Ceriatone Forum

Hi

I m a new user the bluesmaster hrm. My friend wired the amp for me. When i play the clean channel i really satisfied. But at the od channel we have a trebble problem. I try to reduce trebble with using trim pots but i can't reduce enough. When increase the gain the tone getting unsufferable.

Is there any mod or something to reduce trebble at od channel.

Thank you.

Burak

the OD channel shouldnt be that bright. especially on an HRM.

What speakers are you using?
Where do you have the OD trim at? (Gain trimmer)

Speakers are a big part of this amps sound if youre using vintage 30's or something expect a bright sound.
Also the OD trim pot being too high will result in a harsher less dumble tone.

Also i assume you just got this amp? Try letting it (burn in) is will become warmer, smoother and more "touchy"

Ok, here is the deal.Burak gave the amp to me to test it and find a possible solution.

The clean channel sounds pretty nice,however when ı switch to the od channel there is a constant fizz going on.The amp does not sound fat at all.There was this huge flabby resonating bass going on with a very high end trebly fizz,tearing my ears.So I tried to adjust the internal trimpots by decreasing the bass and treble,
After adjustments the bass became neutral but the treble is still to much.Also I noticed that cranking the drive interracts with the fizzy treble and sound becomes to fuzzy.What could be wrong?

I tried it with Ian Anderson standart with Throbak limiteds and a Prs Mccarty with Wolfetone Marshallheads....

Thats why i suggested to lower the overdrive trim pot. Also Let the amp break in dude. it will lose that fizz and tighten up the bass. What speakers ar you using with the amp?

My speakers are fender (from 1970 super reverb)

But I think our problem is not speaker.

IMO the amp just needs to be broken in and could probably use some warmer sounding speakers. I had a similar problem with my non-HRM OTS, the HRM should sound warmer due to it being an HRM and having the internal treble control. Just give it time, the tubes as well as all the components need to break in before they sound their best. after you put about 20 hours on the amp if the amp is still too bright you might need to try some g12-65 or other warmer sounding speakers. Those old 70's speakers can be a bit bright with certain amps. It might sound warmer with a fender due to the mid scoop but the OTS has much more mids which can be percieved as very bright with some speakers

I sent the amp my friend Demir Uyar he tried different speakers but the problem didnt solved.

We tried 9-10 different tube.

I asked the problem Nik. I'm going to rip bright caps.

I learn this morning the phase invertor's value was different then layout. My amp builder said This was not about the tone. But i think there may a problem.

Thanks.

Burak

Burak, great that you got it solved. However, as JD0x0 said you gotta allow the amp time to burn in. I will mellow dramatically after 50-100 hours.

I read about a guy who attach a cd player with jazz guitar to mellow his amps.

I solved my problems today. My bass trimpod was 1 megaohm but it sould be 220k in the layout. I was thinking it is just about the bass but not. All trim pots related each others. when we change the trim to 220k my tone completely changed. So i m happy now :)

Can someone tell me which pot adjusts what as there are 3 and the external OD drive pot ...

have a look at the new BM manual Nik has provided.
I think the Bass one is the one you can get a screwdriver into, the other 2 have dimer attachments. mid is in the middle

From new, the OD was fine on mine, I rolled off the treble a little. but not all the way, and I dial the treble down on all my amps, so definitely not a fizzy amp.

On a general note (and I'm not having a dig at anyone because mistakes happen) but it's always worth running through the components in your amp and validating against the layout that Nik produces.

I've had my OTS for over a year now and have been very happy with it - of course like anyone you always wonder whether a little tweak here or their might improve things even more. I have just upgraded the PSU caps to F&T not sure whether it was worth the effort but whilst doing it I wanted to familiarise myself with the main preamp assembly. I discovered that the slope resistor was 220 K rather than 150 K Specification. I'm going to change this to see if it has any impact on tone - techically it's increasing the impedance of the tonestack so I'm not expecting a massive change but you never know. As I say, it's always worth double checking your existing components before looking at other tweaks.

150k vs 220k slope resistor has a big imapct on the sensitivity of the tonestack.

True; always double check the components. I've had several occasions where the value of a resistor or cap was out of its spec. Changing it to on spec made the amp more brown.

+1 with the 220K youre getting alot less mids and bass. youre probably losing about 6db gain overall. I went from 150k to 90k and couldnt be happier. more bloom more sensativity and less "plastic" sounding mids

Changed the slope resistor and it has made a bigger impact than I thought.

1. More gain (probably due to more lower mids getting through tone stack)

2. It cured another issue that I had with the OD sound in that if I 'popped a string' by pulling it away from the fretboard and letting it snap back, it used to give a really nasty overtone - now it doesn't.

Overall, it's improved things for me - dare I say it the OD is less harsh!!

Worthwhile checking your amp against the published layout as my amp was built by Ceriatone.

Next thing I'm going to do is to change the 3K3 resistor in the power supply to 3K9 or 4K2 to see if I can get the anode voltages at V1, V2 and V3 a bit lower....moving into 'cork sniffing' territory now but who knows?

I am also a new bluesmaster owner with a fizzy gain channel.  I think I will go through and check component values also.  Can anyone tell me which resistor is the slope resistor is?  I feel a little silly asking, but I am not an electronics whiz.  Also, I am assuming that there is no way to measure actual values of the components without removing them from the board?

Mine was a lil fizzy the first few days. Let it burn in before you change anything. The CD player/MP3 player is a great method. Just be sure the volume is turned down a bit due to the impedance difference

I suppose I should have stated my question a little bit more clearly.  I am new to the bluesmaster, but it is not a new amp.  I bought it used, it should be plenty broken in by now.

I am going to give the components a look over even if I do not change anything . . . just like to know what I have in there.  Slope resistor anyone?

OD TRIM?

i've attached a pic of the slop resistor for you, but i have a few suggestions/questions

First of all as T Wilcox suggested, you may want to experiment with the OD trim. By adjusting it you can go from slight overdrive to all out chaos, but it starts to get fizzy as you turn it up.
What kind of preamp/power tubes are you running? Different tubes can yield different results

What kind of speakers are you running? The OTS series is kinda picky when it comes to speakers.

Are you running OD and PAB at the same time? If you aren't you may want to try it. Without the PAB on (which in my opinion should be renamed Tone Stack Lift, since that is what it does) in OD mode on an HRM amp you are sending you signal through two tone stacks which can make your town sound either muddy or harsh depending on your settings.

Also, the Preamp (clean) volume will effect the overall gain as well, as V1 cascades into V2. In otherwords if you crank the clean gain and use your guitar volume to get some nice dirt when pushed, when you kick in the OD channel your OD can be very gainy and fizzy as well.

A C-Lator helps alot, but isn't technically necessary although, mine really woke up and sounded awesome with it

As far as the slope resistor goes, the common mod is to switch it to 68k or 100k and to switch the main tonestack bass pot from 500k to 250k, and i even considered doing it until the amp got nicely broken in, got some great speakers, played around with different tubes, and adjusted the OD tonestack with the PAB engaged, adjusted the OD trim, and got a c-lator.

Hope this helps, and let us know the answers to the questions if ya can; AND above all, remember all that matters is that you find YOUR tone and YOU like the way your amp sounds

Gregg

Thanks for the detailed reply and the pic - awesome helpful

author=plasticvonaband link=topic=1541.msg16592#msg16592 date=1299906498
i've attached a pic of the slop resistor for you, but i have a few suggestions/questions

First of all as T Wilcox suggested, you may want to experiment with the OD trim. By adjusting it you can go from slight overdrive to all out chaos, but it starts to get fizzy as you turn it up.
What kind of preamp/power tubes are you running? Different tubes can yield different results

Experimenting with the OD trim sounds like a good idea.
I am currently running  these tubes:
v1 = RCA black plate 5751     
v2 = Brimar 12AT7WA / CV4024
v3 = GT SAG-AX7-MPI-1104092   
output = TAD 6L6WGC-STR
but I have some more 12ax7's on the way on the way that I want to try out in v1 & v2.

What kind of speakers are you running? The OTS series is kinda picky when it comes to speakers.

I've got a Celestion gold and a Electrovoice EVM-12S in a pair of thiele-style cabs.  Also tried a Celestion G12T-75.  The gold and evm12s are both fairly bright sounding.  I am happy with them, but I wouldn't mind hearing other speaker suggestions though if there is something particularly well suited to the OTS.

Are you running OD and PAB at the same time? If you aren't you may want to try it. Without the PAB on (which in my opinion should be renamed Tone Stack Lift, since that is what it does) in OD mode on an HRM amp you are sending you signal through two tone stacks which can make your town sound either muddy or harsh depending on your settings.

I have tried it this way, but I find the voicing between clean/od channels is too different, with the od channel being much duller/darker.  The previous owner disconnected the OD channel tone trim pots and replaced them with a cap.  I think I should try the amp with this mod reversed to see if it helps.


Also, the Preamp (clean) volume will effect the overall gain as well, as V1 cascades into V2. In otherwords if you crank the clean gain and use your guitar volume to get some nice dirt when pushed, when you kick in the OD channel your OD can be very gainy and fizzy as well.

I typically have the preamp volume at noon (5)

A C-Lator helps alot, but isn't technically necessary although, mine really woke up and sounded awesome with it

I ordered a C-lator, but it is taking a really long time to arrive.  I am really quite curious to see how the amp responds with it.


As far as the slope resistor goes, the common mod is to switch it to 68k or 100k and to switch the main tonestack bass pot from 500k to 250k, and i even considered doing it until the amp got nicely broken in, got some great speakers, played around with different tubes, and adjusted the OD tonestack with the PAB engaged, adjusted the OD trim, and got a c-lator.

I will give the 68k/100k a try.  What effect does 250k bass pot have? Less bass output?

Hope this helps, and let us know the answers to the questions if ya can; AND above all, remember all that matters is that you find YOUR tone and YOU like the way your amp sounds

Gregg

Again, a very helpful reply, thank you.

I keep playing with the OD trim and Im gettin close to where I want to keep it then the PAB on OD sounds fizzy, I have nothing in my loop right now and am waiting for a K-lator to come in mail. Dont know if it will help too much but atleast let me add the effects I like ???
I first tried my amp on my JSX amp speakers and it sounded awesome!
I have since built a 1x12 combo out of a old Peavey bass speaker cab ( will show pics later, but this is hopefully only temporary )
Got a WGS ET-65 and it sounded horrible all day yesterday.
It is just now starting to lose that brand new speaker harshness, ( atleast 10 hrs burnin so far )
It still doesnt sound as good as the JSX speakers which only really sounded good because they were broken in

Hey T,

Felt the same way when I first got my BM100. That was about a year ago.  I think for me, the real help came from letting everything burn in.  I am sure this is posted above, so let this last comment just count as a +1 for me.

Another thing I did that greatly improved the OD was to drop an RCA 12ax7 in the V2.  Got an (Almost)NOS from Mike at kcanostubes.com.  Great guy to work with and at $50, hard to beat let me tell you. 

My 2 cents.

St. Ephen

yeah its starting to sound better already I think they call that dog ears or somethin :)
 heres a crappy pic of my crappy TEMPORARY cab

its actually vertical though in real life ;D
stupid iphone

Don't feel bad, I;m having to play through a Vintage 30 sitting in a Line 6 SpiderValve 112.

BTW, check my other thread.