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Messages - syndromet

#121
Preamps and Effects / Re: Hiwatt-based preamp
July 21, 2006, 06:00:32 AM
Quote from: teemuk on July 21, 2006, 04:44:06 AM
The last two clips sounded very good. By swapping that fet you lowered the gain of the first stage, right? It really made a difference, IMO the first two clips sounded pretty bad while the last two had a "smooth" overdrive sound that I really like. Did you rebias or make any other changes (with MPF102 the circuit sounds less bright)?

I found the circuit to be a little brighter and "rounder"-sounding with the mpf102 in the first stage. The mpf lowers the gain of the first stage, wich affect all the other fet's aswell. IIRC, I had to rebias when installing the mpf. I had to do this at realy low volume, so it's not correctly biased. Thats why it sounds gated and fuzzy. When the bias is set correct you will have a very nice classic rock sound, without the "Fizz" you hear on the mpf102-clipps. (and j201, for that matter). I'll try tweaking it this weakend, and post some new clips, this time with a tuned guitar.... :P

The circuit also have a huge volume-boost, so I think this could be a nice preamp for a chipamp. I'll test it as soon as I find a transformer for my lm1875 kit.
#122
Preamps and Effects / Re: Hiwatt-based preamp
July 21, 2006, 03:29:49 AM
I've got it up and running, but I havent tried it with a higher voltage than 9V. I had a few troubles getting it to work, but they should be corected now. This thing sounds good, and has a very classic rock sound.

Things I like about it:
The Briliance-switch does a lot to the sound, and gives it a little more bite.
Good classic rock distortion
Very silent.
Useable range on the tone-controll.

Things I'll change:
The presence controll needs some work, as it is barely notiseable like it is now
Needs a mpf102 in the first stage, otherwise youll have some oscilation and a harsh overdrive.


Theese clips were recorded Guitar->Hiawatha->soundcard, and I've used guitar rig to simulate a twin reverb through a 1*12 speakercab.

j201 in first stage
Humbucker
Single coil

Mpf102 in fist stage
Single coil
Humbucker

So, RDV, is there anything Hiwatt--like in the sound?
#123
Amplifier Discussion / Re: In progress LM1875
July 13, 2006, 04:35:29 AM
Asembling the PCB's went smooth, and was done in about an hour. The heatsink came from my broken pioneer amp. should be big enough for 3 stereo 1875's.

As for finding an enclosure, I'm planning on taking a trip to the garbage deposit to see if I can find an old radio. Guess that would make a pretty cool amp.
#124
Amplifier Discussion / In progress LM1875
July 12, 2006, 07:54:00 PM
Just wanted to post the first pictures of my in progress of my lm1875-amp. The boards are asembeled, and the heatsinks are cut to the right sizes. Now I just got to find a suiteable transformer and build myself a chassis, wich will be the most time-consuming part....

Big pics ahead

Amplifier board and heatsink 1
Amplifier board and heatsink 2
#125
Quote from: trevize on July 11, 2006, 10:00:09 AM
Ok i received today the lm1875 kit from Joe. I'm thinking about building a stereo guitar amp
(does someone remebers the jazz-chorus with two speakers and two power amps?).

I got a jensen p10r cone for 20 euros from ebay and another one is on the way.

now i need to buy the transformer.

can you tell me the specs for the right transformer?
should i go for a toroidal or not?


That is exactly what I'm planning to do with mine. I will build a stereo top with the two lm1875's and use my digitech multieffect prosessor as a preamp. I will hook this up to two single 1x12" cabbinets, equipped with HH vintage 60's I bought for 30$.
20W should be enough for gigging if you mic it, right? I also wander what kind of transformer I need for this, and if anyone know any shops in Europe with cheap transformers.
#126
Guess I'll buy a transformer! It seems Pioneer uses this transformer for a AC out,  to supply other stereo components with power.
Now I just have to find the right transformer at the right price. I don't really understand why everything has to be so expensive here in Norway. 50$ +shipping for a regular 24V 200vAC torodial. Guess it is worth it anyhow.

Thanx for the help, guys!
#127
Thanx, RDV!
Here is the meaurements:
Side 1
Pin1 and 2 - 8,7 ohm
pin1 and 3 - 1.2 ohm
pin2 and 3 - 9.5 ohm

side 2
pin1 and 2 - 0.9 ohm
pin1 and 3 - 1.5 ohm
pin2 and 3 - 1 ohm


Does this tell you anything? The primary should see 230V, by the way.
#128
I guess I was a little short on my last post, since I'm qiute shure some of you know this.
Here are some pictures of the transformer. Can anyone help me find wich side is the primary?
Pic1
Pic2
Pic3
Pic4

One side is marked with a red dot... Does that mean anything?
#129
Thanks. Guess I was a little to hasty there.. I'll get this started, as soon as I figure out what the secondary voltages on my transformer is, and wich side of the transformer that is primary.. :P
#130
Man, that was fast shipping. The parts arrived to day, all in perfect order.

However, I was wondering if you hava a part-layout for this amp? Or do I have to understand what goes where by myself?  :o Guess I'm not bright enogh for that.

Anyway, Thank you!!!
#131
Preamps and Effects / Re: Hiwatt-based preamp
July 07, 2006, 10:17:52 AM
Well, I guess there will take some time before I can build this. I'm in the middle of redoing my appartment and moving. On the top if this I'm having a daughter in a couple of weeks. But I'll let you all know when I have build my first proto-type.

I've understood that you are a big fan of the Who, RDV. I also understand that you have had a Hiwatt? Let me know if it sounds  anything like your original when I get around to build this.
#132
Preamps and Effects / Hiwatt-based preamp
July 06, 2006, 11:33:33 AM
If anyone is interessted, here is a Hiwatt custom 50 simulator using Jfets. I haven't tried this yet, but I guess this will make a good preamp. Just run it at 18V, and use some 500k or 1M Trimpots.

I have named it Hiawatha 8) Click the images for bigger versions.

Schem:


vero-layout:
#133
I built two of dragonfly's Snake bite boosters in a BB box. Sounds great, and has a neat disortion on it's own. The best booster I've tried, and I've tried a few.

More info and link to the schem on www.syndromet.com
#134
Have you recived my payment too?
#135
Hi.
I have a broken Pioneer amp, and I'we ordered my first amp kit from Joe. I was hoping to use some of the parts of the Pioneer in my kit, mainly the transformer. My question is; how do I measure the secondary voltages on a transformer? And how much power does a stereo LM1875-amp need?

Nice place, by the way.  :tu: