Hasserl.com

Hasse Modifications for the Carvin Vintage Series Amps

This is the place to access all of the modifications Ihave for the Carvin Vintage Series amps, i.e. the Nomad/BelAir/VT 50 amps.

Note that the mods are now all in pdf format. You will need Adobe Acrobat Reader in order to read them (available free from Adobe).  I've made this change now because the pdf files take up much less room on my website and they are easier for you to download and save to your computer. You may do as you wish with these, but I ask that if you share them or use the info that you would give credit where it is due.

I do sell kits for any of the mods I have posted on these pages. Electronic parts are available in many places, and you may have your sources already. If not it makes it a little easier to go with one source where you can get all the parts you need for the job, and be assured they work properly. And that is the benefit my kits bring. Plus my assistance if you need it.

Please contact me at hasserl@netzero.net for information on kits.

Also, I perform these mods, as well as other mods, repairs, services, etc. on amps for people who do not want to do them themselves. Not just for people local to me, but people ship their amps to me for mods quite often. You can ship just the chassis to save on shipping charges, I don't need the entire amp. When I do these mods for people I go ahead and set the bias for the tubes sent with the amp, and give the amp a good once over. If it need serviceing such as pots and jacks cleaned, and/or tube sockets retensioned, I can do that for you also. If you want more info on this service please contact me at the same email address listed above.

1/9/15 Note: I am now taking in amps for mods on a limited basis. My work travel has slowed down, which is nice, but I have become very busy playing music, several nights a week, which is great! But it does keep me away from my work bench. A fellow can only be in one place at a time after all. In any case, if you're interested in having me work on your amp, email me and let's talk about it, but please understand I have limited time available, you'll have to be patient with me. Thanks for your understanding. 

Thanks,
Richard
aka hasserl   

Clipping Diode Removal Mod ------------  

Tone Stack Mod ---------------------------- 

Cathode By-Pass Mod  --------------------  

Presence Control  Mod  ------------------- 

Attitude Control Mod  ---------------------

LED Channel Indicator Mod  ------------- 

Master Volume Mod  -----------------------

How to check/set the bias  ----------------

FS22 LED Mod ------------------------------

Video Information on Attitude, Presence, LED & Master Volume Mods  ---  

Video Demo --------------------------------- 

Mod Kits for all of these mods -----------  

Note: The first four mods listed above  (Clipping diode removeal, Tone stack, Cathode By-pass and Presence Control mods) I now refer to as the Stage I mods, in order to differentiate them from the new set of mods that I call the Stage II mods. The Stage II mods are much more extensive than the Stage I mods and involve changes to almost all of the resistors and capacitors in the lead channel. I do not have detailed instructions written up for the Stage II mods as they are intended for someone with more experience who can work from a schematic, due to the more extensive nature of the mods. The Stage II mods are partly similar to the Stage I mods, but go much further, and though they address some of the same circuits the values of the components used are different.

If you are new to doing these types of mods I suggest you stick to the Stage I mods, plus the Attitude and/or Master Volume mods, as you feel comfortable doing them. The Attitude mod is a standard part of the Stage II mods. The Master Volume is not. Niether is the LED mod.

The results of the Stage I mods are like you've removed a heavy blanket from the front of the amp. They open it up and let it breath better. The amp will have more gain, and the gain is much more useable. Gone is the muddiness of the stock channel.

The Attitude mod lets you adjust the whole attitude of the amp, going from the stock mild setting to one that's much more aggressive. This lets the Clean channel of the amp get nice and dirty when you turn it up. Or leave it turned all the way down for the stock sound. This mod does effect both channels.

The Stage II mods greatly smooth out the distortion while also giving the amp a decidedly Marshall flavor. Except with more gain than is available from a stock vintage Marshall. You will be shocked at the incrdebile sounds available from this little amp with the Stage II mods! If you make this mod, please drop me a line at hasserl@netzero.net and let me know how it went, and any other comments, suggestions or questions.

1/9/15 -  I still get a lot of questions about whether Stage I needs to be done if a person wants the Stage II mods. The short answer is No, you do not have to order both kits and do both sets of mods. If Stage II is what you want, than just go with the Stage II mods, they cover everything the Stage I mods do, and more. 

The long story is, I developed the Stage I mods one at a time, just trying to address the issues I was having with the amp. Carvin had a very active internet forum at the time that I was heavily involved with, and the mods started after a lot of online discussion about the nature of the Soak channel and the problems that many of us had with it. I did one mod, reported back to the group about it. Then later I did another, etc. It was kind of a community thing, where I developed the mods and shared them with the  group, and many of the others in the forum completed the mods along with me, and we all discussed what we liked or didn't like. It was a group effort, so to speak. With the Stage II mods, I designed them as a whole, to work together. I had already done the Stage I mods and thought I was done with them, and was busy working on other amps. I came back to my Nomad after a time, and after several custom amps, and I decided I still wasn't happy with the sound and wanted to redo it all. This time instead of a step-by-step approach, I approached the mods as a complete reworking of the channel. Parts of what I had done earlier with the Stage I mods were reworked for the Stage II mods, so not all the components are the same value, so they really are different mods with different intent. Stage I was just trying to clean up the buzzy or muddy distortion. Stage II was to smooth out the distortion even further and revoice the amp, more along the lines of a hot rodded Marshall JCM. I wanted to emphasize the British character of the amp with its EL84 tubes. I hope that helps clarify things.

Richard