Mesa Subway D-350!

[agedhorse]

It's a volume control between source (Airport Express) and the power amp. It's in a modified Fostex PC1/e which acts both the volume control and a 3.5 aux to RCA splitter. I like an analog volume control rather than a digital slider.

All properly designed products include volume controls. I’m completely not following this.

 

[MCF]

I'd also like to add, that while my post was pretentious, i seriously doubt that many here nerd out on amps the way I do. There really isn't a need to with instrument Amps. You like the way they sound or you don't.
I doubt the "average" user here is clamping amps or running frequency and distortion analysis.
I do it because it's almost habit at this point. (and fun).
I begin to see patterns. I can begin to see what qualities I find pleasing, while also finding things I don't like. (Certian order harmonic distortions I can tolerate on some amps and not so much on others. I dont find odd order distortion is always the enemy with a bass amp, depending on the amps overall character)
I tend towards clean amps though as I find them predictable. I can always add flavor later, but I can't uncook an amps sound (not completely anyway).
Doing these things let's me know (within a very small margin) how much power I'm using and how much distortion the amp itself is producing at a given volume level. This tells me what I can get away with with a specific cab. I really like the use of a resistance swtich on some (all?) of the mesa amps. That's an attractive feature. Also falls into that "future proof" category I mentioned in my last post.
I've taken this thread off the rails. Putting my $00.2 where it doesn't belong again. I'll stop.

I can be an amp snob at times. I love my SVT VR/Berg NV610 and my Mesa TT 800/Subway 410 rigs. I dare anyone to tell me these aren’t great rigs.

But I have a few combos spread out around two homes. Of note is a humble Hartke B600. It sounds great and I can always get my Thunderbird tones from it. The other is an el cheapo Guitar Center Acoustic b200 that I picked up used for next to nothing and use in my office. It has a lot of eq options. Once I figured it out, it sounds remarkably good.

 

[MCF]

It just takes a little awareness. I've gigged this a couple of dozen times. Luckily my bands volume doesn't require me to blow my cabinet.

View attachment 5417334

I have a buddy who does that for his low volume stuff. He has no issues.

 

[MarshallAC50Stack]

All properly designed products include volume controls. I’m completely not following this.

My hifi speakers are driven by a basic stereo power amp that is controlled by a separate, passive volume control. The passive volume control takes the place of a traditional active preamp.

 

[agedhorse]

My hifi speakers are driven by a basic stereo power amp that is controlled by a separate, passive volume control. The passive volume control takes the place of a traditional active preamp.

Most power amps have “passive volume controls” inside, this is nothing new or novel nor is it related to the topic of this thread.

 

[DJ Bebop]

Passive step attenuator. Chinese 21 step, looks like a pot. Cheap'n'cheerful in a little box.

This?

https://www.aliexpress.us/item/2255800052994599.html?gatewayAdapt=glo2usa4itemAdapt

 

[agedhorse]

This?

https://www.aliexpress.us/item/2255800052994599.html?gatewayAdapt=glo2usa4itemAdapt

That’s a normal stepped attenuator, generally they are pretty noisy and do not have a smooth adjustment throughout the range like a pot. That’s why they have for the most part disappeared from modern designs (except for products that try too head to be something they are not).

Taiwan Alpha and Noble made much higher quality stepped attenuators as well, but a special order part only.

 

[MarshallAC50Stack]

Most power amps have “passive volume controls” inside, this is nothing new or novel nor is it related to the topic of this thread.

True enough! Sorry for the derail.

 

[ardgedee]

That’s a normal stepped attenuator, generally they are pretty noisy and do not have a smooth adjustment throughout the range like a pot. That’s why they have for the most part disappeared from modern designs (except for products that try too head to be something they are not).

Taiwan Alpha and Noble made much higher quality stepped attenuators as well, but a special order part only.

They're useful in stereo -- well, multichannel audio -- where getting the channel levels to match closely through the whole sweep is important. Or... maybe I'm sensitive to this because channel balance at low volumes on my vintage hi fi amps tends to be terrible; it's only the receiver with a stepped attenuator that doesn't require fiddling with the balance control.

Anyway, I'm not as clear on their value otherwise. For a single audio channel, uneven pot progression usually just means dialing in a level is just a little fussier than usual.

 

[agedhorse]

Quality pots these days are pretty good with tracking.

For single channel audio, the tracking between channels is a non-issue, though it is important for some filter controls.

 

[MarshallAC50Stack]

Or... maybe I'm sensitive to this because channel balance at low volumes on my vintage hi fi amps tends to be terrible

THIS! (LOL, carry on! I'm outta this one!)

 

[agedhorse]

THIS! (LOL, carry on! I'm outta this one!)

Right, but this doesn’t even exist on bass amps.

 

[ImTheOnlyOne]

What wizardry is this ?

(from the Mesa Subway D350 owner manual)

ACTIVE/PASSIVE SWITCH

This switch (and its associated blue indicator/tally LED) sets the internal sensitivity of the input amplifier stage. Often (though not always), an active bass may have a signal level higher than that of a typical passive bass. If you find that you are operating the input gain control near the low end of the control’s rotation in order to prevent the O/L LED from flashing, switching this switch up (into the ACTIVE position) will reduce the input sensitivity, allowing greater control range and freedom from overload with high output active basses. Simply choose the position that gives you the desired results. This control does not change or lower the input impedance of the amplifier, nor does it “suck tone” like the input pads can do on some other amps.
​

Seriously, how is this accomplished? It performs its function very well.

 

[agedhorse]

What wizardry is this ?

(from the Mesa Subway D350 owner manual)

ACTIVE/PASSIVE SWITCH

This switch (and its associated blue indicator/tally LED) sets the internal sensitivity of the input amplifier stage. Often (though not always), an active bass may have a signal level higher than that of a typical passive bass. If you find that you are operating the input gain control near the low end of the control’s rotation in order to prevent the O/L LED from flashing, switching this switch up (into the ACTIVE position) will reduce the input sensitivity, allowing greater control range and freedom from overload with high output active basses. Simply choose the position that gives you the desired results. This control does not change or lower the input impedance of the amplifier, nor does it “suck tone” like the input pads can do on some other amps.
​

Seriously, how is this accomplished? It performs its function very well.

Magic

Rather than padding the input, this control lowers the gain of the input stage. Same benefit without the loading or noise penalty of a traditional pad network.

 

[ImTheOnlyOne]

Magic

Rather than padding the input, this control lowers the gain of the input stage. Same benefit without the loading or noise penalty of a traditional pad network.

Any impact on dynamic range or incidental HP or LP effect?

I would have guessed reducing gain is what a pad does, or maybe pads mainly add resistance with consequences. I'll read up on that.

 

[agedhorse]

Any impact on dynamic range or incidental HP or LP effect?

I would have guessed reducing gain is what a pad does, or maybe pads mainly add resistance with consequences. I'll read up on that.

No change in dynamic range of HP/LP.

A pad introduces additional losses into a circuit by the means of a voltage divider, the consequence of doing so on the input (as many amps still do) is loading of the instrument pickup and "sucking tone".

 

[ImTheOnlyOne]

A quick search on gain reduction hits a lot of pages on compression, but that switch on the 350 isn't a compressor. The switch feels like an instant gain add/loss of about 1 1/2 ticks of the input gain control.

Trivial side question. What are the knubs, the crests and valleys, on the control dials of the Subway amps called. *everything* has a name right?

BTW, Voltage Division

In electronics, a voltage divider (also known as a potential divider) is a passive linear circuit that produces an output voltage (Vout) that is a fraction of its input voltage (Vin). Voltage division is the result of distributing the input voltage among the components of the divider. A simple example of a voltage divider is two resistors connected in series, with the input voltage applied across the resistor pair and the output voltage emerging from the connection between them.

Resistor voltage dividers are commonly used to create reference voltages, or to reduce the magnitude of a voltage so it can be measured, and may also be used as signal attenuators at low frequencies. For direct current and relatively low frequencies, a voltage divider may be sufficiently accurate if made only of resistors; where frequency response over a wide range is required (such as in an oscilloscope probe), a voltage divider may have capacitive elements added to compensate load capacitance. In electric power transmission, a capacitive voltage divider is used for measurement of high voltage.

 

[ImTheOnlyOne]

Casually A/B-ing the D-350 EQ with a Broughton Fliptop pedal recently acquired, meant to model an Ampeg B-15.

Running the Fliptop at the 3:00 settings with 1/4 - 1/2 cab sim, The D-350 is able to sound quite similar with a bass boost, light voice, bright on, and upper mid and treble tweaks.

The Fliptop's treble has a special character turned up high that the D-350 doesn't completely match. The voice and cab sim controls can produce a similar effect. Easy to dial in the Fliptop to that classic tone, but the D-350 got me 90% of the way there without any pedals.

 

[Chuck M]

I tend to rotate my Mesa heads in my practice room. I was using my WD-800 but took it to my church gig so I am using my D-350 and am once again knocked out by how great it sounds and how much power it has. All the Subway heads are wonderful including this D-350.

 

[Moonskunk]

Agedhorse, this is directed at you, but I appreciate input from anyone. I love my D-350 with my active Stingray Specials but recently I picked up a new Fender Pro 2 precision bass (passive) and I get an annoying hum. When I use one of those orange colored plug in adapters the hum is gone. If however I use the active Stingray along with the orange adapter I get the same hum whereas before no hum without the adapter. I also I have a Angular TH-350 with which I get no hum with either the P bass or active Stingray (no need for orange adapter). So my question is what may be causing this and is it safe to use this orange adapter with the Mesa 350 to avoid the hum? Interestingly, when using a Mesa WD 800 I get no hum with either the P bass or Stingray. Is there some interaction going on between the D-350 and the passive bass that is causing this? Thanks