New HT 50 owner. Dilemma

[bakes11]

Hi all.

Picked up my HT-50 head yesterday and I'm disappointed! Fiddled about with it for a few hours yesterday and managed to get some good tones but it's definitely not what I thought it was going to be. My main problem is it doesn't sound in your face crunch if that makes sense, almost as if it is in a box.

I mainly play 80s/90s metal. So Pantera, Megadeth, Metallica etc. I get a kind of tame metal sound.

My previous amp was a 12 year old Marshall AVT 50 combo, ran through a Marshall 1960 cab. I was thinking this would destroy it in every way but it doesn't. I use a Zakk Wylde OD straight in to the front and that brings the Marshall to a really good high gain sound, not so much on the blackstar. Although I must say the cleans are excellent.


Any help would be great as I don't won't to give in yet.

[JohnBNY]

Marshalls and Blackstars have completely different tones. I think the HT has a smoother OD tone than the Marshall, if that makes any sense. For that reason, I have a Marshall that I use for certain tones, and Blackstar for different tones. You just may be a Marshall guy.

[Enlive]

It's mainly the el34 tubes that give it more of a boxy and mid heavy sound but in general try switching the speakers to v30s. That will make a big difference

[Enlive]

I know what your talking about tho I used to have the ht50 and felt the same. My initial fix was a behringer eq700 pedal in the fx loop did magic. Maybe try speakers and the eq or just the eq. People say shit about behringer but the eq 700 pedal made my ht50 sound beast as fuk!

[bakes11]

Thanks for the replys!

Want to avoid replacing the speakers in the cab in all honesty. Might try an EQ. Going to play around a bit more with the ZW OD first though.

Anyone ever had any experience using the Blackstar Pedals with this head?

[thephantum]

The first question is what cab are you using and what speakers are in it? If it's a Blackstar cab, then it most likely has Celestion 70/80 speakers, which are the problem. 70/80's are a budget Celestion speaker. While it sounds decent, in my opinion, they are one of the worst sounding speakers that Celestion makes. You can try an EQ, but it's not going to make a crappy speaker sound good....it will only make it a crappy speaker sound a little better.

[bakes11]

I'm running a Marshall 1960 cab with celestion G12T-75 speakers.

[thephantum]

I'm running a Marshall 1960 cab with celestion G12T-75 speakers.

It ain't the speakers then.

If you have an EQ you can try what Enlive suggested and put it in the loop. If you don't have an EQ, start by putting the OD pedal the loop. Start with low drive and high output levels (on the pedal) and then just go from there and play with it.

Another thing, like most amp manufactures, B* amps are biased pretty cold from the factory. They do it to prolong power tube life, but it definitely impacts the sound.. Dialing in a warmer setting will definitely make the amp sound better. Just as an example, the OD on my HT-20 head sounded ok, but it was a little flat. I didn't care about the warranty so I opened it and checked...it was biased very cool (62% of max plate dissipation). Once I dialed it in a little warmer (70%), the OD channel came to life. A couple of weeks later I replaced all the stock tubes with Tungsol's in the preamp and Winged C's in the output stage. That was almost two years ago and the head has never sounded better.

The problem is that opening up the amp will void the warranty. So, to avoid that, you'd have to find a tech who is local to you who is also an authorized service center to do the work.

[bakes11]

Going to try my OD in the loop later. I'll let you know the results later

Also is biasing the amp hotter an easy job? Any guides on the forum? I ain't worried about the warranty as its a second hand amp. Although it is only 4 months old! This is my first valve amp so ain't to hot on them .

[thephantum]

It's easy if you understand electronics. However, from a process perspective it's fairly complex and it can be time consuming. It is also inherently dangerous as tube amps have lethal current levels flowing when they are powered on....and all measurements/adjustments have to be performed with the amp powered on.

At a minimum you'll need a decent auto-ranging multimeter. I wrote this on another board. Disclaimer - I take no responsibility for it's completeness and will not be held responsible if you kill/maim yourself and/or turn your amp into a cinder block.

• First you need to measure your plate voltage. The amp should have a cab/speaker connected with the master and channel volumes turned to 0.
  • 1) Set the meter to read Vdc.
    2) Connect the positive lead to pin 3 of an output tube (plate/anode)
    3) Connect the negative lead to pin 8 of the same output tube (cathode)
    4) With amp in standby, power it on and let it warm up for a few minutes
    5) Turn standby off and read plate voltage from the meter. It should be somewhere around 450V
    6) Turn the amp off and repeat the above steps for the other power tube (they should both measure about the same
  
  
  Now you need to calculate the desired bias current. Assuming you want to run the tubes at 70% max plate dissipation, the math is as follows : (Plate dissipation /Plate vdc) x 0.7 = Bias per valve in mA
  
  For example: Plate dissapation for an EL34 tube is 25W. So let's say you measured 450V at each tube. The math would then be: (25W/450V) x 0.7 = 0.03889A or 38.89mA.
  
  Now you can set the bais current on the amp.
  • 1) Set the meter to read mA.
    2) Connect the positive lead to pin 8 one tube
    3) Connect the negative lead to chassis ground
    4) With amp in standby, power it on and let it warm up for a few minutes
    5) Adjust PR2 (Bias) until the desired bias current is reached.
    6) Move the positive lead to pin 8 or the other tube (power down first if this makes you nervous)
    7) Ensure that the bias measurement matches the previous tube. If not, adjust PR1 (Balance) until the bias current for each tube matches. You may have to go back and forth a few times
    8) Go back and start over from the beginning.
  
  
  You need to repeat from the start and do this a few times because adjusting bias current impacts plate voltage (ohms law). So the act of changing bias current changes the plate voltage, meaning you have start all over again and repeat until the amp is dialed in.

You can clearly see that this will take a few hours to get done...mainly because you have to go back and forth taking multiple readings across both tubes multiple times. If you decide to save some time by not powering off the amp when you are switching leads around, it also becomes very dangerous.

My recommendation is to pick up a couple of socket adapter probes and use (at least) two multimeters. That will allow you to take a measurement (plate or bias) on both tubes (or sides of the push/pull pair) simultaneously. You can pick up the probes for around $35 each from different vendors....but be careful. Many of them only have two leads and just measure plate voltage. You want three leads: a ground, a plate and a bias current. Aside from being safer, the other nice thing about probes is that you can measure bias in mV (across a 1 ohm resistor...Ohms Law) instead of mA. So if your meter is auto-ranging, you don't have to switch between Vdc and mA...just leave it on the Vdc setting (or you can use 4 multimeters and see everything at once).

If you like to tinker, TubeDepot sells kits that you can build yourself for $20 each: https://www.tubedepot.com/products/tube ... -scout-kit It's a relatively simple device and there is an instruction sheet posted there....so you can see if it's a project you want to try and attempt.

....OR you can take it to an amp tech and pay him $50-$75 to bias the amp for you.