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Dirty-South Blues Harp forum: wail on! >
VHT Special 6 Harp Mod Kits Now Available!
VHT Special 6 Harp Mod Kits Now Available!
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Matzen
48 posts
Mar 09, 2011
3:30 PM
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A "Tonestack Cap Upgrade" and "Blues Harp Mod Kit" are now available for the VHT Special 6 through Alnicomagnet on Ebay:
http://cgi.ebay.com/Alnicomagnet-Tonestack-Cap-upgrade-kit-VHT-Special-6-/360350266902?pt=UK_MusicalInstr_Amplifiers_RL&hash=item53e68cb616
and:
http://cgi.ebay.com/Alnicomagnet-Mod-Kit-Blues-Harp-VHT-Special-6-/260749156886?pt=UK_MusicalInstr_Amplifiers_RL&hash=item3cb5dc6216
Here's some info on the "Mod Kit" from the auction site:
I've been asked to come up with a decent sounding mod kit specifically for Harp players, so, after many many hours of research and development, tweaking and listening, here is the result.
This kit is suitable for all territories and mains voltages.
This kit is designed to change the voicing of the amp to give a thick, ballsy, Chicago Blues tone, suitable for Blues Harp microphones only. After the amplifier has been modified, you may still use it for guitar, but there will be virtually no clean sound, and it will sound too thick especially with humbucker equipped guitars. The “boost” pot and footswitch are no longer used, so I’ve taken this opportunity to use the boost footswitch jack as a line-out jack, suitable for feeding to a larger amplifier, P.A. mixing desk etc. The line-out jack signal comes after the output transformer so is rich in output valve as well as preamp valve distortion. I’ve also taken this opportunity to replace the poor quality pull switch volume pot and tone pot with high quality Alpha 24mm pots, together with a simple gentle “Treble Cut” control, which is much better suited to Harp microphones to help tune out feedback.
You will probably know that the current stock output valve is a generic Chinese no-name item. It is the same as which is supplied with the Fender Champion 600, which I have had problems with in the past. I therefore recommend you change it to a higher quality name brand. My personal favourite is current production JJ Electronic.
The amp uses a 6V6GT 8-pin international octal type which apparently can be substituted with a 6L6GT, 5881, EL34, KT66, KT77, KT88 etc. However, before doing so, please understand that these valves draw a lot more heater current, compared to the 450mA of a 6V6GT. The mains (power) transformer is identical to the unit fitted in the Fender Champion 600, and I know from experience that this transformer already runs very warm (in both amps) so caution will be required if considering a valve type swap. (Don’t forget that the preamp valve will draw 300mA all the time irrespective of which output valve is fitted).
If you have the combo, I would keep it running a 6V6GT, as there is no room for anything larger, unless you remove the speaker, or fit a driver with a smaller magnet.
With the head amp there are no such space restrictions, and it is reasonably well ventilated. My suggestion would be the JJ 6L6S which draws 900mA, and has a very safe (well over 400V) anode and screen max working voltage. Fitting this valve, and increasing the B+ voltage, changing the cathode resistor, and loading the valve harder will produce around 10watts audio output power. I have included in the kit, various resistors so that you can adjust the B+ to suit the valve type fitted, and your local mains voltage.
Please be aware that installing these modifications may void the manufacturer’s warranty and that this kit and the procedures described are neither affiliated with nor endorsed by VHT.
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jimr
3 posts
Mar 09, 2011
6:26 PM
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I am interested in hearing it, so I will install the mod kit in someone's Special 6 for free. Send me your stock and properly functioning amp and kit, I will expertly install it, you pay for return shipping. I have lots of experience with tube amp builds and mods, including Special 6 mods.
Jim Rossen
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