Amp for fiddle

[Andy Le Blanc]

I work with a lot of fiddlers running sound. usually highpass at 80, theres typically a lo mid pull between 160 an 400.. either for excessive bowing or low resonance issue... a strong pull between 2.5k -4K and 12k+ is turned down to taste... fiddle at volume can rip you a new one, watch out for those upper mids, I'd look to a dark tone for the rig

[gingertube]

Good golly you guys rock! I've definitely got my work cut out and this project is going to force my understanding of frequencies and response, something that has been lacking in my guitar amp building, I feel. For the sake of discussion, I'll ask a very broad question: how would I go about defining my range of frequencies, generally speaking? Pointing to Phil's links, how would I know that everything below 100hz needs to be cut? How would I implement this? I mean, I understand, to an extent, what parts of a circuit boost highs, cut bass, etc but how do I assume complete control, as far as understanding?

We played a gig together last night and he used a 100w SS/6L6 Peavey with the resonance way down. One of his biggest complaints is that his low G is way louder than any of his other strings. He also expressed that he likes his dirt to come from digging in with the bow. Very dynamic player.

Thanks for the references and thoughtful points, I'm going to go read now...

Above from page 1 - Coming to this very late. Look at the Hughes and Ketner TriAmp schematics here:
http://www.webphix.com/schematic%20heav ... triamp.pdf

Check out the "Tight Switch" function on the Clean Channel. It puts low frequency cut on the input tube by messing with the cathode bypass cap circuit (puts an active filter in line with the bypass cap). I guess that means it will have a shelving function.

Somewhere I have the frequency response plots from modelling this circuit and what I recall about it was the sharp cutoff below 100Hz (18dB per octave I think - will check).

Cheers,
Ian

[EtherealWidow]

Might do you some good to experiment with the same fiddle, a graphic EQ (fish n chips?), and a bunch of different amps to see what works before building one with all the necessary filtering.

[Leo_Gnardo]

Above from page 1 - Coming to this very late. Look at the Hughes and Ketner TriAmp schematics here:
http://www.webphix.com/schematic%20heav ... triamp.pdf

Check out the "Tight Switch" function on the Clean Channel. It puts low frequency cut on the input tube by messing with the cathode bypass cap circuit (puts an active filter in line with the bypass cap). I guess that means it will have a shelving function.

Somewhere I have the frequency response plots from modelling this circuit and what I recall about it was the sharp cutoff below 100Hz (18dB per octave I think - will check).

Cheers,
Ian

Good to see you on the case Ian! I think the "tight bass" similar to H&K will be accomplished by cascading triode stages with small-value cathode bypass caps @ 1 uF more or less.

Ethereal's suggestion of trying a graphic to find your fiddlers' "preferred curve" is a good idea.

One of the wild cards still in play here, is choice of speakers. Milkman mentioned a 15 he likes in his pedal steel amps - that could be a contender. And I've used the Recoton-Jensen 120W rated 15, works great with guitar & bass, good clarity & price & not likely to get wrecked by a 50W amp.

[Milkmansound]

Telonics

He only makes them in 4R so keep that in mind

[Smokebreak]

Thanks a bunch guys. Getting my ducks in a row...
Let's start with :
5f6A, 15" combo
-Cut. 250k/.022 with smallish series resistance
-Resonance. Focusing on mids? Or lows?
-Triode switch(still pondering as I've never experienced this)
-Presence? Miles, how would I handle NFB without presence? Just tack it on fixed? I don't understand why we'd lose presence in favor of a cut, but that's only because I'm still coming to understanding of frequency shaping;)
-what about presonance?
-no verb as he is adverse
-baggs in front. He asked me last night if we could do a channel with a baggs built in, and that is still blowing my mind up

We've learned that when he soundchecks, he has to go really bright, but then it's sits right in the mix with the whole band, which is why I bring up the question of presence.

Anyone on this board offer custom punched chassis?I'm gonna need all the time I have here

Hey guys I wanted to repost this as I fear it may have been missed on bottom of page 3... Thanks again! Also, the PT choices seem to either 660CT or dual 610/710CT secondaries..while I like the dual taps, I'm thinking 660 is more appropriate . Any thoughts on this?

[Smokebreak]

I started the fiddle amp yesterday, but am stalled out on speaker selection. I like the Jensen recommendation, but doesn't it drop off too early in the higher freq.?: http://www.jensentone.com/speaker/mod_15_200.
I mean, if we want to cutoff at 10k-12khz, how much drop off is ok?
The Telonics look nice, but I can't find any freq charts for them. This is obviously also an exercise in my learning how to interpret these charts. Very nice amps btw, MMS.

[Leo_Gnardo]

I started the fiddle amp yesterday, but am stalled out on speaker selection. I like the Jensen recommendation, but doesn't it drop off too early in the higher freq.?

The 120W Jensen not the 200. Although, the 200 is an excelled bass speaker, would make a good low end in a PA or hi fi speaker. You'll find the 120W has a dab more response in mids & highs.

Another thing to keep in mind, is the natural "beaming" of higher frequencies from cone speakers. about 800 Hz on up, the dispersion pattern starts to get narrower.

You "may" want to have another hole in the baffle, if your fiddler likes his sizzle, for a tweeter. I don't think you're going to get 10-12KHz out of any 15. Let's see what that Telonics shows us.

[Smokebreak]

Ok thanks. I posted on the fiddle forum, and someone replied that while he wouldn't go with a 15, that the Black Widows have an extended upper range.
I found this Peavey doc http://www.peavey.com/media/pdf/steelguitar/31years.pdf
Citing JBL15s and BW as well for steel guitar, as well as fiddle.

[M Fowler]

The Telonics look nice, but I can't find any freq charts for them. This is obviously also an exercise in my learning how to interpret these charts. Very nice amps btw, MMS.

http://bb.steelguitarforum.com/viewtopic.php?t=250809

[Guus]

I've got a fiddle playin buddy that wants me to build an amp for him. He's a loud player that likes it dirty, but needs headroom too. Wants it bright, but not too bright, strong mids but not muddy...sound like a guitar player eh? He does Texas fiddle stuff to Charlie Daniels/roadhouse rockin stuff.

Hi Smokebreak,
An interesting case.
As a FOH engineer and guitar amp builder my experience:(for what it is worth):
Using a regular guitar amp for fiddle sounds in my opinion like crap. (Frequentie range of an electric guitar amp isn't straight and goes only to 5-6 kHz, mostly the guitar amp is just a distorsion machine which doesn't match with a fiddle)
A fiddle has a completely different sound characteristic in compare to an electric guitar. The same s**t happens if you plug a acoustic guitar straight in an electric guitar amp. Brrrr..

IMO you better try building a kind of acoustic guitar amp which has a greater frequentierange, is more liniair, has a neater tone control, has broadband speaker(s), etc.
Use tubes if you're looking for more harmonics. Sag is not needed, so use silicium diodes for rectifier.

About the important frequenties of a fiddle sound I find out:
- use a decent cardiod mic capsule to pick up the string sound of the fiddle;
- you need a lot of steep low cut (< 150 Hz);
- get fullness around 240 Hz;
- scratchiness sits in the regio at 7 - 10kHz,, you need this important frequenties;
- the speaker is most critical, use true broadband speaker(s) or a mid-low speaker with crossover to a tweeter.

Before start building try, together with the fiddle player, different amp designs to get a direction you can follow in your design, then afterwards tweak the builded amp to get the wanted sound in detail.

regards,
Guus

[Smokebreak]

So I wanted to say thanks a bunch to everyone that helped me here with this fiddle amp. This was pretty much my introduction to understanding frequency responses.
I ended up with a 5F6A with a severely modified tone stack, scratchy presence and a cut control, through a 15" Black Widow, Mojo cab. The owner is over the moon about it, and has since stopped using his DI in front. I was quite nervous the first gig we played together with the amp, that I made him bring another just in case, but so far so good. I'm having a hard time getting it back from him to remeasure for a faceplate and record the stack values, because he is worried I am going to try and tweak it some more. He knows me too well
I can post the stack values at some point, but as I remember I shifted everything over and up quite a bit, using a lot of the information here, and used small bypass caps at the frontend. Guitar sounded pretty awful through it too.
Thanks again!
Jeremy

[xtian]

Wow, sounds like you have kicked that ass. Would live to see photos. Better yet, of violin player in action, with a grin on face. Congrats.

[Smokebreak]

Wow, sounds like you have kicked that ass. Would live to see photos. Better yet, of violin player in action, with a grin on face. Congrats.

Thanks man. I don't have any finished pics but i dug these off my phone, as I was sending him pictures to show him the speaker. This is obviously mid tweak, with components and leads a-flyin. I find those narrow panels quite difficult to keep neat, and the proximity of everything kinda freaks me out a little..I'll get a live action shot next gig

[EtherealWidow]

Wow! That thing looks great! Great job with the tolex