65 and 68 Princeton reissues, negative feedback and noise floors

noisepolluter

I appear to be talking myself into a Princeton as well as my current 65RI Deluxe Reverb rather than instead of, as a bit more of a grab ‘n’ go solution for low volume/guitars only jamming. Might as well convert various small bits of unused gear into something practical.
Given that I therefore wouldn’t need much headroom out of it, and in fact it would be nice to get it growling a bit at lower volumes, I’m tempted by the look of the 68 Custom. There isn’t a huge gulf between the 65 and 68 second hand prices.
Just wondering about the effect of the 68 lower negative feedback on noise floor though, as it would be nice to run it at home without intrusive levels of hiss.
Presumably though, if the background noise did affront my delicate sensibilities I could get the resistor swapped for a higher value?

 

smigeon

FWIW I play my ‘68 quietly at home every day. There is a small amount of hiss, as you’d get from almost any amp. And I am usualky quite sensitive to hiss in general. But l’ve never been bothered by hiss from the ‘68. It just sounds great.

ecc83

I have NO expertize on the 68 Custom but a higher value resistor in the SERIES feedback path will reduce feedback and increase noise.

By the same logic, reducing it will reduce noise but be very careful because increasing feedback can lead to instability. One of the top men here will no doubt put you right.

Dave.

ICBM

The stock value in the '65 Princeton is 2.7K, so you could fit a switch to add a resistor in parallel with the one in the '68 (I'm not sure what that is, but it will be higher) to bring it down to an effective 2.7K. That would give you the option of either.

p90fool

I had a 68 Custom and swapped back and forth a couple of times to 65 spec resistor values in the tonestack and the NFB, and there was no practical difference between them in terms of noise. 

Both Princeton models have a much lower noise floor than either of the Deluxe models. 

I would happily use either Princeton, they made a big deal about the 68 Custom spec, but the changes from the 65 make less difference than speaker choice in my experience, they're both great amps.  

noisepolluter

Thanks all, this is very helpful to know. 

crunchman

p90fool said:

I had a 68 Custom and swapped back and forth a couple of times to 65 spec resistor values in the tonestack and the NFB, and there was no practical difference between them in terms of noise. 

Both Princeton models have a much lower noise floor than either of the Deluxe models. 

I would happily use either Princeton, they made a big deal about the 68 Custom spec, but the changes from the 65 make less difference than speaker choice in my experience, they're both great amps.  

I've got a 68.

The big difference is the speaker as far as I can see.  The Celestion that the 68 comes with just adds mid range mud.  It definitely sounds better with a WGS Veteran in there.

The UK WGS dealer seems to be out of stock at the moment though:

http://www.lean-business.co.uk/eshop/wgs-g10-veteran-20w-10-guitar-speaker-8ohm-p-1939.html

Someone was selling a Weber 10F150 in the Classifieds.  That would probably be perfect in a Princeton.

p90fool

I had a WGS alnico of some sort then a Ragin' Cagin in mine, but put the stock Celestion back in it when I sold it to the other guitarist in my band.

He's been gigging it flat out ever since and it sounds bloody awesome now even with that speaker, I wish I'd kept it!

thecolourbox

I wouldn't have thought you'd get natural breakup on the 68 at home volumes by the way, it's too loud for me playing clean though I'm in a small room. Has to go pretty high to overdrive though

MattFGBI

We did a ltd edition '65 last month in tweed with a 12" speaker. Worth comparing one if you can find one. 

fandango

MattFGBI said:

We did a ltd edition '65 last month in tweed with a 12" speaker. Worth comparing one if you can find one. 

Went looking and found some in Andertons. They've got Cannabis Rex speakers.

Fender also did a limited '65 Princeton Bordeaux Reserve with a 12" Jensen P12Q speaker a couple of years ago.

Spoilt for choice?

badlydrawnbanjo

I have a rajin' cagin in my 68 and it sounds wonderfull. I also had Zilla make me a matching 12" cab for a bit more stage presence. I very rarely use anything else both live and in the studio.

jpfamps

The main effect of reducing the negative feedback wrt noise will be the increase in gain in the power amp, so any noise from the pre-amp will be amplified more.

There will be a small increase in hum from the power amp, however this is probably insignificant.

srato

I bought a Custom 68 new about 2 years ago and there was so much hiss that I had to send it back after a few days.  The reverb was very hissy and the tremolo generated a sort of ticking noise.  I have other amps and some hiss is acceptable but the 68 Custom PR was unusable.

smigeon

srato said:

I bought a Custom 68 new about 2 years ago and there was so much hiss that I had to send it back after a few days.  The reverb was very hissy and the tremolo generated a sort of ticking noise.  I have other amps and some hiss is acceptable but the 68 Custom PR was unusable.

Ouch. Not my experience at all with mine. All just goes to show, best approach, if you can, is to go to a shop, take your own guitar, and try before you buy...

p90fool

srato said:

I bought a Custom 68 new about 2 years ago and there was so much hiss that I had to send it back after a few days.  The reverb was very hissy and the tremolo generated a sort of ticking noise.  I have other amps and some hiss is acceptable but the 68 Custom PR was unusable.

I've no idea why the bias tremolo would tick on a Princeton. 

Deluxe yes, but Princeton? 

That said, my Princeton was noisy when it arrived, the valves just needed a wiggle to reseat them after being in transit. 

thecolourbox

Yes my 68 is noisier with the reverb and or trem on