Chienmortbb

19 minutes ago, PaulWarning said:

Finally, proof that Trace Elliot amps really do go louder

 

Ha someone has obviously fitted extra MOSFETs. 

16 minutes ago, funkle said:

I’ll document the final texture layers as best as I can. 

I sanded off the front edges and repainted with paint brush a few times. Much better. 

This stuff is very tough to sand though! I’m convinced of its durability.

Having gigged my cab for two years I can confirm it is durable. 

26 minutes ago, stevie said:

I suspect 8.4V is enough for most purposes. I wonder if the rechargeable lithium batteries last longer than non- rechargeable alkalines. It wouldn't surprise me.

Hard to say as no manufacturer, that I know of, publishes battery capacity for non-rechargeable batteries. 

Who wants to be Technical? Well nobody does really but as others have said, there are too many other variables to take account to just say a 4x10 is louder than a 1x15.

Efficiency, Xmax, impedance and many more impact the perceived loudness/volume of a cabinet. Is it sealed, ported or some form of horn? 

It is like saying a 3.5 litre car is faster than a 1 litre. Put the 3.5 litre engine in a Hummer and my 1.0 litre Turbocharged Suzuki will our accelerate and have a higher top speed. 

What you can say is that is 4 10” drivers should be louder than a single 15” if they are in similar cabinets and the drivers are of similar quality. 

4 hours ago, funkle said:

Did the felt. Didn’t glue on the bottom parts yet, but cut them so they are ready to go. 

From the front:

Looking through the woofer hole:

Looking up to the top left of the cabinet:

And over to the right and up:

As per Stevie, there’s no felt above the upper brace except on the left hand panel. The port and its surrounding area are to have no damping material. 

The felt needs sharp scissors, but once cut, can lose tufts easily. I treated it carefully. 

Once I can glue in the bottom bits, it will look like this:

I need to buy the battens tomorrow, and get some scrap wood to practice painting on. 

Battens? 

10 minutes ago, funkle said:

Ah, nice one. I’ve just taken the clamps off and there are very slight depressions. I’ll try the water trick. 

I need to see if there are any gaps which need filled after all the hi jinks. Probably not, but even a very small defect should be filled; paint doesn’t hide gaps.

I’ll start sanding when I can after that. I also need to start experimenting with Tuffcab and different rollers/ways of applying it. I need to practice on scrap first. Stevie has already given me some useful tips on using it. 

PVA is not a great gap filler but works well if mixed with sawdust. However I suspect you will have few gaps. 

I also sealed the rounded corners with PVA as TuffCab adheres well to it. I fact I might well prime the whole cab with it when I build mine, although I might still cover it with some form of vinyl. 

Damp cloth over the top and an iron works  as well. 

As for the clamping, ,you can over tighten and the glue does not need megatons of pressure. 

If you are short of clamps, put one in the centre with a sacrificial piece of wood stretching the length of the cab. This will apply pressure to both ends. 

Funkle, you can get a really good rounded edge just with a sander. I tried it first on the prototype and had the same results on the alpha builds that Stevie and I did. We both got really good results. 

Yes that’s the one. 

On 10/08/2019 at 20:46, markdavid said:

To be fair pretty much any flatwound will be brighter than picato which are about the darkest flat out there, Chrome's are bright for a flatwound, people say TIs are but tbh I don't hear it, Cobalt's I can't recommend as they are a flat that is made with the purpose of sounding like a roundwound, don't see the point.

I find Fender (mad by d ' addario) very muddy sounding esp compared to Picato. The must be made to Fender pecs as I found the .same with Fender made flats.  They also manage to put the change in diameter from the wrap to full diameter n the E just at the machine head of my Fender bass, so are a bugger to tune.

My Trustfire also measures a tad over 8.4V fully charged.

On 23/08/2019 at 11:25, hooky_lowdown said:

Check out the Acoustic (brand) forum's, where experts, including engineers who actually made them can answer questions you may have.

I've owned a couple of old Acoustic amp heads and they are far, far, far louder than equivalent modern watts.

The 361 head was rated at 200W, but no impedance was stated. It was sold as a system with the folded horn cabinet ( again no impedance stated). The secret ( in my opinion) is the folded horn cabinet. Compared to a modern ported/ bass reflex design it should be 3-10dB more sensitive. 3dB is the equivalent of doubling the amplifier power ( but not be significantly louder). 10dB would be twice as loud but equivalent to an amplifier power of ten times.

The 361 would be lower powered than the 250W Trace Heads and ( possibly) slightly higher powered than the 150/130W variants BUT the difference would be barely audible.

I will go to the forums but there is no magic.

20 hours ago, hooky_lowdown said:

Do some research my friend. 

45 Years as a Electronics Engineer involved lots of research but I am always willing to learn. Point me to your sources and I will gladly study it.

On 20/08/2019 at 18:58, hooky_lowdown said:

Old solid state watts are not the same as newer one's. I recall the very old Acoustic (brand) SS amps were rated comparable to tube watts. So a 100w Acoustic amp head was as powerful as a 100w tube head = bl**dy loud! A 100w head these days = fart.

Smoke and mirrors my friend, smoke and mirrors.

On 19/08/2019 at 09:14, EBS_freak said:

My hero. At last somebody else is in agreement with me!

The only thing going for the 58 is the fact that every engineer worth their salt knows how to eq out their deficiencies. I’d rather take a 935 over a 58 if we are going bog standard dynamics.

I agree entirely the Sennheiser range as a whole are good the and 935 in particular, but the Sontronics  SOLO is now my go to Mic. 

16 hours ago, Stub Mandrel said:

Old (analogue) Trace amps are conservatively rated for RMS not 'music power' or any other such misleading calculation, and have big hefty transformers with reasonable regulation. They also use a design for the power amps that gives hi-fi levels of quality, so you get maximum headroom with minimal distortion, possibly less than 0.1% at rated output.

<Just looked carefully at my amp and see I've been talking bollocks so I'm editing this>

I'd assumed it was a 150W amp because (1) everyone knows the 1110 combo was 150W and (2) the transformer is marked 39V 0 39V - the later AH150 was rated as 40-0-40 AC input.

But I was just musing at how big the transformer is when I noticed the amp isn't actually powered from the 39V terminals, but from a pair marked 50V.

That explains why the DC rails are at 69 - 0 - 69V.

This probably also explains why a 150 watt amp is so loud...

 

So... this amp is a very early 1110 combo, it has a MPB2 PCB marked 'Issue 2', with two mosfets and a fan.

The issue 4 AH150 board has FOUR mosfets, 40-0-40V supply and no fan.

The Issue 4 AH250 board has four mosfets, 46-0-46V supply and a fan.

 

At the least I am tempted to add  another pair of mosfets... they can drop straight into the board.

 

 

I found the sane thing when I had a BLX130? The board was just asking for another pair of mosfets and, if I remember rightly, two resistors. 

I managed to get in touch with Trustfire and their 9V batteries are nominally 8.4V too. Although lower than a real 9V battery the 550mah capacity is 2-3 times more that a NiMh battery. I also have one in order so will report back soon. 

On 12/08/2019 at 18:07, bazzbass said:

the cardiod pattern is different too iirc iinm

I might very well be  but I believe anything around the capsule will affect the axial response. 

 I have recently been using a Sontronics SOLO. And it is great for cab mic’ing  and vocals. 

g and vocals

On 02/08/2019 at 16:33, EBS_freak said:

Meh. You don't use instrument mics on instruments if you are rock n roll.

Haha I would not use a SM58 for vocals. It may be a standard but the standard was quite low when they were designed, 

9 hours ago, LukeFRC said:

Does that extra resistance add anything to the sound? Like gentle compression of some kind?

Yes a MOSFET acts more like a valve and compresses when pushed ina pleasing way. I think some people that say they love Class A/B mean MOSFET A/B. 

9 hours ago, Telebass said:

They are not equivalent. You might well be able to plug them straight in and bias them up to work well, but they are not the same tube at all.

I don’t  anyone was deliberately trying to mislead and that includes Blackstar, I they could have chosen EL34, KT66, KT77, KT88 6550 or 6L6. The 6550 is probably more we’ll lnowm that any of the others all over the world ye to American influence and immediately gives the end user in indication of  “valvey warmness”. 

I have not touched valves for years but from memory the KT88’s properly (or maybe improperly for hifi purists) biased could outperform all the rest but some preferred the way the 6550 sounded when pushed hard. 

28 minutes ago, ped said:

I wonder why Blackstar (British) chose to use the American valve names (6550 instead of KT88 for example)

Bigger market. For what its worth the KT88 is a monster and I don't like valves. Thanks for the mini review by the way. IT is a shame that some music shops stock the Blackstar guitar range but not the Bass range ( Absolute Music are you watching?).

MOSFETS have as number of advantages over bi-polar transistors especially as they act more like thermionic valves in mnay ways. They are also inherently safe. That is as temperature increases, the MOSFET will become more resistive, reducing the output current and hence dissipation and heat. Bi-Polar transistors allow more current to pass as they get hotter and can suffer from  thermal runaway until they go pop. The downside is that  the power supply voltage for a MOSFET amp needs needs to be higher for a given output. So you need a beefier power supply but if there is enough available it might have a bit more real ,p[ower available at volume but as I always say, a watt is a watt so if they were louder then there must be some way to measure it.

33 minutes ago, SubsonicSimpleton said:

Although Trace made a range of amps badged with different ratings, if you inspected the actual amp modules inside the heads you might just find that they had a practice of putting higher rated modules into lower output badged amps to meet production targets - economies of scale would have made a big difference to their bottom line, and it's important to remember that Trace were not manufacturing on the same scale as Fender/Hartke/Ampeg/Marshall.

Many of their amps were designed around MOSFET output stages and these were easy to scale up to higher powers. The BLX130 that I had spaces for extra output MOSFETs suggesting that the same  PCB was used for a number of models. 

As electronics engineer I must say they  well engineered, maybe over engineered,  by the standards of the time. 

1 hour ago, wateroftyne said:

It’s a class A/B thing, not exclusively Trace.

Edit: Tube too.

I went off ‘Diet watts’ a while ago.

The thing is that when discussing many things with religious zealots you get the same mantra over and over again. There are good amps and bad amps . Some people like bad amps. some like bad backs. The point is that it is the design than counts NOT the technology. Oh and having worked on a few. Trace amps were really well designed.