Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 12AX7 on October 28, 2016, 09:20:58 am
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In a amp such as a 2204 style preamp but with a normal gain stage in place of the cold bias stage, what tricks can i used to get that more focused midrange thats transparent and clear? I've already experimented in every way imaginable with those 470k/470pf filters (location, amount of them, and values of both R and C) and the infamous "enhance cap" across the PI input. Any advice as to what other things tweaks themselves to this sort of tone?
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Don't trust the duncan TSC visual to translate aurally. A .001 there would be unusable. Anyways, thats not the kind of thing i'm looking for. Thats basically standard EQ tweaking and what i'm looking for is different. Many may not understand the description i gave and thats understandable because words are a next to impossible way to explain tone. But some will understand what i mean.
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Have you tweaked the cathode bypass cap value?
You could start with 100nF and increase the value until you hit the sweet spot.
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Yes, and they;re at 1.5k/.68uf, best value for that kind of tone from my experience.
By the way, i replied above to a post someone apparently deleted after i posted a reply which is why the 2nd post appears to me me replying to no one.
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By the way, i replied above to a post someone apparently deleted after i posted a reply which is why the 2nd post appears to me me replying to no one.
I hate it when someone does that! I read the reply but I'm not sure who posted it.
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I hate it when someone does that!
He's NOT part of the establishment! :icon_biggrin:
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Sometimes I delete a post
But never if there is one other post after
Franco
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I think the type of capacitors used in the signal chain can make a BIG difference.
http://el34world.com/Forum/index.php?topic=19534.msg203497#msg203497 (http://el34world.com/Forum/index.php?topic=19534.msg203497#msg203497)
I think getting the caps oriented can also make a difference
http://el34world.com/Forum/index.php?topic=11427.0 (http://el34world.com/Forum/index.php?topic=11427.0)
With respect, Tubenit
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The other idea that I would offer is to try the DanElectro "Fish and Chips" EQ. It's inexpensive. Mine is very quiet in the FX loop of my amp. I don't care for it between guitar and amp.
It is amazing how much you can shape the mid tones with this thing. And it is the best "boost pedal" I've ever used.
http://www.musiciansfriend.com/amplifiers-effects/danelectro-dj14-fish-and-chips-7-band-eq-pedal (http://www.musiciansfriend.com/amplifiers-effects/danelectro-dj14-fish-and-chips-7-band-eq-pedal)
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Well, i haven't experimented with cap types much in recent years because when i did early on i found mallory sounded best to me so i have just always used those for a long time now. I may take your advice tho and look to the coupler after V1. It DOES seem that would set the tone for the entire chain after that and i do have a few other caps i could try including orange drop. Usually when you EQ before the main OD happens, thats where you can get that transparency so i think experimenting with that cap was a good suggestion. (in the thread u linked)
As to the fish and chips, i have one i've had for many years but it's too noisy plus i don't like band aids. I feel if i cant get what i know the amp is capable of out of it i just need to find the right tweak, and it always sounds best when the amp itself is able to create the tone i want, and it's already there just not quite to the degree i want. It's close, and i love it as is but i just feel like i want a little more focus/transparency in the mids.
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Did you try different speakers/cabinets?
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i found mallory sounded best to me
It is totally a personal taste issue & what I prefer certainly doesn't make something "better".
The Mallory caps are my least favorite of all the caps I've tried in the preamp. My experience is that they are the least transparent in tone and often have sounded like a thin blanket was hanging over the front of my speaker.
As an example, I remember being very frustrated with one of my early builds (Marshallish & 6V6's) that had all Mallory caps in it. As I began changing the caps out in the preamp and tone stack, the amp became progressively more transparent and touch sensitive to my ears.
I don't mind them post LTPI though & think they can actually help some there at times, but I doubt I will ever use them in the preamp again. I think in a typical TMB tone stack, they can be effectively used for the mid cap at times on some builds.
With respect, Tubenit
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i found mallory sounded best to me
As I began changing the caps out in the preamp and tone stack, the amp became progressively more transparent and touch sensitive to my ears.
replaced them with what?
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replaced them with what?
did you read the thread "do caps make a difference?"
I've switched to Doug's mojo dijon caps, with a sprinkling of xicons.
I use a regular group of players for running my amps through their paces, they have all commented that the tone quality has greatly improved. But, like everything beyond a meter and scope, I take with a grain of salt!
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replaced them with what
In some builds with Orange Drop 715 series & Xicons such as the Marshallish 6V6 amp I mentioned. .
In D-inspired amps, I tend to use mostly OD PS series, some Xicons and just a few Musicaps in specific chosen locations.
There is some excellent information in the thread I referenced. I am very interested in trying Doug's Jupiter caps in some future build based on Willabe/Brad's findings.
with respect, Tubenit
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for circuitry tweaks I suggest that the voltage divider can be your friend to keep from hitting stages too hard. I like using a split plate load over the traditional voltage divider also in places. Sometimes I don't want the resistance in the signal path. These help give you better control and better working adjustment through the entire pot range. Being on 10 will sound great and you won't have any settings that sound bad.
Use small coupling caps between stages. You can sub a 12at7 in the pi over an ax7 which I find I like between the pre and power amps. you can tweak the tone stack for 100k slope, raise the bass cap to .047 or .1 & lower the mid cap to .01 w/ 250k treb & 1M bass pots. You'll have a lot more range than the usual default stack and it helps give better control being placed after gain stages are cascaded. If inserted earlier it gives more of a blues amp feel & control.
These are things I do and may not be for everyone or even anyone? :) Bottom line is keep at it, this can be a lot of fun (and instant gratification doing rapid fire tweaks in a couple of hours) and there's much to learn with this final tweaking process but for some with little patience maybe not so much?
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(and instant gratification doing rapid fire tweaks in a couple of hours)
I've done this twice with musicians, they say, can you boost the bass a little, I swap, solder, they grin, can you....., I solder.... Take notes, notes that make sense next year!
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..., what tricks can i used to get that more focused midrange thats transparent and clear? I've already experimented in every way imaginable with those 470k/470pf filters (location, amount of them, and values of both R and C) and the infamous "enhance cap" across the PI input. Any advice as to what other things tweaks themselves to this sort of tone?
Do you have a schematic of your amp that you can share so that we can analyse what's going on?