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Amp Classes: A/B v. D


mcgraham
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Hi there

I recently traded my Clarus (Class D) for a Thunderfunk 550A (Class A/:). I am finding that the TF bolsters the low end extension of my sound (over the Clarus) and sounds fuller, however in a mix it lacks the super clean-ness that I prefer (read: crave).

I am assigning this to the fact it is A/B and not D, (particularly as the TF is designed to be solid state and clean, with a hint of warmth more akin to tubes). Anyone agree/disagree/care to comment on this?

Also, I need to rectify this situation by obtaining a super clean amp alternative (not Acoustic Image, the eq didn't match well to my cab). Thoughts? Suggestions?

Mark

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I bypassed the preamp this evening, which helped some, but it's 'base tone' still had the qualities I described above.

Note: it isn't unclean [i]per se[/i], but the added warmth over the previous amp (perhaps this makes a poor comparison) even when set flat seems to mask the clean-ness... if that makes sense.

Mark

Edited by mcgraham
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I actually got to try an Epifani Quest II preamp, which I believe is the same as in the UL502/902. I found that it had great punch, definition, articulation yet balanced with warmth, but it was that same warmth that turned me off as I couldn't dial that quality out in any quantity. Lozbass (who lent it to me for a trial; I believe you sold it to him?) also agreed that this was an innate quality of the preamp. Thanks for the suggestion, but I'm not sure it's for me.

Mark

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I felt the same switching from my mesa boogie walkabout to the phil jones suitcase and cab. But for me both have their benefits and I don't prefer one either way. Although I was partial to the beastly epifani/swr rig of Nicks at the midlands bass bash last year. Being a non driver throws that out of my options though.

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Did you find that the Mesa was cleaner than the PJB? I always felt like the PJB had boatloads of punch and definition.

I'm curious Alex, you say that decent power amp sections vary little in tone. Now that I think about it, the Clarus had a very similar sound (I can't say identical because I'm not doing an A vs B comparison) with the eq bypassed... interesting! Perhaps I'd be better off going for a power/pre combination. That way I'm more likely to be able to get the sound I'm after.

Mark

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I don't know if you tried my U5/PLX rig - that's about as clean as it gets. A lot bigger and louder than the heads you're comparing though!

Maybe what you're hearing is added bass extension and you're perceiving the added warmth as a lack of cleanness. My U5 has a very warm sound if you play a warm sounding bass through it - tons and tons of bottom. Change the sound from the bass radically and the sound from the amp changes just as much.

If you really do want a clean and true sound then your choice of cab is a little perplexing!

Alex

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I did indeed try your rig Alex. It was a truly awesome rig. A shining example of simplicity creating elegance.

The 'L' series of Schroeder cabs are not quite as mid humped as the 'R' series. Whilst not as true/flat as PA cabs, it isn't too far off. However, your point about the added bass extension is more than likely true. I'm going to suggest that the Schroeder is not so great at reproducing the low end response/frequencies that the TF outputs, hence the perceived lack of clarity of the amplified sound.

Mark

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As I've just done the reverse experience (TF>Clarus) I'd have to say the Clarus is more "clinical" heard on its own, but in a gig setting seems to be pretty warm and clear, with surprising headroom. The eq is limited for BG use, but useful. If you really like the flat sound of your bass, then it works.

The TF reminded me a lot of the SWR 220 - I thought its basic tone was "clean", and the timbre control was the key to warming it up, or making it brighter/clearer. The 4 band eq takes some getting used to. As an essentially 25 year old design its pretty impressive.

I think the cab element is worth considering - I use Euphonic Audio's (1x10 or 1x12) and they do allow an amps' character to show through very well, sometimes too well. But they also work in gig environments much better than any more traditional cabs (SWR, Eden, Ashdown etc) I've used. Small eq changes can actually be heard and they maintain clarity on stage, even those boooomy 'orrible ones.

It would be worth trying to do a "side by side" comparison of your current cab, with some others? Unfortunatley, using your ears, with the same bass/amp, in the same room, at the same time, seems to be the only way to evaluate these things. I was shocked when I first heard the EA 1x12 on its own - dry, brittle, flat - not exactly flattering. But after one gig I loved it. I still sometimes use my SWR 4x10, but now I know what's missing (and those gigs are so loud I've got plugs in, so who cares!?).

BB

Edited by BassBod
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:) I'm really glad to hear the Clarus is working for you bud! Despite the above issue I know I've moved forward in the right direction.

I definitely want to give it another shot at a practice and gig when I've got some time to fiddle in the mix. If I can get a medium between the Clarus and the TF I'll be very happy, as I moved away from the Clarus to get some bass extension. I just need to improve the clean-ness a teeeeeny bit. I'm sure if I explore the controls I'll be able to find out how to accomplish that.

Alex, can you perhaps explain to me what the difference would be between setting the gain on your amp to max and setting the volume control to achieve a given perceived sound level, and setting the gain lower (say half?) and then setting the volume control to achieve the [i]same[/i] perceived sound level as in the first scenario?

Mark Edited by mcgraham
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If you get the chance to try a Glock amp do so (I'm referring to the Bass Art but I think the range in general are similar). It has the warmth of a TF but has all the clarity you could want in a band mix. The only limitations that I found with the Glock was that the EQ was very musical and couldn't do extreme which I can get on the TF. I only require the TF EQ as I'm likely to be running a fretted/fretless and EUB through the same rig on any given night.

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Thanks for that Warwickhunt. Unfortunately I've never even heard of anyone using Glock amps other than your good self, so may be a bit difficult to try. As I say above, I will keep fiddling with it in the meantime, as I hate rapid gear hopping.

Mark

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[quote name='mcgraham' post='231177' date='Jul 2 2008, 10:55 AM']Alex, can you perhaps explain to me what the difference would be between setting the gain on your amp to max and setting the volume control to achieve a given perceived sound level, and setting the gain lower (say half?) and then setting the volume control to achieve the [i]same[/i] perceived sound level as in the first scenario?[/quote]

If there is one I can't hear it!

There is a ton of nice EQ on the Thunderfunk so you should be able to get the shape you want. However whether you can get quite as clean is a different matter as there is a smidgeon of dirt and compression added by the preamp design, increasing at high volumes when the power amp supply is sagging.

Alex

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As I was after a bit more low end extension anyway, so it's just a matter of tightening it up til I'm happy with it.

I was under the impression that there was some kind of a difference running an amplifier in this way. I could of course be wrong, and I wouldn’t be the first (or last!) musician to imagine that they’re hearing something that isn’t [i]actually[/i] there, but I felt it helped improve the clarity of the sound, i.e. tighter bottom, cleaner/clearer top.

Mark

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[quote name='mcgraham' post='231177' date='Jul 2 2008, 10:55 AM']Alex, can you perhaps explain to me what the difference would be between setting the gain on your amp to max and setting the volume control to achieve a given perceived sound level, and setting the gain lower (say half?) and then setting the volume control to achieve the [i]same[/i] perceived sound level as in the first scenario?[/quote]
Not sure what you are getting at here as you seem to think gain and volume are different things. Have a read of the article on the wiki concerning this very subject.

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[quote name='mcgraham' post='231255' date='Jul 2 2008, 12:40 PM']I was under the impression that there was some kind of a difference running an amplifier in this way. I could of course be wrong, and I wouldn’t be the first (or last!) musician to imagine that they’re hearing something that isn’t [i]actually[/i] there, but I felt it helped improve the clarity of the sound, i.e. tighter bottom, cleaner/clearer top.[/quote]

If the preamp doesn't have much headroom or is designed to add compression/overdrive then preamp gain can sound quite different to power amp gain. I wouldn't be surprised if the Thunderfunk is obviously like this.

Alex

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[quote]Not sure what you are getting at here as you seem to think gain and volume are different things. Have a read of the article on the wiki concerning this very subject.[/quote]
I have read the wiki, it didn't really answer my question. Please correct me if I get the terminology wrong, but I was getting at whether maxing your gain knob (rather than volume) to get you a given sound pressure level would yield a different tone to getting the same sound pressure level but maxing out the volume knob (rather than gain).

[quote]If the preamp doesn't have much headroom or is designed to add compression/overdrive then preamp gain can sound quite different to power amp gain. I wouldn't be surprised if the Thunderfunk is obviously like this.[/quote]
If this is the case, would I be right in saying that by increasing output SPL (correct me if I've got the term wrong) using the gain control rather than volume control, I will be getting a 'less coloured' resultant output?

Mark

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[quote name='mcgraham' post='231336' date='Jul 2 2008, 02:14 PM']If this is the case, would I be right in saying that by increasing output SPL (correct me if I've got the term wrong) using the gain control rather than volume control, I will be getting a 'less coloured' resultant output?[/quote]

Preamp gain low, volume high. However this is likely to raise the noise floor of your amp which could be a problem if you're a tweeter person.

Alex

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One thing about that Tfunk - "the switch" is American style - up is on, and down is off. I think the cleaner setting is up, and the "saggier/warmer" setting is down. Its pretty subtle but makes a more noticable difference at higher volumes.

BB

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If you read [url="http://wiki.basschat.co.uk/info:amps:gain_power_and_volume_-_a_confusing_menage_a_trois"]this[/url] it does have a bit of a rant about the labelling of volume knobs on amplifiers. The problem is they are all different and I am assuming that by gain you mean the input level next to the jack and by volume you mean the master. That is my assumption based on your assumption that we all know how the knobs on your amp are labelled.

Many amps now have led's on the input level and suggest that for best signal to noise the level is set so that the light flashes briefly when playing the loudest notes. In the absence of a flashing light you have to use your ears. Doing this may well sound different to turning the output level to full and using the input level to set your volume because there will be a hotter signal going through the pre-amp.

f*** about with it - try both approaches and trust your ears as to which sounds best.

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