Disconnecting Speaker Question

[Gutter Puppy]

Hi.
Want to disconnect one of the two speakers in my 65 Fender 2x12" blackface Pro Reverb amp. What should I do re: the disconnected leads - eg. tape them ? separately ?

- btw: Yes, this is a volume issue, and yes, this is gonna set off the alarm bells . . . but, have already looked into/considered the 4ohm-signal-into-8ohm speaker issue, as well as all available options I know of: eg. different speakers, different amp, reactive loadbox attenuator, pedals, digital amp modeling, eg.
- and, unfortunately, none will work for me at the present.

Thanks for any suggestions !

[Wonks]

Is this a genuine 1965 amp, or a later model based on it?

On pictures I've seen of the speakers in the 1965 amps, the leads seem to be soldered on. Yes, you'd certainly need to tape up the ends of the disconnected wires but I'd be tempted to make up or buy a replacement speaker lead with just the single connections on the end to rule out the chance of any mishaps.

But just dropping down to one speaker won't make much of a volume difference.

Have you considered swapping out the 7025 preamp valves (a low noise version of the 12AX7) for lower gain valves such as the 12AY7? You could try one in just one channel to see what you think.

[Sam Spoons]

As Wonky says you won't hear a massive difference after disconnecting a speaker. Probably a stupid question (I am a valve amp loving guitarist too) but I guess just turning it down doesn't work?

Either way disconnecting a speaker to try it out is not difficult so give it a go and see if it works for you.

[Wonks]

I'll just add that if you do tape them, they should very much have the loose ends taped up separately. You do not want to ever have them touch.

[ef37a]

Whist I completely agree with Wonks that a valve amp tapped at 4R driving a nominal 8R speaker is normally quite safe it is not ideal (and you don't know how closely the transformer 'match' was in the first place) Under normal, even very loud levels of drive, probably fine but sustained overdrive would IMHO put the OP valve. s and transformer in peril. Then, some valve amps are more fragile in this respect than others! Where that Fender lies on the "feeble to bombproof" scale I do not know.

Regarding the actual disconnection, I would suggest just chopping the wires, 200mm say from the speaker tags and protecting the amplifier end with some 5A 'choc block' readily available at B&Q or Wickes. Even better, insert a 5A inline mains switch? Thus you can diss' the speaker when you want quiet* but turn it back on for total mayhem.

*As everyone has said, this will make very little difference to the loudness of the amps.

Dave.

[Wonks]

If it is a true 1965 amp, then as long as the speaker cable is fine, cutting it in half is not going to do much for the amp’s value. Working original is always best for that

Which is why I think keeping it intact and using a replacement is a better option.

If the speaker cable is looking rather tired and frayed in places, then I’d be looking at replacing it with a look-alike when the second speaker is reinstated.

[Murray B]

Just to check regarding replacement speakers - you've seen the Celestion Peacekeepers?

There not a cheap solution though and of course you'd want to be very careful when doing the replacement job on the amp.

[James Perrett]

If it is a true 1965 amp, then as long as the speaker cable is fine, cutting it in half is not going to do much for the amp’s value. Working original is always best for that

That's why I think this whole idea of modifying the amp to make it something that it was never intended to be isn't really sensible. This looks like a pretty valuable amp so anything that might endanger the output transformer or reduce the authenticity should be avoided in my view.

[ef37a]

Certainly if the amplifier is a valuable model do not modify it in any way. I was merely pointing out some practicalities. The OP might not for instance have any soldering kit?

In any case, due to the nature of the question and the fact that removing one speaker will have very little effect on the sound level, I think this post belongs in the area of "If you have to ask you probably shouldn't be doing it".

Dave.

[Murray B]

I have an unsolicited plan B...

If you accept that you have a loud heavy amp that is also valuable and shouldn't be messed with... Use an external Cab with a single lower sensitivity speaker of a suitable impedance in it and leave the combo unmodified - just bypass the internal speakers.

This will definitely work for at home playing - you could even do a bit of DIY - open back guitar cab design doesn't need a lot of planning work you and could just match the dimensions of the current cab and stick a hole in the front to mount the speaker. This will make a stack and have the same footprint.

It's another box to take to a gig - but it might be worth it for the sake of the show/ stage balance.

[ef37a]

I have an unsolicited plan B...

If you accept that you have a loud heavy amp that is also valuable and shouldn't be messed with... Use an external Cab with a single lower sensitivity speaker of a suitable impedance in it and leave the combo unmodified - just bypass the internal speakers.

This will definitely work for at home playing - you could even do a bit of DIY - open back guitar cab design doesn't need a lot of planning work you and could just match the dimensions of the current cab and stick a hole in the front to mount the speaker. This will make a stack and have the same footprint.

It's another box to take to a gig - but it might be worth it for the sake of the show/ stage balance.

It's a plan but good (for guitar) 4 Ohm speakers are rare, the Peacekeeper for instance is only available in 16 and 8R flavours. Not much point I can see in going to all that trouble and still putting the amp at some risk?

Then, if you are going to the trouble and expense of another cab and speaker, never mind the "lug" factor, might as well get a power soak?

The idea that you can attenuate 50 odd OD watts to mW so as not to wake the chavvy in the next room AND sound like a stage stack is not viable IMHO but OP just wants I think to knock the SPL down by 10dB or so? That I think is doable.

Again, the load impedance is an issue, most soaks it seems to me are 8R and fewer at 16. Four Ohms seems much rarer?

Ooooo! I am wrong! https://www.thomann.co.uk/two_notes_tor ... _4_ohm.htm
Found on my first search. Bit o money but comparable I would say to a second speaker cab? Plus you get a DI etc.

Dave.

[Gutter Puppy]

Hey, thanks for all of your ideas and suggestions.
1. It is a 1965 Blackface Pro Reverb that I've had for 20+ yrs - using it the both for gigging and recording. Problem is I'm now a feeble, old retired fart and not playing out where volume is needed. I've also moved to a place where it might cause problems if I crank the Pro Reverb enough to get to that "sweet spot".

While I could probably play with enough volume to get a nice old, pre-CBS blackface Fender Deluxe Reverb or Princeton Reverb sounding good (trivia: I'd replace the baffle and swap the 10" spkr for a 12") - but I've thusfar been unable to find one locally, and am not comfortable purchasing an old, vintage tube amp on-line - ie. without seeing and hearing it first.

I was also considering running the 4ohm Pro Reverb amp through an external cabinet with a single 8ohm speaker . . . I've run my
my little 8ohm Pro Junior tube amp through a Bogner extension cab with a 16 ohm (Celestian) speaker, and it actually gets very cool overdriven tone at a lower volume - but I also want to be able to have reverb, as well as get a "crisper/cleaner" tone when needed - having cool Fender amp vibrato (like in the Pro Reverb) is even better !!!

I've read an article or two stating that old Fender tube amps tend to be pretty solid, and should be able to tolerate a single level upward - not downward - mismatch: eg. 4 to 8, or 8 to 16. Long, long ago - in the horse and buggy days - I worked as a kid in a guitar shop, and people sometimes plugged in/used Fender tube amps with different cabinet and speaker configurations - without first checking for ohm matching admittedly not a wise idea by any means. However, the shop did do a lot of amps repairs, and I don't recall the amp tech ever mentioning having to repair a Fender tube amp (eg. transformer) due to an "upward" ohm mismatch - but then again (of course) such anecdotal evidence does not necessarily conclusively prove the point . . .

Sorry for rambling on and on ... !
The only other person around here to talk to is the wife - and she's not nearly as nice as you guys ! She just wants to know what the hell new expensive piece of music equipment I'm thinking of spending our (uh, I mean her) money on ! : >

[Gutter Puppy]

Ooops. I forgot to acknowledge Murray B.'s prior "Plan B" suggestion.

[Wonks]

Thanks for filling us in on the details.

Unfortunately the reality is that you won't get much of a volume reduction just be going down to an existing single speaker. I'd still guess about a 3dB reduction, which isn't much at all. You'll mainly get it from the increased impedance the amp is running into.

I don't know by how much reduction you think you'll need but I don't think you'll get to the level for quiet home use with the amp just running into mild distortion and still getting the same sound/amp feel without using a reactive power soak.

Have you tried out a Fender Tone Master amp, such as the Princeton Reverb or a 65 Deluxe Reverb? Both have reverb and 'vibrato'. They get very close to the originals whilst being able to set the output levels down to very quiet indeed. I'm not saying they are perfect, but given that two similar amps of 1965 vintage can sound pretty different now due to variances in component values over time (and what's been replaced), then you can never expect a new amp to sound quite like an old one. I'd suggest trying one and seeing if they could meet your needs.

I don't think you'll be able to do what you want without spending money or changing to a different amp.

[ef37a]

I really do think you would do better with one of these...
https://www.thomann.co.uk/harley_benton ... nuator.htm

It has a 4 Ohm load position and will be safer than the speaker mismatch*.As Wonks has reiterated, going one Z setting away will hardly make any subjective change in the loudness. I don't have any knowledge of that HB soak but they seem to have been around quite a while and I have never read anything bad about them in any of the 3 forums I infest.

*You might have found those Fenders to be tough and forgiving but electronic failures are "statistical" the technical term is 't'appen. Why take even a tiny chance when the consequences could be very expensive indeed? In the world I used to inhabit you would have immediately voided your warranty!

Dave.

[Wonks]

Those Harley Bentons are purely resistive attenuators, and whilst making it quieter, you simply don’t get the same sound from the amp.

[ef37a]

Those Harley Bentons are purely resistive attenuators, and whilst making it quieter, you simply don’t get the same sound from the amp.

I dare say not Wonks but I was looking at cheaper solutions. Even a 5W amp into any kind of guitar speaker is going to kick over 100dB SPL at full whack and if he does not give it the beans he won't I think get the sound he wants. Another type of speaker will be less sensitive but even further from the desired sound.

It would help if we knew what sort of level he is aiming for? If something that will not upset next door...fairly doable (but "nuisance" tolerance can be very fickle!) If low enough not to disturb someone watching Corrie in the next room, pretty impossible AND get a decent OD tone.

We are talking about The Holy Grail of Rock Guitar Tone at mW levels and I don't think anyone has cracked that yet?

Dave.

[Sam Spoons]

Nobody has mentioned the isolation cab option. I built a sturdy MDF box with a speaker/baffle in the middle and a mic in the 'front' half. Both halves have a fair bit of foam and I can wind an amp up to gig volume without upsetting the neighbours*. Cheap and easy to DIY.

But I have to ask whether simply reducing the volume by 20-30 dBs is going to work for you, you can't replicate the sound and feel of a loud amp in a room without actually having a loud amp in the room so is it the experience of tracking with the volume turned down that is not working for you or the final recorded tone that is unsatisfying? The latter is easy enough to solve these days with plug ins* or hardware amp modelling but the former is much harder to fix.

* For the record I don't use the Iso cab at the moment as my studio is sufficiently well soundproofed to allow me to play my 18 watt combo at a reasonable level. And, yes I get that you may not like plug ins for guitar tone, I too much prefer hot bottles making that noise but if I had to record at seriously low volume I would accept that embracing the tech is the only sensible solution.

[SecretSam]

Sell the historic amp to some stamp collector type at a stupidly inflated price, buy a modern amp that does what you want, and spend some of the profits on a nice present for your wife. Then spend the rest on whisky, viagra, prostitutes, antibiotics and heart attack medicine.

Sorry, by "Viagra and prostitutes," I meant "Very nice Presents for your grandchildren." It's a sad indictment of modern priorities that my spellchecker would make a mistake like that.

[Gutter Puppy]