Blackheart 5 watt

Redfoxfur · 10th March 2008, 06:35 AM

I just got a new Blackheart little giant 5 watt head and was wondering if anyone knew any easier or less expensive mods besides the mercury magnets upgrade kits. They are a bit pricey and involve replacing both transformers and adding a choke. I thought maybe i could just replace the output transformer but I'm unsure on what transformer to use and what modifications i would need to make to the circuit. I Haven't done much tinkering with this kind of stuff so just replacing the transformer would be a big project for me. Another question i had was if it is possible to use an adapter to use A 6V6 instead of the el84 i know it can go the other way but i wasn't sure if it could be done this way.

Geek · 10th March 2008, 06:50 AM

Hi,

I've been reading about that one but haven't seen a schematic.

There's easier things to tweak than iron and output tube. Play with the tonestack a bit. Use Duncan Amps Tone Stack Calculator program for help with values.

Changing the input tube can have a far more profound effect than the output tube. What is it? Let me guess... another 12AX7

12AT7, 5751, 12AV7, 12AY7... go nuts

Cheers!

Redfoxfur · 10th March 2008, 07:01 AM

I have a few preamp tubes in mind to swap out it is a 12ax7 and at the very least i'm going to use a NOS RCA 12ax7 but i also have some 12dw7s, 12at7s and 12au7s i'm wondering if there are any tubes other then the 12xx7s that can be used i have allot including 6c4s and 6au6s i doubt those would work although i haven't actually looked anything up on these tubes.

Geek · 10th March 2008, 09:23 AM

Hi,

If you're going to go through the trouble of re-basing the socket for another 9-pin, try a 6EJ7. Of the single pentodes I tested (a lot), it had the most gain and least microphonics. Only the EF86 was better in the microphonics department (still had less gain though).

I'm designing a simple 10-watt head geared for hard rock (heh, a VJ for metalheads?) and a single 6EJ7 front end is more than enough to drive the tone stack and push the PP output triodes into ear-splitting OD

Cheers!

Redfoxfur · 10th March 2008, 10:50 PM

I replaced the stock Chinese 12ax7B(The chassis indicates a 12ax7A should be there) With a NOS RCA 12ax7 and instantly i could tell it was allot warmer and it had a nice bass to it. The Chinese tube was a bit harsh to me i was having to turn the treble down and bass all the way up. Now it doesn't take as much to get the tone i wanted. The Breakup is a lot creamier now before it was a bit to tingy for lack of a better description. Maybe in the future ill try a 12ay7or a 12dw7 i used one in my fender super210 And it gave it a bit more of a unique sound. The 12dw7 is unbalanced it has 20 gain factor on one side and 100 gain factor on the other i'm not sure what this will sound like in this one or if its a good idea i'm not sure if the swap will work in all circuits.

Cycline3 · 27th March 2008, 02:33 AM

Hey now... if you're going to all the trouble and expense to replace all the transformers and choke and maybe tubes - you need to rethink things! In that case, I'd build a NEW amp with the new iron and have two amps to choose from! Currently I have four guitar amps I built and they all sound different - depends on the day which one I want to play... certainly an idea.

As for tubes, I've become real fond of the new Sovtek 12AX7LPS - it really sings in my guitar amps and is pretty fine at audio too. And at $11, it's way cheaper than good NOS.

kd0bdk · 27th March 2008, 06:48 AM

regarding re-design, if you are out to go with a more muscular amp, check out the 6L6gc or perhaps the 6550...single ended 6L6gc gives 8-11 watts out, 6550 can give as much as 20 watts for single ended, and 100 watts in push-pull for as little as $19.95 each...6146 beam pentodes also work quite well for as little as $17.95, but they require a plate cap, but can quite easilybe coaxed to put 120 + watts out! regarding the pre-amp and voltage amps, you can use pentodes for extra gain, but if you simply add in extra stage you can use a 6sn7gt for as little as $5.95...and you are dealing with octal sockets which means more room to work!

Geek · 27th March 2008, 09:44 AM

Hi,

Quote:

Originally posted by kd0bdk
regarding re-design, if you are out to go with a more muscular amp, check out the 6L6gc or perhaps the 6550...single ended 6L6gc gives 8-11 watts out, 6550 can give as much as 20 watts for single ended, and 100 watts in push-pull for as little as $19.95 each...6146 beam pentodes also work quite well for as little as $17.95, but they require a plate cap, but can quite easilybe coaxed to put 120 + watts out! regarding the pre-amp and voltage amps, you can use pentodes for extra gain, but if you simply add in extra stage you can use a 6sn7gt for as little as $5.95...and you are dealing with octal sockets which means more room to work!

It's not just tube cost though. You need to figure a good $100 for the beefed power supply to handle a 6L6/6550 and ilk. And OPT's for a 6146? EEEK!

Cheers!

10th March 2008, 06:35 AM	#1
Redfoxfur diyAudio Member Join Date: Dec 2007	Blackheart 5 watt I just got a new Blackheart little giant 5 watt head and was wondering if anyone knew any easier or less expensive mods besides the mercury magnets upgrade kits. They are a bit pricey and involve replacing both transformers and adding a choke. I thought maybe i could just replace the output transformer but I'm unsure on what transformer to use and what modifications i would need to make to the circuit. I Haven't done much tinkering with this kind of stuff so just replacing the transformer would be a big project for me. Another question i had was if it is possible to use an adapter to use A 6V6 instead of the el84 i know it can go the other way but i wasn't sure if it could be done this way.

27th March 2008, 02:33 AM	#6
Cycline3 diyAudio Member Join Date: Jul 2007	Hey now... if you're going to all the trouble and expense to replace all the transformers and choke and maybe tubes - you need to rethink things! In that case, I'd build a NEW amp with the new iron and have two amps to choose from! Currently I have four guitar amps I built and they all sound different - depends on the day which one I want to play... certainly an idea. As for tubes, I've become real fond of the new Sovtek 12AX7LPS - it really sings in my guitar amps and is pretty fine at audio too. And at $11, it's way cheaper than good NOS. __________________ My site: http://www.seanrose.com

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10th March 2008, 06:50 AM	#2
Geek diyAudio Member Join Date: Sep 2004	Hi, I've been reading about that one but haven't seen a schematic. There's easier things to tweak than iron and output tube. Play with the tonestack a bit. Use Duncan Amps Tone Stack Calculator program for help with values. Changing the input tube can have a far more profound effect than the output tube. What is it? Let me guess... another 12AX7 12AT7, 5751, 12AV7, 12AY7... go nuts Cheers!

10th March 2008, 07:01 AM	#3
Redfoxfur diyAudio Member Join Date: Dec 2007	I have a few preamp tubes in mind to swap out it is a 12ax7 and at the very least i'm going to use a NOS RCA 12ax7 but i also have some 12dw7s, 12at7s and 12au7s i'm wondering if there are any tubes other then the 12xx7s that can be used i have allot including 6c4s and 6au6s i doubt those would work although i haven't actually looked anything up on these tubes.

10th March 2008, 09:23 AM	#4
Geek diyAudio Member Join Date: Sep 2004	Hi, If you're going to go through the trouble of re-basing the socket for another 9-pin, try a 6EJ7. Of the single pentodes I tested (a lot), it had the most gain and least microphonics. Only the EF86 was better in the microphonics department (still had less gain though). I'm designing a simple 10-watt head geared for hard rock (heh, a VJ for metalheads?) and a single 6EJ7 front end is more than enough to drive the tone stack and push the PP output triodes into ear-splitting OD Cheers!

10th March 2008, 10:50 PM	#5
Redfoxfur diyAudio Member Join Date: Dec 2007	I replaced the stock Chinese 12ax7B(The chassis indicates a 12ax7A should be there) With a NOS RCA 12ax7 and instantly i could tell it was allot warmer and it had a nice bass to it. The Chinese tube was a bit harsh to me i was having to turn the treble down and bass all the way up. Now it doesn't take as much to get the tone i wanted. The Breakup is a lot creamier now before it was a bit to tingy for lack of a better description. Maybe in the future ill try a 12ay7or a 12dw7 i used one in my fender super210 And it gave it a bit more of a unique sound. The 12dw7 is unbalanced it has 20 gain factor on one side and 100 gain factor on the other i'm not sure what this will sound like in this one or if its a good idea i'm not sure if the swap will work in all circuits.

27th March 2008, 06:48 AM	#7
kd0bdk diyAudio Member Join Date: Mar 2008	regarding re-design, if you are out to go with a more muscular amp, check out the 6L6gc or perhaps the 6550...single ended 6L6gc gives 8-11 watts out, 6550 can give as much as 20 watts for single ended, and 100 watts in push-pull for as little as $19.95 each...6146 beam pentodes also work quite well for as little as $17.95, but they require a plate cap, but can quite easilybe coaxed to put 120 + watts out! regarding the pre-amp and voltage amps, you can use pentodes for extra gain, but if you simply add in extra stage you can use a 6sn7gt for as little as $5.95...and you are dealing with octal sockets which means more room to work!

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