|
|
Post by firebird on Feb 16, 2009 15:16:39 GMT -5
OK! I DID IT!!! I followed the diagrams and instructions that FRPC posted and it made the Nitro have even a more of tight and defined bottom end and smoothed out the gain a bit. It makes it sound a bit more like my Pro Mod but with a darker more crushing gain. I love this amp. Pro Mod might have to find a new home now.  |
|
|
|
Post by firebird on Feb 16, 2009 15:34:01 GMT -5
Also, I biased mine a bit cold 40ma (I also have my PM this way too) so when I use the head in 1/2 power mode my around 52ma this way I don't have to re-bias at the lower wattage setting.
|
|
|
|
Post by korovamilkdud on Nov 14, 2009 21:38:19 GMT -5
I want to try this with some 6L6 tubes. I bet it would rock in a Quickrod. Are you going to want to drain the capacitors for this? Or isn't it necessary since your just working with resistors?
I bet this would be great with a DPDT switch actually! Actually build a switch to install on the back so that you could toggle KT88/EL34...
|
|
|
|
Post by joelaroint on Nov 19, 2009 12:32:14 GMT -5
I want to try this with some 6L6 tubes. I bet it would rock in a Quickrod. Are you going to want to drain the capacitors for this? Or isn't it necessary since your just working with resistors? I bet this would be great with a DPDT switch actually! Actually build a switch to install on the back so that you could toggle KT88/EL34... I have givin' this some thought before. I think all you would need is a SinglePoleSingleThrow(SPST). You would only need to connect or disconnect one end of a 47K resistor. The KT88s in my supercomp enhances it's voicing I believe so I'll be sticking with those. What I REALLY want is bias connections(plate v&ma) on the back that can be checked with a multi meter and a recessed bias adjustment. |
|
|
|
Post by SavedByGrace on Nov 19, 2009 18:26:11 GMT -5
I want to try this with some 6L6 tubes. I bet it would rock in a Quickrod. Are you going to want to drain the capacitors for this? Or isn't it necessary since your just working with resistors? I bet this would be great with a DPDT switch actually! Actually build a switch to install on the back so that you could toggle KT88/EL34... I have givin' this some thought before. I think all you would need is a SinglePoleSingleThrow(SPST). You would only need to connect or disconnect one end of a 47K resistor. The KT88s in my supercomp enhances it's voicing I believe so I'll be sticking with those. What I REALLY want is bias connections(plate v&ma) on the back that can be checked with a multi meter and a recessed bias adjustment. Man major +1 on the external bias checking and external bias pot!! I'm not sure how difficult this would be or how much cost it would add to the amp's production, but man it should would be a big convenience! Just the other day I went to re-check the bias on the new EL34s that I had dropped into my nitro once they had worn in a bit, and it was runnin too hot. So i had to take it all apart again to get to my friend, the little blue bias box lol. Maybe I'm just bein lazy, but havin it on the back would reduce the wear of takin it in and outa the headshell a million times too (not to mention the chance of accidents  ). |
|
|
|
Post by cujo on Jul 5, 2010 15:37:38 GMT -5
will i lose that growl from el34s if i put in kt88s?  |
|
|
|
Post by fastredponycar on Jul 29, 2010 11:32:05 GMT -5
no
|
|
|
|
Post by MetalHeart on Sept 2, 2010 15:28:03 GMT -5
I'm going to do this mod I got a pair of Gold Lion KT88s a coming. And Radio Shack is about a mile away from my house so I can pick up the resistor. Can't wait to hear it. Also with this mod you could go back to stock anytime,right? Which is pretty cool  |
|
|
|
Post by bubbastain on Sept 2, 2010 15:39:14 GMT -5
I'm going to do this mod I got a pair of Gold Lion KT88s a coming. And Radio Shack is about a mile away from my house so I can pick up the resistor. Can't wait to hear it. Also with this mod you could go back to stock anytime,right? Which is pretty cool I take it you already ordered the KT88s? I did this mod to my Competition. I knew I may want to go back and forth without having to resolder the resistor. When I ordered my KT88s from Eurotubes I told them what I wanted to do and the gave me a "cold" pair of 88s. They were numbered 24. I also ordered a "warm" pair of KT77s (#46). Same would apply to EL34s. There is enough of a sweep on the bias pot to run either set of tubes with just a bias adjust. I biased the 88s to 48ma. I can get them as low as 33. I biased my 77s at 34ma. May be something to consider. |
|
|
|
Post by MetalHeart on Sept 2, 2010 16:01:24 GMT -5
Yeah,I got them coming from tubedepot. That is a great ideal you are using. I will probably just be sticking to one or the other KT88s or EL34s. I've used 6550s in other amps and like those so I'm thinking they are not much difference between them and 88s.
I want so far away from these EL34bs. Man ,I must have gotten a sh!tty quad .
|
|
|
|
Post by MetalHeart on Sept 3, 2010 22:00:25 GMT -5
The new tubes will be here in the mourning,so I wanted to go ahead with the mod. But before I did, I hooked up my biasrite to see where the EL34bs were reading. 25ma,is that kinda low? I tried to bias up to 30 and 29 is all I could go. Does this sound right? |
|
|
|
Post by ldm on Sept 4, 2010 11:23:04 GMT -5
The new tubes will be here in the mourning,so I wanted to go ahead with the mod. But before I did, I hooked up my biasrite to see where the EL34bs were reading. 25ma,is that kinda low? I tried to bias up to 30 and 29 is all I could go. Does this sound right? You just need "hotter" tubes or you need to change the bias resistor. The range on those trim pots is not huge so the easiest thing to do is to get tubes that are in the proper range. What you have mentioned is fairly common. |
|
|
|
Post by MetalHeart on Sept 4, 2010 15:12:47 GMT -5
Kt88s came and I installed the pair and then broke off the base! Its the center piece with the guide  I installed anyway and fired up to bias. It seems to still work,but I could not bias as low as I needed to. 69ma is as low as I could go. I must be doing something wrong. I did play with it a little and I do like the sound I'm getting. 1st off it lost the farting out I was getting with the EL34bs. Tighten up the bottom bigtime. I'm just kinda pizz about this whole thing. $154 for tubes to have the base break off 2 mins after I got em,can't get a good enough bias reading,and I've own this amp about 6 months and having to retube the whole thing. If anybody has a ideal about whats going on with the bias ,please let me know. |
|
|
|
Post by bubbastain on Sept 4, 2010 18:01:39 GMT -5
You did add the 47k 1/2 watt resistor right? If so, Maybe it's not making a good electrical connection and the current is still going through the stock resistor. In looking back, were you a little over anxious with the new tubes? That sucks that it broke but you should be able to have them send you a one tube that matches the set they gave you(if there is some sort of record of it).
|
|
|
|
Post by MetalHeart on Sept 4, 2010 19:02:04 GMT -5
Yeah,I added the resistor and I also recheck it. I was thinking the same thing. My soldiering skills are not the best The new tube snapped pretty easily,I'v pulled tubes before and never had I one that snapped. |
|
).
