Gig report with the 100 watt HRM

[Bob-I]

In case inquiring minds want to know.

Friday night I took the 100Watt HRM in the Brandon chassis to the gig. Smallish bar in North Jersey, power trio with a female vocalist (see link below). I used a thiele cab with an Emi Delta-pro 12A, dumbleator and a Quadraverb set to a room reverb and some delay at about 200ms.

First set we had to play quiet so I had the masters barley cracked open. The ODS was full and rich anyway but the cleans were a tad brittle, even with the treble way down.

The rest of the night I opened it up a tad more, but never above 9:00 on the masters. The ODS really shines, especally with the PAB and humbuckers but the cleans never really sounded right, always too bright.

After the gig our soundman commented that there was an imbalance between the clean and OD tones, mostly in the 4Khz range.

At dogears suggestion, I used .022uF power tube couplers and I think this is the cuplrit. I swapped to .1uF and readjusted the HRM. This weekend will tell, another smallish bar.

[dogears]

I use .02uf in my Bluesmaster PI amps. Never in regular PI amps. Both of my non BM HRM amps have .1uf couplers. Is yours a Bluesmaster? I can definately say I have never recommended using .02uf couplers in a non BM amp.

At dogears suggestion, I used .022uF power tube couplers and I think this is the cuplrit. I swapped to .1uF and readjusted the HRM. This weekend will tell, another smallish bar.

[Bob-I]

I use .02uf in my Bluesmaster PI amps. Never in regular PI amps. Both of my non BM HRM amps have .1uf couplers. Is yours a Bluesmaster? I can definately say I have never recommended using .02uf couplers in a non BM amp.

Hokay, I stand corrected. Maybe I mixed up my notes.

[ayan]

In case inquiring minds want to know.

Friday night I took the 100Watt HRM in the Brandon chassis to the gig. Smallish bar in North Jersey, power trio with a female vocalist (see link below). I used a thiele cab with an Emi Delta-pro 12A, dumbleator and a Quadraverb set to a room reverb and some delay at about 200ms.

First set we had to play quiet so I had the masters barley cracked open. The ODS was full and rich anyway but the cleans were a tad brittle, even with the treble way down.

The rest of the night I opened it up a tad more, but never above 9:00 on the masters. The ODS really shines, especally with the PAB and humbuckers but the cleans never really sounded right, always too bright.

After the gig our soundman commented that there was an imbalance between the clean and OD tones, mostly in the 4Khz range.

At dogears suggestion, I used .022uF power tube couplers and I think this is the cuplrit. I swapped to .1uF and readjusted the HRM. This weekend will tell, another smallish bar.

Something I do not understand: if you use a Dumbleator, why would your masterS (note plural) be so low? If your clean channel has a 47pF brightness cap on it, it will sound bad set at 9 o'clock. I would set the amps masters as high as you need to to get a good sound (but without clipping the input of the cathoe follower on the Dumbleator, and you would hear this) and then use the return on the Dumbleator as your master volume. As per my experience, that means the masters will end up anywhere between say 11 and 1 o 'clock.

IMHO, no amp sounds good with the masters set that low, and that is independently of whether there is a subsquent master volume (ss would be the Dumbleator return level control) or not, or even of whether there is a brightness cap.

Gil

[Bob-I]

Something I do not understand: if you use a Dumbleator, why would your masterS (note plural) be so low? If your clean channel has a 47pF brightness cap on it, it will sound bad set at 9 o'clock. I would set the amps masters as high as you need to to get a good sound (but without clipping the input of the cathoe follower on the Dumbleator, and you would hear this) and then use the return on the Dumbleator as your master volume. As per my experience, that means the masters will end up anywhere between say 11 and 1 o 'clock.

IMHO, no amp sounds good with the masters set that low, and that is independently of whether there is a subsquent master volume (ss would be the Dumbleator return level control) or not, or even of whether there is a brightness cap.

Gil

Well, not exactly a Dumbleator. My loop is a parallel loop. The CF drives both dry and wet sides, then the output is summed at a feedback amp.

Since this is an HRM amp, there are 2 masters unlike the non-HRM's where you have one master and a ratio. I lowered the cap in the clean master to 22pF.

You bring up a good point though. It would be easy enough to put a master volume on the loop device and allow me to crank up the masters.

[ayan]

Well, not exactly a Dumbleator. My loop is a parallel loop. The CF drives both dry and wet sides, then the output is summed at a feedback amp.

Since this is an HRM amp, there are 2 masters unlike the non-HRM's where you have one master and a ratio. I lowered the cap in the clean master to 22pF.

You bring up a good point though. It would be easy enough to put a master volume on the loop device and allow me to crank up the masters.

Hi Bob,

Gotcha, and that is one reason I think parallel loops are a bit of a pain in the neck to deal with, since most do not have a mater volume, so trying to get the sound to be louder implies messing with the mix. But yes, I suggest you do whatever you have to do to be able to open up the masters in the amp, otherwise I think you will be missing out on a few good things.

Cheers,

Gil

[Bob-I]

Hi Bob,

Gotcha, and that is one reason I think parallel loops are a bit of a pain in the neck to deal with, since most do not have a mater volume, so trying to get the sound to be louder implies messing with the mix. But yes, I suggest you do whatever you have to do to be able to open up the masters in the amp, otherwise I think you will be missing out on a few good things.

Cheers,

Gil

I put the master into the loop. I simply put a 1M pot at the output. It allowed me to open the master up to about 12:00. What a difference, huge tone and I was able to balance in the mix. Since I use in-ear monitors I had the amp very low on stage and let the PA do all the real work.

[ayan]

I put the master into the loop. I simply put a 1M pot at the output. It allowed me to open the master up to about 12:00. What a difference, huge tone and I was able to balance in the mix. Since I use in-ear monitors I had the amp very low on stage and let the PA do all the real work.

Excellent!

Gil

[talbany]

Bob
Did you notice any difference bringing it back through the feedback side vers the non feedback side... Just wondering.... Thanks



Tony VVT

[Bob-I]

Bob
Did you notice any difference bringing it back through the feedback side vers the non feedback side... Just wondering.... Thanks



Tony VVT

I'm not sure I understand the question. Bringing what back? are you talking about the loop?

If this question is about the loop, there is no non-feedback side. I used a feedback amp so both sides, dry and effect, mix at the feedback. The feedback is .022 -> 220K from plate to grid, the 2 signals come through 100K resistors into the grid. There's NO ground reference to the grid as the feedback acts as a virtual ground. It sounds great and is virtually 0 gain or loss. I can measure a slight increase at the output of the feedback amp on the scope but you really can't hear it.

[talbany]

Bob
Thanks for the in depth description about the feedback amp..we are trying to work out a loop and spring reverb for a 3 channel amp and am running into issues with phase inverter loading... Kind of a nightmare for us so far.. Thanks again...


Tony VVT

[Bob-I]

Bob
Thanks for the in depth description about the feedback amp..we are trying to work out a loop and spring reverb for a 3 channel amp and am running into issues with phase inverter loading... Kind of a nightmare for us so far.. Thanks again...


Tony VVT

Aiken has a good article on feedback amps that I used as a reference as I was designing this. Also, I found that an ECL86 makes a great reverb tube. Use the pentode side as a driver and the triode as a recovery. Watch the screen current, it'll arc easily so I used 330K screen resistor. Ther rest of the design parameters are pretty straight forward as it's similar to an EL-84 and 12AX7. The only problem is finding the tube if you need any quantity.

Can't help you with the PI loading, not a problem I've run into, good luck.

[talbany]

Bob

Gracious!!! will take a look at it