An HRM I like - And just how much do I like it?

[ic-racer]

Let's face it, the non HRMs are easier to play, there, I've said it.

Gil

Thanks for sharing your experience with your amps. The first post listed the specs of the HRM amp, but how about the specs on the non-HRM/100K amp?

I have been trying to read all your old posts on 100k, as I have been experimenting with it in my Fender conversion. You know where this is leading...I am on the brink of converting my #124 clone over to full 100k specs.

[ayan]

Thanks for sharing your experience with your amps. The first post listed the specs of the HRM amp, but how about the specs on the non-HRM/100K amp?

I have been trying to read all your old posts on 100k, as I have been experimenting with it in my Fender conversion. You know where this is leading...I am on the brink of converting my #124 clone over to full 100k specs.

I suspect I have posted all the values at some point or another. Off the top of my head, here it is:

1. Start with the schematic for ODS 124

2. I use a 100K pre OD trimmer (VS 350K trimmer)

3. I did not include the "brightness network" (220K//250pF) in the FX loop

4. I used a 30pF brightness cap on the amp's master volume, not 15pF

5. I used a 100KL "level" pot, not 250KA

6. I put a treble gate/tone control at the output of the OD, from the input of the 100KL "Ratio" control to ground. It has a 1,000pF cap in series with a trimmer (variable resistor). Setting is around 150K to ground or so

7. I use 5.1K grid stopper resistors and 1K 5W screed grid resistors on the power tubes

8. I use EL34s in this amp, at least at the moment

9. I use Marshall-style iron in my amp

I think that covers everything. Basically, this is a standard Skyliner amp with 100K plate load resistors

Cheers,

Gil

[Smitty]

The 100K amp is deceiving: harsh at home and doesn't sound so complete without the Dumbleator. But it has turned into, possibly, the best amp I have played through live. I glad I didn't sell it, after all. :)

Gil

Gil,

I'm mostly a lurker and haven't built a D-style amp in years, but your comment on the 100K amp is really insightful.

I custom build amps for a living (no stock amps and very little old Fender repairs). One of the most important things I do in determining circuit values is trying to understand how much clarity to build into an amp for each customer. No two customers are the same. My customers exist on a continuum: What I call 'Speaker Sniffers' (like wine cork sniffers). These are guys who play at home and generally at lower volumes with no accompaniment and really disect the tone for any harshness or anomolies. At the other end of the spectrum are guys like Joe Don Rooney who play in stadiums and hear everything through in ears or Tom Bukovac who plays in the studio and hears everything through headphones.

What I've learned is that with a good amp circuit, you reach a point of trade-off between clarity and smoothness. IME, the Speaker Sniffers will trade clarity for smoothness and vice versa for the pro-players. Most of my customers exist somewhere in the middle.

RDH4 tells us that lower plate loads mean wider frequency response (spelled more trable and bass to tame), but there are other things going on as well. While I haven't measured it, I think the 100k vs 220K/150K thing might have something to do with slew rate. I think you get the clearest sound on a voltage gain stage at two times the internal resistance of the stage. I think you get the smoothest overdrive at higher plate loads, but clarity suffers.

In a live setting, I find clarity trumps smoothness relative to distance and volume. You may be surprised to compare your amps from about 40 feet away with someone else playing them in a club setting.

BTW, the new Kimmocks are 100K amps $7K street price.

[heisthl]

I'm mostly a lurker and haven't built a D-style amp in years, but your comment on the 100K amp is really insightful.

I custom build amps for a living (no stock amps and very little old Fender repairs). One of the most important things I do in determining circuit values is trying to understand how much clarity to build into an amp for each customer. No two customers are the same. My customers exist on a continuum: What I call 'Speaker Sniffers' (like wine cork sniffers). These are guys who play at home and generally at lower volumes with no accompaniment and really disect the tone for any harshness or anomolies. At the other end of the spectrum are guys like Joe Don Rooney who play in stadiums and hear everything through in ears or Tom Bukovac who plays in the studio and hears everything through headphones.

What I've learned is that with a good amp circuit, you reach a point of trade-off between clarity and smoothness. IME, the Speaker Sniffers will trade clarity for smoothness and vice versa for the pro-players. Most of my customers exist somewhere in the middle.

RDH4 tells us that lower plate loads mean wider frequency response (spelled more trable and bass to tame), but there are other things going on as well. While I haven't measured it, I think the 100k vs 220K/150K thing might have something to do with slew rate. I think you get the clearest sound on a voltage gain stage at two times the internal resistance of the stage. I think you get the smoothest overdrive at higher plate loads, but clarity suffers.

In a live setting, I find clarity trumps smoothness relative to distance and volume. You may be surprised to compare your amps from about 40 feet away with someone else playing them in a club setting.

BTW, the new Kimmocks are 100K amps $7K street price.

Interesting observations and as far as pros VS joes very accurate in my opinion - most good performance amps don't sound that good in the living room and ask anyone who has a lot of amps lying around why they bought them - Answer - It sounded good in the store but doesn't cut it on the gig. I do have a different take on the 40 foot away test - a Dclone with 220k/150k plates has much better coverage and clarity(presence) than a 100k plate Fender with the same speakers. Of course that could be because of other factors beside plate size.

[JimiB]

BTW, the new Kimmocks are 100K amps $7K street price.

would you like to expound on that

[Smitty]

BTW, the new Kimmocks are 100K amps $7K street price.

would you like to expound on that :)

Sorry. As I reread my comment it is kind of confusing. Mixing my "K"s.

V1 A and B as well as V2 A and B are all 100K plate load resisitors with 1K5 cathode resistors.

The company uses the terms responsive and articulate to describe the amp. Compared to one of their 220K/150K models, I'd say that was acurate.

I hope I'm not divulging anything top secret. Hard to think that after more than half a century 100K/1K5 would be considered innovation. It's just basic electronics.

[ayan]

Gil,

I'm mostly a lurker and haven't built a D-style amp in years, but your comment on the 100K amp is really insightful.

I custom build amps for a living (no stock amps and very little old Fender repairs). One of the most important things I do in determining circuit values is trying to understand how much clarity to build into an amp for each customer. No two customers are the same. My customers exist on a continuum: What I call 'Speaker Sniffers' (like wine cork sniffers). These are guys who play at home and generally at lower volumes with no accompaniment and really disect the tone for any harshness or anomolies. At the other end of the spectrum are guys like Joe Don Rooney who play in stadiums and hear everything through in ears or Tom Bukovac who plays in the studio and hears everything through headphones.

What I've learned is that with a good amp circuit, you reach a point of trade-off between clarity and smoothness. IME, the Speaker Sniffers will trade clarity for smoothness and vice versa for the pro-players. Most of my customers exist somewhere in the middle.

RDH4 tells us that lower plate loads mean wider frequency response (spelled more trable and bass to tame), but there are other things going on as well. While I haven't measured it, I think the 100k vs 220K/150K thing might have something to do with slew rate. I think you get the clearest sound on a voltage gain stage at two times the internal resistance of the stage. I think you get the smoothest overdrive at higher plate loads, but clarity suffers.

In a live setting, I find clarity trumps smoothness relative to distance and volume. You may be surprised to compare your amps from about 40 feet away with someone else playing them in a club setting.

BTW, the new Kimmocks are 100K amps $7K street price.

Very cool post, Smitty. I play in a band with 3 horn players - plus another 8 of us - so it's not wonder I gravitate towards more "clarity."

Never measured slew rate and I have no means of doing that at home, but I would be curious to get that piece of information if someone could make it available here.

As for anything being super secretive, not around here. We all play tribute to the big guy, with some folks injecting varied degrees of originality to the common platform that wouldn't be there if Dumble hadn't built amps before all of us in the first place.

Best,

Gil

[jelle]

[/quote]
RDH4 tells us that lower plate loads mean wider frequency response (spelled more trable and bass to tame), but there are other things going on as well. While I haven't measured it, I think the 100k vs 220K/150K thing might have something to do with slew rate. I think you get the clearest sound on a voltage gain stage at two times the internal resistance of the stage. I think you get the smoothest overdrive at higher plate loads, but clarity suffers.
[/quote]

Smitty,

Did you post on the ampage as well? I remember your name. Anyway, cool post indeed!

I agree about the sound of a tube stage with the plate resistor being 2x internal resistance of the stage. The sound is much clearer with lower plates. As you already know, the plate voltage is a factor as well since the internal resistance a function of the plate voltage.

I do not have numbers but as a speaker sniffer myself:mrgreen:, I find that the 100k amps respond faster and tighter. Maybe that is the reason why you simply cannot touch those 100k plates in a marshall amp without changing the sound and feel too much.

As for the 2x internal resistance rule...CBS did that right in the phase inverter of the silverfaces! HAD also used this rule for the PI as far as I know.

jelle

[Smitty]

Smitty,

Did you post on the ampage as well? I remember your name. Anyway, cool post indeed!

I agree about the sound of a tube stage with the plate resistor being 2x internal resistance of the stage. The sound is much clearer with lower plates. As you already know, the plate voltage is a factor as well since the internal resistance a function of the plate voltage.

I do not have numbers but as a speaker sniffer myself:mrgreen:, I find that the 100k amps respond faster and tighter. Maybe that is the reason why you simply cannot touch those 100k plates in a marshall amp without changing the sound and feel too much.

As for the 2x internal resistance rule...CBS did that right in the phase inverter of the silverfaces! HAD also used this rule for the PI as far as I know.

jelle

Jelle,

Yes. I'm the same guy. Haven't posted much in the last year, though. I've been really busy building amps. Wish I could spend more time communing!

I completely agree on the plate voltage vs internal resisitance thing. For phase inverters the thing I always care about is getting enough headroom so that the output overdrives before the PI. I've never been able to get PI to overdrive gracefully. That falls into the bad distortion category for me.

IMHO, those silverface 49K PIs sound great until you run out of headroom.

Smitty

[jelle]

As for anything being super secretive, not around here. We all play tribute to the big guy, with some folks injecting varied degrees of originality to the common platform that wouldn't be there if Dumble hadn't built amps before all of us in the first place.

Best,

Gil

I echo that. On top of that: Gil, you have shared so much. Without people like you we'd be all in the dark in this forum. Thank you, Gil.

jelle

[jelle]

Jelle,

Yes. I'm the same guy. Haven't posted much in the last year, though. I've been really busy building amps. Wish I could spend more time communing!

I completely agree on the plate voltage vs internal resisitance thing. For phase inverters the thing I always care about is getting enough headroom so that the output overdrives before the PI. I've never been able to get PI to overdrive gracefully. That falls into the bad distortion category for me.

IMHO, those silverface 49K PIs sound great until you run out of headroom.

Smitty

Smitty,

I appreciate your posts a lot! I'm busy too...

Thanks for the reply.

jelle

[JimiB]

I hope I'm not divulging anything top secret.

I hope you are!