Lindley Tone-Homing In on #8

[David Root]

As far as I've seen HAD designed his PI to have the Q point in the middle of the loadline.

If I assume he used a 2K2 dropping resistor from screen to PI node, with Bassman iron that would be around 435V on the PI node with a 12AT7.

Midpoint is about 240Vp, 5mA. Sounds reasonable with about 22K500 tail + Bias and about 100V at the cathodes. Fairly Fendery I think, and well balanced.

Presumably dropping a 12AX7 in there would cut the current in half about and reduce the headroom some too.

[Max]

#13 which was an ODSR 100 watt was very similar to #40..This amp was built around 8-28-76... Although it had reverb... aside from the different pot values Middle-250k/Bass-1m/Treble-1m/OD-100k/ Vol-1m/Master-1m
It still had 47k/51/k PI plates....100k plate 1.5 w/4.7 throughout..OD entrance the same 220k/w 500pf---33k to ground bypass 1.2M..This being 5 amps away from #8..




Tony VVT

Tony,

ODSR#13 is already s e c o n d generation and by this could/should indeed be similar to #40 but still may be n o t similar to #8: different tonestack, different OD circuit, different chassis, different power supply and so on. And the second generation reverb amps I know are different from the usual second generation amps without reverb in regard of the OD circuit (less gain as a result e. g.). The first generation amp I know as far as I remember has around 20 different part values in the preamp compared to a second generation preamp.

All the best

Max

[Max]

Plus the reports from Max that stated that many 70's ODS owners replaced the 12at7 for a 12ax7 because they liked the OD tone better with the 12ax7 make the actual tube in the socket not a good indicator. The question is: 'What was the designers' intention?'

jelle

Jelle,

on the chassis of all second generation amps I know Dumble wrote next to the sockets, what tubes should be used in this socket. And on all second generation I know you find written "12AT7" for phase inverter. In regard of third generation I am not sure right now, but I will check it and report. On first generation: nothing written.

Have fun

Max

[David Root]

Thank you again Max.

When you say "different power supply" on the first generation amps, I thought both first and second used Bassman iron, is that not so? Or are you referring to PS cap sizes and/or dropping resistors?

[talbany]

#13 which was an ODSR 100 watt was very similar to #40..This amp was built around 8-28-76... Although it had reverb... aside from the different pot values Middle-250k/Bass-1m/Treble-1m/OD-100k/ Vol-1m/Master-1m
It still had 47k/51/k PI plates....100k plate 1.5 w/4.7 throughout..OD entrance the same 220k/w 500pf---33k to ground bypass 1.2M..This being 5 amps away from #8..




Tony VVT

Tony,

ODSR#13 is already s e c o n d generation and by this could/should indeed be similar to #40 but still may be n o t similar to #8: different tonestack, different OD circuit, different chassis, different power supply and so on. And the second generation reverb amps I know are different from the usual second generation amps without reverb in regard of the OD circuit (less gain as a result e. g.). The first generation amp I know as far as I remember has around 20 different part values in the preamp compared to a second generation preamp.

All the best

Max

Max Thanks for clarifying this.. your a gem to the forum!!

T.

[Max]

Thank you again Max.

When you say "different power supply" on the first generation amps, I thought both first and second used Bassman iron, is that not so? Or are you referring to PS cap sizes and/or dropping resistors?

Iron is the same for first and second generation amps but cap values etc. are a bit different as far as I remember now and the filter caps are placed different.

This is a most complicated matter:

a) these first 10 or so first generation amps with the small chassis are special beasts anyway.

b) When Lindley recorded ROE, Dumble already made second generation amps.

c) All guitar players I know who ever played both, a first and a second generation amp, always judged these two kind of amps as sounding rather different.

d) Lindley once told, that Alexander did a lot of mods in at least one of Lindley's amps.

e) Lindley obviously once told, that he used #8 for ROE and to someone else he told, that he used #2 (at least this is, what I understood from some reports posted here).

f) As these first generation amps have been the first "series production" ODS, it may well be, that #2 was a bit different from #8 from the start and without any mods to one or both of these two amps.

So how shall we know, what kind of circuit (still "first generation"?, updated to "second generation" or whatever other specs?) was in the amp he really used?

Cheers

Max

[Max]

The first generation amp I know as far as I remember has around 20 different part values in the preamp compared to a second generation preamp.

All the best

Max

I am no longer sure about the exact number of different values in the preamp of first generation, but I am completely sure, that it is somewhere between 10 and 20.

Max

[talbany]

Schematic for #13 preamp/Reverb.. As per layout..Forgot I had it..DOH!!

[Runaway J]

Does anyone have a picture of #13 ?
Who owns it now?
Is it the same type as Rick Vitos old ODR ?
I think his slide tone came pretty close to Lindleys when he was with Jackson Browne.

[Max]

Does anyone have a picture of #13 ?
Who owns it now?
Is it the same type as Rick Vitos old ODR ?
I think his slide tone came pretty close to Lindleys when he was with Jackson Browne.

On Rob's page http://www.roblivesey.com/dumble/ you find a pic of #57. Rick Vito's is #58 and looks identical (front), but at the time when Rick sold it, it had chickenhead knobs.

Rick Vito's ODR #58 is third generation ODR. Third generation ODR are very different from second generation ODR:

As far as I remember now, the second generation ODR like #13 did have the reverb before the OD to achieve a bit of the kind of reverb response you get, if you put a reverb device in front of an usual amp and then achieve "overdrive" by power amp clipping. By this with a second generation ODR and OD engaged, the reverb part of the signal gets more pronounced the more the overdriven tone decays.

Third generation ODR as far as I remember now did have the reverb after the OD like in the ODS 150 Watt (see signal path of ODS 150 Watt in the Tube Amp book 4th edition) or in Santana's ODR.

Otherwise (tonestack etc.) third generation ODR similar to third generation ODS (and different from second generation). But remind: The circuits of many of these third generation ODR have been changed by Alexander at some point (the two Santana plays e. g.).

Cheers

Max

[marcos]

FWIW: As Max stated, the on "second generation" amps the tube type was written on the chassis, next to the sockets, and it says 12AT7 for the PI.However, when I got my amp new in 1979, it already came with a 12 AX7.(Didn´t buy it from HAD himself).
Obviously the PI circuit was designed for a 12 AT7.The 12 AX7 works and
adds some distortion, but the later versions with larger plate resitors
work and sound much better to my ears.Just my experience

Marcos

[David Root]

Thank you Marcos. There's no doubt in my mind that the 47/51 plate loads are intended for the 12AT7.

Tony, your preamp dwg is very useful, but of course it doesn't show the PI. Do you (or anyone) know what the PI bias and tail resistors were? I imagine there is a progression from straight BF Fender in prototypes through to the 820/24K. For example #40 shows 470/22K.

[talbany]

Thank you Marcos. There's no doubt in my mind that the 47/51 plate loads are intended for the 12AT7.

Tony, your preamp dwg is very useful, but of course it doesn't show the PI. Do you (or anyone) know what the PI bias and tail resistors were? I imagine there is a progression from straight BF Fender in prototypes through to the 820/24K. For example #40 shows 470/22K.

Dave

The layout I have was sent with the promise not to post so got to honor it.. I will be happy to tell what's in it.. It's a scanned copy and a bit blurry in places but the the PI is as follows... 100K grid feeders.. .05 couplers 47/51 plates discussed.. 2 -1m/grid w/470 cath. 22k tail 110 gnd refrence/ .001 PI entrance cap and 820 NFB resistor... Hope it helps..

Tony

[David Root]

Thank you very much Tony! That is the same as #40 except for the 110 ohm ground reference. #40 is the standard Fender value of 100 ohms. So slightly more feedback on #13.

[Runaway J]

Does anyone have a picture of #13 ?
Who owns it now?
Is it the same type as Rick Vitos old ODR ?
I think his slide tone came pretty close to Lindleys when he was with Jackson Browne.

On Rob's page http://www.roblivesey.com/dumble/ you find a pic of #57. Rick Vito's is #58 and looks identical (front), but at the time when Rick sold it, it had chickenhead knobs.

Rick Vito's ODR #58 is third generation ODR. Third generation ODR are very different from second generation ODR:

As far as I remember now, the second generation ODR like #13 did have the reverb before the OD to achieve a bit of the kind of reverb response you get, if you put a reverb device in front of an usual amp and then achieve "overdrive" by power amp clipping. By this with a second generation ODR and OD engaged, the reverb part of the signal gets more pronounced the more the overdriven tone decays.

Third generation ODR as far as I remember now did have the reverb after the OD like in the ODS 150 Watt (see signal path of ODS 150 Watt in the Tube Amp book 4th edition) or in Santana's ODR.

Otherwise (tonestack etc.) third generation ODR similar to third generation ODS (and different from second generation). But remind: The circuits of many of these third generation ODR have been changed by Alexander at some point (the two Santana plays e. g.).

Cheers

Max

Max,
thanks alot for the information. Two more question if you don't mind:
On Rob' page there are two ODR "Dumble unknown 5" and "Dumble unknown 10" that seem to be of the same generation.
"10" was part of the batch shipped to germany in 1979/1980 and was my brother's amp. Those amps should be 2nd generation right ?
From the layout of #13 it seems to me that the filter caps are placed outside the chassis. Am I correct ?

Thanks again.