Will a 60 watt solid state amp rated at 4ohms work with a 300 watt 4×10 bass cab rated at 8ohms?

[Folkcafe]

Could you provide any references for this recommendation? Screen clip from a book or database?

My guitar cabinets are matched in rating. Or close to. The EL34 100/100watt block has 1960A cabinet and B with G12T-75's. 4x75watt speakers loaded x 2. My EL84 20/20 marshall is 20 watts and has 20 watt green backs loaded G12M? or whatever they are...

The speakers react perfectly to me.

My Pa has 150 watts 15" speakers, and an amp that pushes 275 watt RMS. Following the Sweetwater guide , it sounds nice.

You'll find even in publications that there is a lot of contradictory information on this. It is a bit easier if you separate guitar from everything else though. The reason for this is that guitar speakers are pretty much the only types of drivers that are purposely designed for non-linear response. What was initially accidental (distortion) and to a great degree destructive, is now designed into guitar speakers. The cone membranes are built with corrugations and less than rigid materials as to work non-linearly (distort). This is what is meant when a speaker manufacturer talks about early breakup. It is the cone that is the source of the distortion and not the voice coil operating outside its range. It is a big difference that separates it from other speakers.

This is what makes it a lot more complicated as there are so many variable to take into account in getting the sound you are after, even before you take into account pedals and amps. A speaker with a high degree of early breakup will not be able to produce clean tones at loud volumes for instance. The solution is to use speakers that are more rigid with less breakup and use an amp or pedal as the source of distortion. The overall sound is often a combination of these choices. Hence the complexity and all the different choices.

The video I posted offered a bit of insight into speaker choices and options. I had been looking at all the options on the Weber site and was looking for some information on doping the cone edges. Because Weber builds to order, the choices requires a bit of understanding.

 

[ecc83]

"Could you provide any references for this recommendation? Screen clip from a book or database?" No, and even if I could someone could find a dozen references to the contrary.

My statement is based on the measurement of several valve guitar amplifiers. One nominally 60W amp (2X EL34) was found to deliver an easy and clean 80W and would go on to put out close to 100W at hard clipping. Clearly a 60W rated speaker such as the Celestion V30, a very commonly used motor, would be at risk with such an amplifier. This 'over rated power' capability of valve amplifiers carried through to other models. A "5 watt" design could deliver some ten watts at clipping and the combo version was equipped with a G10-N40 so had a good 4 times safety margin.

I was also asked to test some 100W (4x EL34) chassis for their power output at 10%thd All could deliver over 130W for a 1kHz sine and could therefore be justifiably marketed as "120W" amplifiers.
Please note, all these tests were done at a mains input of a measured 230 volts rms whereas most places in UK get 240V+ and so the amplifiers would have even more headroom in practice.

There used to be a conception that only when a guitar speaker is driven close to its last gasp does it produce the desired tone. The tech guys at Celestion tell me this is definitely not the case (and a moments considered thought would surely make it obvious that it would not be!)

I am guided in the above from the experience of several people from the industry, most notably Marshall. Some were excellent guitarist with lots of band experience, one a production manager and two very capable graduate electronics engineers. I was little more than a "bottle washer" in the lab but some of the teaching stuck!

People are free to drive whatever speakers they have with any amplifier they come across. When asked I give my considered opinion. Nothing more.

Dave.

 

[rob aylestone]

In my office, I am editing video with two RCF 5" monitors for my sound. Mainly because I have quite a few of them and they sound fine. I was looking for an amp - the first one I pulled out wasn't what I thought was in the case - it was a 2U 2400W version, not the 400W I intended - I turned the gains up to about a quarter - it works fine.

 

[snow lizard]

I'm certainly not an expert but I believe the "considered opinion" could change depending on who you're talking to. The JTM 45 began life as a Fender Bassman clone. I think a significant difference between Fender vs. Marshall sound in general has to do with negative feedback and midrange. I suspect many of Leo Fender's designs don't peak so high above rated output numbers, and don't have the non-linearities of Marshall designs. It's not so much right vs. wrong, as much as what sound are you after? A Fender Twin Reverb sounds good at "reasonable" (full band with acoustic drums) volume levels and as you crank it up it gets extremely loud and stays clean, beyond moderate sized club levels. In my opinion, the high input of the bright channel of a Super Lead Plexi sounds like crap until you open the throttle to a certain point. The Volume control on that channel is one of the most powerful tone controls on the amp. Below a certain point it sounds like an ice pick with weak mids and no bottom end. As you crank it up the frequencies balance out and you start getting a glorious breakup from the power section of the amp, and you're at ear crushing stadium or outdoor festival volume levels. Power attenuators or load boxes are popular with those amps.

The impact of speaker design on the sound is huge. I can't imagine a Plexi would be a good fit for a cab loaded with Altecs or JBLs designed for massive headroom. The speaker is a factor in the distortion of those amps. A Fender Twin or Ampeg V4 might be a different story. It's certainly a different sound.

For shits and giggles I hooked up a Marshall Origin 50 head to a Fender red knob Twin cabinet. It sounded surprisingly much like a Twin.

As far as loads I just match the output transformer to the load for a tube amp or stay at or above the minimum for solid state. I did a gig where the sound guy decided to daisy chain 3 passive wedge monitors. Sounded great until the first chorus at sound check when it stopped working.

 

[LazerBeakShiek]

For giggles I hooked up a Marshall Origin 50 head to a Fender red knob Twin cabinet. It sounded surprisingly much like a Twin.

As far as loads I just match the output transformer to the load for a tube amp or stay at or above the minimum for solid state. I did a gig where the sound guy decided to daisy chain 3 passive wedge monitors. Sounded great until the first chorus at sound check when it stopped working.

Marshall has not made its traditional sound in decades. Probably leading to Marshall's death with the Code series. The JCM 800 was the one.

There are a couple of solid state amps I like. The Fender M-80(still own). The Roland JC-120. ADA made power amps the MicroTube hybrid, and the MicroFet. Those are excellent pieces. Back in the late 80's they were advertised as having extended freq ranges. The SS amps went 20-30k instead of 20-20k. I currently own both ADA pieces and there is something extra to them. Mosfets were billed as having infinite response times.

By the way, the MicroTube flashes the 12AX7's in front. Like flash bulbs when you turn it on. It promotes warming. Never seen that on anything else.

ADA was the best.

 

[LazerBeakShiek]

Tube flash.

 

[Folkcafe]

Tube flash.

There are probably good reasons why you never saw it on anything else. Just saying.

If you want a really deep dive into tube amps I'd suggest two books. One is Richard Kuehnel book Circuit Analysis of the Fender Bassman 5F6-A and any electrical engineering book prior to when the diode was invented, so 40's era. I gave the one I had to one of the engineers I used to work with. He now builds and restores old tube preamps and amps. He made far better use out of it than I did.

 

[snow lizard]

"Marshall has not made its traditional sound in decades. Probably leading to Marshall's death with the Code series. The JCM 800 was the one."

Really?

The JTM 45 was the first one, followed by in no specific order the JMP series of lead, bass and PA heads, plus the Marshall Major. People started modding their plexis to do various things differently so Marshall introduced the JMP 2203 and 2204 heads which were basically the plexi with the addition of a master volume and cascading gain stages in the preamp. The JCM 800 2203 is essentially the JMP 2203 with a different head shell. Throughout the '80's there were other "JCM 800" amps that followed which had the addition of things like channel switching and reverb as well as a diode clipping circuit that some people like to frown on. The Silver Jubilee is also part of the JCM 800 family, none of which sound like a 2203. If you dime the master volume on the 2203 and just use the preamp volume control it sounds very much like a Plexi. If the JCM 800 was the one, which one?

Marshall currently makes reissues of the JTM 45, 1959 SLP, 1987 50 watt, JCM 800 2203 as well as 20 watt "studio" versions modeled after the 1959, JCM 800 2203 and Silver Jubilee. With the possible exception of the Silver Jubilee, I'd say these models tend to nail the "traditional sound" easily. There are also the current JCM 900, DSL and JVM models as well as the Origin. The Origin can sound eerily close to a Plexi if you crank it up. 2203, not so much unless you throw an overdrive pedal in front of it. The other ones from the Silver Jubilee onward are designed for higher levels of gain and might not do the Plexi or 2203 thing as effectively.

 

[LazerBeakShiek]

Out of the 800, 900, DSL, and valvestates (Hybrid tech stolen from ADA(who stole it from Lee Jackson)) The 800 made the vintage Marshall tones.

Hybrids , the ADA and Lee jackson hybrids are much better than the Marshall or Fender offerings.

Figure 1985-1994. Everything after 94' is garbage.