F-30 through a Mesa Recto 2x12 cab

Anyone tried this?

Does it help in getting a very good heavy tone?

I ran an F-50 preamp thru a 20/20 (basically a stereo F30) into 3/4 cabs and 1x12 recto cabs. I think they were both pretty heavy.

I think the 2x12 will give a good sound, but you will need to tune the amp as well. An EQ in the FX loop should help a lot. If you are looking for super heavy low end, you need to crank 80-250Hz post distortion. I'd try the Eq before dropping big $$ on a cab.

ALso, the EL84 output stage will drive OK at low volume, but it loses bass at high volume as it runs out of gas. Low frequencies take way more power to reproduce than high frequencies.

Almost forgot - that's why I switched to a 50/50.

An eq in the loop doesn't work really fine. It is a parallel loop. The whole circuit is wired parallel. At 100% mix it is still not like a serial loop.

Also I find that I like the way EL84's "loose bass" (not that they have a lot anyway) because the sound becomes more aggresive and cuts nicely. In simple words the mids and high mids start to be more pronounced.

Still it is a mid heavy amp. The 30 watt AB1 class steam off quickly in large venues and in the clean channel even in smaller ones. As the amp compresses, it is better to reduce some gain. I am not quite sure how it will match eq wise to an already bassy dark cab as the mesa recto 2x12. A guy that sounds excellent with an f-30 switched to a mesa thiele from a recto 2x12 (which he said already sounded quite nice!!!)

The loop is close enough to series that the EQ will work fine in the loop. You can prove it by putting a tuner with a mute function in the loop. Turn the loop mix to as wet as it will go, and click the tuner mute on and off while playing. You will notice that the volume is much lower when only the internal path is active.

Hi there.
"A guy that sounds excellent with an f-30 switched to a mesa thiele from a recto 2x12 (which he said already sounded quite nice!!!)"
First of all, IF it is me you are talking about, I say thank you for your kind words (IF it's me...;-)

Well, just to be clear it wasn't a 2x12" recto cab i used with my F30 combo, but a 2x12" 3/4-back mesa cab I was using. Indeed sounds nice, so do the Thiele I now use with it....and it looks a little cooler ;-)
It certainly makes the overall sound alot "fuller" or "heavier". The Celestion Vintage 30 that comes with the combo stock has a great sound on its own; very old school, rough sounding (at least in my head...). Well, combined with Thiele or 3/4-back its a totally different story. The cleans coming from this setup is amazing. And it takes the dynamic feeling of the amp to a whole new level.
So I don't know how it sounds through a 2x12 recto. But with both my cabs it raises the "usefullness" (??) of the amp alot! Hope this can help you a little bit.
best regards
andershoeg

Yeah it is you!!! I always thought it was a 2x12 recto though!!! Sorry!!! I remebered reading about it in the f-series lounge one day. I read through the entire 6500+ posts!!!

Anyway, I always thought of adding a thiele for personal pleasure but live, I used my f-30 unmiced, miced and DIed. I always wandered if I get the thiele which one to mic the V30 on top or the bass coupled theile box on the bottom?

Whenever a player such as you tried an odd number of speakers, which is for example 3 like the v30 and the 2x12 simultaneously I wandered if the 2x12 can be heard along the V30. Sure it will fill out the sound but any time the amp puts out two watts, the one goes to the v30 the other one goes to the 2x12 and its one of its speakers takes only half...So the internal speaker is always getting more power and the...more decibels.

elvis said:

The loop is close enough to series that the EQ will work fine in the loop. You can prove it by putting a tuner with a mute function in the loop. Turn the loop mix to as wet as it will go, and click the tuner mute on and off while playing. You will notice that the volume is much lower when only the internal path is active.

Click to expand...

Yes it will work but the end result never satisfied me at all. To tell you the truth I don't think any parallel loop will work. I tried an incredible but long forgotten multi fx unit/preamp by boss the gx 700. It was so flexible that makes todays unit seem like toys. Soundwise good but that is another story. To make matters short it had excellent routing capabilities including putting any module where you want in the signal chain (pod xt???no way!) plus two great loops!!! One serial one parallel...I put its own parametric eq through the loop and it worked perfectly fine through the serial mode but as with the f-30 blurry and undefined in the parallel mode. So I guess what is left is to make the loop serial which I don't want because I like to overdrive its buffers (the v3 tube to be exact) in low volumes and throw whatever in there and never care about its bypass quality as the mix controlo retains the amps sound...Maybe a push pull pot but this one is tricky and needs a relay or something...

It may not have been the slight parallel signal that caused your problem. Mesa amps have high output impedance in their loops, and if your effect box did not have super-high (1Meg Ohm or more) input impedance, it wil cause tone loss due to impedance mismatch filtering. Adding a buffer will fix that.

Also, if the EQ block was either digital, or routed after a digital processor, the latency could have caused comb-filter artifacts.

An analog EQ with high input impedance (like a GE-7) should work just fine in the loop. It's not the best quality EQ out there, but a lot of the high performance rack EQ units are designed for line-level, so they do not buffer the input signal, which is absolutely required for most tube amps.

The parallel path also depends on your volume setting. There is a bleed path that has nothing to do with the loop. One of the preamp tubes has one chanel working pre-loop, and the other channel post-loop, so there is crosstalk in parallel with the loop. Even if the loop were 100% parallel, this would make it not 100% parallel. The crosstalk is at a fixed level, not affected by the master volume. At high master volume settings, the bleed path is swamped out by the main path. AT very low master volumes (like what you'd use at home), it's very noticeable. The cure is to turn up the master volume.

Actually I put a soldered tip on one effect jack (i think it is return) and a non soldered tip in the send I think jack. It is the thing I described above. Then the fx-mix acts as a "final master volume control" that makes night and day difference to low volume practicing. I can run the preamp better, the master with its shamelss full on taper is now useable and there is a noticeable compression that tightens the overall sound. You can notice something of a phasing effect when you change the fx mix control from silent(mix 100% wet or "90%") to an intermediate position.

I was told that this is similar to running a volume pedal in the loop, and I e-mailed boogie about this and the tech said is fine and does not cause damage. Actually I am quite pleased with the results in a manner that now it is totally useable at almost whisper volumes. Another person posted that this trick is due to the effects loop beiing buffered. As a result, I am putting the effects loop dedicated 12ax7 into play by running it harder? he said? and perhaps the additional compression comes from this. Does it have to do with the bleed you mentioned?

Changing the loop to serial will change this trick and make it not useable? In this way, I'd never changed it I think it is a hidden "gem"!!! I also found out that many DC users did this. I also tried it in a single recto, which had a parallel similar(?) loop with 90-10% function but also had another final master volume. It did not work. I am actually more in love with the low volume tricked loop thing compressed sound than the actual sound of the amp. In low volumes only. In high volumes I do not see much difference as I usually cranck it high enough. The little f-30 played unmiced just fine in two clubs!!!

The FX loop is not a separate circuit and it does not use any extra tubes. The loop just breaks the normal signal path to insert external FX. The FX loop send is driven by the EQ, which is a transistor circuit, and the return is buffered by a tube.

There are no tubes between the master volume and the FX loop, and the tube after the FX loop is used with or without external FX.

The FX loop volume trick is clever, but does not drive the amp any differently than without it. Using a GE-7 in the loop would give you the same ability to control volume, but also give EQ and the ability to add other external FX in the loop.

The bleed path is most likely from V3. One half of that 12AX7 is before the master volume, and the other half is after the FX loop. If you crank up the input gain on the lead channel, it will drive the heck out of V3.

That is really interesting but I swear I hear a night and day difference to how the amp sounds with and without the trick. I just looked at the schematic and it is indeed the graphic eq that is before the loop. But the eq, is off at all but the gain+contour channel. Is it bypassed or does it affect the circuit?

Another question (I pm'ed boogiebabies about this but no reply). How whould you describe the position of the tone controls? Pre distortion? Post distortion recto style?

I have a good but not thourough view of the schematic and it goes like input------v2a---lead gain---v2b----tone controls lead channel----v1a-----v3a----reverb---level master, reverb mix-----loop and mix control------v3 b...Am I correct?

So where does it fit? After one gain stage? Mark style? Two? (any other amp that does this?)? After all the gain stages recto-style? It does not feel like the latter but not like mark exactly. Anyway, this more of a curiosity thing rather than something practical. Also I looked at a dc-schematic and the tone controls where recto style positioned at the end of the preamp. Right? Still they are described sonically as very mark-style distortion amps.

I have no doubt that you hear a change in tone and drive. By shunting signal in the FX loop, you are changing the impedance, which loads the EQ output differently. Some people would call this "tone suck", but you get to pick which you prefer.

The tone controls are post-gain.

For rhythm the signal goes thru V2b, rhythm tone, rhythm gain, V1b, V3a, Master
For lead the signal goes thru V2a, Lead gain, V2b, lead tone, V1a, V3a, Master

That is what I figured when I saw the schematic. But I still don't understand how they react? I thought post gain tone controls would affect the tone much like the graphic eq, ie tone-sculpting treble=more treble, mids=more mids etc. But in the f-30 if you lower the tone control pots, the overall gain is lowered, as in the preamp does not distort. I can set the gain at maximum, yet if the tone stack is set low overall (all at 9 o'clock and below or zeroed and only one slightly above) then I hear a sound that is as if the amp doesn't break up as if the gain pot is almost zeroed. But it is dimed. Raising the treble or the others releases or adds gain. The mid control in the manual I can't remember exactly but it says it adds gain after the first half?

Then if you set bass mid treble at above 12 o'clock you can thrash all day even if the gain control is set at below 1/4 of its turn...Why?

Is it like cascading gain, with the tone controls in between or something?

I have the studio pre and triaxis and the behaviour is slightly similar but not the same. They with the exception of lead 2 red have pre distortion tone controls.

The only other amp that reminded me of the f-series is fender's red knob twin. In the way it distorts and reacts to the tone controls. Both it and my f-30 don't care about the tone controls if the gain is dimed!!! Their effect becomes minimal...

The F-series amps are not very high gain. They are more like a Fender in that respect than what most people think of as Mesa. The front end gets a bit of grit, but really starts to drive at V3, after the tone controls. The tone controls shunt signal to ground, especially the treble control, so they can cut the gain to nothing. You should really be running the tone controls as high as you can stand if you want decent gain. I can't imagine why you would turn them all down to 9:00.

By comparison the studio preamp signal path for lead channel:

V1a, tone controls, V1b, V3a, V3b, V2a, V2b, EQ. The lead channel adds both V3a and V3b to get over-the-top gain.

If you want more gain from the F-series, I recommend an OD808 in front.

It is the first time that somebody actually explains these technicalities with simple expressions, thank you very much!!! I actually am more, than enough covered with the gain of the f-30...I try to riff with as low the gain as possible to retain definition even in high gain modes and I do have a strong pick attack. Although not a thrash amp per se it does a good job live mic'ed! For experimenting, I tried boosting but never liked the results, even for lead playing. I just got better overall results with the tone controls. At home I favor bass mid to zero or 9 o'clock and treble high, or full-on mids and the others zeroed... Live I always keep the mid pretty high...the bass to 8 o'clock maximum. I wonder how much in common does the f-series with the dc as it shares the same patent number for the preamp. Or the fender red knob twin that I mentioned or other fender high gain amps. Maybe the f symbolizes something :wink: