Tuesday, November 30, 2010

VHT Special 6 Amp - Modified for Blues Harp

This is an amazing little amp to start with, and these mods make it even better.

Bruce Collins at Mission Amps modified the voicing and tone stack as described in the previous blog post. The changes were actually very small: a few components on the eyelet circuit board. Anybody who can solder could do it.

I installed an Eminence Lil' Buddy speaker, mostly because it has a hemp cone similar to the Cannabis Rex speaker I use in my Mission Chicago 32-20 amp.

The amp has a JJ Tesla 6V6 S power tube in it in this video, but the stock power tube sounds the same.

The delay pedal -- with a small amount of delay -- is ON when the video starts. The delay is OFF after you see me hit the button.

Here are the differences I hear in the modified amp:

-It is louder than the stock amp. The Eminence speaker is more efficient.

-It is warmer/darker than the stock amp. Bruce voiced it lower, and the Eminence speaker is less bright. IMPORTANT NOTE: The amp is sitting on a pedestal in this video, up off the floor and away from the walls and corners. That gives it a truer sound, with less exaggeration of the bass tones. If you put the amp on the floor or against the wall the bass with be more apparent.

-The sound is bigger and less boxy.

-The break-up is more organic. The stock amp had a slight crackly, reedy quality to the tone.

-The amp tips over into nice distortion when you push it a little bit. You can hear that in the second part of this video when I play the blues riff a second time a little harder. This is because of the circuit mods.

-The amps seems more dynamic and musical. I gotta tell ya... it is a blast to play!

I played this amp at a loud blues jam at Ziggies Saloon in Denver on Sunday and it did well. I got lots of nice comments on my tone. It is not as robust and powerful as my normal gig rig, so I had trouble hearing myself in the loudest moments. The next mod will be a line out, so I can put a bit of the amp through the monitors. That will be perfect. In all but the loudest situations I think the amp will do just fine by itself.

So, I paid $200 to Amazon.com for the amp. It arrived in five days, no shipping charge. The speaker sells for $75. There is no real need to change the stock tubes unless you are an inveterate tinkerer (like me). The tubes sound fine. For $275 you can own a killer little harp amp that beats the pants off the EL84 amps like Kalamazoo, Epiphone, and Fender Pro Jr.

With the circuit mods the amp steps up to a whole new level and becomes a true harp amp. It has the tone and feel you crave... It's a boutique harp amp for a fraction of the cost.

I am thinking of offering a kit for the circuit mods. If there is interest in this, let me know. I will produce detailed instructions including a video, and include all parts and wires. I may also offer complete conversions. If I get some demand for this I'll come up with some prices and publish them here. The price of the mod kit would be quite modest, for sure.


Unknown said...

Sounds great, Rick! Can you let us know what mods were done when you brought it to Bruce?

What mic were you playing through on this clip?

Rick Davis said...

Hi Josh-


I'm playing a Front & Center mic with crystal element in this video.

The mods are described in general in the previous blog post.

Unknown said...

Hi Rick,

I saw the earlier post. I was hoping for the specifics in case I get this amp and decide to mod it. Might you and Bruce publish the mods in detail at some point?

Spritty said...

Hi Rick,

I'd have interest to get detailed information of the mods you did to the circuit, maybe as video or drawing (not native speaker english)

Thanks in advance

Unknown said...

Rick, Did you mic the amp at the jam? I would be surprised if you didn't. I played through one of these amps and also agree that is a nice harp amp out of the box. -Joe

Rick Davis said...

Joe, I did throw a mic in front of it, mostly for some monitors. But the mic got kicked away from the amp on the first song, so it wasn't much help.

I plan to get a line out on the amp, maybe today.

I wonder if anybody has tried using TWO of these amps....

Rick Davis said...

Josh, that would be up to Bruce Collins at Mission Amps. The mods are proprietary at this point. Try asking custom amp makers for schematics. No way.

That said, the VHT Special 6 amp is very easy to mod. The components are right there on the eyelet board, very easy to get to and solder. Anybody who knows his way around vintage tube amps could modify the tone of the amp without any guidance.

exdmd said...

I'd be glad to buy the kit if/when you make it available. Or buy an amp already modded. Wanna sell yours :)

Rick Davis said...

exdmd, Sorry, can't sell mine. I plan to offer converted VHT Special 6 amps in the near future. I'm working out details now. Stay tuned, it won't be long.

Mattias said...

I would surely like to buy such a mod kit if you are going to put together and sell them.

Best regards
Mattias, Sweden

Unknown said...

Hi Rick, I bought a Special 6 last week and used it at a gig. I put an old RCA 6V6 in it and it sounded really smooth and creamy. I did have some trouble with feeback on stage (which is sort of rare for me) so I'm thinking of trying a lower gain preamp tube. Most people have said you don't need to do this but I'll see how it goes.

If you do end up offering mods for this amp, I hope you'll offer fully modded amps as well as mod kits for those of us who already have the amp. Cheers.

Rick Davis said...

Josh, I'd suggest a 5751 for replacement of the preamp tube. btw, the circuit mods help with the feedback. The tone stack is darker and the reedy highs (good for guitar, bad for harp) are gone.

Ron Bowman said...

Rick, I would also be interested in the mod kit for the VHT amp. Hope there is enough interest to go ahead with that.

Nice Blog. Great information.

Thank you,

Big Ernie Fuller said...


This amp gives a real big sound for it's size? I'm curious if it uses a solid state rectifier?

Rick Davis said...

SS rectos sound good in small Class A amps... These small amps never get sag anyway, because they are always cooking on high. SS rectos are fine for them.

Unknown said...

I have just taken delivery of one of these amps and mut say I find it better than the previous two small "harp" amps I've had and that include one that had already been modified.

I would certainly be interested in a mod kit if you ever bought one out.

Unknown said...

I'd be interested in a modified Special 6 if you've been able to work out the details...

Melodious Thunk said...

If you ever offer a mod kit I'd really like to get one!

Anonymous said...

I would be interest in the kit as well.

Question: have you tried a Eminence Red Coat Series Ramrod Guitar Speaker in the VHT vs the Eminence Lil' Buddy speaker you mentioned?
I am curious in the difference between the two speakers.

Unknown said...

Hopefully very soon Alnicomagnet (Ebay name) will be producing a very interesting harp mod kit for this amp.

Unknown said...

There is now a mod kit on Ebay UK by Alnicomagnet the item number is 260749156886. Looks like he has done some interesting changes, including a line out facility.

Soloharp said...

Hi, I want to ask for advice, please.
¿What would be the best of these 3 options for harp amp?, I mean always amps without mods:
1-VHT Special 6 combo 1X10"
2-VHT Special 6 head with 1x12" cabinet
3-VHT Special 6 combo 1X12"

Please could you tell me so I can decide to buy.

Thank you very much everyone!

Soloharp said...

I was wrong, the third option I referred to the Special 6 Ultra Combo 1X12"


Soloharp said...

Sorry, the 3 option I referred to the Special 6 Ultra Combo 1X12 "


Unknown said...

Rick, did setting something up to sell hot rodded VHT Special 6's happen or perhaps the mod kit became available? Thanks for all the info your blog offers.

Rick Davis said...

Sorry, John. Bruce at Mission Amps got too busy with his own line of amps, so the VHT mod kit project did not go forward.

Deemoid said...

Hi Rick,

just wondered if you[ve had a chance to hear a special six with the alnicomagnet mods in place.

I'd be more trusting of Bruce at Mission's adjustments and the alnicomagnet kit sounds like it might make the amp too gainy.

Any thoughts would be very welcome.



ps, thanks for introducing me to the great playing of young Nic Clark! Sick!