Modding Laney Lionheart for stronger / wetter reverb level

[spiral]

I just got a Laney Lionheart amp and it sounds pretty good except for the reverb level. When the reverb is at 100% it still is maybe 1/3rd to 1/2 of what my fender does. It is way too timid.

The Lionheart has a type 4 accutronics tank, so i believe it is the same part used in fender amps so i am wondering if there is a simple mod to get a stronger reverb signal in the return, like maybe changing out the value of the pot or swapping a resistor or cap. I'm guessing the theory would apply to most tube amps with spring reverb so any experience is appreciated!

[Robert M. Martinelli]

Hi spiral,
Do you have a schematic diagram?

I' ve been repairing some Laney VC/LC series amps in the past, and they use ( dual ) op-amps for the reverb drive/signal recovery; I don't know if the Lionheart series uses the same circuitry for the reverb path, so it could be good to have a schematic as a reference for discussing about your issue.

Cheers

Bob

[spiral]

Thanks for replying Bob. HTH was kind enough to share the Lionheart schematics with me as Laney said i needed to be a tech.
Laney L5T-112 (lionheart) schematic.pdf
You are absolutely right. Two TL072 op amps on the send and a single one on the return.

Any thoughts?

Thanks.

[tedmich]

swap R35 for a 5k trimmer and dial in the level you like?

[Robert M. Martinelli]

swap R35 for a 5k trimmer and dial in the level you like?

R35 and C18 is a HPF network that "sets" the lower reverb recovery stage's working frequency ( some 720 Hz ), which, being in the mid-lows, renders any shifting of the cutoff freq clearly audible ( maybe too much ). I'd leave that alone and rather swap R38 for a 100K trimmer, or ( better yet ) add a 47 K trimmer in series with R38, this way it would be possible to ( almost ) double the reverb recovery stage's gain ( +6dB ).

The R38/C20 ( feedback network ) "stock" cutoff frequency is about 15300 Hz, so , if after adding the trimmer you find the reverb loses some "spark" at the highest gain trimmer setting, you can change C20 accordingly ( 100-120 pF ) to bring the stage's frequency response back where it belongs.

Hope this helps

Best regards

Bob

[spiral]

Thanks so much for the answers. I understand practically what to do and will get the parts to start experimenting, but i don't understand technically why that is / what is happening.

So what you are saying is the 100% reverb level is being sent back to the amp, but it gets partially filtered off by that resistor and cap before being inserted back into the audio path resulting in a lower level? What would happen if you just bypassed those?

Thanks!

[Robert M. Martinelli]

So what you are saying is the 100% reverb level is being sent back to the amp, but it gets partially filtered off by that resistor and cap before being inserted back into the audio path resulting in a lower level? What would happen if you just bypassed those?
Thanks!

Not exactly, the 100% of the reverb recovery stage is present at its output and only SOME FREQUENCIES get attenuated by the RC network. You have to understand that a reverb pan is everything but linear, so, if you don't filter some of the frequencies, the sound out of it would be awful, not to mention the possibility of mechanical resonance.

If you bypass an RC network, all the frequencies coming out of the reverb stage would pass untouched ( including the ones that would make it sound awful ) so this is NOT feasible.

This is why designers include RC high-pass and low pass filters in the reverb signal path.

Combining an HPF and an LPF you can get a band-pass filter or a band-reject ( notch ) filter.

The formula for calculating the frequency of an RC filter/network is very simple:

F0=1/(2pi*R*C) where F0 is the frequency, pi is 3,1415926....., R is the resistance in ohms and C is the capacitance in Farads.

The formula is the same for LPFs and HPFs.

....Back to your problem:

Since you are not satisfied with the reverb level ONLY, you ONLY have to increase the recovery stage's gain ( level ) without altering its frequency response.

This means that, if you double R ( 47K---->100K ) in that RC network
( which in your case also acts as the the NFB loop setting the reverb recovery op-amp gain ) to increase gain, then you also have to halve the C value to keep the frequency response the same as before.

As I said, a good starting point would be to use 100K for R38 and 100-120 pF for C20, with these values you should get some +6 dB, hopefully this should be enough; if this is not the case, switch to 150 K for R38 and 68-82 pF for C20 ( some +9dB ).

Hope I managed to be clear enough.

Best regards

Bob

[spiral]

I wanted post back and give an update: RESULT! I did the mod last weekend and of course this board went down so i couldn't reply.

So i had it in my mind that you had said "10k trimmer", which i tried and obviously had an opposite effect. So through trial and error i arrived at your recommendation of 100k, which worked great. i didn't have the correct value for the filter but got pretty close with more trial and error and it sounds good (i may try 150k but the noise was getting pretty bad). It did add a slight bit of noise which i am OK with as the amp is already dead quiet to start with.

Thanks so much for the direction and explanation Robert. The Lionheart is a pretty great amp, especially for the money and now it's even better.

thank you!

[Robert M. Martinelli]

Hi spiral,
I'm glad your mod attempt turned out right, and I'm glad I've been able to point you in the right direction!

Just a footnote about noise; you raised that stage's gain, so getting more noise is normal; if you like, you can try to sub NE5532s in place of the original TL072s, as they're pin-to-pin compatible and have a ( much ) better noise figure.

Best regards

Bob

[petlus]

Following this thread and looking at the schematic diagram of the L5T I can say that the preamp stage concept is pretty much the same as the one of the Laney VC15 that I own - including the FX section...

[headstate]

hi,
i have a laney l5t, its only a few weeks old, i've just noticed that when i change channel from clean to overdrive i get a pop sound, it may have been there from day one, but only just noticed it.
it happens when i change channel with the footswitch or the switch on the amp, and is more noticeable if i have alot of reverb on.

If any of you guys have a laney l5t, could you see if yours does the same
not that bothered if they are meant to do that, just whats bugging me is never noticed it before, to thinking its just come on

thanks

[maio996]

Hi to everybody!
My name is Maurizio and I am happy to be part of this community, this is my first post!
I also have a l5t-112 that I really love but I have also an issue with the reverb and the footswitch: the pedal switch sometimes works some not.. so I disassembled the amp and the pedal and measured continuity, review the soldering of the FS plug in the PCB particularly the ground and after that, it increased the hum of reverb at maximum level (even if that is no so strong as in other amps like fenders as for the OP) but the FS worked properly.
Today after few days after I switched on the amp the reverb was on and I could not control the FS and the hum was low even if the reverb was at max level, surely not so strong as usual but no hum.
Now I switched off and on the amp and the FS works again and the hum is as before...
It seems this amp decide by itself how to behave!! :-)
Any suggestion on something to check?
Thanks
Maurizio

[maio996]

Just for your information I verified that both the amp and the FS were ok, the only issue was that the cable of the FS was close to a Plug extension with many devices attached and this has generated some kind of parassite currents in the FS that both generated noise and also grounded the lead of the reverb making it bypassed... I could not immagine that an external cable could lead such induction...
Changed the position of the FS cable and no noise and the FS works as it should..