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Author Topic: built another amp  (Read 6015 times)

Dmoney

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built another amp
« on: March 03, 2011, 02:37:21 PM »
So, with some help in form of parts and advice from JPF, I managed to build this thing out of some spare parts I had kicking about.



its a 6V6 in push-pull single channel head. The single channel is based on the SLO lead channel with a couple of differences.
Node & Star grounding with elevated AC heaters to reduce noise.
hard wired output jacks (1x16ohm and 2x8ohm)
currently running a 5751 in V1 and a 12AU7 in V4
Potted Toroidal PT and a 15watt OT.

I made a pretty poor demo with my macbook. Just waiting for a friend to return my SM58 so I can have another go at clips.
I'll be getting panels from JPF and a shell from Paul at Zilla Cabs in the near future. I'm very very happy with how it has come out!

http://www.youtube.com/watch?v=Kq7109j7Rwc

s'cuse the poor sound. better clips to come.

PhilKing

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Re: built another amp
« Reply #1 on: March 03, 2011, 03:43:54 PM »
The spec looks great, I bet it is a nice size for smaller gigs
So many pickups, so little time

Dmoney

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Re: built another amp
« Reply #2 on: March 03, 2011, 03:54:11 PM »
i'm hoping so. I think it's loud enough.

the chassis is aluminum and the weight is pretty low.
The shell will have a grill on the front and back, mainly so it looks like a mini version of my Avenger, but it will cut a little weight down as well. Should be really easy to carry about and it'll be loud enough for practice at least, and most smaller venues.

I have a band practice in brighton this weekend so I intend to take it down to that.

The chassis and transformers are the ones JPF uses for the 15watt Sir Charles. The JPF's are designed with portability in mind. If you need a simple and portable amp that is really good quality and great sounding, any of the JPF amps would be great.

Dmoney

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Re: built another amp
« Reply #3 on: March 04, 2011, 09:01:49 AM »
Is it good?
it ain't bad!

I haven't played too many amps at this output level. It basically a soldano avenger with a parallel triode for the first stage. The power circuit is different but the preamp is pretty much the same (parallel triode is the main difference).

It's sounds better than some mass produced heads I've played. It hisses less than a 5150/6505 as well. Plenty of gain too.

Dmoney

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Re: built another amp
« Reply #4 on: March 04, 2011, 09:34:13 AM »
I'll have my SM58 back from tonight, so tomorrow I'm hoping to get some better clips done. I'll also get to crank it tomorrow at practice.

Maxed out gain isn't really necessary. past a point, it just sounds fuzzier and starts to loose the tight aggressive edge. Same as the Avenger. Its a useful sound at all levels of gain, but just I just prefer it at 2 o'clock or under. (same as my avenger)

sounds REALLY nice on lower gain settings with my VHII equipped ES-333

JacksonRR

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Re: built another amp
« Reply #5 on: March 04, 2011, 01:13:49 PM »

First off, great job. I can tell it sounds excellent and await another clip. VHT Deliverance uses a parallel triode for the first stage, are you liking that a lot? Did you have to change much else to compensate for the difference in impedance?
Second, how did you get the light on the front to blink like that? That's actually kinda cool.

Frank

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Re: built another amp
« Reply #6 on: March 04, 2011, 02:45:15 PM »
Looks nice from the outside - let's see the wiring job though!

I've got the soldering iron out myself this week, just bought some transformers for something tubey and top secret. More news when I finish burning my fingers and blowing up capacitors.

Dmoney

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Re: built another amp
« Reply #7 on: March 04, 2011, 03:17:25 PM »

First off, great job. I can tell it sounds excellent and await another clip. VHT Deliverance uses a parallel triode for the first stage, are you liking that a lot? Did you have to change much else to compensate for the difference in impedance?
Second, how did you get the light on the front to blink like that? That's actually kinda cool.

There you go.
Save? This doesn't exist anywhere outside my flat, unless someone else has built one. I know some people have 6V6 Plexi's and 800.

xicon caps, metal film resistors, F&T filters. I decided not to use Orange Drops to save on the costs bit.
I decided to save some cash and use a combo of what I had lying around, plus some new parts.
Clarostat pots I had kicking about.
External Bias
Silicon wire (kind of looks weird to me)
4ohm tap is wired directly to the DC blocking cap in the negative feedback loop. I never use a 4ohm cab, so I added hard wired 16 and 8 ohm outputs. (1x16 and 2x Parallel 8's)
I didn't do much to add the parallel triode. I just added the same value cathode and anode resistors in parallel to the orginal values. Making the total resistance at those points exactly half the original value.

I'm sure I could do more by splitting the cathodes and biasing the two triodes differently. I've never tried that. The main benefit I was hoping for was the 3dB noise reduction I believe you get.

The standby cuts the HT right after the secondary and before the rectifier.

The pilot light flickers at 50hz (mains frequency) since it is a 240v AC lamp. not a 6.3v pilot powered from the heaters.
In person, the light doesn't really appear to flicker like that. It looks worse on youtube because the refresh/frame rate of my macbook camera must be close to 50hz or something similar. It's a standard kind of video 'distortion' you get.




« Last Edit: March 04, 2011, 03:19:39 PM by Dmoney »

Dmoney

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Re: built another amp
« Reply #8 on: March 07, 2011, 11:13:16 AM »
Hello all,

for those who might be interested...
I did a better clip. http://www.youtube.com/watch?v=Lk7vLcKV8M8

I'm not that good at mic placement and all that... so I don't find the recording as good as the room sound but it's better than the last clip.

 recorded using a SM58 on a pile of stuff half a meter in front of my 4x12 (V30's and T75s). Chord was going into my PODxt in bypass, and recorded via USB into Garageband. No effects, just a volume increase.


gain: 6, Bass: 8.5, Middle: 3.5, Treble: 6, Master Vol: 1, Presence: 6, Depth: 8.5.
5751 in V1, Tungsram 12AU7 for the PI. The Tungsram adds a bit of fizz when replacing the sovtek 12AX7LP ive been using in that position.

excuse my playing if you watch that clip. I tried to remember some cro-mags and breakdown tunes.

JacksonRR

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Re: built another amp
« Reply #9 on: March 07, 2011, 06:50:48 PM »
Crunchy and lively!

Transcend

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Re: built another amp
« Reply #10 on: March 08, 2011, 04:26:28 PM »
I think this build has been 100% a success.

I'd like to hear it in a mix situation though

Dmoney

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Re: built another amp
« Reply #11 on: March 08, 2011, 04:34:06 PM »
well... at practice is a JUST loud enough. I was up against an Orange TH30 and a mark bass combo though. It has no hum at all, which is great and I'd say it cuts through as long as your not being straight up drowned out.
It could do with more clean headroom in the power section and if I made another it would probably be better to go for a bigger bottle and go up to 30watts.

It does sound nice however using the MV higher up and a gain down. That way you get some nice 6V6 breakup plus a bit of preamp clipping. That gives you a really nice lead tone. I wouldn't say its a metal tone, more like a heavy blues kind of thing. With my VHII ES-333 that kind of setting just sounds really fat and nice.

I think it would be good for recording with. The crunchiness on that youtube clip comes across more there than when you're in the room. I don't know much at all about how to record to get a good example... so it'll have to do for now. I might be joining a band that does this really heavy blues kind of thing (earth - pentastar - in the style of demons vibe) and I think this amp would be great for recording with the 6V6's clipping and the preamp gain backed off.

MrBump

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Re: built another amp
« Reply #12 on: March 08, 2011, 04:34:42 PM »
Very cool.
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