground when unused, while jack #1 is a direct link. Presumably then #2 on its own will give a divide by 2 signal attenuation, and #1 on its own won't, it'll be pretty much unattenuated. Well just slightly.

Plus I'm sorry but I haven't heard any digital amp sound anything like as good as a proper valve amp. Call me old fashioned.

No, but they can sound 95% as good as 20 amps and 20 cabs, and a floor full of pedals, are easy to carry to gigs, can sound good at both bedroom practice and playing with drums volume, and have DI outputs if needed.

And TBH, for most of us that 95% is really 100%. Most of the sound is still in the hands, and the amp will not fix that. Sad though it is, you can't buy talent as much as we might hope it was possible.