New mesa subway amps and cabs!

[tombowlus]

Here you go:

 

[Lowendtech]

Here you go:

View attachment 3624542

Does that make it a 3 ohm cab as that seems to be the lowest impedance on the curve or do you average it out more?

 

[agedhorse]

View attachment 3624542

Thanks Tom.

Let me provide an analysis from the amplifier's point of view as this might be enlightening to those of you who are wanting to understand more about what nominal impedance means and why the actual impedance might be critical to amplifier health/safety.

Also, so there are no misunderstandings, my comments are not a violation of the CUP under any reasonable interpretation of the rules as this is a simple, factual analysis of published data, answering questions specifically as they applies to amplifier performance and safety.

If there is a different interpretation of the CUP, please discuss it with me via PM rather than jumping to conclusions, because this information and the underlying concepts are important and relevant to the specific questions I was asked regarding the impedance mode of the Subway amplifiers and which position is appropriate.

Amplifiers do 3 things simultaneously, they provide an increase in voltage (voltage amplification) an increase in current (current amplification), and must dissipate waste heat from the process of voltage and current amplification (which is called power amplification)

The load impedance primarily affects the amp's current and power parameters since these types of amps are considered "ideal voltage sources" (meaning that they have very low output impedances, so voltage doesn't change with current (or loading). There are 2 separate conditions, one for linear (class AB) amps and the other for non-linear (class D amps).

Everything (voltage, current, power, impedance) are all inter-related by Ohm's Law. If you change one, the others will change according to the equations.

For class AB amps, the most common limiting factor is power dissipation (or waste heat) in the power transistors, removing the heat from the silicon die through the package, the thermal interfaces to the heatsink and ultimately the air. It's limits are governed by the principle of safe operating area of the output stage, and this is represented by the voltage across the output transistor (not the output voltage) and the current through the device. When a speaker impedance decreases, the current increases without a change in voltage. This increases the power being dissipated across the output transistors in direct proportion to the increase in current. When the current increases by 25% (from 4 ohms to 3 ohms), the curve shifts upward with power being dissipated increasing by ~the same amount. The power dissipation curve is not a straight line but a parabolic curve while the SOA curve represents a negative parabolic(ish) shape. Under rated minimum load, there is generally not a lot of margin between the actual SOA available and the SOA capacity being used. When this is increased by 25%, it's quite possible for there to be either failure or, if lucky, activation of the SOAR (VI) limiters. Generally, SOA is the limiting factor as it's much more limited than Ic (current) capacity.

For class D amps, since they are operating non-linearly, the output stage is always in saturation or cutoff and thus the power dissipation is low BUT the current becomes the dominant limiting factor (for several technical reasons unrelated to the discussion) When the impedance drops by 25% (from 4 ohms to 3 ohms), the current increases by 25%. In the Subway amps, the 2 ohm operating mode re-scales the "voltage to current" curve of the output stage so that the load current always remains within a safe area. There is also an increase in power dissipation in the output stage but it's usually not as much of an issue as the current.

When designing output stages, the lower the load impedance, the higher the current (and power dissipation in linear amps) so costs increase. Also, the output LPF choke (in class D amps) must be able to handle the increased current and not saturate, which drives cost and size up. Generally (though each designer is different), we design with a margin of roughly 25% to accommodate normal variations/tolerances in manufacturing and components, so reducing the load by 25% is clearly risky.

Generally, power dissipation limitations are based on average power dissipation, whereas current limitations are based on short term or peak current. This is critical to the analysis.

Most designers who understand real world conditions will look at the typical load curve to determine the amount of bandwidth that is "sub-nominal" as well as how much below nominal the load represents to the amp. Looking at the published curve, a couple of things stand out as red flag hazards to a typical output stage, they are the amplitude of the sub-nominal regions and the widths of those regions.

In this curve, I see the following:

From 20Hz - 55Hz: this region of ~1.5 octaves is quite wide and occurs in an area where slappers might very well have significant program material. A HPF will help the lowest part of this but say for the D-800, the HPF of ~30hz leaves almost an octave of exposure with a load of roughly 3.25 ohms.

From 125Hz - 400Hz: this region of ~2 octaves is also quite wide, with an average impedance of roughly 3.25 ohms. A HPF won't help here, and since the bandwidth is high, it suggests that the harmonics analysis of a typical bass guitar signal might be a good idea.

For a class D amp, since the limitations are due to peak current, and since the bass signal is not a single tone but a percentage of fundamental plus harmonics, let's look at what happens when a "typical low note" is played with the above conditions.

Using a note of 55Hz (open A string), it's safe to assume (for dominant power bandwidth) that there will be about 50% fundamental, 25% first harmonic and 25% second+third harmonic of 165Hz + 220hz. Looking at the plot, the entire bandwidth of the signal will fall into regions where the cabinet is ~20% sub-nominal impedance (or ~3.25 ohms) and IMO/IME, this is risky and ill-advised, representing an illegal load. We would normally do this analysis note by note (via a spreadsheet) for a speaker to assess the aggregate stress that the amp experiences. I do this with every speaker I design, and now you can see why it's important.

If you were to play a higher note such as 100Hz, 50% of the signal (the fundamental) will fall outside the sub-nominal range, but 50% would still be sub-nominal... risky but not AS risky.

Given the data published, as an amp designer I would absolutely consider this a 2 ohm nominal cabinet, it could also be considered a 3 ohm nominal cabinet (though 3 ohms is not one of the typical nominal values used), which is why I strongly suggested that the 2 ohm mode on the amp be used. While the amp will generally protect itself from overcurrent events like this, no protection circuits are 100% effective.

Hope this helps with why these kinds of details are so important from an amp designer's perspective. It's not as simple, or as easy is it seems, but that doesn't make it not important either.

 

[RudyTardy]

Ladies and gentleman, @agedhorse just took all of us back to school. Does Talkbass bestow honorary PhDs?

 

[9mmMike]

Any amazing Christmas sales on the Mesa cabs.....anywhere?

 

[pfschim]

Any amazing Christmas sales on the Mesa cabs.....anywhere?

hate to be the one who says it, but sales generally don't happen with Mesa gear unless a retailer has decided to make an unusual offer on a specific piece (very rare), or a demo/used piece. Similar to Apple products, the only thing I have seen retailers do is to offer a gift card on the purchase which, if you accept the premise, would net you a lower overall price, but you still pay the MSRP.

 

[Lowendtech]

Thanks Tom.

Let me provide an analysis from the amplifier's point of view as this might be enlightening to those of you who are wanting to understand more about what nominal impedance means and why the actual impedance might be critical to amplifier health/safety.

Also, so there are no misunderstandings, my comments are not a violation of the CUP under any reasonable interpretation of the rules as this is a simple, factual analysis of published data, answering questions specifically as they applies to amplifier performance and safety.

If there is a different interpretation of the CUP, please discuss it with me via PM rather than jumping to conclusions, because this information and the underlying concepts are important and relevant to the specific questions I was asked regarding the impedance mode of the Subway amplifiers and which position is appropriate.

Amplifiers do 3 things simultaneously, they provide an increase in voltage (voltage amplification) an increase in current (current amplification), and must dissipate waste heat from the process of voltage and current amplification (which is called power amplification)

The load impedance primarily affects the amp's current and power parameters since these types of amps are considered "ideal voltage sources" (meaning that they have very low output impedances, so voltage doesn't change with current (or loading). There are 2 separate conditions, one for linear (class AB) amps and the other for non-linear (class D amps).

Everything (voltage, current, power, impedance) are all inter-related by Ohm's Law. If you change one, the others will change according to the equations.

For class AB amps, the most common limiting factor is power dissipation (or waste heat) in the power transistors, removing the heat from the silicon die through the package, the thermal interfaces to the heatsink and ultimately the air. It's limits are governed by the principle of safe operating area of the output stage, and this is represented by the voltage across the output transistor (not the output voltage) and the current through the device. When a speaker impedance decreases, the current increases without a change in voltage. This increases the power being dissipated across the output transistors in direct proportion to the increase in current. When the current increases by 25% (from 4 ohms to 3 ohms), the curve shifts upward with power being dissipated increasing by ~the same amount. The power dissipation curve is not a straight line but a parabolic curve while the SOA curve represents a negative parabolic(ish) shape. Under rated minimum load, there is generally not a lot of margin between the actual SOA available and the SOA capacity being used. When this is increased by 25%, it's quite possible for there to be either failure or, if lucky, activation of the SOAR (VI) limiters. Generally, SOA is the limiting factor as it's much more limited than Ic (current) capacity.

For class D amps, since they are operating non-linearly, the output stage is always in saturation or cutoff and thus the power dissipation is low BUT the current becomes the dominant limiting factor (for several technical reasons unrelated to the discussion) When the impedance drops by 25% (from 4 ohms to 3 ohms), the current increases by 25%. In the Subway amps, the 2 ohm operating mode re-scales the "voltage to current" curve of the output stage so that the load current always remains within a safe area. There is also an increase in power dissipation in the output stage but it's usually not as much of an issue as the current.

When designing output stages, the lower the load impedance, the higher the current (and power dissipation in linear amps) so costs increase. Also, the output LPF choke (in class D amps) must be able to handle the increased current and not saturate, which drives cost and size up. Generally (though each designer is different), we design with a margin of roughly 25% to accommodate normal variations/tolerances in manufacturing and components, so reducing the load by 25% is clearly risky.

Generally, power dissipation limitations are based on average power dissipation, whereas current limitations are based on short term or peak current. This is critical to the analysis.

Most designers who understand real world conditions will look at the typical load curve to determine the amount of bandwidth that is "sub-nominal" as well as how much below nominal the load represents to the amp. Looking at the published curve, a couple of things stand out as red flag hazards to a typical output stage, they are the amplitude of the sub-nominal regions and the widths of those regions.

In this curve, I see the following:

From 20Hz - 55Hz: this region of ~1.5 octaves is quite wide and occurs in an area where slappers might very well have significant program material. A HPF will help the lowest part of this but say for the D-800, the HPF of ~30hz leaves almost an octave of exposure with a load of roughly 3.25 ohms.

From 125Hz - 400Hz: this region of ~2 octaves is also quite wide, with an average impedance of roughly 3.25 ohms. A HPF won't help here, and since the bandwidth is high, it suggests that the harmonics analysis of a typical bass guitar signal might be a good idea.

For a class D amp, since the limitations are due to peak current, and since the bass signal is not a single tone but a percentage of fundamental plus harmonics, let's look at what happens when a "typical low note" is played with the above conditions.

Using a note of 55Hz (open A string), it's safe to assume (for dominant power bandwidth) that there will be about 50% fundamental, 25% first harmonic and 25% second+third harmonic of 165Hz + 220hz. Looking at the plot, the entire bandwidth of the signal will fall into regions where the cabinet is ~20% sub-nominal impedance (or ~3.25 ohms) and IMO/IME, this is risky and ill-advised, representing an illegal load. We would normally do this analysis note by note (via a spreadsheet) for a speaker to assess the aggregate stress that the amp experiences. I do this with every speaker I design, and now you can see why it's important.

If you were to play a higher note such as 100Hz, 50% of the signal (the fundamental) will fall outside the sub-nominal range, but 50% would still be sub-nominal... risky but not AS risky.

Given the data published, as an amp designer I would absolutely consider this a 2 ohm nominal cabinet, it could also be considered a 3 ohm nominal cabinet (though 3 ohms is not one of the typical nominal values used), which is why I strongly suggested that the 2 ohm mode on the amp be used. While the amp will generally protect itself from overcurrent events like this, no protection circuits are 100% effective.

Hope this helps with why these kinds of details are so important from an amp designer's perspective. It's not as simple, or as easy is it seems, but that doesn't make it not important either.

Thank you Andy. You are an invaluable resource for we on TB.
On top of that, a scholarly gentleman to boot.
The detailed “lesson” is much appreciated.

 

[Element Zero]

hate to be the one who says it, but sales generally don't happen with Mesa gear unless a retailer has decided to make an unusual offer on a specific piece (very rare), or a demo/used piece. Similar to Apple products, the only thing I have seen retailers do is to offer a gift card on the purchase which, if you accept the premise, would net you a lower overall price, but you still pay the MSRP.

Unless you’re GC and whore out a bunch of H code gear... perhaps why they don’t carry them anymore...

 

[/\/\3phist0]

Thanks Tom.

Let me provide an analysis from the amplifier's point of view as this might be enlightening to those of you who are wanting to understand more about what nominal impedance means and why the actual impedance might be critical to amplifier health/safety.

Also, so there are no misunderstandings, my comments are not a violation of the CUP under any reasonable interpretation of the rules as this is a simple, factual analysis of published data, answering questions specifically as they applies to amplifier performance and safety.

If there is a different interpretation of the CUP, please discuss it with me via PM rather than jumping to conclusions, because this information and the underlying concepts are important and relevant to the specific questions I was asked regarding the impedance mode of the Subway amplifiers and which position is appropriate.

Amplifiers do 3 things simultaneously, they provide an increase in voltage (voltage amplification) an increase in current (current amplification), and must dissipate waste heat from the process of voltage and current amplification (which is called power amplification)

The load impedance primarily affects the amp's current and power parameters since these types of amps are considered "ideal voltage sources" (meaning that they have very low output impedances, so voltage doesn't change with current (or loading). There are 2 separate conditions, one for linear (class AB) amps and the other for non-linear (class D amps).

Everything (voltage, current, power, impedance) are all inter-related by Ohm's Law. If you change one, the others will change according to the equations.

For class AB amps, the most common limiting factor is power dissipation (or waste heat) in the power transistors, removing the heat from the silicon die through the package, the thermal interfaces to the heatsink and ultimately the air. It's limits are governed by the principle of safe operating area of the output stage, and this is represented by the voltage across the output transistor (not the output voltage) and the current through the device. When a speaker impedance decreases, the current increases without a change in voltage. This increases the power being dissipated across the output transistors in direct proportion to the increase in current. When the current increases by 25% (from 4 ohms to 3 ohms), the curve shifts upward with power being dissipated increasing by ~the same amount. The power dissipation curve is not a straight line but a parabolic curve while the SOA curve represents a negative parabolic(ish) shape. Under rated minimum load, there is generally not a lot of margin between the actual SOA available and the SOA capacity being used. When this is increased by 25%, it's quite possible for there to be either failure or, if lucky, activation of the SOAR (VI) limiters. Generally, SOA is the limiting factor as it's much more limited than Ic (current) capacity.

For class D amps, since they are operating non-linearly, the output stage is always in saturation or cutoff and thus the power dissipation is low BUT the current becomes the dominant limiting factor (for several technical reasons unrelated to the discussion) When the impedance drops by 25% (from 4 ohms to 3 ohms), the current increases by 25%. In the Subway amps, the 2 ohm operating mode re-scales the "voltage to current" curve of the output stage so that the load current always remains within a safe area. There is also an increase in power dissipation in the output stage but it's usually not as much of an issue as the current.

When designing output stages, the lower the load impedance, the higher the current (and power dissipation in linear amps) so costs increase. Also, the output LPF choke (in class D amps) must be able to handle the increased current and not saturate, which drives cost and size up. Generally (though each designer is different), we design with a margin of roughly 25% to accommodate normal variations/tolerances in manufacturing and components, so reducing the load by 25% is clearly risky.

Generally, power dissipation limitations are based on average power dissipation, whereas current limitations are based on short term or peak current. This is critical to the analysis.

Most designers who understand real world conditions will look at the typical load curve to determine the amount of bandwidth that is "sub-nominal" as well as how much below nominal the load represents to the amp. Looking at the published curve, a couple of things stand out as red flag hazards to a typical output stage, they are the amplitude of the sub-nominal regions and the widths of those regions.

In this curve, I see the following:

From 20Hz - 55Hz: this region of ~1.5 octaves is quite wide and occurs in an area where slappers might very well have significant program material. A HPF will help the lowest part of this but say for the D-800, the HPF of ~30hz leaves almost an octave of exposure with a load of roughly 3.25 ohms.

From 125Hz - 400Hz: this region of ~2 octaves is also quite wide, with an average impedance of roughly 3.25 ohms. A HPF won't help here, and since the bandwidth is high, it suggests that the harmonics analysis of a typical bass guitar signal might be a good idea.

For a class D amp, since the limitations are due to peak current, and since the bass signal is not a single tone but a percentage of fundamental plus harmonics, let's look at what happens when a "typical low note" is played with the above conditions.

Using a note of 55Hz (open A string), it's safe to assume (for dominant power bandwidth) that there will be about 50% fundamental, 25% first harmonic and 25% second+third harmonic of 165Hz + 220hz. Looking at the plot, the entire bandwidth of the signal will fall into regions where the cabinet is ~20% sub-nominal impedance (or ~3.25 ohms) and IMO/IME, this is risky and ill-advised, representing an illegal load. We would normally do this analysis note by note (via a spreadsheet) for a speaker to assess the aggregate stress that the amp experiences. I do this with every speaker I design, and now you can see why it's important.

If you were to play a higher note such as 100Hz, 50% of the signal (the fundamental) will fall outside the sub-nominal range, but 50% would still be sub-nominal... risky but not AS risky.

Given the data published, as an amp designer I would absolutely consider this a 2 ohm nominal cabinet, it could also be considered a 3 ohm nominal cabinet (though 3 ohms is not one of the typical nominal values used), which is why I strongly suggested that the 2 ohm mode on the amp be used. While the amp will generally protect itself from overcurrent events like this, no protection circuits are 100% effective.

Hope this helps with why these kinds of details are so important from an amp designer's perspective. It's not as simple, or as easy is it seems, but that doesn't make it not important either.

I am enlightened, and appreciate the summarized, layman language deep dive explanation. You are incredibly generous with your accumulated knowledge , and experience.
Thanks for the effort I for one greatly appreciate it.

 

[pickles]

In other words, its a 3 ohm cab. Unsurprisingly.

 

[agedhorse]

Except, it's surprisingly labeled as a 4ohm cabinet.

• Connect 2 of those together in parallel for a resulting 1.5ohm impedance, below the more typical 2ohm impedance

• Even using just 1 cabinet, it results in 3-ohm impedance that is lower than many amp ratings of 4ohms

Either way, possibly be surprised at what happens to your amp in terms of its performance, reliability, and longevity?

This is one reason why amp designers have to spend so much time, effort and cost of developing and implementing effective protection circuits. The costs are necessary and of course get passed onto the consumer.

It should be noted that while the better protection circuits are quite effective, they are not foolproof.

 

[mmbass21]

I've personally used a mix of 4 ohm and 8 ohm barefaced cabs with my WD set at 2 ohms and was reassured by email from Alex that it's safe for the cab and amp. I kept that email for "just in case".

Now I know absolutely nothing in regards technical data from cabs to amps and their inner workings. This is probably better served in the barefaced thread but since Andy is always on point I have this question. The cab we're talking about is a Two10s which is switchable from 4 to 12 ohms. Their older model the Two10 is just a 4 ohm cab. You can buy a conversion kit to make the cab switchable like the newer "S" model. How would this conversion kit do such a thing if this is really a 3 ohm cab? Again I'm clueless and looking for an education on this subject matter.

 

[pickles]

It switches between 3 and 12 ohms. Because it has two 6 ohm drivers. Alex wrote a 4 on it instead of a 3 because it would be difficult to sell a 3 ohm cab and he thinks its “ok”.

FWIW they are great sounding cabs and I have not seen any threads about blown up amps. But personally I would consider it a 3 ohm cab and act accordingly.

 

[Rodslinger]

Friend/bassist from another band brought his Mesa WD 800 to our practice last night. I run (on regular) my Ampeg svt 7 or 4 Pro head and last night I A/B tested the WD800 against the SVT 7 Pro through my Ampeg 810. Played through most of the set with the 7Pro. Hooked up the WD800 and the looks on everyone’s faces was priceless. We were all kind of floored. Much booty to be had and very mid forward like I love. Went back and forth between the two for an hour or so. Everyone loved the WD800 just as much as the 7pro if not a bit more. As my drummer put it, “the WD800 doesn’t have that BUTTER, all over the tone like the 7Pro does. Just doesn’t have those thick thighs lol” and the notes just didn’t seem to hold together or were as cohesive like they were on the 7Pro. I said maybe if I put a compressor pedal in front of the WD800 to add some sustain and note to note evenness. I’m very tempted to buy a WD800. I’m very heavy handed and play quite aggressively. I’ve always used compression and it’s generally built into the amps I use. Has anyone run a compressor pedal with the WD800? If so how well did they work together?

 

[mmbass21]

Friend/bassist from another band brought his Mesa WD 800 to our practice last night. I run (on regular) my Ampeg svt 7 or 4 Pro head and last night I A/B tested the WD800 against the SVT 7 Pro through my Ampeg 810. Played through most of the set with the 7Pro. Hooked up the WD800 and the looks on everyone’s faces was priceless. We were all kind of floored. Much booty to be had and very mid forward like I love. Went back and forth between the two for an hour or so. Everyone loved the WD800 just as much as the 7pro if not a bit more. As my drummer put it, “the WD800 doesn’t have that BUTTER, all over the tone like the 7Pro does. Just doesn’t have those thick thighs lol” and the notes just didn’t seem to hold together or were as cohesive like they were on the 7Pro. I said maybe if I put a compressor pedal in front of the WD800 to add some sustain and note to note evenness. I’m very tempted to buy a WD800. I’m very heavy handed and play quite aggressively. I’ve always used compression and it’s generally built into the amps I use. Has anyone run a compressor pedal with the WD800? If so how well did they work together?

I always run the Ovnifx Smoothie which is the best compressor I've ever had with my WD and any other amp I've owned. You definitely need to play around with the eq more on the WD. There is plenty of girth to be had with tinkering with the damper control and HPF. I'd bet the HPF was set higher than maybe you're used to hearing creating more articulation than the 7 Pro at the time.

 

[Jackass76]

Has anyone had a chance to try out a Subway 4x10? I have asked a few times, but it seems like they are an elusive unit...I'm still on the fence of getting one...the 55 pound 410 that can handle the D800+ sounds awesome to me...I have the TPH 610 and love it, but at 2x+ the weight, it's making me consider the SW410...

I just don't know how it compares...and there are zero review video reviews out there of it. Even Mesa pulled their's...

Thanks in advance!

 

[DrThumpenstein]

Works beautifully with my Markbass Compressore. It's a tube compressor that can add some warmth when the gain is cranked, which I used to do when I played through a more sterile sounding amp.

But now I just use light compression and set the release for more sustain, and dial that fat tubalicious WD to whatever level of warmth and breakup I need. Others have weighed in on different compressors and the WD seems to play nice with them too.

I tried putting the Compressore through the effects loop but I didn't care for it there. I have it last in my (short) chain and it gives me just what I need.

 

[IvanBassist]

Friend/bassist from another band brought his Mesa WD 800 to our practice last night. I run (on regular) my Ampeg svt 7 or 4 Pro head and last night I A/B tested the WD800 against the SVT 7 Pro through my Ampeg 810. Played through most of the set with the 7Pro. Hooked up the WD800 and the looks on everyone’s faces was priceless. We were all kind of floored. Much booty to be had and very mid forward like I love. Went back and forth between the two for an hour or so. Everyone loved the WD800 just as much as the 7pro if not a bit more. As my drummer put it, “the WD800 doesn’t have that BUTTER, all over the tone like the 7Pro does. Just doesn’t have those thick thighs lol” and the notes just didn’t seem to hold together or were as cohesive like they were on the 7Pro. I said maybe if I put a compressor pedal in front of the WD800 to add some sustain and note to note evenness. I’m very tempted to buy a WD800. I’m very heavy handed and play quite aggressively. I’ve always used compression and it’s generally built into the amps I use. Has anyone run a compressor pedal with the WD800? If so how well did they work together?

I'm using an origin effects cali compact bass in front of my WD-800. I'm gonna be doing a video review on that pedal early next year and the tone you'll hear will be going through the DI out of the amp. That might help you with the decision

How were you running the gain on the WD? You can get a very different and more tube-like character out of the amp by pushing the input gain a bit

 

[Rodslinger]

I'm using an origin effects cali compact bass in front of my WD-800. I'm gonna be doing a video review on that pedal early next year and the tone you'll hear will be going through the DI out of the amp. That might help you with the decision

How were you running the gain on the WD? You can get a very different and more tube-like character out of the amp by pushing the input gain a bit

I was pushing the gain right before clip. Didn’t want to run it like a mad man since it wasn’t my amp

 

[Rodslinger]

Works beautifully with my Markbass Compressore. It's a tube compressor that can add some warmth when the gain is cranked, which I used to do when I played through a more sterile sounding amp.

But now I just use light compression and set the release for more sustain, and dial that fat tubalicious WD to whatever level of warmth and breakup I need. Others have weighed in on different compressors and the WD seems to play nice with them too.

I tried putting the Compressore through the effects loop but I didn't care for it there. I have it last in my (short) chain and it gives me just what I need.

Nice! I use to have that same compressor. Loved to actual tube warmth.