hello,

Today i picked my cab and went to my friend house to check with his MG30DFX. Now i quite surprised that the speaker contains more treble than his(though high freq response). but unfortunately it lacks freq just before that. and the bass response is pretty poor compared to his G10. overall the speaker lack some 'x' thing i dont know and sound thin.

overall impression: my friend prefers my speaker, but i like his.is thinness  due to pine cab? although his speaker rated at 4ohm, mine one is 8ohm, but for both speaker we are getting almost same loudness for an equal volume. My speaker seems to be more efficient. I think with good and careful preamp design treble will not be any issue. yea "Divide et impera"

Thanks Fahey for calculating those values.
paku

Thnks Fahey..

Yea i know 4.7k alternatively written as 4k7. But we have available pot values of 1k,10k,47k,100k,470k. Thats the reason i am asking here.

taking only the preamp section with chipamp yield the same result?? Not to mention now, but if i find this preamp beautiful can i add fx loop to it, since i have some pedal that need to be added after drive.

video link posted by you sounds good

Thanks

Thanks Roly for your reply...

yea, its time to attend college. I think i need to stop my project works for some days since my exam is almost knocking the door. I will start after the end of this semester with fresh mind. I will continue posting in this page then. Hope i will get the same  help and support from you guys.

Hello Fahey,

Thanks for your reply. I will implement preamp section. But can I change the pot values to regular values like 10k,47k,100k etc?

Firstly thanks to all of you for sharing your thoughts.

Let me discuss something..

I am a student from India. Basically its my passion to build an amplifier. First of all in India you will not get most of the things required. In India we have the dealer of eminence only and when i bought this speaker they had stock for two speakers, 1. governor 2. some legend series speaker. after watching some reviews and videos I went for governor. I dont know but there is something wrong with the speaker sound. its not that Fender sound not coming good, the marshall type sound is not coming good as well. can you guys please tell me how to detect faulty speaker? I had dreamt of implementing many things including remote foot channel switching etc. But when you are having dull sound coming from it, who like to spend time and money into this!

As per your suggestion, I will build tonemender and connect it. One of my friend has a Marshall MG 30 amp, I will test my speaker disconnecting his. I think that will give some sort of indication. What do you think? Because I cannot tolerate this anymore. its been three or more months i have been working on this without attending college and still its a garbage.
 

which vox clone you are referring?

Quote from: Roly on October 27, 2012, 10:28:05 AM
As a general rule of thumb the top end rolloff of a guitar driver is about 80 times the bass resonant frequency, e.g. 50Hz x 80 = 4000Hz.  If you really want some top end (as you do with a synth) then you really need to add a "low reach" tweeter, one that picks up where the main driver rolls off.

{I have seen a pic of a beetle with a fake RR radiator - and it just looked bloody strange  :duh }

I do not know much details of my driver but in their datasheet resonant freq mentioned as 101hz

Quote from: Roly on October 27, 2012, 03:27:20 AM
Divide and conquer.

Just a general thought; you have a long chain from guitar to speaker and if you want to isolate a problem (in this case lack of trebles) then the rule is "Divide et impera" - divide and conquer.

Try driving just your speaker from a known good amp (and say MP3 player) and see if it can produce sufficient trebles - yes/no?

Try feeding the same programme into just the power amp and speaker (ditto) - yes/no?

Keep adding stages one at a time backwards towards the guitar input and testing with the same signal at each stage.  Perhaps somewhere you will notice that the last stage you added is eating your trebles, so that is where your attention must be concentrated until that problem is fixed.

Dumb questions - are the strings on your guitar a set, or an odd collection from individual string breakages?  How are the pickups and adjustable poles (if any) set?

{Nice looking cab BTW  :dbtu: }

Thank you Roly for your thoughts in my problems.

1. I will connect all those effects circuits later though they are already complete. Now i am only connecting things in this fashion.

Guitar-->GT2-->delay-->Power amp

delay can be bypassed and have no contribution in adding gain or treble. So its neutral.

2. I have tried connecting the power amps and cab with my computer initially to check the response. the treble comparatively less than the full range speakers. but if i make 6khz band of my computer graphic equalizer full, i get some cymbals sound. but still mid is so heavy..I have some solo guitar track. When i listen to normal speaker it has some sharpness but when i listen to governor, its kinda blunt.

3. yea tried connecting the speaker from my computer power amp. response is more or less same. But when i connect my computer speaker power amp after Gt2 and taking speaker o/p from that power amp, i have got some treble making the sound more beautiful...

4.I think this is not an issue of guitar. every guitar cant be wrong..

looking for such suggestions..

photos of cab

Thanks Fahey for your reply.

More specifically when i play strings of my guitar I have found that the response of E A string moderate. D G string very loud. B is medium and for high E string i think i have to break it to make it sound. It's not only for my guitar but also for other guitars i have tried and it is worse when playing a Ibanez guitars.

You are right. Actually volume is pretty loud but again i can not measure whether i am getting the correct loudness/watts.

First I have used a 12 0 12 transformer to drive the lm3875 power amp. Then i use 18 0 18 transformer. But i haven't noticed any significant increase in Volume(there may be but not too much).

earlier i have tried connecting mxr microamp between guitar and power amp. But then also it lacked treble. I just dont know if speaker's own emphasis on mid causing this problem.

I never saw people turning their amp treble full. But I have to make it full but still not getting the required sound. and i thing increasing too much treble from Gt2 making the tone harsh and scratchy. 

So the question is whether GT2(tonepad version ) is a true preamp that can drive power amp. or basically it requires another sort of preamp (whether in mixture/PA or power engine from Tech21 which has +-12db eqs).
or there is some problem in my cab chocking treble.

Fahey, I will definitely give TM a try....

Please check these photos..

Hello,

I am currently building SS guitar amp (i have earlier asked here for suggestions). As stated in the earlier post,
please see my details once again..

mostet booster-->phasor-->compressor-->Gt2 clone(tonepad)-->delay-->power amp

power amp :lm3875 datasheet schematic with added input Rf circuit.

Cab: Eminence Gov with pine cab and plywood baffle.

Eminence Governor:"The ultimate expression of that '60s/'70s British sound. Thick, raunchy tone with lots of mids"

www.eminence.com/pdf/Governor.pdf


Problem:

I am not getting much treble when connecting Gt2 directly with the power amp. Gt2 doesn't have any mid control.
and i have found that for each setting there is right bass,too much of mid and lack of treble. it does not have the punch i require.

Then i put the Gt2 output to my small home theater which i think has preamp and there are volume/bass controls only. taking speaker output from home theater has helped increased
the treble but not that much.

so my humble question is whether the o/p of Gt2 is weak enough that it cannot drive power amp directly..if not then,
can i use tone mender from runoff groove prior to power amp

http://www.runoffgroove.com/tonemender.html

is there no other alternatives?

hi guys
the picture uploaded below is a circuit for a buffer. after etching i did tin electroplating on it. since in our locality there is no such liquid tin.

how ever the result of the plating incomplete. the ground plane was tinned but the inner tracks were not tinned. i have tried it for so many times.

my suspection is that may be this is because of loop in the ground plane?? or something else. is this good to keep loop in ground plane.

plz loot at the text also. the texts that were very closed to the ground plane got tinned. what's happening!!!
plz help
thanks

ofcourse!!

thank Fahey for your input...

hey all

finally i have decided that i will go with lm1875. because i have realized that 20-25 watt is enough for me for my efficient guitar speaker (eminence governor) having spl of102.

now i am bit confused with which schematic to adopt for my guitar amp.(+vcc -vee) type
1. do i require any buffer between the preamp and power amp.

2. for guitar amp what should be the uF value for the filter capacitor.

3. i have decided to run it through 18 0 -18 ct transformer. for moderate efficiency what should be the ampere rating of the transformer.

4. many one are suggesting to use good grounding techniques for minimal noise and hum.. any advise ?

5. what is zobel network? do i have to adopt this for good. where i have to add this in the ckt?

6. what type of delay ckt i can add to minimize on pop sound
(plz see the attachment. this is what i have found by googling) .

7. do i have to attach the earth wire (green ) with the zero voltage pin for safety?

additionally if some one to share his opinion on lm1875 or any thing related to amp building then plz write here..

let me have those answers plz and i will start working on the project. during the time if i have any problem i will post here to get feedback from gurus..

thanks  to all