agedhorse

Yes, in part because speakers were being discussed within this thread as well and the combined measurements of speakers and amps tend to go hand in hand with these discussions.

Yes, you want to be VERY careful with bridged amps, and most class D amps are internally bridged. Most are not protected from a short between 1/2 of the output bridge and ground, this is not the normal way a fault occurs on a speaker out, the protection typically looks at either 1/2 of the bridge or (indirectly) the difference in current between the two halves of the bridge. Also, the level is (or can be) higher than many scopes can handle. This is a common way folks who are new to testing, or are new to electronics, or do electronics as a hobby destroy their laptops or interface (depending on where the interface is located). The fault is large enough that it typically lets the magic smoke out pretty instantaneously and catastrophically. I've been testing class D amps professionally for over 20 years, there are a lot of necessary tricks to get good results and data, especially power and THD data (depending on the modulation scheme and output reconstruction filter type). It's harder than it looks, especially if the numbers need to be accurate.

Beware that it's MUCH easier said than done. It's common for folks who do not do this all the time, with a setup that allows for anechoic measurements 1/2-space measurements (1/2-space is most commonly used for stage speakers because that's the closest approximation of the real world environment) to have errors of between 3 and 6dB SPL. Then they go proclaiming things that are simply not true because they have drawn conclusions based of incorrect and/or inaccurate data, which is unfair to everyone.

What is magnetic plywood?

You have to remember that we are primarily a tube guitar amp company and the marketing/website folks use a template that describes the output stage by what tubes are used (or no tubes at all, which would then be in the case of all the new bass amps "class D" because nobody uses power amp tubes in class D amps). When we used class AB output stages in bass amps, it was described as MOSFET - class AB It's assumed that players purchasing this level of equipment will understand this, and have done their homework by doing at least a little bit of research. There are numerous reviews, videos, forum discussions and even the owner's manual is available on line. In the back of the owner's manual is a tutorial on what class D is and how it works. We even discuss switchmode power supplies. I don't think it's misleading, and in fact in the entire 8 years of the Subway line this is the first time this has come up.

I am going to respond assuming that you have grossly misunderstood the manual rather than being intentionally disrespectful. The manual is crystal clear and accurate in its description of what the amp is and how it works. There is also a block diagram in the back that clearly shows the signal paths throughout the amp. There are also extensive specifications published at the end of the manual. The TT-800 is a 2 channel preamp, with a Boogie channel and a Subway channel. Both channels are tube driven and have tube gain stages. There is switching between the two channels, which then drive an 800 watt RMS class D power amp. If you are looking for an overdriven tone, I would suggest the Boogie channel to start, be sure the gain switch is in the high gain position, start with the channel master at the 9:00 position, all of the eq controls at noon, the high pass filter set to the 10:00 position, and turn the gain up until you hear the overdriven tone. Once you get this, use the channel master volume to set the overall volume of the overdrive tone. This is a starting point. If you have a low output bass or the setup of the bass had greater pole clearance than stock, or you have a light touch, you may not get as much overdrive as another bass with higher output. This channel has roughly the same gain structure as the Bass 400. That said, if this is confusing to you, or you continue to have difficulty understanding this amp, it simply may not be the right amp for you. It’s not as simple as other amps on the market (including the other amps in the Subway line) Another thing you can do is follow the sample settings page, but for overdriven tones, these settings were developed with specific bass types more commonly associated with overdriven and distorted tones. Hope this helps.

Correct, these amps are WAY too much power for any commercially available power attenuator on the market. Also, some attenuators are NOT isolated from common signal ground, which means that on a bridged (BLT) amp, it's possible to short 1/2 of the amp and damage it. No tube guitar amp has this configuration, so a common ground won't hurt anything (except may be a little noisy)

The ShuttleMax was (and still is) a very popular model. Most players didn’t have a problem understanding it.

All of the above. They are all different and more likely the cause of problems than the quality of the components themselves IME.

Could it also be that the designs aren't as good?

It’s very unusual for the mute switch to fail. Possible, but I haven’t seen one in over 10 years. I believe I do have the 5 button footswitches in stock, do you have someone here in the states that could be a domestic shipping address? They are $75 USD plus shipping,

Aguilar did derate the output of the modules, the rating is 250 watts at 8 ohms and 500 watts at 4 ohms to prevent OC or thermal shutdown. It's tricky to get more power out of these parts without really understanding what's going on under the hood, but if you do there's a ton of off sheet potential that can be exploited. I hold a US patent that specifically addresses this (and with this module specifically but the patent applies to the techniques which apply in general, which means that others couldn't use this approach without licensing in from the company we assigned it to.

Nope, all the parts of the module factor into this. In fact the power supply is likely the less likely part.

It’s not uncommon to get AC mains frequency feed-through noise on generic power supplies. Can you return it if it doesn’t work out?

On the D-800, use the Aux input and be sure to use a tip-sleeve cable, this will bypass the D-800 preamp.

When dealing with servicing, generally there's either a declaration or specific harmonized code for a product being returned for factory service when you send it to the factory, and they will use a similar code or declaration when returning it to you. If there is a charge to you, then there may be duty and/or VAT on that charge but not on the entire value of the amp.

Both of the two speaker output terminals are not at ground potential, so when one of these terminals (say the shell/barrel of a 1/4" plug) touches ANY ground including the chassis, it shorts that amplifier to ground. Depending on how the protection circuit is designed, it can damage one or both channels pretty much instantly. The shell/barrel of the 1/4" plug is not at ground but is a driven connection. On high powered amps this can be a shock hazard, though generally you won't get injured unless you are surprised and jump backwards into something else. On very large amps, the shock can certainly hurt. As long as nothing grounded (another cable plug that's ground referenced) happens to touch the shell/barrel of the bridged amp's output plug. Then it's a short circuit and the amp can be damaged.

It’s not 2kW rms like most other amps/brands are rated. From the AC input power and the calculations used by the safety agencies, it calculates to between 650 and 709 watts rms. I explained these calculations and then did them in another thread.

The version is not 94V0, that's the flame spread rating of the PCB! This amp is difficult to repair, it generally costs as much to repair as it does to replace the main PCB, which is why Ampeg offers this as a repair part.

Naaah, just correcting scrumpymike's post in the event that somebody reads it and is confused.

Actually, it does not say this in the instant gratification section. It says to start at 1:00 on the channel masters. It’s also a full 2 channel amp, so the master volume controls are used to balance between the two channels for channel switching purposes. In the feature set descriptions, it clearly describes decreasing the channel master when using high gain settings and increasing the channel master when using lower gain settings. All of the controls operate as described throughout the manual, and provide the expected results. Features that are unique or unusual (like the symmetry control) are described in detail, which is why I always recommend to spend some time reading and understanding the owner’s manual. A lot of time and effort go into writing good ones. What does the Handbox owner’s manual say about the operation of the master control?

I posted this over on TalkBass in response to jb90’s comments, but I think it’s applicable here as well: My feeling is that one benefit of a public forum is an open discussion of both the benefits AND drawbacks of a piece of equipment, as well as potential challenges in learning how to operate a new piece of gear. Everyone benefits from these kinds of discussions provided they remain civil and respectful. What is not cool is when the discussions evolve into accusations based on incorrect information leading to false accusatory conclusions. Life is not all “glitter and unicorns”, there are going to be issues with any new gear. To avoid such discussions really do the community a disservice in the bigger picture IMO

This is simply not true in general. Tube amps do not have a problem with low master volume control settings unless that is an inherent part of a specific design, in which case suggests that a master volume control should not be included if it’s not intended to be used as such.

I’m sorry, since this is a bass forum I thought you intended to use the sub as a bass amp/cab full range. For its intended use, as a pa sub under tops, it’s fine.

The cabinet cuts off between 100 & 200 Hz based on the crossover control. It’s unsuitable as a bass guitar speaker without a full range cabinet to cover above the HF cutoff of the sub cabinet