Heavy on the Bass?

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yaemish
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Heavy on the Bass?

Post by yaemish »

I finished my TMB and it seems heavy on the bass. I am using a Warehouse speaker G12 (like the Greenback). I built a large cab. Can an over sized cab cause this?
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Post by rjgtr »

yes a large cabinet can increase the apparent bas. However, it could also be the amp. What value cathode cap did you use for the power tubes?

If it is 250-500uf, try reducing it to 50uf, to keep the same feel but control the lows a little, or 1000uf, which will tighten the bottom end and make the amp a little tighter sounding.
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Post by yaemish »

I'm using this layout.

http://www.ceriatone.com/images/layoutP ... iatone.jpg

The enclosure is 24"W x 17" H x 9" deep and there is 1 12" speaker in it.
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Post by rjgtr »

At 100uf the power tube cathode cap isn't too high.

What about the speaker you are using? Maybe a tighter sounding speaker would help.

I know this sounds funny, but where are you running the bass? Try it at 9:00 or below. I almost never use anything higher than a 500k for a bass control anymore because when you turn up, the bass control generally needs to be set lower.
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yaemish
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Post by yaemish »

I am using a Warehouse speaker G12 and the bass is high when I have it on 0.
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Post by zaphod_phil »

yaemish wrote:I'm using this layout.

http://www.ceriatone.com/images/layoutP ... iatone.jpg
Is the excessive bass present in both channels or just the TMB channel?

One thing I would recommend in the TMB channel is to reduce the 0.022uF cap connected to V1 pin 1, down to 0.01uF or even 0.0047uF (4.7nF). In your case you may prefer the latter. The other thing which will give the Bass tone control a better sweep, is to solder a 1M resistor across the two end lugs of the bass pot, effectively making it a 500k pot. You can try lower values of fixed resistor, down to 300k.
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Post by Brewmaster »

The cap connected to V1 pin 1 should be .0022 according to the Ceriatone layout. This is one of the many changes I made a few years ago when I had an older Ceriatone kit I put together. Going by this layout you shouldn't have excess bass coming from the amp unless one of the caps Phil and rjgtr mentioned has its value off. You can double check your cap values but I'm starting to suspect the speaker. Oh, and double check the cap coming off the wiper of the MV pot and make sure it is .0047 and not .047. That is another spot where I had to change my cap value.
I'm not familar with the Warehouse G12 but if it is like a 25 watt(G12m) or 30 watt(G12H) Greenback, the bass should not be too heavy at all. A Vintage 30 clone on the other hand may give you a problem.
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Post by Z_Stingray »

I prefer using 0.0022uF coupling cap after the first gain stage to keep the bass in check. It's a necessity with an efficient speaker. Its seam excessively small, but it's a value that's commonly used in many amps (Plexi, JCM800, etc.).

I think an amp like the 5E3 gets by with larger values (0.1uF) due to the inefficient speaker used [in the combo cab] and the style of guitar the amp targeted (Strat and Tele).
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Post by zaphod_phil »

Z_Stingray wrote:I prefer using 0.0022uF coupling cap after the first gain stage to keep the bass in check. It's a necessity with an efficient speaker. Its seam excessively small, but it's a value that's commonly used in many amps (Plexi, JCM800, etc.).
Actually that value is normally only used in the bright channel of Marshall amps. It's also used in some Vox and Matchless amps which IMO would be excessively bright, if it weren't for the "Cut" control they also have in the power stage. In this particular Ceriatone layout, we also have 1uF cathode caps at the first preamp stage, rather than the usual 50uF you find in most 18W amps. So I reckon that 5nF (or 0.0047uF) should give a good even response without making the amp either too bassy or too trebly. YMMV of course.....
Brewmaster wrote:The cap connected to V1 pin 1 should be .0022 according to the Ceriatone layout.
I must have mis-read that value. I thought it said 0.022uF :oops:
Last edited by zaphod_phil on Tue 10/27/09 10:14 am, edited 1 time in total.
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Post by Z_Stingray »

I like 0.0047uF, too. So you have some options. Try each one (a 0.0022uF AND 0.0047uF) to see which one you like. They will both cut the bass but you'll need to decide on which one makes it just right for your tastes.

In my first LiteIIb I ran a 0.01uF with a WGS Vintage 30 and had to much bass as well. A 0.0047uF solved that problem. Which, BTW, is the spec'd value that I should have used in the first place.
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Post by rjgtr »

Along with all the great suggestions above, maybe get the Richie TMB schematic from downloads and see where ceriatone layout has varied from it.
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Post by yaemish »

Thanks for all the replies. I haven't had much time to play with the caps, but I may have some time this weekend.

As for the question about the box dimensions, does it seem a little too spacious for a single 12" speaker?
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Post by yaemish »

Oh, and this is a link to the speak I have. Its called the "Green Beret"

http://warehousespeakers.com/proddetail ... green25_12
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