modding my HT-5R (cleans and blues)

Liquid State

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I have had my HT-5R for about a year. I also have a BDRI (with Weber attenuator) and was looking for something with a different tone and that would be much much easier to haul to these blues sessions I play in a few times a month.

Did not take me long to reach the conclusion that the Blackstar HT-5R is basically a "high gain" bedroom amp. Great tube tone in a portable 5 watt package, but is mostly geared towards hard rock and metal. Is tough to get an "edge of break-up" blues tone out of the OD channel as the gain knob goes from 0 to 150mph with the slightest turn. I also found the clean channel to be very stale and boxy sounding. That said, I do like the overall platform: size, weight, volume, tube based, and the tone adjustment that goes from Marshall to Vox. I did all the obligitory research to see if I could help get this thing closer to "my sound". I went with the stuff outlined below.

mods: in order of impact

1) I put an EQ pedal in the effects loop (I have an MXR 10-band velcro'd into the back of the amp and it is always on). It made a huge positive impact on the tone and especially made the clean channel useable. It also improved the gain channel as well. In my opinion, this is how the EQ of the amp should have come from Blackstar. I picked up a used ebay deal.




2) Tame the gain. By changing the pre-amp tube with a lower gain tube, a much more useful range of gain can be adjusted with the gian knob. The original Sovteck 12AX7 is a "high gain" tube. I tried a JJ's ECC81, a JJ's 5751 (from Eurotubes), and eventually settled on a Electro-Harmonix 12AY7 that I picked up on Amazon for about $15.00. I can now run the gain knob at about 11 o'clock for a nice smooth bluesy break-up. This also helped the overall tone on the clean channel

3) I swapped the speaker from the original Blackstar Blackbird 50 to a Celestion G12M that I picked-up off craigslist. Again - I think this helped/altered the tone, but not nearly as much as the other two mods.

all in all, easy mods and this thing now works for me. I can still twist up the gain knob and have it get as heavy/dirty/driven as I will ever need, but now has a much more useful range. I can also find myself clicking on the clean channel and just jamming for an hour..... that never happened before.
 

MidlifeCrisis

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This is good stuff - thanks for sharing your research.

I agree that the amp has too much gain too soon. I'm going to experiment with a lower gain preamp tube if I ever get my HT-5R back from the repair shop (been in for FOUR MONTHS waiting for a new board - factory service is awful :mad:). But that's another story.
 

Liquid State

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I did notice an impact to volume, but for my usage it has not been an issue as I was not diming it anyways. I do have to turn the volume knobs up a bit less than a quarter turn higher to hit same volumes, but it is plenty loud for bedroom playing and jam sessions (without drums) that I play in.

At 5 watts, this is a tone (vs. volume) oriented amp in the first place and "for me" the improvements far outweighed the impact to max volume.
 

Gerr

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I did several of SloppyLicks recommended upgrades and got very good results. I did 3 upgrades to my HT-5C...

1. Switched the pre-amp tube to a 12AY7. According to the site I listed earlier, this tube only offers 45% of the gain that the 12AX7 does. This did two things to the amp. First is it gave the clean channel much more headroom, almost too much as I now hardly get any natural tube distortion off of the clean channel even at max volume. It also seems to have improved the sound of the clean channel overall, at least IMO. Where I noticed the biggest difference was in the dirty channel. Like the OP said, the amp no longer goes into full gain mode early on, but now needs the gain turned up much higher. This also allows better access to tube overdrive and crunch sounds at the lower gain settings. Overall, I think this is an improvement. However, might try a 12AT7 in the pre-amp to see what that does as it's a 60% gain factor tube, so doesn't take as much gain away.

2. I upgraded the speaker to an Eminence Redcoat Governor 8ohm speaker. This speaker is around 3db higher in efficiency than the stock speaker, so will make the amp louder overall. Plus running the amp at 8ohms instead of 16ohms just sounds better to me as it does have a slight effect on tone. Some people report a small volume drop when going to lesser gain pre-amp tubes, so this offset that and actually made it louder.

3. I replaced the cheap cable that ran from the speaker to the amp with a heavier one with gold connectors. While it's hard to measure an improvement, the thicker wire with better connectors should in theory transfer more signal to the speakers and thus make them even louder.

I have not played with an EQ pedal in the FX-loop, but I probably will at some point.
 

cybermgk

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I did several of SloppyLicks recommended upgrades and got very good results. I did 3 upgrades to my HT-5C...

1. Switched the pre-amp tube to a 12AY7. According to the site I listed earlier, this tube only offers 45% of the gain that the 12AX7 does. This did two things to the amp. First is it gave the clean channel much more headroom, almost too much as I now hardly get any natural tube distortion off of the clean channel even at max volume. It also seems to have improved the sound of the clean channel overall, at least IMO. Where I noticed the biggest difference was in the dirty channel. Like the OP said, the amp no longer goes into full gain mode early on, but now needs the gain turned up much higher. This also allows better access to tube overdrive and crunch sounds at the lower gain settings. Overall, I think this is an improvement. However, might try a 12AT7 in the pre-amp to see what that does as it's a 60% gain factor tube, so doesn't take as much gain away.

2. I upgraded the speaker to an Eminence Redcoat Governor 8ohm speaker. This speaker is around 3db higher in efficiency than the stock speaker, so will make the amp louder overall. Plus running the amp at 8ohms instead of 16ohms just sounds better to me as it does have a slight effect on tone. Some people report a small volume drop when going to lesser gain pre-amp tubes, so this offset that and actually made it louder.

3. I replaced the cheap cable that ran from the speaker to the amp with a heavier one with gold connectors. While it's hard to measure an improvement, the thicker wire with better connectors should in theory transfer more signal to the speakers and thus make them even louder.

I have not played with an EQ pedal in the FX-loop, but I probably will at some point.
In a Lot of amps, 12AT7 in V1 (or in this case all of the preamp) makes a very lifeless amp. Instead look at maybe a 5751.
 

Rhust

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the tube swap will have the biggest difference in the OD channel... the opamps kicking the pre amp in the teeth... for me, when I wanted the best low gain sound, I used a 12AU7... you can always hit it with an OD pedal to push it higher. the EQ pedal in the loop can push it too, and be very transparent.

alternatively, you can try a low-gain pedal like the sweet honey (or joyo sweet baby)- this is what worked for me that I liked best for low gain on the amp...


FWIW, the speaker I liked best was the G12T75 (or G12H30, both sounded very similar with the amp) - a V30 was too bright/middy, a peavey scorpion and the 70/80 was a little darker... I really wanted to try the K100, but have not bought one to try...
 

Dr. Pain

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I use my MXR 10 band KFK in front to push my HT-5. But can understand why you have one in the loop. I tried mine in the loop and the volume felt like it went through the roof! But I'm happy with mine as a mid range boost in front. :)
 

Boso

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I like your idea with the EQ. It gives you the ability to adjust the base voicing without losing the flexibility of the tone knobs on the front panel. Good stuff.

I'd turn that bad boy around so nothing could possibly mess with the sliders.
 

DHC

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Great thread, as I'm looking to tame some of the HT-5's gain.

So I go onto Eurotube's website and figure I'll try a few tubes (12ay7 and 12at7) and it asks if I want standard, balanced, matched triode, matched and balanced ...

Should I get the standard?

Thanks!
 

Liquid State

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hi
yeah... hmmmm - you are already over my head with those questions. I just bought one each of the different pre-amp tubes with different gain ratings. I am guessing I got standard..... it worked. You can call the guys at Eurotubes and talk it over. They were very helpful/patient with me
 

DHC

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Ok, went ahead and ordered a 5751 and a 12AT7 from Eurotubes.

Will report back when they arrive and I've had a chance to play around with them.
 

DHC

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Ok, installed the 5751 instead of the stock 12ax7 and, after fooling around for 15-20 minutes, it is a major improvement. The amp's usability is much better, where I can actually use the gain knob.
 

rem22

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Thank you for this post ! Very interesting !!

I liked the sound of the HT-5 and I have a few questions :

- if you do your mods (swapping the tubes) will you still get the '80s hard rock metal sound ? I mean, GnR and Iron Maiden are the heaviest things I play, but I really like these bands so I bought the HT5R mainly for this kind of sound. But I also like "cooler" music, like classic rock (or even pops songs but that would be the clean channel I guess).
- replacing a tube does not void the warranty ?
- replacing a tube does need to modify the bias or something else, or is it just plug and play ?
- the integrated reverb...does it affect the clean channel only, or both channels ? (I'll have my amp tomorrow)

thanks guys
 

Rhust

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Thank you for this post ! Very interesting !!

I liked the sound of the HT-5 and I have a few questions :

- if you do your mods (swapping the tubes) will you still get the '80s hard rock metal sound ? I mean, GnR and Iron Maiden are the heaviest things I play, but I really like these bands so I bought the HT5R mainly for this kind of sound. But I also like "cooler" music, like classic rock (or even pops songs but that would be the clean channel I guess).
- replacing a tube does not void the warranty ?
- replacing a tube does need to modify the bias or something else, or is it just plug and play ?
- the integrated reverb...does it affect the clean channel only, or both channels ? (I'll have my amp tomorrow)

thanks guys
you can still get gnr and maiden with a 12AU7 (lowest gain tube, gain on max) but a 12AY7 or AT7 would get you there too.. and open up more options for lower-gain sounds..

replacing the tube shouldn't void the warranty, and if it did you'd just put stock tubes back in before sending it in...

the tubes are plug and play... they have said the power needs bias, but I think that's a fine-tuning bias... I changed my power tube 2 years ago, and no issues... preamp tube never needs bias

I believe the reverb is on either channel... mine's the older non-reverb unit
 

rem22

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Thank you Rhust, I'll see how it sounds out of the box. Because if I had to push it more for GnR sound, it'll probably be louder and then the wife will complain :(
 

MidlifeCrisis

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In a Lot of amps, 12AT7 in V1 (or in this case all of the preamp) makes a very lifeless amp. Instead look at maybe a 5751.
Totally true. I was looking to tame the gain on my HT-5R so I followed some recommendations to swap into a 12AT7. Lower gain, but the tone was just... lifeless. Tried a 5751 and it made a HUGE difference. The gain comes on more gently and is less... fizzy than the stock HT-5R.

The bad news is that I came across a new Marshall DSL5 that, in my opinion, blows away the tone of the Blackstar, which is now collecting dust.
 

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