Hello! for long time i haven't had any bass amp to gig but i have some parts at hand to build one, i had experience giging with a improvised 12W tube amp for rock/heavy blues with a dirty bass tone with no issues, but i need a bit more power in the range to 18-30W to play more versatily with more headroom with enough OD.
Short story, my plan is to build a Marshall 1959SLP clone with a pair of EL84 at the end fixed bias, at 450V B+... yes is kinda high but has anyone tried it before? btw the screens are on the range, at <300V and plates idle at 24mA, with those voltages the amp gives me 25W-ish (10%-ish distortion) and 30W full clipping.
I've heard some people prefer cathode bias over fixed for this tubes because at higher voltages don't sound very good nor the linearity, anyway i'll attach the circuit if you wanna check if i'm way out of spec or there is any hope.
Short story, my plan is to build a Marshall 1959SLP clone with a pair of EL84 at the end fixed bias, at 450V B+... yes is kinda high but has anyone tried it before? btw the screens are on the range, at <300V and plates idle at 24mA, with those voltages the amp gives me 25W-ish (10%-ish distortion) and 30W full clipping.
I've heard some people prefer cathode bias over fixed for this tubes because at higher voltages don't sound very good nor the linearity, anyway i'll attach the circuit if you wanna check if i'm way out of spec or there is any hope.
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Even the Traynor Guitar Mate only pushes out a plate voltage of 420 volts for 25 watts , at 450 volts you really are pushing a bog standard EL84 , you wont be expecting a long life then ?
There is a Russian version that many guitarist use probably a better choice .
This tube was originally used in UK radios as the high mu factor discounted the need for a preamp tube .
There is also an American version , if you want more power use EL34,s its got the same high mu--PS- DONT use the TV version PL84 in your configuration it was downrated in plate/anode voltage .
There is a Russian version that many guitarist use probably a better choice .
This tube was originally used in UK radios as the high mu factor discounted the need for a preamp tube .
There is also an American version , if you want more power use EL34,s its got the same high mu--PS- DONT use the TV version PL84 in your configuration it was downrated in plate/anode voltage .
i'd use el34 tubes if i could but i plan using what i have at hand, i already got a output tranny and the tubes, pretty much everything is done except for the chassis and the power tranny
At that high voltage you will need a mains transformer of at least 150ma as you don't want it to heat up.
For realistic Bass along a drummer you need at least 60W; EL84 will give you 20W; never ever measured a pair giving 25 clean watts, let alone higher power.
Use at least 2 x 6L6 or EL34; not even 4 x EL84 will do.
Plan B: build a nice Guitar amp with what you have, sell it, and with that money build a real Bass amp.
Use at least 2 x 6L6 or EL34; not even 4 x EL84 will do.
Plan B: build a nice Guitar amp with what you have, sell it, and with that money build a real Bass amp.
You will probably find difference in power gives minimal increase in sound power.
For twice the loudness you need 10 times the power as the ear is logarithmic.
I would suggest at least a 100 watt amp.
For twice the loudness you need 10 times the power as the ear is logarithmic.
I would suggest at least a 100 watt amp.
As this is a guitarists question related to low frequencies here is Fender,s take on buying a guitar amp and the relationship with low frequency reproduction .-
My high-power amplifier doesn't seem to produce as much volume as I would expect. What gives? – Fender
My high-power amplifier doesn't seem to produce as much volume as I would expect. What gives? – Fender
Yes, but with EL34's, not EL84's that are discussed in this thread.
400 V plate voltage and more surely will stress common 6BQ5/EL84's well beyond their capabilities. As a musical instrument amplifier get's used on stage at least sometimes, you want some reliability from it, don't you? So go and get some very scarce and vertiginously expensive 7189A's. They are EL84's with a 440 V plate voltage rating.
Best regards!
400 V plate voltage and more surely will stress common 6BQ5/EL84's well beyond their capabilities. As a musical instrument amplifier get's used on stage at least sometimes, you want some reliability from it, don't you? So go and get some very scarce and vertiginously expensive 7189A's. They are EL84's with a 440 V plate voltage rating.
Best regards!
Although hard to believe/imagine, I do think it's about a pair of EL84's (in the Music Reference RM-10).
Have a read through ---ALL -- the posts in-
EL84 max power for HiFi Amp
Notice much speculation on the version of the EL84,s --I mentioned the Sovtek--EL84M in my post .
Russia continued to make tubes long after the west cut back on production due to the fact they incorporated them in their attack jets to stop radiation from an aerial nuke explosion blowing solid-state devices .
The US obtained one via a defecting Vietnam pilot and checked it out .
It therefore stands to reason that their military tubes were made to stand harsher conditions.
EL84 max power for HiFi Amp
Notice much speculation on the version of the EL84,s --I mentioned the Sovtek--EL84M in my post .
Russia continued to make tubes long after the west cut back on production due to the fact they incorporated them in their attack jets to stop radiation from an aerial nuke explosion blowing solid-state devices .
The US obtained one via a defecting Vietnam pilot and checked it out .
It therefore stands to reason that their military tubes were made to stand harsher conditions.
Same with SQ tubes in the Western world. Btw, the datasheets for the E84L, a 6BQ5/EL84 SQ variant, show a plate voltage rating of 450 V 😉.
Best regards!
Best regards!
Do you mean that the power transformer has to be of higher current capability than for running a pair in class B at Va = Vg = 300 V (Iaa + Ig2g2 max. at 17 W = 114 mA)?
I would think that pushing a pair deeper into class B, at a substantialy higher anode voltage, makes the current draw go down and the power efficiency go up. So even when squeezing 25 W out of a pair, I don't expect the current draw to go up.
No PCL200 ,the standard current draw for a pair of EL84,s in Class AB1 including the screen is ( approx) nearly 120ma , I always allow a safety margin as heating up transformers is not advised.
To run then at the "supposed " HT + rail of 450V would drop the plate current down a bit but up the screen a bit ( depending on the transformer load resistance ) but at the output he wants on a standard circuit you would still need a heavy current HT output .
I would love to see this "famed " circuit being talked about --anybody got a copy ?
To run then at the "supposed " HT + rail of 450V would drop the plate current down a bit but up the screen a bit ( depending on the transformer load resistance ) but at the output he wants on a standard circuit you would still need a heavy current HT output .
I would love to see this "famed " circuit being talked about --anybody got a copy ?