Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Preamps and Effects => Topic started by: syndromet on July 06, 2006, 11:33:33 AM

Title: Hiwatt-based preamp
Post by: syndromet on 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:
(http://www.syndromet.com/bilder/hiwatttumb.jpg) (http://www.syndromet.com/bilder/hiwatt22.jpg)

vero-layout:
(http://www.syndromet.com/bilder/hiawatatumb.jpg) (http://www.syndromet.com/bilder/hiawata.jpg)
Title: Re: Hiwatt-based preamp
Post by: RDV on July 07, 2006, 09:35:50 AM
Looking forward to sound samples.  :tu:

RDV
Title: Re: Hiwatt-based preamp
Post by: syndromet on 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.
Title: Re: Hiwatt-based preamp
Post by: RDV on July 07, 2006, 09:13:18 PM
Wow, I yak about me a lot on line don't I! :duh

I had a Hiwatt that never worked right till I had it retubed and biased and then found out that no one wanted to hear me that loudly so I sold it to a heavy metal bass player.

I may try out the circuit myself this weekend. I'll let you know.

RDV
Title: Re: Hiwatt-based preamp
Post by: syndromet on 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 (http://www.syndromet.com/sounds/hiawatha1.mp3)
Single coil (http://www.syndromet.com/sounds/hiawatha2.mp3)

Mpf102 in fist stage
Single coil (http://www.syndromet.com/sounds/hiawatha3.mp3)
Humbucker (http://www.syndromet.com/sounds/hiawatha4.mp3)

So, RDV, is there anything Hiwatt--like in the sound?
Title: Re: Hiwatt-based preamp
Post by: 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)?
Title: Re: Hiwatt-based preamp
Post by: syndromet on July 21, 2006, 06:00:32 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.
Title: Re: Hiwatt-based preamp
Post by: joecool85 on July 21, 2006, 07:35:42 AM
Sounds good to me!  I especially like the MPF102 clips, mostly the humbucker.  What type of guitar is that?
Title: Re: Hiwatt-based preamp
Post by: syndromet on July 21, 2006, 08:36:16 AM
That is my trusted Epiphone Les Paul. It's a great giutar, but you have to try them out if you're buying one. Some of them are realy bad too. I used to have a set of di-marzios in it, but found out I like it a lot better with the stock PU's. This guitar gets better for every year that goes, and I'we never had a problem with it for the nine years I've owned it. Top quality for a great price.
Title: Re: Hiwatt-based preamp
Post by: joecool85 on July 21, 2006, 08:52:29 AM
Les Paul Standard?  I've been looking at getting a Epi LP JR.  I need to find a place around here that carries them so I can play one.
Title: Re: Hiwatt-based preamp
Post by: syndromet on July 21, 2006, 09:16:39 AM
Yes, it's a Standard. I've played a few specials, and some of them are prety good. I don't think you'll save anything on buying a special, since they need a a major upgrade in the hardware section to be useable.

I'ce never tried a JR yet, but I thinkI would miss the neck pickup if I did. I'm sure it's a great guitar, though.
Title: Re: Hiwatt-based preamp
Post by: joecool85 on July 21, 2006, 12:08:33 PM
I dunno, I never use the neck pickup on the guitar I have now.  I really like bridge pickup sound.
Title: Re: Hiwatt-based preamp
Post by: syndromet on July 25, 2006, 04:03:30 AM
I dunno, I never use the neck pickup on the guitar I have now.  I really like bridge pickup sound.

I know what you mean. I used to be a metal-to-the bone kind of guy, always using my bridgepickup. I actually thought about ripping ot the neck pickup, and make the cavity a place to put pyrotechnics. Glad I didn't do that.....

As the year envolved, I found that I started using the middle-possition more, and more, with the volume of the bridge a little higher than the vol of the neck. This fattens up the sound when riffing, and when it's time for a solo, you just flick the switch to the bridge possition. Also, if you're using octave effects, they sound a 1000 times better with the neck pickup and tone rolled down. Now I can't see myself playing a guitar without a neck pickup.
Title: Re: Hiwatt-based preamp
Post by: Stompin_Tom on August 16, 2006, 05:15:05 PM
hmmm... I really like the idea of this preamp for a chipamp because the hiwatt power amp was pretty clean/hifi back in the day. That is, unlike marshalls and the like, there was less sag in the power amp. Should be able to make this into a good sounding solid state. My friend actually has two hiwatts (100 watt head and 4X12 cab and a very strange 100watt 2x12 combo - not too many of those were made) and this sounds way grainier and muddy to my ears. For me the defining tonal characteristic of his amps are how clean they sound. I'm not talking jazz amp clean, but clear and chimey... I think of it as just about as HiFi as you can get a big honking tube amp. If you think of pete and the who, his tones were never really that overdriven. I think the idea was to see how loud you could get a clean tone (with a little bite added). And, fyi, the presence knob on a hiwatt really adds a world of bite.

Anywho, I wish I knew more about electronics so I could help tweek this circuit, cause I'd really like to build one when it sounds good!
Title: Re: Hiwatt-based preamp
Post by: syndromet on August 17, 2006, 10:36:31 AM
Hi.
This preamp add a great distortion when the knobs are turned all the way up, and there is a lot of different sounds playing with the gain and volume controlls. It can go from a clean, sparkley sound to a classic rock-type distortion/overdrive. I guess it sounds a lot like a hiwatt, and when cranked it sound like a tube-amp pushed hard. I really like the sound of this, but I really wish I could get the presence-controll to do something. I don't have a lot of time to work on stompboxes these days, but when I'll get the time I'll try to get the presence to do something.

Running this on 18 volt would give you a lot more headroom, giving you less distortion at higher volumes. Running this on 18v I guess this will be a really good tube-like preamp, giving a great breakup ehen pushed. I'm planning on trying this when my Lm1875 amp is finnished.

I changed the Gain and Volume-controlls on the schem and layout, but they should be 500k as they were on the first schem. The reason I changed them was that I had misswired the pots, so they didn't work propperly.  8) When wiring things up the right way, 500k turned out to be theperfect value.
 
Even if the precence controll doesen't work at the moment, I encourage you to build this. As soon as I get the presence controll to work, it will (hopefully) only be a few components that should be changed. I would really like the feedback from someone who knows what a Hiwatt sounds like.

I finnished the box for this earlier today, so I'll post pics and soundclipps when it's finnished.
Title: Re: Hiwatt-based preamp
Post by: Stompin_Tom on August 17, 2006, 10:41:24 AM
Great! You've made me very excited... I'll probably want to figure out a 18vdc supply for this somewhere along the way, but 9v will be easy to start with. Thanks for all your effort!

Now I need to order more parts.

Also looking foward to seeing and hearing it some more.
Title: Re: Hiwatt-based preamp
Post by: Stompin_Tom on August 17, 2006, 10:44:41 AM
Wait... just noticed that you went with a tone control instead of a full tone stack (treb, mid, bass)... was that just to make it simpler?
Title: Re: Hiwatt-based preamp
Post by: syndromet on August 17, 2006, 11:01:06 AM
Wait... just noticed that you went with a tone control instead of a full tone stack (treb, mid, bass)... was that just to make it simpler?

Yes. The TMB controll from the hiwatt schem can easily be put back in place, but for stompbox-use, I figured 6 controlls and a swich was a little too much. I'm allso a "less is more" kind of guy, and I figured that a bright switch, a tone-, middle, and bass-knob and a presence knob was to many ways for me to change the voicing. A TMB-tonestack
always give me a headache, as I feel I have to twist knobs for hours to find a sound I like. Thats why I like the simplicity of a simple knob.

It would also recuire a somewhat larger layout, but it can easily be done. If you have the oppertunity to wait a few days, I might be able to draw up a new schem and layout with the full tonestack. I think this circuit could benefitt from the full tonestack, as I've heard much of the "Hiwatt-magic" lies in this tonestack. Nyway, it makes a pretty good overdive with the tonestack that I've added, but I would really like to change the tone-circuit a little, as it doesen't have that much affect on the sound. Anyway, I like this enough to use it as my main overdrive, but I might be a little biased.  :tu: Thats why I would like to hear what others think.
Title: Re: Hiwatt-based preamp
Post by: Stompin_Tom on August 17, 2006, 12:28:22 PM
Cool. Keep me posted on the progress... I think as a stompbox a tone stack is not so important, but as a preamp it's very important... So, if you get around to adding it back in, let me know!! When I have some more time I'll look into myself... Thanks.
Title: Re: Hiwatt-based preamp
Post by: syndromet on August 18, 2006, 09:38:24 AM
Here is a few soundclipps that does it a little more justice than the earlier ones... Backing is with gain and vol at 12, while the solos are with the knobs dimed. The playing sucks, as everything you hear is first take. It's recorded Guitar -> Hiawatha -> SB Audigy SE -> Cab sim in Guitar rig.

Single coil (http://syndromet.com/sounds/hisingle.mp3)
Humbuckers (http://syndromet.com/sounds/hihum.mp3)

(http://i36.photobucket.com/albums/e48/syndromet/hiawatha1.jpg)
Title: Re: Hiwatt-based preamp
Post by: Stompin_Tom on August 18, 2006, 09:44:23 AM
Sounding good! Nice solos...
Title: Re: Hiwatt-based preamp
Post by: syndromet on August 18, 2006, 10:25:08 AM
Sounding good! Nice solos...
Thanks. Don't know about the solos, though, as there is a lot of laatency on my soundcard, I miss the high e on my les paul, and the playing was really sloppy.

So, does it sound anything like a Hiwatt?
Title: Re: Hiwatt-based preamp
Post by: Stompin_Tom on August 18, 2006, 02:41:07 PM
My friend likes to use his with hardly any eqing (more or less flat) and that sounds much like your clips... I personally like Hiwatts set up to be really bright and cutting with my tele. It's hard to say if your pedal could do that from the sound clips. I think your pedal sounds good, even if it's not *exactly* like a hiwatt... and that's probably all that matters.

One thing I had thought of is bridging the norm and brill inputs with separate volume controls (instead of a switch between the two). Using both 'channels' at the same time on a hiwatt sounds really excellent. I'm not sure if that would have much effect on your pedal, though, as it wouldn't really drive the 'tubes' in the same way... but I'm curious.
Title: Re: Hiwatt-based preamp
Post by: syndromet on August 18, 2006, 03:50:16 PM
Two different inputs is probably a good idea, since the Brilliant input has a boost cap that I left out. I think if you follow the original Hiwatt schem with Jfets instead of tubes, you will probably have a really good preamp.
Title: Re: Hiwatt-based preamp
Post by: Georgedepinedo on April 08, 2013, 11:36:06 PM
Can you please repost the vero and schematic, I cannot open them.